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Applied Surface Science (v.261, #)

Editorial Board (pp. ii).

Improvement in antibacterial properties of Ti by electrodeposition of biomimetic Ca–P apatite coat on anodized titania by Sanaa M.F. Gad El-Rab; Sahar A. Fadl-allah; A.A. Montser (pp. 1-7).

► Ca–P coating on titania titanium surface was directly fabricated successfully by electrochemical deposition. ► Treatment the titanium surface by TiO₂ could improve the adhesion strength between the Ca–P coating and the surface. ► Anodization treatment in phosphoric acid is benefit to inhibit the oral bacteria. ► According to the electrochemical corrosion test, corrosion resistance of Ti was improved by both anodization and electrodeposition of the Ca–P/titania coating. ► Ca–P/titania sample is believed to be a functional biomaterial which combines antibacterial activity and good corrosion resistance in bioenvironment.Titanium metal (Ti) with antibacterial function was successfully developed in the present study by electrodeposition of biomimetic Ca–P coat in simple supersaturated calcium and phosphate solution (SCPS). The electrochemical behavior and corrosion resistance of Ca–P deposited on anodized titanium (AT) have been investigated in SCPS by using electrochemical impedance spectroscopy (EIS). The plate-counting method was used to evaluate the antibacterial performance against Staphylococcus aureus (ATCC6538). In vitro antibacterial activity study indicated a significantly reduced number of bacteria S. aureus on Ca–P/AT plate surface when compared with that on Ti or AT surfaces and the corresponding antibacterial mechanism is discussed. The morphology and chemical structure of different titanium samples were systematically investigated by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The study confirmed that the antibacterial properties of the samples were related to chemical composition of sample surface.

Keywords: Titania; EIS; SEM; XDX; Biomimetic Ca–P apatite coat; Antibacterial properties; S. aureus

Improved performance of dye-sensitized solar cells: An TiO₂–nano-SiO₂ hybrid photoanode with post-treatment of TiCl₄ aqueous solution by Ling Liu; Haihong Niu; Shouwei Zhang; Lei Wan; Shiding Miao; Jinzhang Xu (pp. 8-13).

► A TiO₂–nano-SiO₂ hybrid film was prepared by depositing a paste of TiO₂ (P₂₅) incorporated with SiO₂. ► The optimal concentration of TiCl₄ solution was found to be 75mM for the post-treatment. ► A photoelectron conversion efficiency of 6.39% was achieved for the prepared dye-sensitized solar cells (DSSCs). ► SiO₂ gives a significant improvement in the performance of the DSSCs.A TiO₂–nano-SiO₂ hybrid film was prepared on a conductive F-doped tin oxide (FTO) substrate by depositing a mixture paste of TiO₂ (P₂₅) and nano-sized SiO₂ particles. The hybrid film was further treated by a titanium tetrachloride (TiCl₄) aqueous solution with different concentrations before it was assembled as a photoanode in dye sensitized solar cells (DSSCs). We studied the performance of DSSCs by using the dye molecule of cis-bis(isothiocy-anato)-bis-(2,2′-bipyridyl-4,4′-dicarboxylato)-ruthenium(II) bis-tetrabutylammonium (N719) as sensitizer. Results suggested that the post-treatment using TiCl₄ could enhance the dye adsorption. The thin TiO₂ layer hydrolyzed from TiCl₄ could fill gaps between nanoparticles in the composite film, leading to a better electron transport than non-treated films, and improve the light harvesting efficiency. The optimal concentration was found to be 75mM for the post-treatment of TiO₂–SiO₂ hybrid film by TiCl₄ solution. A photoelectron conversion efficiency of 6.39% was achieved in the back-side illuminated dye-sensitized solar cells, which is ∼105% higher than the basic efficiency of the bare TiO₂ sensitized sample. TiO₂–nano-SiO₂ hybrid photoanode was prepared by incorporation of nano-sized SiO₂ in the TiO₂ film. The introduced SiO₂ as a wide band-gap material gives a significant improvement of the performance of corresponding DSSCs in terms of photocurrent densities and energy conversion efficiency.

Keywords: TiO; ₂; –nano-SiO; ₂; hybrid photoanode; Dye-sensitized solar cells; TiCl; ₄; post-treatment

Immobilization of Tin (IV) molybdophosphate onto mesoporous silica SBA-15 and its application on strontium removal from aqueous solution by H. Aghayan; A.R. Mahjoub; A.R. Khanchi (pp. 14-20).

Display Omitted► Immobilization of Tin (IV) molybdophosphate onto mesoporous silica is performed by two step aqueous impregnation method. ► High dispersion of Tin (IV) molybdophosphate is obtained upon immobilization. ► By supporting Tin (IV) molybdophosphate onto mesoporous silica adsorption rate and ion exchange capacity is increased for strontium removal from aqueous solution.Ordered mesoporous silica materials are one of the most extensively used adsorbents for trapping pollutants. They have many advantages such as good accessibility to active sites, rapid mass transport inside the nanostructures, and good hydrothermal stability, but most mesoporous materials do not themselves have the appropriate surface properties. To address this issue, we reported a simple method for immobilization of heteropolymetalate onto mesoporous, because they have potential sorption and ion exchange properties. Here we attempted to immobilized Tin (IV) molybdophosphate onto mesoporous silica SBA-15 and used for strontium removal from aqueous solution. The obtained products were characterized by inductively coupled plasma (ICP), XRD, N₂ adsorption–desorption isotherms, scanning electron microscopy (SEM) and FT-IR. This work provides new methodology for the general synthesis of supported heteropolymetalate with large surface areas, and ordered nano porous structures.

Keywords: Mesoporous silica; Adsorption; Ion exchange; Tin (IV) molybdophosphate

Cathodoluminescence of Cr-doped diamond-like carbon film by filtered cathodic vacuum arc plasma by Meng-Wen Huang; Jui-Yun Jao; Chun-Chun Lin; Wei-Jen Hsieh; Yu-Hsiang Yang; Li-Shin Cheng; F.S. Shieu; Han C. Shih (pp. 21-24).

► The formation of the DLC:Cr films dependent on the flow rates of C₂H₂/Ar have been achieved in our FCVA plasma. ► The amorphous DLC:Cr have high sp² content can be completely converted to nanocrystalline Cr₃C₂. ► The effect of doping with Cr is apparently to change the band structure of the DLC and its consequent cathodoluminescence property.Cr doped diamond-like carbon (DLC:Cr) film was synthesized in various flow rates of C₂H₂/Ar under a substrate voltage of −50V at 500°C by a filtered cathodic vacuum arc plasma. This work has found that the structure of the films was correlated to the flow rate of C₂H₂/Ar but the luminescence properties are similar. The cathodoluminescence spectra of DLC:Cr films obtained at 1.9–2.4eV verifies that the luminescence from the films is in the visible region. The incorporation of Cr into the carbon network results in red emission shifted to 1.99eV and the orange emission (2.03eV) also appeared due to the transitions between chromium-related electron levels and σ* states. The peak at 2.10eV may result from the defects of the structures in DLC:Cr films.

Keywords: Luminescence; X-ray photoelectron spectroscopy; Raman; Diamond-like carbon

Osteoblast growth behavior on porous-structure titanium surface by Yuan Tian; Siyang Ding; Hui Peng; Shanming Lu; Guoping Wang; Lu Xia; Peizhi Wang (pp. 25-30).

► Micro-arc oxidation technology formed a porous feature on titanium surface. ► This porous surface accelerated adhesion, proliferation and differentiation compared with smooth surface. ► Osteogenesis-related proteins and genes were up regulated by this porous surface. ► It is anticipated that micro-arc oxidation surface could enhance osteoblastic activity and bone regeneration.A bioavailable surface generated by nano-technology could accelerate implant osteointegration, reduce healing time and enable implants to bear early loading. In this study, a nano-porous surface of titanium wafers was modified using micro-arc oxidation technique; surface of smooth titanium was used as control group. Surface characteristic was evaluated by investigating morphology, roughness and hydrophilicity of titanium wafers. In vitro studies, osteoblastic adhesion, proliferation and ALP activity, as well as gene and protein expressions relative to mineralization were assayed. Our results showed that a crater-liked nano-porous surface with greater roughness and better hydrophilicity were fabricated by micro-arc oxidation. It was further indicated that nano-porous surface could enhance adhesion, proliferation and ALP activity of osteoblasts compared with smooth surfaces. In addition, gene and protein expression of collagen-I, osteocalcin and osteopontin were also obviously increased. In summary, micro-arc oxidized techniques could form an irregular nano-porous morphology on implant surface which is favorable to improve osteoblastic function and prospected to be a potent modification of dental implant.

Keywords: Micro-arc oxidization; Dental implant; Osteoblast; Regeneration

Preparation of porous monolayer film by immersing the stearic acid Langmuir–Blodgett monolayer on mica in salt solution by S. Wang; Y.L. Li; H.L. Zhao; H. Liang; B. Liu; S. Pan (pp. 31-36).

► Porous film has been prepared by immersing the stearic acid Langmuir–Blodgett monolayer on mica in salt solution. ► The mechanism relies on the electrostatic screening effect of the cations in salt solution. ► The factors influencing the size and area of the pores were investigated.Porous materials have drawn attention from scientists in many fields such as life sciences, catalysis and photonics since they can be used to induce some materials growth as expected. Especially, porous Langmuir–Blodgett (LB) film is an ideal material with controlled thickness and flat surface. In this paper, stearic acid (SA), which has been extensively explored in LB film technique, is chosen as the template material with known parameters to prepare the LB film, and then the porous SA monolayer film is obtained by means of etching in salt solution. The main etching mechanism is suggested that the cations in the solution block the electrostatic interaction between the polar carboxyl group of SA and the electronegative mica surface. The influencing factors (such as concentration of salt solution, valence of cation and surface pressure) of the porous SA film are systematically studied in this work. The novel method proposed in this paper makes it convenient to prepare porous monolayer film for designed material growth or cell culture.

Keywords: Porous material; LB film; Etching; AFM

MAO-derived hydroxyapatite/TiO₂ nanostructured multi-layer coatings on titanium substrate by S. Abbasi; F. Golestani-Fard; H.R. Rezaie; S.M.M. Mirhosseini (pp. 37-42).

► HAp-TiO₂ nanostructured porous multi-layer coatings were derived by MAO technique. ► The relation between electrolyte concentration and properties of coatings was studied. ► A specific electrolyte concentration resulted in producing coatings with nest morphology. ► By increasing the coating duration time the nesting amount would face a decrease. ► A increasing in electrolyte concentration led to thickening coatings.In this study, titanium substrates which previously oxidized through Micro arc oxidation method, was coated by Hydroxyapatite (HAp) coating once more by means of the same method. Morphology, topography and chemical properties as well as phase composition and thickness of layers were studied to reveal the effect of the electrolyte concentration on coating features. According to results, the obtained coatings are consisted of HAp and titania as the major phases along with minor amounts of calcium titanate and α-tri calcium phosphate. Ca and P are present on surface of obtained layers as well as predictable Ti and O based on the XPS results. Thickness profile of coatings figured out that by increasing the electrolyte concentration, especially by addition of more Calcium Acetate (CA) to electrolyte, the thickness of HAp layer would rise, consequently. However, the influence of coating time on thickness of obtained coatings would be more considerable than electrolyte concentration. High specific area coatings with nest morphology were obtained in Electrolyte containing 5g/L β-Glycero Phosphate (β-GP) and 5g/L CA. Increasing coating duration time in this kind of coatings would cause deduction of the nesting in their structure.

Keywords: Micro arc oxidation; Hydroxyapatite; TiO; ₂; Layered structures; Nanocomposites; Porosity

Oxygen plasma induced hydrophilicity of Parylene-C thin films by Tatiana Trantidou; Themistoklis Prodromakis; Chris Toumazou (pp. 43-51).

► Surface modification of Parylene-C films with oxygen plasma. ► Surface hydrophilicity increases with power and duration at high power values. ► Larger power or treatment duration is required for thicker films. ► Parylene-C restores its surface hydrophobicity 40–50% of its initial state. ► Selective patterning of hydrophilic/hydrophobic areas is demonstrated.This paper investigates the surface modification of Parylene-C thin films under various oxygen plasma treatment conditions, such as power intensity (50:400W) and exposure time (1:20min). The extent of hydrophilicity was investigated through contact angle measurements, and correlations between treatment parameters, film thickness, restoration of hydrophobicity and etching rates were experimentally established. We also demonstrate the selective modification of Parylene-C films, facilitating distinct hydrophilic and hydrophobic areas with μm-resolution that can be exploited in self-alignment applications.

Keywords: Parylene-C; Oxygen plasma; Surface modification; Hydrophobic; Hydrophilic; Hydrophobicity restoration; Selective patterning

Cobalt doped antimony oxide nano-particles based chemical sensor and photo-catalyst for environmental pollutants by Aslam Jamal; Mohammed M. Rahman; Sher Bahadar Khan; Mohd. Faisal; Kalsoom Akhtar; Malik Abdul Rub; Abdullah M. Asiri; Abdulrahman O. Al-Youbi (pp. 52-58).

A dichloromethane chemical sensor using cobalt antimony oxides has been fabricated. This sensor showed high sensitivity and will be a useful candidate for environmental and health monitoring. Also it showed high photo-catalytic activity and can be a good candidate as a photo-catalyst for organic hazardous materials.Display Omitted► Reusable chemical sensor. ► Green environmental and eco-friendly chemi-sensor. ► High sensitivity. ► Good candidate for environmental and health monitoring.Cobalt doped antimony oxide nano-particles (NPs) have been synthesized by hydrothermal process and structurally characterized by utilizing X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transforms infrared spectrophotometer (FT-IR) which revealed that the synthesized cobalt antimony oxides (CoSb₂O₆) are well crystalline nano-particles with an average particles size of 26±10nm. UV–visible absorption spectra (∼286nm) were used to investigate the optical properties of CoSb₂O₆. The chemical sensing of CoSb₂O₆ NPs have been primarily investigated by I–V technique, where dichloromethane is used as a model compound. The analytical performance of dichloromethane chemical sensor exhibits high sensitivity (1.2432μAcm⁻²mM⁻¹) and a large linear dynamic range (1.0μM–0.01M) in short response time (10s). The photo catalytic activity of the synthesized CoSb₂O₆ nano-particles was evaluated by degradation of acridine orange (AO), which degraded 58.37% in 200min. These results indicate that CoSb₂O₆ nano-particles can play an excellent research impact in the environmental field.

Keywords: CoSb; ₂; O; ₆; nano-particles; Structural properties; Optical properties; Photo-catalytic degradation; Chemical sensing

Characteristics and corrosion studies of vanadate conversion coating formed on Mg–14wt%Li–1wt%Al–0.1wt%Ce alloy by Yibin Ma; Ning Li; Deyu Li; Milin Zhang; Xiaomei Huang (pp. 59-67).

► Vanadate film forms on the surface of Mg–Li–Al–Ce alloy. ► Vanadate coating improves the corrosion resistance. ► Vanadate coating is composed of Mg(OH)₂, Li₂O and V₂O₅.Mg–14Li–1Al–0.1Ce alloy is immersed in NH₄VO₃+K₃(Fe(CN)₆) solutions with different NH₄VO₃ and/or K₃(Fe(CN)₆) concentrations, and different immersion time. The surface morphology and composition of the vanadate coating are then characterized by scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), and the corrosion behavior of the conversion coating is studied by polarization technique and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the vanadate film with better corrosion resistance forms on Mg–Li–Al–Ce surface after the sample is immersed in 30gL⁻¹ NH₄VO₃+3.75gL⁻¹ K₃(Fe(CN)₆) solution at 80°C for 10min. The coating consists of V₂O₅, Li₂O and Mg(OH)₂.

Keywords: Magnesium–lithium alloy; Vanadate conversion coating; Anticorrosion; Polarization technique; Electrochemical impedance spectroscopy; X-ray photoelectron spectroscopy

F₂-laser modification and patterning of silicone films by A. Syring; T. Fricke-Begemann; J. Ihlemann (pp. 68-74).

► 157nm F₂-laser irradiation of silicone films is investigated. ► Multipulse-irradiation at 30mJ/cm² leads to carbon free silica like material. ► Irradiation above 100mJ/cm² leads to clean ablation of silicone. ► Patterned silica films are made by combined modification and ablation of silicone.Pulsed laser irradiation of 3μm thick silicone films at 157nm below and above the ablation threshold of about 100mJ/cm² has been investigated. Significantly above the ablation threshold, clean material removal is observed. Irradiation below threshold leads to surface swelling and a modification of the chemical composition as revealed by Raman spectroscopy. After 10,000 pulses at 30mJ/cm² a nearly carbon free silica like material is obtained. The 157nm-ablation threshold of this modified material amounts to 800mJ/cm², which is similar to that of fused silica. At 60mJ/cm², the CH₃-content is similarly reduced, but a graphitization is observed after about 10 000 pulses. In both cases the modified material exhibits broadband visible luminescence. Combinations of modification and ablation are used to fabricate patterned silica films.

Keywords: F; ₂; -laser; Silicone; Silica; Swelling; Ablation; Modification

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob by N.V. Sych; S.I. Trofymenko; O.I. Poddubnaya; M.M. Tsyba; V.I. Sapsay; D.O. Klymchuk; A.M. Puziy (pp. 75-82).

Display Omitted► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0.Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400°C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI=1.0 ( S_BET=2081m²/g, V_tot=1.1cm³/g), while maximum amount of acid surface groups was observed at RI=1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (p K=2.0–2.6), weakly acidic carboxylic (p K=4.7–5.0), enol/lactone (p K=6.7–7.4; 8.8–9.4) and phenol (p K=10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI=1.0).

Keywords: Corncob; Chemical activation; Phosphoric acid; Surface chemistry; Acid surface groups; Pore size distribution

The extremely narrow hysteresis width of phase transition in nanocrystalline VO₂ thin films with the flake grain structures by Xiaofeng Xu; Xinfeng He; Haiyang Wang; Quanju Gu; Shuaixu Shi; Huaizhong Xing; Chunrui Wang; Jing Zhang; Xiaoshuang Chen; Junhao Chu (pp. 83-87).

► It is found that the hysteresis width of MIT is only 0.4°C because of the flake nanocrystallines at 132W sputtering power. ► It shows that the transition of the film is very steep with the sheet resistance changes of 3–4 orders at MIT. ► The optimal hysteresis width and the steepest sheet resistance are determined with small flake nanocrystalline. ► The mechanism of narrowing hysteresis width is mainly the strain imbalance of the surface flake structure VO₂ thin films in MIT.The nanocrystalline VO₂ thin films, which surface has a flake grain structure, are achieved by DC sputtering deposition at different sputtering powers. It is found that the hysteresis loop of metal-insulator phase transition (MIT) is almost superposition, and the hysteresis width is only 0.4°C for the surface flake grain structure that obtained at 132W DC sputtering power. Moreover, it is shown that the phase transition is very steep, and the film displays 3–4 orders of the change of sheet resistance at MIT. The characterizations of SEM, AFM and four-point probe methods show that the hysteresis width, the orders of the change of sheet resistance and the phase transition become narrower, higher and steeper at MIT, respectively when the surface shapes of the nanocrystalline VO₂ thin films change from nanoparticle structures to flake structures with the DC sputtering powers increased from 66W to 132W and the surface flake grain sizes reduced gradually to minimum at 132W. Meanwhile, the surface roughness also changes into minimum. However, with the powers further increased from 132W to 176W, the surface flake grain sizes become bigger, and then the surface roughness changes poor. At 176W, the surface flake structures begin to turn into nanoparticle structures. The hysteresis width, the orders of the change of sheet resistance and the phase transition become wider, lower and poorly steeper at MIT, separately. The results reveal that the nanocrystalline shapes and the surface roughness can affect the hysteresis width and the sheet resistance steepness in MIT. Our analysis shows that the mechanism of the narrowed hysteresis width mainly depends on the strain imbalance of the nanocrystalline VO₂ thin film of the flake structures at MIT.

Keywords: PACS; 81.15.C; 68.55.J; 81.40.TvFlake structure; Nanocrystalline VO; ₂; Strain; Hysteresis width; DC sputtering powers; Surface roughness

Preferential growth of Si films on 6H-SiC(0001) C-face by Xie Long-fei; Chen Zhi-ming; Li Lian-bi; Yang Chen; He Xiao-min; Ye Na (pp. 88-91).

► Si films are prepared on SiC C-face by low-pressure chemical vapor deposition. ► Preferential growth orientation of 〈111〉 can be achieved in a temperature range. ► Si films grown on SiC C-face show a better crystal quality than that of Si-face. ► Si/SiC structures are analyzed by GULP. ► Each of Si/SiC C-face interface energy are calculated.Si/SiC heterojunctions are successfully prepared on 6H-SiC(0001) C-face by low-pressure chemical vapor deposition. X-ray diffraction and scanning electron microscopy are used to investigate the growth orientation and the surface morphology of the Si films. The results indicate that preferential growth orientation of 〈111〉 can be achieved in a temperature range of 825–1000°C. Within the temperature range, grain size of the Si films becomes larger as temperature increases. Molecular dynamics calculation results indicate that the interface formation energy of the Si(111)/6H-SiC(0001) C-face is smaller than that of Si(110)/6H-SiC(0001) C-face. This is the reason why the Si films prefer to grow on the (111) crystal plane.

Keywords: Si/6H-SiC heterojunction; C-face; Low-pressure chemical vapor deposition

Biodegradation behavior of micro-arc oxidized AZ31 magnesium alloys formed in two different electrolytes by A. Seyfoori; Sh. Mirdamadi; A. Khavandi; Z. Seyed Raufi (pp. 92-100).

► Phosphate coating has lesser degradation rate than silicate coating in r-SBF solution. ► Farringtonite phase is chemically more stable than forsterite phase in SBF solution. ► Apatite forming ability of forsterite containing coating is better than farringtonite containing film. ► The hydrophilisity nature of silicate film on magnesium alloy with respect to its roughness, is greater than phosphate film.Degradation behavior of coated magnesium alloys is among most prominent factors for their biomedical applications. In this study, bio-corrosion behavior of micro-arc oxidized magnesium AZ31 alloys formed in silicate and phosphate baths was investigated in r-SBF medium. For this purpose polarization behavior and open circuit profile of the coated samples were achieved by electrochemical and immersion tests, respectively. Moreover, the morphology and composition of the coatings were evaluated before and after immersion test using scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The results showed that the phosphate film had better corrosion resistance and greater thickness than silicate film and, in turn, the lesser degradability in SBF solution, so that Ca²⁺ and PO₄³⁻ containing compounds were more abundant on silicate film than phosphate film. Moreover phosphate film had greater surface roughness and lesser hydrophilic nature.

Keywords: Micro-arc oxidation; Silicate; Phosphate; Corrosion resistance; r-SBF

Effect of ambient environment on excimer laser induced micro and nano-structuring of stainless steel by Umm-i-Kalsoom; Shazia Bashir; Nisar Ali; Mahreen Akram; Khaliq Mahmood; Riaz Ahmad (pp. 101-109).

► Effect of ambient environment on micro/nanostructuring of laser irradiated stainless steel targets has been investigated. ► The surface morphology and crystallinity are investigated for various laser fluences. ► Various features, such as laser-induced periodic surface structures, cavities and hillocks are observed by SEM analysis. ► From XRD analysis it is revealed that no new phases are formed under vacuum condition. ► A phase change in oxygen ambient is observed.The effect of laser fluence and an ambient environment on the formation and development of the micro and nano-structures on the laser irradiated stainless steel (AISI-304) targets have been investigated. For this purpose KrF excimer laser ( λ=248nm, t=20ns, repetition rate 20Hz) has been used. The targets are exposed for various laser fluences ranging from 0.72Jcm⁻² to 1.27Jcm⁻² under the vacuum condition and in the oxygen environment at a pressure of 133mbar. Various features of treated targets, such as surface morphology, chemical composition and crystalline structure are analyzed by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction techniques, respectively. Scanning electron microscope analysis reveals the formation of laser-induced periodic surface structures (LIPSS), cavities, hillocks in both ambient environments (vacuum, oxygen). Cone-formation on the top of wave like ridges is observed under vacuum condition. In case of oxygen only redeposition is observed. Energy dispersive X-ray spectroscopy analysis exhibits that there is variation in chemical composition in both environments. When the target is treated in oxygen environment enhancement of the surface oxygen content is observed. X-ray diffraction exhibits that no new phases are formed under vacuum condition but a phase change in oxygen ambient is observed. For various fluences the variation in the peak intensity, crystallinity and d-spacing is observed under both ambient conditions.

Keywords: Stainless steel; Laser ablation; Microstructure formation

Optimization of sputtering parameters for SmCo thin films using design of experiments by G. Venkata Ramana; P. Saravanan; S.V. Kamat; Y. Aparna (pp. 110-117).

► DOE was used to study the effect sputtering process parameters on SmCo films. ► Significance of each process parameters was calculated using ANOVA calculations. ► Sputtering pressure was significant factor in controlling crystallite size. ► Sputtering pressure and sputtering time were the most important factors for high coercivity. ► Optimal combination of process parameters for desired film characteristics was established.A design of experiments (DOE) study on the optimization of DC magnetron sputtering parameters for SmCo films was carried out using a Taguchi-fractional factorial, L8 (2⁴⁻¹) design methodology. Four important sputtering parameters, viz., sputtering pressure, DC power, substratetarget distance and sputtering time were considered in their upper, standard and lower levels of their predefined range in order to investigate the range of processing conditions and their effect on the film quality. The attributes of SmCo thin films were quantified with respect to surface roughness, thickness, crystallite size, phase composition and coercivity. The significance of each process parameter as well as the optimal combination of sputtering parameters to achieve the desired film characteristics such as finer crystallite size, low surface roughness and high coercivity was obtained using statistical analysis of the experimental results by the analysis of variance (ANOVA) method.

Keywords: PACS; 75.50.Ww; 75.50.Tt; 81.15.Cd; 07.05.FbSm; Co films; Sputtering; Design of experiments

Preparation of Y₂O₃:Er,Yb nanoparticles by laser ablation in liquid by Takashi Nunokawa; Yuji Onodera; Masahiko Hara; Yoshitaka Kitamoto; Osamu Odawara; Hiroyuki Wada (pp. 118-122).

► We prepared a Y₂O₃:Er,Yb nanoparticles by laser ablation in liquid. ► The particle size increased with the increasing energy density of the laser. ► At low energy density, dot-like nanoparticles were observed. At high energy density, worm-like nanoparticles were observed. ► In the photoluminescence spectra, green and red fluorescence were observed using a 980nm laser diode as the excitation source. ► The fluorescence intensity increased with increasing energy density of the laser.We prepared a Y₂O₃:Er,Yb nanoparticles by laser ablation in liquid. The laser used the second harmonic generation Nd:YAG (532nm). A preparation process and measurement of upconversion properties were performed by varying the range of the energy density of the laser. Images from scanning electron microscopy (SEM) indicated that two types of nanoparticles existed in the product of laser ablation in liquid. We concluded the following: one type of nanoparticles was prepared from the nucleation of materials in a plume and the other was prepared by fragmentation. In the photoluminescence spectra, green (²H_11/2,⁴S_3/2→⁴I_15/2) and red (⁴F_9/2→⁴I_15/2) fluorescence were observed using a 980nm laser diode (LD) as the excitation source. We confirmed that the fluorescence intensity increased with increasing energy density of the laser. Thus, we concluded that the number of the nanoparticles increased as the energy density of the laser was increased.

Keywords: Nanoparticle; Upconversion; Y; ₂; O; ₃; Laser ablation; Nanosecond laser

Near ultraviolet photodetector fabricated from polyvinyl-alcohol coated In₂O₃ nanoparticles by Dali Shao; Liqiao Qin; Shayla Sawyer (pp. 123-127).

► UV photodetector was fabricated from In₂O₃ nanoparticles coated with polyvinyl-alcohol (PVA). ► PVA provide surface passivation and reduce density of surface defects for In₂O₃ nanoparticles. ► Photodetector with PVA coating show improved transient response and higher photoresponsivity.A near ultraviolet (UV) photodetector is fabricated from colloidal In₂O₃ nanoparticles coated with polyvinyl-alcohol (PVA). The device exhibits lower dark current and higher responsivity compared with a photodetector fabricated from uncoated In₂O₃ nanoparticles. The rise and fall time of the PVA coated photodetector is about 500s and 1600s, respectively, one half of the uncoated device. The faster response time of the PVA enhanced photodetector is due to surface passivation which reduces the surface defects while enhancing desorption of oxygen from the nanoparticle surface, thus increasing free carrier concentration.

Keywords: PVA coated In; ₂; O; ₃; nanoparticles; Near UV; Surface oxygen vacancy defects; Enhanced photoresponsivity

Impact of sintering temperature on the structural, electrical, and optical properties of doped ZnO nanoparticle-based discs by Rabab Khalid Sendi; Shahrom Mahmud (pp. 128-136).

► 20nm zinc oxide (ZnO) nanoparticles were used to make high-density ZnO discs doped with Bi₂O₃ and Mn₂O₃. ► The strong solid-state reaction during sintering that attributed to the high surface area of the 20nm ZnO nanoparticles. ► The sintering process can be used as a new technique for controlling the breakdown voltage of doped ZnO discs.In the current study, 20nm zinc oxide (ZnO) nanoparticles were used to make high-density ZnO discs doped with Bi₂O₃ and Mn₂O₃ via the conventional ceramic processing method. Different sintering temperatures were found to have significant impacts on the ZnO discs, especially on enhancing grain growth even at a low sintering temperature of only 980°C. The strong solid-state reaction during sintering may be attributed to the high surface area of the 20nm ZnO nanoparticles that promoted a strong surface reaction even at low sintering temperatures. Moreover, the sintering process also improved the grain crystallinity, as shown in the lowering of the intrinsic compressive stress based on the X-ray diffraction lattice constant and full-wave half-maximum data. The sintering temperatures also significantly influenced the electrical properties of the doped ZnO discs with a marked drop in the breakdown voltage from 330V (sample at 980°C) to 80V (sample at 1380°C). The resistivity also experienced a dramatic drop from 304.4kΩcm (sample at 980°C) to 98.86kΩcm (sample at 1380°C). The observed shift in the energy band-gap from a higher to a lower value may be attributed to the conversion of compressive stress to tensile stress with increasing sintering temperature. The Raman spectra indicate that the sintering temperatures and dopants in the discs had significant effects on theE2(high) phonon mode and ZnO crystal structures. Therefore, the sintering process can be used as a new technique for controlling the breakdown voltage of doped ZnO discs made from ZnO nanoparticles with improved structural and optical properties.

Keywords: ZnO; Nanoparticles; Sintering; High temperatures; Growth; Grain boundary

Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln³⁺-TiO₂ surface under UV/solar light by L. Gomathi Devi; S. Girish Kumar (pp. 137-146).

The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency.Display Omitted► The degradation of structurally different anionic dyes under different pH conditions is reported. ► Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. ► Adsorption of dye on the catalyst surface depends on the substituent's attached to it. ► The dopant with half filled electronic configuration served as shallow traps for charge carriers.The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln³⁺ (Ln³⁺=La³⁺, Ce³⁺ and Gd³⁺) doped TiO₂ at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd³⁺ (0.15mol%)-TiO₂ exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd³⁺ ions. It is proposed that Ln³⁺ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR>FR>MO>MR>ARS>BY>CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

Keywords: Lanthanide ion doped TiO; ₂; Dopant effects; Degradation of anionic dyes; Adsorption and pH effects; Photocatalysis

Influence of atmospheric pressure plasma treatment on surface properties of PBO fiber by Ruiyun Zhang; Xianlin Pan; Muwen Jiang; Shujing Peng; Yiping Qiu (pp. 147-154).

► PBO fibers were treated with atmospheric pressure plasmas. ► When 1% of oxygen was added to the plasma, IFSS increased 130%. ► Increased moisture regain could enhance plasma treatment effect on improving IFSS with long treatment time.In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and CO, OCO groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.

Keywords: APPJ; PBO fiber; Surface property; XPS; IFSS

Novel investigation on nanostructure Ni–P–Ag composite coatings by S. Alirezaei; S.M. Monir Vaghefi; M. Ürgen; A. Saatchi; K. Kazmanli (pp. 155-158).

► Uniform co-deposition of silver particles in Ni–P metallic matrix by electroless plating. ► Phase transformation in metallic matrix by heat treatment at 400°C. ► The relationship between phase transformation and mechanical properties of Ni–P–Ag composite coatings.In this research, silver particles with different contents were co-deposited within Ni–P coating on AISI 1045 steel samples by electroless plating process and then Ni–P–Ag composite coatings were heat treated at 400°C for 1h. The concentration of silver particles in Ni–P metallic matrix was determined by using scanning electron microscopy (SEM) and image analysis software. The phase transformation of deposits was analyzed by X-ray diffraction (XRD) and differential thermal analysis (DTA). Also, the mechanical properties of coatings were evaluated by microhardness and indentation tests. The results showed that the content of silver particles and heat treatment have the great effects on hardness and mechanical properties of Ni–P–Ag electroless composite coatings. Also, heat treatment can lead only to phase transformation in metallic matrix of nanostucture Ni–P–Ag composite coatings.

Keywords: Composite coating; Mechanical properties; Silver particles; Nanostructure; Electroless

Carbon spheres surface modification and dispersion in polymer matrix by Guo Xingmei; Yang Yongzhen; Zhao Xuexia; Liu Xuguang (pp. 159-165).

► Vinyl groups were grafted onto the surface of CSs by acryloyl chloride. ► Vinyl-functionalized CSs were dispersed well in organic solvent. ► Non-covalent functionalization was used to functionalize the surface of CSs. ► Functionalized CSs dispersed uniformly in the PMMA matrix with good compatibility.Polymer/carbon spheres (CSs) composite materials, in which polymer was used as continuous phase and CSs as dispersed phase, were synthesized by in situ bulk polymerization. In order to improve CSs dispersibility in polymer matrix and compatibility with polymer matrix, the functional double bonds were introduced onto the surface of CSs by covalent and non-covalent method. Covalent functionalization was accompolished through mixed acid oxidation and subsequent reaction with acryloyl chloride. Field-emission scanning electron microscopy, Fourier-transform Infrared spectrometry and thermogravimetry were used to characterize the morphology, structure and effect of functionalization of CSs. Vinyl-functionalized CSs by acryloyl chloride were well dispersed in organic solvents, such as DMF, acetone and chloroform. Non-covalent functionalization by surfactant was accompolished by electrostatic interaction. Covalent and non-covalent functionalization enabled CSs to be homogeneously dispersed in poly(methyl methacrylate) (PMMA) matrix with good compatibility. These studies lay the foundation of preparing the non-close packed three-dimensional carbon-based photonic crystals.

Keywords: Carbon spheres; Polymer; Functionalization; Dispersibility; Compatibility

An optimization analysis on electroless deposition of Al₂O₃/Cu core-shell nanostructures by H. Beygi; S.A. Sajjadi; S.M. Zebarjad (pp. 166-173).

► Al₂O₃/Cu core-shell nanostructure fabricated by electroless copper plating on Al₂O₃ particles. ► Optimization on bath composition and electroless parameters performed by Taguchi method. ► Using minimum chemicals usage, maximum plating rate of copper obtained. ► Uniform copper shells with 10nm thicknesses were fabricated on the Al₂O₃ nanoparticles.In this study, Al₂O₃/Cu core-shell nanostructure was fabricated by electroless plating of copper on Al₂O₃ particles. In order to reach to the maximum efficiency of electroless deposition, the influence of main effective parameters such as type of pretreatment process, HCHO/CuSO₄·5H₂O molar ratio, C₄H₄O₆KNa·4H₂O/CuSO₄·5H₂O molar ratio, pH, pouring rate, concentration of Al₂O₃ particles, bath temperature, plating time, stirring speed and Al₂O₃ particle size were investigated. The morphology, uniformity, and chemical composition of the activated and Cu coated Al₂O₃ particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that, by optimization on the electroless bath composition and the process parameters, using minimum chemicals usage maximum copper plating rate of 19.51% on the surface of Al₂O₃ particles is obtained. As result of copper deposition on the surface of Al₂O₃ nanoparticles, uniform shells with about 10nm thicknesses was fabricated on the Al₂O₃ nanoparticles.

Keywords: Core-shell nanostructure; Electroless copper deposition; Taguchi method; Process efficiency

Pre-ablation features formed by focusing a femtosecond laser beam with dual axicons to c-Si in vacuum by Go Odachi; Kento Hara; Ryosuke Sakamoto; Takashi Yagi (pp. 174-181).

► Focusing a femtosecond laser beam with dual axicon optics to the vacuum chamber was demonstrated. ► 786 and 393nm of the wavelength focused on the c-Si in the vacuum formed a hole with submicron-meter scale. ► Irradiation of 786nm wavelength formed humps and swells on a scale of ∼100nm, leading to the periodical ripple pattern. ► The 393nm laser irradiation created the regular rippled pattern with the spatial period of 60nm.The focusing of a 786nm femtosecond laser beam and a second harmonic at 393nm with dual axicon optics to the surface of c-Si in a vacuum chamber was performed. We demonstrate the importance of avoiding atmospheric effects in order to form and preserve submicron features associated with laser interactions with the solid surface. A submicron hole was formed at the central spot of the Bessel–Gaussian (BG) beam pattern with the fluence just above the ablation threshold. Pre-ablation features consisted of humps and swells on a scale of ∼100nm and were formed through the surface modification fluence at the first fringe position of the BG pattern. Laser modified zones were always associated with periodic ripple structures with low and high spatial frequencies during the early stages of laser irradiation. This observation demonstrates the role of the ripple formation in commencing the surface removal processes. Hump and ripple formation mechanisms are considered with respect to volume expansion of the amorphous layer and a conventional model involving the surface electromagnetic wave by taking into account the transient refractive index.

Keywords: Femtosecond laser; Micromachining; Axicon; Ripples; Silicon; Nano-humps

Synthesis and characterization of calcium hydroxy and fluoroapatite functionalized with methyl phosphonic dichloride by Hassen Agougui; Abdallah Aissa; Mongi Debbabi (pp. 182-188).

► Surface reactivity of apatites toward methyl phosphonic dichloride is tested. ► Chemical analysis shows that hydroxyapatite is more reactive. ► NMR spectra show the formation of CaOP_org and P_inorgOP_org bonds. ► AFM indicated that the texture surface was changed by grafting.The nature of apatite–organic molecule interaction was the subject of many investigations. Grafting the organic molecule onto the inorganic support may precede through either formation of covalent bonds or ionic interaction between superficial hydroxyl on the apatite surface and organic functions. The hybrid materials obtained by functionalization of apatite surfaces with phosphonate moieties are of interest for their potential applications such in catalysis, chromatography and biomedical domain. In this scope, calcium hydroxyl and fluoroapatite (CaHAp and CaFAp) were prepared in the presence of the methyl phosphonic dichloride (MPO), by contact method in organic solvent at 25°C for 2 days. The products are rigorously characterized by chemical analysis, infrared (IR), MAS-NMR spectroscopies, powder X-ray diffraction (XRD), atomic force microscopy (AFM) and specific surface area (SSA). The X-ray powder analysis showed that the crystallinity was sensibly affected by the presence of organic moieties. The IR spectroscopy showed new vibration modes appearing related to phosphonate groups essentially at 2930, 1315, 945, 764 and 514cm⁻¹. The³¹P MAS NMR spectrum for hydroxy and fluoroapatite exhibits a single signal at 2.8ppm. After reaction with (MPO) the spectra show the presence of new signals, assigned to the formation of organic–inorganic bond between the superficial hydroxyl groups of the apatite (CaOH) and (POH) and methyl phosphonic dichloride. The SSA decreases with increasing phosphonate amount especially for CaHAp modified by (MPO). AFM indicated that the texture surface was changed by grafting.

Keywords: Grafting; Methylphosphonic dichloride; AFM

Preparation of Cu₂ZnSnS₄ film by sulfurizing solution deposited precursors by Chao Gao; Honglie Shen; Feng Jiang; Hao Guan (pp. 189-192).

► Cu₂ZnSnS₄ films are prepared by sulfurizing (Cu, Sn)S/ZnS structured precursors. ► The precursors are prepared by a combination of low cost solution methods. ► Pure Cu₂ZnSnS₄ phase is obtained after annealing the precursor with sulfur vapor. ► The structure, composition and optical properties of the Cu₂ZnSnS₄ films are studied.Cu₂ZnSnS₄ (CZTS) film was obtained by sulfurizing (Cu, Sn)S/ZnS structured precursor that was prepared by a combination of the successive ionic layer adsorption and reaction method and the chemical bath deposition method. Pure Cu₂ZnSnS₄ phase was obtained when the precursor was annealed at 500°C for 2h. The structure, composition, morphology and optical properties of the CZTS film were studied. The results show that the CZTS film has a relatively compact morphology, and the composition of the film is close to the stoichiometric ratio of Cu₂ZnSnS₄. The film presents a large optical absorption coefficient (larger than 10⁴cm⁻¹ when the photo energy is beyond 1.47eV). The optical band-gap of the film is around 1.56eV. This method is considered a potential way to prepare high quality CZTS film.

Keywords: Cu; ₂; ZnSnS; ₄; Thin film; Low cost method; Solution deposited precursor

The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films by Jianjun Ren; Yu Zuo (pp. 193-200).

► The definite porous structure has been formed within the first transient stage. ► The critical current density for local burning decreases with acid concentration. ► The super-high current density improves the cells order greatly. ► The higher electrolyte viscosity decreases the film growth rate.The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films were studied. The voltage–time response for galvanostatic anodization of aluminum in malonic acid solution exhibits a conventional three-stage feature but the formation voltage is much higher. With the increase of electrolyte concentration, the electrolyte viscosity increases simultaneously and the high viscosity decreases the film growth rate. With the concentration increase of the malonic acid electrolyte, the critical current density that initiates local “burning” on the sample surface decreases. For malonic acid anodization, the field-assisted dissolution on the oxide surface is relatively weak and the nucleation of pores is more difficult, which results in greater barrier layer thickness and larger cell dimension. The embryo of the porous structure of anodic film has been created within the linear region of the first transient stage, and the definite porous structure has been established before the end of the first transient stage. The self-ordering behavior of the porous film is influenced by the electrolyte concentration, film thickness and the applied current density. Great current density not only improves the cell arrangement order but also brings about larger cell dimension.

Keywords: Aluminum; Anodization; Malonic acid; Cell arrangement; Porous film

The effect of powder composition on the morphology of in situ TiC composite coating deposited by Laser-Assisted Powder Deposition (LAPD) by Ali Emamian; Stephen F. Corbin; Amir Khajepour (pp. 201-208).

► The novel idea was to develop FeTiC containing high volume fraction of TiC. ► Increased TiC volume fraction enhanced clad hardness profile. ► Both, laser conditions and fed powder compositions affected the clad microstructure. ► Hardness and TiC volume fraction was maximized by control over melt pool composition. ► Hardness/TiC volume fraction was maximized by controlling of laser parameters.In this paper, the effect of powder composition on in situ TiC formation within an Fe-based matrix coating during laser cladding was studied. Different atomic ratios of C:Ti (45% and 55%) were selected in order to adjust the matrix from an FeTi-based composition to an FeC-based one. Fe percentages of 70, 60, 50 and 10wt% were explored to increase the volume fraction of TiC in the clad. Results showed that chemical composition affects the TiC morphology as well as the TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45at% to 55at%, the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad resulted in increases clad hardness. SEM and EDS analyses were used to characterize the phases in the clad, while increasing the C ratio promoted the formation of excess graphite in the Fe matrix.

Keywords: Laser-Assisted Powder Deposition; Composite coating

The effect of X-ray photoelectron spectroscopy measurement on P(VDF-TrFE) copolymer thin films by Dipankar Mandal; Klaus Müller; Karsten Henkel; Dieter Schmeißer (pp. 209-213).

► XPS is a very sensitive tool for investigating the surface properties of P(VDF-TrFE) thin films. ► Prolonged X-ray irradiation can accelerate the crosslinking of P(VDF-TrFE) and diminish the ferroelectric phase which leads to paraelectric phase, whereas ferroelectric phase is the main focus of interest. ► X-ray irradiation dose during XPS measurement was optimized. ► Ferroelectrc phase to Paraelectric phase transformation was confirmed by FT-IR Spectroscopy. ► NEXAFS was undertaken to check the degradation phenomena.The impact of prolonged X-ray irradiation during X-ray photoelectron spectroscopy (XPS) measurement was investigated on poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) thin films. It was observed that prolonged X-ray irradiation can accelerate the crosslinking of P(VDF-TrFE) and diminish the ferroelectric phase. Fourier transform infrared spectroscopy (FT-IR) data indicate that the ferroelectric phase diminishes completely after 360kJ of X-ray irradiation dose and it induces the paraelectric phase. In this work, the main emphasis was given to the optimization of the X-ray irradiation dose during XPS measurements to maintain the ferroelectric phase within the copolymer films.

Keywords: P(VDF-TrFE) copolymer thin film; XPS measurement; X-ray irradiation; Ferroelectric to paraelectric phase transformation

Adsorption of atomic oxygen on HfC and TaC (110) surface from first principles by Dongliang Liu; Jianguo Deng; Yongzhong Jin; Cheng He (pp. 214-218).

.Display Omitted► Atomic oxygen adsorption on HfC and TaC (110) surfaces were investigated. ► Oxygen atom prefers the C–Hf, Ta–Ta site on the HfC and TaC (110) surface, respectively. ► The CO bond exists in O/HfC (110), while no CO bond is found in O/TaC (110). ► The initial adsorption of oxygen atom on TaC (110) is different from that on HfC (110).We investigated the initial adsorption of oxygen atom on the HfC (110) and TaC (110) surface using first principles. Both the carbides have the same crystal structure, a sodium–chloride structure. The (110) surfaces of the carbides were modeled with (2×1) supercells. Every supercell is composed of five atomic planes. Our results demonstrate that the preferred site for oxygen atom is the C–Hf bridge site and the Ta–Ta bridge site on the HfC (110) and TaC (110) surface, respectively. The adsorption sites are different from the one on the (100) surfaces of the carbides. For the carbides, the adsorption energies of oxygen on the (110) surfaces are larger than that on the (100) surfaces. There exists the CO bond in O/HfC (110), while no CO bond is found in O/TaC (110), indicating that the adsorption mechanism of atomic oxygen on the TaC (110) surface is different from that on the HfC (110) surface at initial adsorption stage.

Keywords: Hafnium carbide; Tantalum carbide; (1; 1; 0) Surface; Adsorption; Oxygen; Density functional calculations

Fabrication and electron field-emission of carbon nanofibers grown on silicon nanoporous pillar array by Haiyan Wang; Yongqiang Wang; Renzhong Xue; Liping Kang; Xinjian Li (pp. 219-222).

► Carbon nanofibers were grown on silicon nanoporous pillar array by a CVD method.► Low turn-on field, high density and stable FE current were obtained in CNTs/Si-NPA.► Defects in CNTs and Si array substrate contributes the excellent FE property.Random orientation carbon nanofibers (CNFs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition (CVD) method with acetylene (C₂H₂) as carbon precursor and Ni as the catalyst. The synthesized CNFs were mainly composed of amorphous carbon and disordered graphite layers with a core–shell like structure. And, the tangled CNFs and the regular silicon-pillar array formed a nanometer-micron hierarchy structure. The electron field-emission (FE) property of CNFs/Si-NPA was measured and low turn-on field, high-density and stable FE current, high enhancement factor were obtained. The outstanding FE performance of the CNFs/Si-NPA emitters was attributed to the random orientation and defects of CNFs, the undulate surface of the Si-NPA substrate.

Keywords: Keyword; Carbon nanofibers; Silicon nanoporous pillar array; Field emission

Enhancement of field emission and hydrophobic properties of silicon nanowires by chemical vapor deposited carbon nanoflakes coating by D. Banerjee; N.S. Das; K.K. Chattopadhyay (pp. 223-230).

Chemically prepared silicon nanowires can be made super hydrophobic as well as excellent field emitter by thin coating of chemical vapor deposited carbon nanoflakes.Display Omitted► Silicon nanowires (SiNWs) have been synthesized by metal assisted chemical etching. ► As synthesized SiNWs were coated with quasi vertical carbon nanoflakes (CNF) with different thickness by plasma enhanced chemical vapor deposition. ► The coated SiNWs shows superhydrophobic behavior. ► The coated SiNWs shows significantly improved field emission characteristics.Vertically aligned silicon nanowires (SiNWs) have been synthesized by chemical etching process on commercially available p-type silicon wafer substrates. The surfaces of the as-synthesized nanowires have been modified with plasma enhanced chemical vapor deposited carbon nanoflakes. All the pure and coated SiNWs have been characterized by field emission scanning electron microscope, high resolution transmission electron microscope, Raman spectrometer and photoluminescence spectrometer. Surface wettability of the pure and carbon coated SiNWs has been studied and calculation of porosity has been done by using Cassie's equation. It has been found that hydrophobicity of the coated SiNWs varied with deposition time of carbon and for deposition time of 3min the surface showed super hydrophobicity. For showing versatility of applications of the carbon coated SiNWs we have also investigated its electron field emission characteristics. Our results showed significant improvement of emission characteristics after carbon flakes with turn-on field downshifted from 9.30 to 2.77V/μm. The results were explained due to enhanced surface roughness leading to higher enhancement factor, favorable band bending for electron emission and overall reduction of potential barrier on application of external electric field.

Keywords: Silicon nanowires; Carbon nanoflakes; Raman study; Hydrophobicity; Field emission

Multifractal, structural, and optical properties of Mn-doped ZnO films by C.Y. Ma; W.J. Wang; S.L. Li; C.Y. Miao; Q.Y. Zhang (pp. 231-236).

► Zn1−_xMn_x O ( x≈0.07) films were sputter deposited. ► The influence of postgrowth annealing on multifractal, structural and optical properties of films was studied. ► We developed the multifractality and its formalism to investigate the surface morphologies of films. ► HRTEM and SAED studies indicate that the Zn1−_xMn_xO ( x≈0.07) film is of high quality, uniform, and free of clustering/segregated phases.Zn1−_xMn_xO ( x≈0.07) films were sputter deposited on Si (001) and fused SiO₂ substrates and were annealed at different temperatures ranging from 600 to 800°C. The influence of postgrowth annealing on multifractal, structural and optical properties of Zn1−_xMn_xO films has been investigated by atomic force microscope (AFM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV/vis spectrophotometry. A statistical analysis based on multifractal formalism show the nonuniformity of the height distribution increases as the annealing temperature is increased. All as grown and annealed films are textured having preferred orientation along the wurzite c axis. The HRTEM and SAED studies indicate that the Mn doped ZnO film is of high quality, uniform, and free of clustering/segregated phases. The as grown film is in a state of compressive stress and the stress can be largely relieved with annealing temperature of above 700°C. The optical band gap was found to be 3.25eV for undoped ZnO film and 3.12eV for as grown Zn1−_xMn_xO ( x≈0.07) film. For annealed ZnMnO films the band gap was found to increase continuously with an increase in annealing temperature.

Keywords: ZnMnO films; Multifractal analysis; Structure; Optical properties

Adsorption kinetics of 3-alkoxy-2-hydroxypropyl trimethyl ammonium chloride at oil–water interface by Xi-lian Wei; Xiu-hong Wang; Jie Liu; De-zhi Sun; Bao-lin Yin; Xiu-jie Wang (pp. 237-241).

► The effects of concentration and temperature of R_nHTAC on the DIT were investigated. ► Interfacial adsorption mechanism of the aqueous R_nHTAC solutions was studied. ► These studies can extend the application of R_nHTAC in a wide variety of fields.Dynamic interfacial tension (DIT) between aqueous solution of 3-alkoxy-2-hydroxypropyl trimethyl ammonium chloride (R_nHTAC) and n-octane was measured using spinning drop method. The effects of R_nHTAC concentration (the concentration below the CMC) and temperature on DIT have been investigated. The cause of the change of DIT with time has been discussed. The effective diffusion coefficient, D_a, and the adsorption barrier, ɛ_a, have been obtained with extended Word–Tordai equation. The results show that the higher the concentration of the surfactant is, the smaller the DIT will be and the lower the curve of the DIT, and the aqueous R_nHTAC solutions follow a mixed diffusion–activation adsorption mechanism. With increase of R_nHTAC concentration in the bulk solution, D_a decreases and ɛ_a increases. D_a of aqueous R₁₄HTAC solution decreases from 0.090×10⁻¹³m²s⁻¹ to 0.081×10⁻¹³m²s⁻¹ and ɛ_a increases from 10.12kJmol⁻¹ to 11.89kJmol⁻¹, with the temperature increasing from 30°C to 50°C. This phenomenon indicates that the diffusion tendency becomes weak with the strengthening of the interaction between the surfactant molecules and that the thermo-motion of molecules benefits interface adsorption.

Keywords: Dynamic interfacial tension (DIT); Liquid–liquid interface; Adsorption kinetics; Adsorption barrier; Effective diffusion coefficient

Investigation of adsorption of polymers on metallic nanowires: A molecular dynamics study by Kavoos Mirabbaszadeh; Esmaeil Zaminpayma (pp. 242-246).

► We simulated absorption of P3HT and MEH-PPV on Ag and Au NWs. ► We studied influence of temperature and radius of NW on interaction energy. ► We found that NW with large radius increased interaction energy. ► Temperature and radius of NW have not any effect on radius of gyration. ► P3HT-Au shows the strongest interaction energy, then MEH-Au, P3HT-Ag, and MEH-Ag.Composite of polymer with a small content of strong material, such as carbon nanotube (CNT) and metallic nanowire (NW) has interesting mechanical, thermal, optical and electrical properties. For the first time, we used molecular dynamics simulations (MD) with polymer consistent force field (PCFF) to study adsorption of polymers involving Poly(3-hexythiophene) (P3HT) and Poly[[[(2ethylhexyl)oxy]methoxy-1,4-phenylene]-1,2-ethenediyl] (MEH-PPV) on metallic NW including silver and gold. The influence of main factors such as NW radius and temperature on the interfacial adhesion of NW–polymer and radius of gyration of polymers ( R_g) were studied. We showed that the interaction energy decreases slowly with increasing temperature, thus the temperature influence is very weak. Our results showed that P3HT-Au has the strongest interaction energy, then MEH-PPV-Au, P3HT-Ag, and finally MEH-PPV-Ag. In addition, the interaction energy increased with increasing NW radius, thus the NW with large radius is the best type for reinforcement. We studied the influence of NW radius and temperature on the radius of gyration ( R_g). We found that R_g oscillated slowly and no obvious trend was seen. In other words, NW radius and temperature had no influence on R_g value. We showed that the R_g value for P3HT was higher than MEH-PPV, thus P3HT expanded more than MEH-PPV on NW surface.

Keywords: Molecular dynamics simulation; Polymer; Nanowire; Adhesion

Preparation and surface characterization of activated carbons from Euphorbia rigida by chemical activation with ZnCl₂, K₂CO₃, NaOH and H₃PO₄ by Murat Kılıç; Esin Apaydın-Varol; Ayşe Eren Pütün (pp. 247-254).

Display Omitted► An arid land plant evaluated as low cost activated carbon precursor. ► Four types of different chemical activation agents are used. ► Higher surface area (2600m²/g) obtained by chemical activation. ► Obtained activated carbon can be effectively used as an adsorbent for the removal of toxic pollutants from aqueous solutions.Preparation of activated carbons from Euphorbia rigida by chemical activation with different impregnation agents and ratios was studied. ZnCl₂, K₂CO₃, NaOH and H₃PO₄ were used as chemical activation agents and four impregnation ratios (25–50–75–100%) by mass were applied on biomass. Activation is applied to impregnated biomass samples at 700°C under sweeping gas in a fixed bed reactor. For determination of chemical and physical properties of the obtained activated carbons; elemental analysis was applied to determine the elemental composition (C, H, N, O) and FT-IR spectra was used to analyze the functional groups. BET equation was used to calculate the surface areas of activated carbons. For understanding the changes in the surface structure, activated carbons were conducted to Scanning Electron Microscopy (SEM). Maximum BET surface area (2613m²/g) was reached with 75% K₂CO₃ impregnated biomass sample. Experimental results showed that impregnation types and ratios have a significant effect on the pore structure of activated carbon and E. rigida seems to be an alternative precursor for commercial activated carbon production.

Keywords: Activated carbon; Chemical activation; Characterization; Euphorbia rigida

Study on silk anti-crease finishing with polycarboxyl-terminated trichlorotriazine derivatives by surface analysis methods by Xiaoshan Liu; Tieling Xing; Dongmei Xu; Guoqiang Chen (pp. 255-261).

► Silk fabric was modified with polycarboxyl-terminated trichlorotriazine derivatives. ► The treated fabric exhibited high wet resiliency and strength retention rate. ► The treated fabric showed good whiteness and washing durability. ► The modification process could be carried out at lower temperature. ► Surface analysis methods were employed to study the anticreasing mechanism.The natural silk fabric was finished with polycarboxyl-terminated trichlorotriazine derivatives for anticreasing purpose. The treated fabric exhibited better wet resiliency, higher strength retention rate and whiteness than those treated with 1,2,3,4-butane tetracarboxylic acid (BTCA) under the same conditions, and they also have similar good washing durability to those treated with BTCA. Infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) analysis indicated the crosslinking reaction between the chlorine atom, the carboxyl in the trichlorotriazine derivatives and the amino, the hydroxyl on the surface of the silk fabric. Scanning electron microscope (SEM) observation showed that the surface of the treated fabric became a little rough. The chlorine atom and the carboxyl in the trichlorotriazine derivatives, and the surface roughness of the treated silk fabric were all contributive to the wrinkle resistance of silk.

Keywords: Silk fabric; Surface analysis; Anticreasing; Trichlorotriazine; X-ray photoelectron spectroscopy (XPS)

Theoretical investigation of OCN⁻ adsorption onto boron nitride nanotubes by Alireza Soltani; Nasim Ahmadian; Abolfazl Amirazami; Anis Masoodi; E. Tazikeh Lemeski; Ali Varasteh Moradi (pp. 262-267).

► Adsorption behavior of OCN⁻ on (6,0) and (8,0) BNNTs based on density functional theory. ► OCN⁻ is strongly bound to BNNTs in corresponding configurations. ► The effect of the OCN⁻ adsorption on the geometries and electronic properties of related BNNTs is investigated. ► BNNTs is suggested as superior sensor for OCN⁻ comparing with CNTs.First-principles calculations based on density functional theory (DFT) method are used to investigate the adsorption properties of OCN⁻ on H-capped zigzag and armchair single-walled BN nanotubes (BNNTs). The results indicate that OCN⁻ is strongly bound to the outer surface of zigzag (6,0) BNNTs in comparison with armchair (5,5) BNNT. Binding energy and equilibrium distance corresponding to the most stable configuration are found to be −486.79kJmol⁻¹ and 1.526Å, respectively being typical for the chemisorptions. Energy gap, dipole moment, natural atomic orbital occupancies and global indices for most stable configuration are calculated. Furthermore, the effect of the OCN⁻ adsorption on the geometries and electronic properties of related BNNT is also studied. The calculated density of states (DOS) reveals that there is a significant orbital hybridization between two species in adsorption process being an evidence of strong interaction. Therefore, one can conclude that BNNTs play an important role as suitable sensor.

Keywords: Adsorption; Nanostructures; Ab initio calculations; Chemisorption

Study of ZnO:Al films for silicon thin film solar cells by H. Zhu; J. Hüpkes; E. Bunte; S.M. Huang (pp. 268-275).

► ZnO:Al films deposited from dual rotatable ceramic targets are investigated systematically. ► The discharge power plays a great role in different properties of sputtered ZnO:Al films. ► High rate ZnO:Al films (more than 90nmm/min) with high carrier mobility of about 45Vs/cm² are achieved. ► The surface-textured ZnO:Al films were applied in silicon thin film solar cells and high efficiencies were achieved.In this study, aluminum doped zinc oxide (ZnO:Al) films deposited from dual rotatable ceramic targets are systematically investigated. The influences of substrate temperature and working pressure as well as discharge power on different properties of ZnO:Al films including deposition rate, surface structure, optical and electrical properties as well as etching behaviors are studied. It is found that in addition to substrate temperature and working pressure the discharge power plays an important role in material properties of ZnO:Al films. Low rate ZnO:Al (LR-AZO) films with high carrier mobility of about 50Vs/cm² and high rate ZnO:Al (HR-AZO) films of more than 90nmm/min with high carrier mobility of about 45Vs/cm² are achieved. However, there is only a narrow parameter window to achieve a regulated crater-shape surface structure for ZnO:Al films after a chemical wet etching process. The surface-textured ZnO:Al films were applied in silicon thin film solar cells and high efficiencies of 8.5% and 11.3% are achieved for single junction hydrogenated microcrystalline silicon (μc-Si:H) solar cells and amorphous/microcrystalline silicon (a-Si:H/μc-Si:H) tandem solar cell, respectively.

Keywords: ZnO:Al thin films; Magnetron sputtering; Chemical wet etching; Rotatable target

Study on the bonding strength between calcium phosphate/chitosan composite coatings and a Mg alloy substrate by Jie Zhang; Chang-Song Dai; Jie Wei; Zhao-Hui Wen (pp. 276-286).

► Calcium phosphate/chitosan composite coatings on the MAO-AZ91D alloy were prepared. ► The bonding force between the coating and the magnesium alloy was optimized. ► The composite coating slowed down the corrosion rate of magnesium alloy in m-SBF.In order to improve the bonding strength between calcium phosphate/chitosan composite coatings and a micro-arc oxidized (MAO)-AZ91D Mg alloy, different influencing parameters were investigated in the process of electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). Surface morphology and phase constituents of the as-prepared materials were investigated by using X-ray diffractometer (XRD), Fourier-transformed infrared spectrophotometer (FTIR), Raman spectrometer, scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS), and a thermo gravimetric and differential thermal analyzer (TG–DTA). Scratch tests were carried out to study the bonding properties between the coatings and the substrates. In vitro immersion tests were conducted to determine the corrosion behaviors of samples with and without deposit layers through electrochemical experiments. In the EPD process, the acetic acid content in the electrophoresis suspension and the electrophoretic voltage played important roles in improving the bonding properties, while the contents of chitosan (CS) and nano-hydroxyapatite ( nHA, Ca₁₀(PO₄)₆(OH)₂) in the suspension had less significant influences on the mechanical bonding strength. It was observed that the coatings showed the excellent bonding property when an electrophoretic voltage was in a range of 40–110V with other reagent amounts as follows: acetic acid: 4.5vol.%, CS≤0.25g, nHA≤2.0g in 200ml of a CS–acetic acid aqueous solution and nHA≤2.5g in 300ml of absolute ethanol. The morphology of the composite coating obtained under the above optimal condition had a flake-like crystal structure. The EPD in the nHA/CS–acetic acid/ethanol suspension resulted in hydroxyapatite, chitosan, brushite (DCPD, CaHPO₄·2H₂O) and Ca(OH)₂ in the coatings. After the as-prepared coating materials were immersed into PBS, Ca(OH)₂ could be converted into HA and DCPD. The results of the electrochemical tests manifested that the corrosion resistance of the Mg alloy was improved by coating this composite film.

Keywords: Electrophoretic deposition; Mg alloy; Hydroxyapatite; Chitosan

The role of formation of continues thermally grown oxide layer on the nanostructured NiCrAlY bond coat during thermal exposure in air by Mohammadreza Daroonparvar; Mohammad Sakhawat Hussain; Muhammad Azizi Mat Yajid (pp. 287-297).

► Growth of CSN at the Al₂O₃/YSZ interface of nano TBC system was much lower. ► Formation of dense and continues Al₂O₃ (TGO) layer on the nanostructured NiCrAlY. ► Formation of discontinues and thicker Al₂O₃ (TGO) layer on the normal NiCrAlY coating. ► Bi-layered TGO thickness in normal TBC system was higher than that of nano TBC system. ► Continues Al₂O₃ layer on the nano BC would act as a strong barrier for oxygen infiltration.In recent years, the life expectancy of thermal barrier coatings is expected to be improved by applying the nanostructured NiCrAlY bond coat. The present paper reviews the main technique used in the synthesis of nano-crystalline NiCrAlY powders using a planetary ball mill and investigates the microstructural evolution of thermally grown oxide (TGO) layer on the conventional and nanostructured atmospheric plasma sprayed (APS) NiCrAlY coatings in thermal barrier coating (TBC) systems during oxidation. Microstructural characterization showed that the growth of Ni(Cr,Al)₂O₄ (as spinel) and NiO on the surface of Al₂O₃ layer (as pure TGO) in nano TBC system was much lower compared to that of normal TBC system during thermal exposure at 1150°C. These two oxides play a detrimental role in causing crack nucleation and growth, reducing the life of the TBC in air. This microstructure optimization of TGO layer is primarily associated with the formation of a continuous, dense, uniform Al₂O₃ layer (at first 24h of isothermal oxidation at 1000°C) over the nanostructured NiCrAlY coating.

Keywords: High temperature oxidation; Nano-structured NiCrAlY layer; Thermally grown oxide (TGO); Spinels; YSZ layer

Fe₃O₄/reduced graphene oxide nanocomposite as high performance anode for lithium ion batteries by Mei Zhang; Mengqiu Jia; Yuhong Jin (pp. 298-305).

► Fe₃O₄/graphene composite is fabricated by interface reaction and in situ reduction. ► The method leads to well-organized flexible interleaved structure. ► The interface reaction is benefit to ensure strong interfacial interaction. ► The nanocomposite shows high reversible capacity and super long cycling stabilityFe₃O₄/reduced graphene oxide (Fe₃O₄/RGO) nanocomposite was prepared by a facile interface reaction and subsequent in situ reduction process. The electrochemical performances of the as-prepared Fe₃O₄/RGO nanocomposite were evaluated in coin-type cells. It delivers high reversible capacity of 1025mAhg⁻¹ at 100mAg⁻¹ after 50 cycles and outstanding cycle stability. Even after 800 cycles at various rates from 100 to 4000mAg⁻¹, the capacity still retains 959.4mAhg⁻¹ at 100mAg⁻¹. A transmission electron microscopy image has shown the flexible interleaved structure of nanocomposite, and the interface reaction is also benefit to ensure strong interfacial interaction between Fe₃O₄ nanoparticles (50nm) and RGO nanosheets. The designed structure plays key role in improving electrochemical performance. The Fe₃O₄/RGO nanocomposite with super long cycling life will be an ideal candidate of anode material for lithium ion batteries.

Keywords: Graphene; Fe; ₃; O; ₄; nanoparticles; Interface reaction; Anode; Lithium ion batteries

Electrochemical performance and safety features of high-safety lithium ion battery using novel branched additive for internal short protection by Yu-Han Li; Meng-Lun Lee; Fu-Ming Wang; Chang-Rung Yang; Peter P.J. Chu; Shueh-Lin Yau; Jing-Pin Pan (pp. 306-311).

► N-phenylmaleimide-containing branched oligomer has been employed as an additive in lithium cells. ► The branched oligomer additive enhances safety and cycling performance of Li ion battery. ► The highest temperature of branched oligomer-containing battery was only 85°C in the nail penetration test.In this study, we have investigated N-phenylmaleimide/bismaleimide-containing branched oligomer (BO1) as additive in Li-ion batteries to increase the safety performance by reducing the probability of batteries suffering an internal short circuit. In the nail penetration test, a LiCoO₂/MCMB full battery with N-phenylmaleimide/bismaleimide-containing branched oligomer (BO1) showed a significant improvement in thermal stability and was able to restrain the temperature of the battery at about 85°C. Furthermore, we found that N-phenylmaleimide/bismaleimide-containing branched oligomer (BO1) contained battery revealed better cycling and electrochemical performance, compared with the battery with bismaleimide-containing branched oligomer (BO3) in the electrolyte. The improvement might result from the favorable ionic conductivity, Li ion mobility and lower resistance in the battery. This additive can meet the cycling performance and safety requirements for Li-ion batteries.

Keywords: Branched oligomer (BO); Safety additives; Internal short

Preparation and bioactivity of TiO₂ nanotube arrays containing calcium and phosphorus by Xiufeng Xiao; Jianhe Liang; Haizhen Tang; Xiaojuan Yang; Rongfang Liu; Yirong Chen (pp. 312-319).

► TiO₂ nanotube containing Ca and P were prepared through anodization and hydrothermal treatment. ► The tubular anatase nanotubes were transferred into four pillars after hydrothermal treatment. ► Apatite forming ability of TiO₂ nanotube after hydrothermal treatment in Ca(OH)₂ are excellent.With NH₄H₂PO₄ and NH₄F glycerin/water mixed solvent as electrolyte, through the anodic oxidation and calcium hydroxide hydrothermal treatment, TiO₂ nanotube arrays containing calcium and phosphorus were prepared. Moreover, the influence of the processing time, titania crystalline phase and pH value of the solution were investigated. And the bioactivity of the nanotube arrays were examined by soaking in simulated body fluid. The results showed that the TiO₂ nanotube arrays prepared in the phosphate-containing glycerin system can contain a small amount of phosphorus. When the processing time <0.5h, the nanotube arrays maintained the original tubular structure, but the quantity of Ca element reduces. When the processing time was ≥2h, the original tubular structure of the anatase nanotube arrays was transferred into nano four pillars, and with extending the processing time, the sizes of nano four pillars were slightly increased. But the morphology of the as-prepared nanotube arrays changed very slightly. And a content of Ca element increased with the increase in the hydrothermal treatment time. The existence form of Ca element is calcium titanate. The samples after hydrothermal treatment in saturated Ca(OH)₂ solution are clearly more efficient in promoting apatite formation than the as-prepared or anatase nanotube arrays.

Keywords: TiO; ₂; nanotube arrays; Anodization; Bioactivity; Hydrothermal treatment

Optimization of electrospun TSF nanofiber alignment and diameter to promote growth and migration of mesenchymal stem cells by Jing Qu; Dandan Zhou; Xiaojing Xu; Feng Zhang; Lihong He; Rong Ye; Ziyu Zhu; Baoqi Zuo; Huanxiang Zhang (pp. 320-326).

► Our data suggest a strong correlation between topography and growth behavior of MSCs. ► Aligned smaller diameter TSF scaffolds are more favorable to the growth of MSCs. ► The increased migration speed of MSCs induced by TSF scaffolds was verified. ► 400nm aligned TSF possess the maximum ability to promote migration of MSCs.Silk fibroin scaffolds are a naturally derived biocompatible matrix with the potential for reconstructive surgical applications. In this study, tussah silk fibroin (TSF) nanofiber with different diameters (400nm, 800nm and 1200nm) and alignment (random and aligned) were prepared by electrospinning, then the growth and migration of mesenchymal stem cells (MSCs) on these materials were further evaluated. CD90 immunofluorescence staining showed that fiber alignment exhibited a strong influence on the morphology of MSCs, indicating that the alignment of the scaffolds could determine the distribution of cells. Moreover, smaller diameter and aligned TSF scaffolds are more favorable to the growth of MSCs as compared with 800nm and 1200nm random TSF scaffolds. In addition, the increased migration speed and efficiency of MSCs induced by three-D TSF were verified, highlighting the guiding roles of TSF to the migrated MSCs. More importantly, 400nm aligned TSF scaffolds dramatically improved cell migratory speed and further induced the most efficient migration of MSCs as compared with larger diameter TSF scaffolds. In conclusion, the data demonstrate that smaller diameter and aligned electrospun TSF represent valuable scaffolds for supporting and promoting MSCs growth and migration, thus raising the possibility of manipulating TSF scaffolds to enhance homing and therapeutic potential of MSCs in cellular therapy.

Keywords: Tussah; silk fibroin; Electrospinning; Fiber diameter; Fiber alignment; Mesenchymal stem cell; Migration

Structural phototransformation of WO₃ thin films detected by photoacoustic analysis by Argelia Pérez Pacheco; C. Oliva Montes de Oca; R. Castañeda-Guzmán; A. Esparza García (pp. 327-331).

► The phototransformation of WO₃ thin films were studied by photoacoustic technique. ► The phase transition in WO₃ thin films was induced by laser irradiation fluence. ► The onset and end of the phototransformation in the thin films was identified. ► The ablation threshold for each sample was identified.The photoacoustic technique (PA) was used to detect the phase transformation from amorphous to crystalline state of tungsten oxide (WO₃) thin films induced by UV pulsed laser radiation at low energy (<1.5mJ). The evolution of photoacoustic signal was studied by a correlation analysis, comparing successive signals at fluences ranging from 0 to 20mJ/cm². In this interval, it was possible to observe structural changes and the ablation threshold in films due to incident laser fluence effect. Thin films of WO₃ were deposited by DC reactive magnetron sputtering over glass substrates at different deposition times. The results obtained by correlation analysis were compared with Raman spectroscopy data.

Keywords: Thin films; Tungsten oxide; Phototransformation; Photoacoustic analysis; Raman spectroscopy

Synthesis of magnetic nanoparticles by pulsed laser ablation by L. Franzel; M.F. Bertino; Z.J. Huba; E.E. Carpenter (pp. 332-336).

► Magnetic nanoparticle generation by laser ablation of Fe in ethanol. ► Creation of superparamagnetic nanoparticles with a saturation magnetization M_s=124emu/g. ► Laser ablation in liquids is a promising technique for chemical-free fabrication of biocomposites.Magnetic nanoparticles were prepared by laser ablation of Fe foil in ethanol. The nanoparticles consisted of Fe₃O₄ and Fe₃C and were superparamagnetic with a saturation magnetization M_s=124emu/g. Zero field cooled (ZFC) measurements collected at an applied field of 50Oe displayed a maximum magnetic susceptibility at 120K with a broad distribution. Field cooled (FC) measurements collected during cooling and heating showed a thermal hysteresis indicative of temperature dependent magnetic viscosity. The magnetic viscosity was calculated from thermoremanent magnetization (TRM) plots and it increased with decreasing temperature. The activation volume of these non uniform magnetic states was calculated from TRM measurements and it was found to decrease with decreasing temperature. The decrease in activation diameters was interpreted as a decrease in exchange length, and hence a decrease in particle-particle interactions.

Keywords: Laser ablation; Magnetic nanoparticles; Iron carbide

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser by Chunyong Liang; Hongshui Wang; Jianjun Yang; Baoe Li; Yang Yang; Haipeng Li (pp. 337-342).

► We fabricated different micro-patterns (grooves, ripples, holes and nanoparticles) on NiTi alloy surfaces to improve the biocompatibility. ► The new method of femtosecond laser (FSL) machining technique was used to obtain the novel micro-patterns, and the authors explored the mechanism of the FSL machining process. ► We the surface characteristics of NiTi surfaces before and after the FSL treatment, and evaluated the influence of FSL treatment on biocompatibility of NiTi alloys.Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser (FSL) was studied in this work. The surface characteristics of the laser treated NiTi alloys were investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectrum (XPS). The biocompatibility was evaluated by in vitro cell culture test. The results showed that, grooves, ripples, which covered by nanoparticles were formed on the sample surfaces, and the Ni/Ti ratio on the alloy surface increased with increasing laser energy. The crystal structure was not changed by laser treatment. However, the cell culture test proved that the micro-patterns induced by FSL were beneficial to improve the biocompatibility of NiTi alloys: the growth of osteoblasts oriented along the grooves, a large amount of synapses and filopodias were formed due to the ripples, holes and nanoparticles on the alloy surface, and the proliferation rate and alkaline phosphatase (ALP) content of cells were increased after FSL treatment. However, due to the toxicity of Ni ions on cell growth, the NiTi alloy surface should not be treated by laser fluence of more than 3.82J/cm² to obtain the ideal biocompatibility.

Keywords: Micro-pattern; NiTi; Femtosecond laser; Biocompatibility

Preparation of highly porous TiO₂ nanofibers for dye-sensitized solar cells (DSSCs) by electro-spinning by Won Ho Jung; Noh-Seok Kwak; Taek Sung Hwang; Kwang Bok Yi (pp. 343-352).

► Highly porous TiO₂ nanofibers have been fabricated using an electro-spinning method. ► Larger amount of glycerin caused an increase in the surface area of the nanofibers. ► The efficiency of porous TiO₂ nanofibers was higher than non-porous TiO₂ nanofibers.TiO₂ nanofibers for use in dye-sensitized solar cells (DSSCs) were prepared from a solution of polymerized titanium tetraisopropoxide using a modified electro-spinning process to create fibers with high specific surface areas. The sol–gel technique was utilized to prepare the spinning solution, and glycerin was added to investigate its effects on the surface area and porosity of the TiO₂ nanofibers. The spinning rate, tip-to-collector distance, voltage, and amount of glycerin were varied simultaneously and independently to determine the optimal conditions for the preparation of highly porous TiO₂ nanofibers. The optimal conditions for producing such electrospun TiO₂ nanofibers were 0.4g of glycerin per 29ml of spinning solution, an applied voltage of 22kV, a flow rate of 0.1ml/h, and a tip-to-collector distance (TCD) of 20cm. The thermal decomposition of glycerin during the calcination process increased the surface area of the finished TiO₂ nanofibers. SEM and XRD analyses confirmed that the TiO₂ nanofibers had an anatase crystallite structure and possessed thicknesses of 80–150nm, a maximum specific surface area of 103.3m²/g, maximum porosity of 80.5% and maximum efficiency of 4.6%, which was significantly higher than that of typical TiO₂ nanofibers. Thermogravimetric analysis revealed that the solvent, binder, and impurities were removed at 100°C, 250°C and 450°C, respectively.

Keywords: TiO; ₂; nanofibers; Highly porous nanofibers; DSSC; TiO; ₂; surface area

Properties of different temperature annealed Cu(In,Ga)Se₂ and Cu(In,Ga)₂Se_3.5 films prepared by RF sputtering by Zhou Yu; Lian Liu; Yong Yan; Yanxia Zhang; Shasha Li; Chuanpeng Yan; Yong Zhang; Yong Zhao (pp. 353-359).

► The Cu(In,Ga)Se₂ and Cu(In,Ga)2Se_3.5 films follow different process to form CIGS phase. ► Composition loss of the annealed Cu(In,Ga)Se₂ and Cu(In,Ga)₂Se_3.5 films are different. ► Hexagonal CuSe phase exhibits unique transport feature. ► Conductivity of the CIGS films is affected by the “variable range hopping” mechanism.We have investigated the effect of annealing temperature on structural, compositional, electrical properties of the one-step RF sputtered Cu(In,Ga)Se₂ and Cu(In,Ga)₂Se_3.5 films. After the annealing at various temperatures, loss of Se element is significant for the Cu(In,Ga)Se₂ films and meanwhile composition of the annealed Cu(In,Ga)₂Se_3.5 films keeps almost constant. The as-deposited Cu(In,Ga)Se₂ and Cu(In,Ga)₂Se_3.5 films show amorphous structure and they follow different transformation process to form chalcopyrite structure. Electrical conductivity of the annealed CIGS films related to their chemical composition. Cu(In,Ga)Se₂ films annealed at 150°C show unique electron transport mechanism for the formation of hexagonal CuSe phase. Electrical conductivity of the chalcopyrite structure films are dominated by the “variable range hopping” transport mechanism. The annealed Cu(In,Ga)₂Se_3.5 films present higher density of disorders than the annealed Cu(In,Ga)Se₂ films for their significant Cu deficient composition.

Keywords: Cu(In,Ga)Se; ₂; Thin films; Composition; Annealing; Electrical properties

Transparent Al-doped ZnO anodes in organic light-emitting diodes investigated using a hole-only device by Zong-Liang Tseng; Po-Ching Kao; Chi-Shin Yang; Yung-Der Juang; Sheng-Yuan Chu (pp. 360-363).

► OLED devices with AZO films and commercial ITO. ► Hole-only devices with AZO film and commercial ITO anodes were used to examine the efficiency of hole injection. ► AZO films are suitable as anodes of OLED devices under a high applied voltage. ► The indium diffuses into the organic layer.Al-doped ZnO (AZO) films with a thickness of ∼400nm were prepared by sputtering on glass substrates for use as transparent anodes of organic light-emitting diodes (OLED) devices. The operation voltages (at 100cd/m²) of OLED devices with AZO and ITO anode materials were 10.5 and 5.5V, respectively. The maximum luminance output of the AZO device was 6450cd/m² (achieved at 12.5V) and that of the ITO device was 9830cd/m² (achieved at 10.5V). We demonstrate that a hole-only device method can be used to estimate the suitability of AZO and ITO anodes in the OLED devices and to verify experimental results. The AZO thin films with low price and non-toxicity may be suitable as alternative anodes in OLED devices under high voltage.

Keywords: ZnO; OLED; AZO; TCO

Crystallization behavior of MgB₂ films fabricated on copper cathodes via electrochemical technique by Huazhe Yang; Xiaguang Sun; Xiaoming Yu; Yang Qi (pp. 364-368).

► A modified electrolysis cell was devised to prepare MgB₂ films on copper cathode. ► Crystallization behavior of MgB₂ phase of films was investigated. ► Phase transformation of Mg–B and Mg–Cu compound was discussed. ► Mechanism for the dendritic growth of MgB₂ phase was proposed.An electrochemical technique was devised and settled to prepare MgB₂ films on copper cathodes in MgCl₂–Mg(BO₂)₂–NaCl–KCl molten salts. X-ray diffraction and scanning probe microscopy were adopted to investigate the phase composition and elements distribution of sample. R– T curve of film was monitored through standard four-probe method. Transmission electron microscope and scanning electron microscope analysis were chosen to investigate the crystallization behavior and morphology of the films at different electrolytic temperatures. The results indicated that MgB₂ films were successfully fabricated on the copper cathodes, and the optimal electrolytic temperature was 601°C. It was presumed that the non-conducting MgO impurities hindered continuous growth of MgB₂ grain, which may result in dendritic growth of MgB₂ grain.

Keywords: MgB; ₂; film; Crystallization behavior; Electrochemical technique

In situ ATR-IR spectroscopy study of adsorbed protein: Visible light denaturation of bovine serum albumin on TiO₂ by A. Bouhekka; T. Bürgi (pp. 369-374).

► We study the behavior of BSA protein adsorbed on TiO₂ using in situ IR spectroscopy. ► We examine the secondary structure changes during light exposure. ► Visible light illumination creates random coil in the secondary structure of BSA. ► The denaturation of BSA adsorbed on TiO₂ under visible light irradiation is irreversible.In this work in situ Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy in a flow-through cell was used to study the effect of visible light irradiation on bovine serum albumin (BSA) adsorbed on porous TiO₂ films. The experiments were performed in water at concentrations of 10⁻⁶mol/l at room temperature. The curve fitting method of the second derivative spectra allowed us to explore details of the secondary structure of pure BSA in water and conformation changes upon adsorption as well as during and after illumination by visible light. The results clearly show that visible light influences the conformation of adsorbed BSA. The appearance of a shift of the amide I band, in the original spectra, from 1653cm⁻¹ to 1648cm⁻¹, is interpreted by the creation of random coil in the secondary structure of adsorbed BSA. The second derivative analysis of infrared spectra permits direct quantitative analysis of the secondary structural components of BSA, which show that the percentage of α-helix decreases during visible light illumination whereas the percentage of random coil increases.

Keywords: In situ spectroscopy; TiO; ₂; Visible light; BSA adsorption; Denaturation; Protein structure

Diverse 2D structures obtained by adsorption of charged ABA triblock copolymer on different surfaces by Katri S. Kontturi; Arja-Helena Vesterinen; Jukka Seppälä; Janne Laine (pp. 375-384).

Display Omitted► Morphologies of an adsorbed amphiphilic triblock copolymer were investigated. ► On silica, irregular aggregates or a continuous film emerged. ► On polystyrene, globular or relatively evenly shaped aggregates were observed.In the larger context of 2D polymeric structures, the morphologies obtained by adsorption and subsequent drying of charged, ABA type amphiphilic triblock copolymer of poly[2-(dimethylamino)ethyl metacrylate] (PDMAEMA) and poly(propylene oxide) (PPO) were investigated with atomic force microscopy and X-ray photoelectron spectroscopy as well as in situ adsorption analysis with quartz crystal microbalance with dissipation monitoring. Hydrophilic silica and hydrophobic polystyrene (PS) were used as substrates for adsorption. The structures emerging from the self-assembly of adsorbing polymer were profoundly influenced by composition of the aqueous solution and the choice of substrate. When adsorbed from dilute polymer solution where the concentration is so low that the polymer does not yet show surface-active behavior, the triblock copolymer unimers associated on hydrophilic silica surface forming large, irregular clustered aggregates, with sizes increasing with electrolyte concentration of the solution. On a hydrophobic PS substrate, on the other hand, unimers spread much more evenly, forming clear surface patterns. The roughness of these patterned structures was tuned with the electrolyte concentration of the solution. Adsorption from a more concentrated polymer solution, where the surface-activity of the polymer is perceptible, resulted in the formation of a smooth film with complete coverage over the hydrophilic silica substrate when the electrolyte concentration was high. On PS, on the other hand, nucleation of evenly scattered globular, disk-like micelles was induced. Besides the dry film morphology, the even distribution of the irreversibly adsorbed polymer over the PS surface was likely to serve as an optimal platform for the build-up of reversible hydrophobically bound multilayers at high electrolyte concentration. The multilayer formation was reversible because a decrease in the electrolyte concentration of the solution re-introduces strong electrostatic repulsion between the multilayered polymer coils which results in breakdown of the layer.

Keywords: Triblock copolymer; Polyelectrolyte adsorption; Morphological patterns

Synthesis and photoluminescence properties of comb-like CdS nanobelt/ZnO nanorod heterostructures by Changyong Lan; Jiangfeng Gong; Chunming Liu (pp. 385-389).

► Comb-like CdS nanobelt/ZnO nanorod heterostructures were synthesized. ► ZnO nanorods epitaxially grew on the (100) surface of the CdS nanobelts along [100]. ► A preliminary growth mechanism was proposed.Comb-like CdS nanobelt/ZnO nanorod heterostructures were synthesized by a two-stage method. X-ray diffractometer, scanning electron microscopy, transmission electron microscopy were used to characterize and analyze the as-synthesized products. The results demonstrate that the CdS nanobelt backbones grow along [210] and the ZnO nanorod branches epitaxially grow on the (001) surface of the CdS nanobelt with a growth direction of [001]. The as-prepared heterostructures exhibit an important feature of single-crystallinity. At room temperature, the comb-like CdS nanobelt/ZnO nanorod heterostructures show strong green emission.

Keywords: Heterostructures; Nanobelts; Nanorods; Photoluminescence

Rhenium coating prepared on carbon substrate by chemical vapor deposition by Yonggang Tong; Shuxin Bai; Hong Zhang; Yicong Ye (pp. 390-395).

► Rhenium coating was prepared on the isotropic graphite and C/C composite by chemical vapor deposition. ► The rhenium coating on the isotropic graphite was compact and crack-free with a preferential growth orientation of 〈002〉. ► The cracks in the coating on C/C composite were resulted from thermal expansion mismatch and anisotropy of C/C composite. ► The bond strength between the rhenium coating and substrate was tested by the coating-pull-off method.Rhenium coating was prepared on the isotropic graphite and C/C composite by chemical vapor deposition. The phase composition and microstructure of the coating were studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results show that the rhenium coating on the isotropic graphite was compact and crack-free with a preferential growth orientation of 〈002〉 while two kinds of cracks were found in the coating on the C/C composite. The formation of the two cracks in the coating on the C/C composite was mainly attributed to the residual stress resulting from the mismatch in the thermal coefficient of expansion and the anisotropy of the C/C composite. Furthermore, the bond strength between the rhenium coating and the substrate was tested by the coating-pull-off method. The graphite substrate fractures with the tensile strength about 4.5MPa for the coating on the graphite, while the rupture is at the interface of coating-adhesive for the coating on the C/C substrate with the tensile strength of 15MPa.

Keywords: Rhenium coating; Graphite; C/C composite; Chemical vapor deposition

Effect of relative humidity constraint on the metal exchanged montmorillonite performance: An XRD profile modeling approach by Walid Oueslati; Hafsia Ben Rhaiem; Abdesslem Ben Haj Amara (pp. 396-404).

.Display Omitted► An interstratified (1W–2W) hydration state appeared after 10 Hydr-Dehyd sequence. ► Co-existence of more “crystallite” specie saturated by more Exchang.Cation. ► After 20 cycles the CEC of the starting sample is partially saturated. ► The amounts ofExchang.Cat . varied vs the number of the Hydr-Dehydr cycles.This work aims at examining the effect of an applied hydrous strain on the cation exchange process of a dioctahedral smectite by quantitative XRD analysis. The hydrous constraint is created by a continuous, in situ, hydration–dehydration cycles using variation of %RH (relative humidity) rate. In order to examine the effect of the retained materials stress on the cation exchange capacity of the host materials, the starting, the intermediate and the final stressed samples are deposed in contact with saturated Cd(II), Co(II), Zn(II) and Ni(II) chloride solutions. To characterize structural changes, an XRD profile modeling approach is used. This investigation allowed us to determine parameters related to the nature, abundance, size, position, organization of exchangeable cation and water molecule in the interlamellar space, along the c* axis. Qualitatively, the hydration behavior is affected by the number of hydration–dehydration cycle, and an interstratified hydration phases due probably to a new organization of the interlamellar space content is observed. Quantitatively, the theoretical mixed layer structure (MLS) suggests the coexistence of more one “crystallite” specie which are saturated by more than one exchangeable cations indicating a partial saturation of all exchangeable sites. Using optimum structural parameter values, deduced from the theoritecals models, some equations which described the evolution of exchangeable cation amount versus the applied hydrous strain were derived.

Keywords: Na rich-montmorillonite; Hydrous strain; Ionic exchange; Quantitative XRD analysis

Influence of simultaneous doping of Cd and F on certain physical properties of ZnO nanopowders synthesized via a simple soft chemical route by K. Ravichandran; K. Saravanakumar; R. Chandramohan; V. Nandhakumar (pp. 405-410).

► Simultaneous doping of Cd and F in ZnO nanopowder for first time. ► Zeta potential study. ► Properties are influenced by Cd than F.The effect of simultaneous doping of cadmium and fluorine on certain physical properties of ZnO nanopowders synthesized using a simple soft chemical route is reported for the first time. The structural studies indicated that doping do not alter the overall structure. However, the values of lattice constants are found to increase with the increase in the dopant levels. The optical studies showed a decrease in band gap for doped system associated with Moss–Burstein effect. The composition and morphology are reported and correlated with FTIR and photoluminescence studies. The morphology is explained on the basis of zeta potential measurements.

Keywords: Simultaneous doping; Soft chemical; Nanopowder; Structural; Optical properties; Zeta sizer

Effect of QPQ nitriding time on wear and corrosion behavior of 45 carbon steel by Wei Cai; Fanna Meng; Xinyan Gao; Jing Hu (pp. 411-414).

► Hot water immersing test was designed to investigate the corrosion resistance of samples. ► Corrosion resistance of samples was improved dramatically. ► Wear resistance of samples was also improved. ► With suitable QPQ treatment 45 steel can be used in water lubricant.QPQ salt bath treatment of 45 steel was conducted by nitriding at 565°C for various time (60min, 90min, 120min, 150min and 180min), followed by the same post-oxidation process with heating temperature of 430°C and holding duration of 40min. Characterization of modified surface layers was made by means of optical microscopy, microhardness test, X-ray diffraction analysis, corrosion and wear resistance test. The results showed the formation of a very thin Fe₃O₄ oxide layer during post-oxidation on the top of the bright nitrides compound layer formed during nitriding. The maximum microhardness value of 630HV_0.01 was obtained after nitriding at 565°C for 120min, which was two times higher than that of the untreated sample. The corrosion and wear resistance of 45 steel could be significantly improved by QPQ complex salt bath treatment, and the optimum nitriding duration for improving the wear and corrosion resistance was 120min and 90min, respectively.

Keywords: 45 steel; Corrosion resistance; Wear resistance; Microhardness; QPQ salt bath

Comparison studies of surface cleaning methods for PAN-based carbon fibers with acetone, supercritical acetone and subcritical alkali aqueous solutions by Linghui Meng; Dapeng Fan; Yudong Huang; Zaixing Jiang; Chunhua Zhang (pp. 415-421).

Display Omitted► Cleaning with supercritical acetone is appropriate to wipe off the oxygenated contaminants. ► Cleaning with supercritical acetone causes smaller damage to bulk strength of carbon fibers. ► Cleaning with subcritical alkali aqueous solution can thoroughly remove silicious contaminants.Four kinds of polyacrylonitrile-based carbon fibers were cleaned by three methods and were characterized by X-ray photoelectron spectroscopy, monofilament tensile strength test and atomic force microscopy (AFM). Experimental results of these tests reveal that the method using supercritical acetone or subcritical potassium hydroxide aqueous solution act as the processing medium shows a better cleaning effect compared to the traditional method, Soxhlet extraction with acetone. The method using supercritical acetone is more appropriate to wipe off the oxygenated contaminants on carbon fibers’ surfaces and causes a relatively smaller damage to the bulk strength of each carbon fiber. As far as treating method using the subcritical alkali aqueous solution, it can thoroughly remove silicious contaminants on the surfaces of treated fibers.

Keywords: Carbon fiber; Surface cleaning; Supercritical acetone; Subcritical aqueous

The effect of ion implantation on the oxidation resistance of vacuum plasma sprayed CoNiCrAlY coatings by Jie Jiang; Huayu Zhao; Xiaming Zhou; Shunyan Tao; Chuanxian Ding (pp. 422-430).

► We used ion implantation to improve the oxidation resistance of CoNiCrAlY coating. ► The oxidation process of CoNiCrAlY coating at 1100°C for 1000h was studied. ► The Nb ion implanted coating exhibited better oxidation resistance. ► The influences of Nb and Al ion implantation into CoNiCrAlY coatings were evaluated.CoNiCrAlY coatings prepared by vacuum plasma spraying (VPS) were implanted with Nb and Al ions at a fluence of 10¹⁷atoms/cm². The effects of ion implantation on the oxidation resistance of CoNiCrAlY coatings were investigated. The thermally grown oxide (TGO) formed on each specimen was characterized by XRD, SEM and EDS, respectively. The results showed that the oxidation process of CoNiCrAlY coatings could be divided into four stages and the key to obtaining good oxidation resistance was to remain high enough amount of Al and promote the lateral growth of TGO. The implantation of Nb resulted in the formation of continuous and dense Al₂O₃ scale to improve the oxidation resistance. The Al implanted coating could form Al₂O₃ scale at the initial stage, however, the scale was soon broken and TGO transformed to non-protective spinel.

Keywords: CoNiCrAlY coating; Ion implantation; High temperature oxidation resistance; Thermally grown oxide

Adsorption of 2,6-di-t-butyl-p-hydroxytoluene (BHT) on gold nanoparticles: Assignment and interpretation of surface-enhanced Raman scattering by Ying-Ying Sun; Yun-Fei Xie; He-Ya Wang; He Qian; Wei-Rong Yao (pp. 431-435).

► Raman spectrum of BHT by density functional theory calculation with Gaussian 03 at B3LYP/6-311G(d). ► The limit of detection of BHT reached the level of 10μg/mL with SERS in methanol. ► BHT adsorbed on to gold nanoparticles by PhO(H) (Ph=phenyl).2,6-Di-t-butyl-p-hydroxytoluene (BHT), a common antioxidant, has been implicated in oil foods and food packaging materials as a substance that could migrate into the food supply chain and cause suppression of human respiratory enzymes. In this study, BHT solutions in different solvents were measured by surface enhanced Raman spectroscopy (SERS) in combination with SERS-active substrates: gold colloidal nanoparticles. The limit of detection of BHT can reach the level of 10μg/mL with SERS in methanol. The Raman peak at 766cm⁻¹ was used as the index of quantitative analysis and the correlation coefficient was 0.9761. These results demonstrated the applicability of utilizing SERS to detect low concentrations of BHT. By comparing the features of SERS peaks with the density functional theory (DFT)-calculated Raman spectrum, the adsorption behavior of BHT on the surface of gold nanoparticles was analyzed in detail and it was determined that the dominant contribution to the SERS signal in this case should be the electromagnetic enhancement mechanism. A charge-transfer mechanism also contributed to the SERS signal for BHT adsorbed on gold nanoparticles by the PhO(H) (Ph=phenyl) coalescent format.

Keywords: Surface-enhanced Raman scattering; Gold nanoparticles; 2,6-Di-t-butyl-p-hydroxytoluene; Density functional theory calculation; Limit of detection

Preparation of flexible BOPP/SiO_x/TiO₂ multilayer film for photodegradation of organic contamination by Changwen Zhao; Xiaoli Yao; Yuhong Ma; Pengfei Yuan; Wantai Yang (pp. 436-440).

► Flexible BOPP/SiO_x/TiO₂ multilayer film. ► Sequential deposition by spin-coating and sol–gel processes. ► Multilayer composite film with photoinduced hydrophilic transformation capability. ► Photocatalytic degradation ability.First a SiO_x layer, as a barrier layer between a photo active anatase TiO₂ layer and BOPP substrate, was coated on hydroxylated BOPP film by a sol–gel process. Then, TiO₂ layer was formed on SiO_x surface through liquid phase deposition. Thus a flexible BOPP/SiO_x/TiO₂ multilayer film which has photocatalytic activity was fabricated. The coating processes were monitored by FT-IR and UV–vis spectroscopy, scanning electron microscopy, atom force microscopy and water contact angle (CA) measurements. The thickness of SiO_x and TiO₂ layer was about 600nm and 135nm, respectively. Root mean square (RMS) roughness of the SiO_x layer was about 2–3nm while the surface of TiO₂ layer was much coarse with RMS roughness about 30nm which offered the large surface area. The TiO₂ layer endowed multilayer film photoinduced hydrophilic conversion property evidenced by the fact that its surface water contact angle could reduce to about 5° after 1h of UV irradiation. The photocatalytic degradation ability of multilayer film was evaluated using methyl orange as model contamination and the results indicating that the degradation is efficient.

Keywords: Multilayer films; Titanium oxide; Inorganic/organic composites; Polypropylene; Silica; Spin-coating

Anti-adhesion treatment for nanoimprint stamps using atmospheric pressure plasma CVD (APPCVD) by Chien-Li Wu; Cho-Yun Yang; Tai-Pang An; Je-Wei Lin; Cheng-Kuo Sung (pp. 441-446).

► Anti-adhesion treatment for imprint stamps using APPCVD process was demonstrated. ► Contact angle, surface roughness and adhesion force were investigated and optimized. ► Three stamp materials: Si, Ni, and Ni–P were applied for comparison. ► Sub-50nm linewidth imprint process with large-area uniformity was obtained.Nanoimprint lithography (NIL) provides a practical method for producing high-precision nanostructures efficiently and at low cost. Interfacial interactions between the imprint stamp and the forming material are crucial for high-quality pattern transfer, with critical dimensions and large aspect ratios. This study conducted an in-depth investigation into anti-adhesion treatments for imprint stamps using atmospheric pressure plasma chemical vapor deposition (APPCVD). Quantitative analyses of adhesion force, surface roughness and contact angle were applied to verify the enhanced imprint capability and release performance of the stamps. Experimental results confirmed that APPCVD-prepared anti-adhesion coatings provided improvements in quality and produced few defects in imprinted replicas. The proposed technique can simultaneously provide surface modification and thin-film deposition, depending on the precursors used. Additionally, the use of oxygen-containing plasma resulted in greater durability of the anti-adhesion coatings. The major advantages of the technique include low-temperature treatments, large-format scalability with good uniformity, short process times, and a non-vacuum process environment.

Keywords: Anti-adhesion; Atmospheric pressure plasma CVD (APPCVD); Nanoimprint; Stamp

Preparation and characterization of TaNbTiW multi-element alloy films by Xingguo Feng; Guangze Tang; Le Gu; Xinxin Ma; Mingren Sun; Liqin Wang (pp. 447-453).

► Multi-element alloy films were deposited by a novel combination approach. ► Alloy films are the single phase solid solution with the bcc structure. ► Structure and property of alloy film strongly depend on the film composition. ► Maximum hardness and elastic modulus of alloy films reached 5.2 and 127.2GPa.In this study, a novel combination approach is used to prepare TaNbTiW multi-element alloy films. The composition, microstructure and mechanical properties of the alloy films are investigated. X-ray diffraction (XRD) shows that the films have bcc structure, and the lattice constant strongly depends on film composition. The films have residual stress in the range of −0.1 to −2.63GPa. Their hardness and modulus attain to the values about 5.2 and 127.2GPa, respectively. After annealed at 500°C and 700°C for 90min in vacuum, the films reveal no phase transformation.

Keywords: Multi-elements alloy films; Multi-targets magnetron sputtering; Structure; Hardness

Phase and morphological transformations of GaS single crystal surface by thermal treatment by E. Filippo; T. Siciliano; A. Genga; G. Micocci; M. Siciliano; A. Tepore (pp. 454-457).

► GaS layer was thermally treated under Ar flow for 4h at two different temperatures. ► GaS transformed into β-Ga₂O₃ through the formation of Ga₂S₃ intermediate phase. ► Ga₂S₃ sub-micron crystallites grew at a temperature of 700°C. ► Ga₂O₃ nanowires (length up to 4μm) grew at a temperature of 900°C on crystallites.GaS single crystal layers have been thermally treated under argon flow for 4h at two different temperatures (700°C and 900°C). The starting GaS sample and the annealed ones have been characterized by X- ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy. It was found that GaS transformed into β-Ga₂O₃ through the formation of Ga₂S₃ intermediate phase. Moreover, such an oxidation process involved the growth of dense Ga₂S₃ sub-micron crystallites at a temperature of 700°C and relatively long β-Ga₂O₃ nanowires (up to 4μm) at a temperature of 900°C. Experiments also evidenced that an intentional supply of oxygen was unfavourable both to the formation of Ga₂S₃ phase and to the growth of sub-micron crystallites and nanowires.

Keywords: Gallium sulfide; Phase transformation; Oxidation; Thermal treatment; Microstructures

Surface modification of the patterned Al6061/SUS304 metal plates using the large electron beam by Dong Min Kim; Jisu Kim; Sung Soo Park; Hyung Wook Park; Hyungson Ki (pp. 458-463).

► We performed the large-electron-beam polishing of the patterned metal plates. ► We observed its effect on surface hardness, surface roughness, and water repellency. ► The contact angle for Al6061 and SUS304 increased after the electron-beam irradiation. ► We observed the microstructure after the electron beam irradiation.Polishing is a finishing process used to improve surface integrity by reducing surface roughness and residual stress caused by other machining processes. The recently developed electron beam polishing method was used in this study to improve surface quality. In this process, an electron beam with a maximum diameter of 60mm was applied for a few microseconds to melt and evaporate a metal surface. Al6061 and SUS304 metal plates were prepared with different geometric patterns and subjected to electron beam polishing. The surface roughness of the patterned SUS304 metal plate was significantly improved. However, the surface roughness of the patterned Al6061 metal plate became worse. Although the surface hardness decreased by approximately 10% on the re-solidified layers on both types of plates, the contact angle increased due to changes in surface morphology. The microstructure variation after the electron beam irradiation was also examined and compared with the thickness prediction of the re-solidified layer for Al6061 and SUS304 metal plates.

Keywords: Electron beam polishing; Surface roughness; Al6061; SUS304

Investigation of shadow effect in laser-focused atomic deposition by Xiao Deng; Yan Ma; Pingping Zhang; Wanjing Zhang; Sheng Chen; Shengwei Xiao; Tongbao Li (pp. 464-469).

► Cr nanostructures change gradually in the atom flux divergent area in laser focused atomic deposition. ► The nanostructure's FWHM broadens and its height increases as atom flux increases. ► BD surface growth model is optimized to simulate the Cr atom deposition. ► Shadow effect explains the FWHM broadening in laser focused Cr atomic deposition.The feature width broadening and height increasing of the Cr nanostructure have been experimentally observed in the gradual atom flux distribution divergent area on one sample along the standing wave direction in laser-focused atomic deposition. By applying an optimized ballistic deposition surface growth model to simulate this situation, it is demonstrated that the shadow effect of the forming nanostructure influences the deposition sites of the subsequent incident atoms, which leads to feature broadening and contrast decreasing of the nanostructures. The shadow effect theory provides a new understanding for the explanation of the discrepancy between the calculated results and the experimental observations.

Keywords: Laser-focused atomic deposition; Feature broadening; Shadow effect; Ballistic deposition model

One-step process to fabrication of transparent superhydrophobic SiO₂ paper by Jian Li; Hongqi Wan; Yinping Ye; Huidi Zhou; Jianmin Chen (pp. 470-472).

► Superhydrophobic SiO₂ paper was fabricated by a simple spray-coating method. ► The superhydrophobic SiO₂ paper showed a high water contact angle of 162±1° and a low water sliding angle of 3±1°. ► The superhydrophobic SiO₂ paper was found to be highly transparent.A simple technique for fabrication of superhydrophobic SiO₂ paper was developed by spraying hydrophobic SiO₂ nanoparticles suspension on paper substrate. The hydrophobic SiO₂ nanoparticles were prepared by imparting octadecyltrichloro group on SiO₂ nanoparticles. The as-prepared superhydrophobic SiO₂ paper exhibted high water contact angle and low water sliding angle. Futhermore, the obtained superhydrophobic SiO₂ paper was found to be highly transparent and the visibility of the character on the paper was not changed after spray-coating the hydrophobic SiO₂ nanoparticles.

Keywords: Superhydrophobic paper; Transparent; SiO; ₂; nanoparticles; Contact angle

Influence of the carbon fiber surface microstructure on the surface chemistry generated by a thermo-chemical surface treatment by F. Vautard; S. Ozcan; F. Paulauskas; J.E. Spruiell; H. Meyer; M.J. Lance (pp. 473-480).

► Continuous thermo-chemical surface treatment used to functionalize different types of carbon fibers. ► Surface density of functional groups directly correlated to the size of the surface microstructure. ► Preferential creation of hydroxyls and carboxylic acids confirmed regardless of the type of carbon fiber. ► Effective surface treatment regardless of the fiber surface microstructure. ► Potential alternative to electro-chemical surface treatment.Carbon fibers made of textile and aerospace grade polyacrylonitrile precursor fibers were surface treated by a continuous gas phase thermochemical treatment. The surface chemistry generated by the surface treatment was characterized by X-ray photoelectron spectroscopy. The surface and the average entire microstructure of the fibers were characterized by Raman spectroscopy and X-ray diffraction, respectively. Depending on the grade of the precursor, the final surface concentration of oxygen was comprised between 14% and 24%, whereas the typical commercial electrochemical surface treatments led to concentrations of around 8% with the same fibers. The final concentration of oxygen was directly correlated to the size of the crystallites which was a function of the grade of the polyacrylonitrile precursor and to the corresponding surface microstructure. The thermochemical surface treatment enabled a better control of the nature of the oxygen-containing functionalities as well. Whatever the grade of the precursor, desired hydroxyl groups and carboxylic acid functionalities were preferably generated, which is observed to be difficult with electrochemical surface treatments.

Keywords: Carbon fiber; Surface chemistry; Surface functionalization; Interface adhesion

Structural, optical and chemical characterization of Rhodamine (B) doped poly (vinyl) alcohol films by J. Tripathi; J.M. Keller; K. Das; S. Tripathi; A. Fatima; T. Shripathi (pp. 481-487).

► Polyvinyl alcohol films were doped with a range of Rhodamine B concentrations. ► With increasing doping wt%, Rhodamine B XRD peaks appear. ► It reveals a change in crystallinity and breaking of bonds. ► Also results in modified optical properties morphology (FTIR measurements). ► XPS spectra show strong modifications as a result of doping.The results obtained on poly (vinyl) alcohol (PVA) films doped with a range of Rhodamine B concentrations are reported here. While Fourier transform infrared and X-ray photoelectron spectroscopy measurements show a drastic change in chemical bonding in PVA upon doping with a maximum concentration of 2wt%, X-ray diffraction pattern reveals a slight change in PVA lattice spacing, which may occur due to incorporation of bigger size nanocrystals of Rhodamine B dye. At this highest doping percentage, changes in the degree of crystallinity are also observed. The results are interpreted in terms of variations in vibrational frequencies of different CC, CO, CH and OH bonds in doped samples where the dye breaks the original bonds present in undoped PVA.

Keywords: Rhodamine (B); PVA; FTIR; XRD; XPS

Irradiation of the graphite-like carbon films by ns-laser pulse by Liutauras Marcinauskas; Alfonsas Grigonis; Pranas Valatkevicius; Artur Medvid (pp. 488-492).

► The ns-laser irradiation leads to the surface ablation and partial disarrangement of the graphite-like carbon coatings. ► The laser irradiation increases the fraction of the sp² carbon sites and lead to the formation nano-graphite structure. ► The GLC films reflectance decreases after laser irradiation.The effect of a nanosecond laser irradiation of graphite-like carbon (GLC) films deposited on Si substrate by the plasma jet technique was analyzed in this work. The GLC coatings were irradiated by the nanosecond Nd:YAG lasers operating at 1064nm (infrared (IR) radiation) and 532nm (visible (VIS) radiation), using a multi-shot regime. The laser irradiations lead to the surface ablation and partial disarrangement of the GLC coatings. The IR laser irradiation stimulates an increase in the fraction of the sp² carbon bonds and formation of the nano-graphite cluster. The formation of SiC and graphite nanocrystallites was observed after VIS laser radiation by 24MW/cm² energy density. FTIR results demonstrated that the reflectance of the laser irradiated carbon films decreases.

Keywords: Graphite-like carbon; Laser irradiation; Raman spectroscopy

Characterization and electrochemical properties of Ni(Si)/Ni₅Si₂ multiphase coatings prepared by HVOF spraying by M.M. Verdian; K. Raeissi; M. Salehi (pp. 493-498).

► Ni(Si)/Ni₅Si₂ multi-phase powders were produced by mechanical alloying. ► The phase composition of Ni(Si)/Ni₅Si₂ powders was preserved during HVOF spraying. ► Ni(Si)/Ni₅Si₂ coatings exhibited high microhardness values up to 746HV. ► Ni(Si)/Ni₅Si₂ coatings exhibited good corrosion behavior in NaCl solution.Ni(Si)/Ni₅Si₂ powders were produced by mechanical alloying (MA) of Ni–25at.% Si powder mixture. Then, the as-milled powders were sprayed onto copper substrate using high velocity oxy-fuel (HVOF) process. The phase composition and microstructure of the coatings were examined by X-ray diffractometry and scanning electron microscopy. Polarization tests and electrochemical impedance spectroscopy (EIS) measurements were also employed to study corrosion performance of the coatings in 3.5% NaCl solution. The results showed that although single phase Ni₃Si was formed during annealing of Ni(Si)/Ni₅Si₂ powders, but, only Ni(Si) and Ni₅Si₂ are present in HVOF coatings and no new phase has been formed during spraying. The coatings had microhardness up to 746HV_0.05. Further investigations showed the corrosion performance of multiphase coatings in 3.5% NaCl solution was better than that of copper substrate. The phase transitions during MA, HVOF and annealing processes were discussed in association with Ni–Si phase diagram and nature of each process.

Keywords: Mechanical alloying; Intermetallic, HVOF; Corrosion; Electrochemical impedance spectroscopy; Ni–Si

Functionalization of electrospun β-cyclodextrin/polyacrylonitrile (PAN) with silver nanoparticles: Broad-spectrum antibacterial property by Shan Wang; Jie Bai; Chunping Li; Jianbin Zhang (pp. 499-503).

► Novel PAN nanofibers contained β-cyclodextrin and Ag nanoparticles. ► The composite nanofibers as antibacterial material. ► The composite nanofibers showed stronger antibacterial activity.Polyacrylonitrile (PAN) nanofibers containing β-cyclodextrin (β-CD) and Ag nanoparticles have been prepared by electrospinning technology. The silver nanoparticles were obtained from the AgNO₃/PAN/DMF solution, in which AgNO₃ acted as the precursor, DMF as reducing reagent, and PAN as protective agent. Then, β-CD was added to above solution and the resultant Ag/β-CD-PAN/DMF solution was directly electrospun to prepare Ag/β-CD-PAN nanofibers. The morphology of the nanofibers has been characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The antimicrobial properties were investigated by Gram-positive Staphylococcus aureus ( S. aureus) and Gram-negative Escherichia coli ( E. coli) bacteria, and the results indicated that the composite nanofibers showed stronger antibacterial activity.

Keywords: Nanofibers; Silver nanoparticles; β-Cyclodextrin; Antibacterial property

Preparation and characterization of Fe₃O₄/graphene nanocomposite and investigation of its adsorption performance for aniline and p-chloroaniline by Yan-Ping Chang; Cui-Ling Ren; Ji-Chun Qu; Xing-Guo Chen (pp. 504-509).

.Display Omitted► Fe₃O₄/graphene nanocomposite was prepared by solvothermal method and characterized. ► Aniline and p-chloroaniline can be efficiently removed without adjusting pH. ► The adsorption obeyed pseudo-second-order kinetic model. ► The adsorption showed agreement with Freundlich isotherm model. ► Fe₃O₄/graphene nanocomposite was a suitable adsorbent for anilines.In the present study, Fe₃O₄/graphene nanocomposite was prepared by solvothermal method and characterized by transmission electron microscope, Fourier transform infrared spectrometer and vibration sample magnetometer. Effects of different factors, including initial solution pH, agitation time and adsorbate concentration, on adsorption capacity of Fe₃O₄/graphene nanocomposite for aniline and p-chloroaniline were investigated. Experimental results demonstrated aniline and p-chloroaniline could be effectively removed from aqueous solution by Fe₃O₄/graphene nanocomposite within 60min without adjusting solution pH. The adsorption of aniline and p-chloroaniline onto Fe₃O₄/graphene nanocomposite obeyed pseudo-second-order kinetic model and Freundlich isotherm model. The saturation magnetization of the Fe₃O₄/graphene nanocomposite was about 120emug⁻¹, which ensured the convenient magnetic separation after adsorption.

Keywords: Fe; ₃; O; ₄; /graphene nanocomposite; Aniline removal; p; -Chloroaniline removal; Adsorption kinetics; Adsorption isotherm

Preparation and characterization of Sb₂Se₃ thin films by electrodeposition and annealing treatment by Yanqing Lai; Zhiwei Chen; Can Han; Liangxing Jiang; Fangyang Liu; Jie Li; Yexiang Liu (pp. 510-514).

► Sb₂Se₃ thin films were prepared by electrodeposition and post annealing. ► The prepared Sb₂Se₃ films possess orthorhombic structure and p-type conduction. ► The Sb₂Se₃ films have proper optical and electrical properties for solar cells.Antimony selenide (Sb₂Se₃) thin films were prepared on SnO₂ coated glass substrates from acidic aqueous solution by potentiostatic electrodeposition and then post annealed at 300°C in Ar atmosphere. Cyclic voltammetry (CV), energy dispersive X-ray spectroscopy (EDS), and environmental scanning electron microscope (ESEM) studies were performed on as-deposited Sb₂Se₃ thin films to obtain suitable electrodeposition conditions. The annealed film shows improved crystallinity with a basic structure of orthorhombic Sb₂Se₃, and exhibits an optical absorption coefficient of higher than 10⁵cm⁻¹ in the visible region and an optical band gap of 1.04±0.01eV. Photoelectrochemical (PEC) tests confirm the p-type conductivity and good photovoltaic conversion characteristics of the annealed film.

Keywords: Sb; ₂; Se; ₃; Thin films; Electrodeposition; Annealing; Solar cells

Molten salt synthesis and characterization of Li₄Ti5−_xMn_xO₁₂ ( x=0.0, 0.05 and 0.1) as anodes for Li-ion batteries by V.D. Nithya; R. Kalai Selvan; Kumaran Vediappan; S. Sharmila; Chang Woo Lee (pp. 515-519).

► Submicron sized Mn doped Li₄Ti₅O₁₂ crystals were prepared by simple molten salt method. ► The detailed structural, morphological and electrochemical studies were carried out. ► The charge–discharge study reveals that Li₄Ti_4.9Mn_0.1O₄ possesses a better discharge capacity (305mAh/g) than both Li₄Ti_4.95Mn_0.05O₁₂ (265mAh/g) and Li₄Ti₅O₁₂ (240mAh/g). ► The low charge transfer resistance was obtained for Li₄Ti_4.9Mn_0.1O₄ than its pristine LTO.Sub-micrometer sized Li₄Ti5−_xMn_xO₁₂ ( x=0.0, 0.05 and 0.1) particles were synthesized by a single step molten salt method using LiCl–KCl as a flux. The synthesized material was structurally characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra. The XRD analysis revealed the particles to be highly crystalline and have a face-centered cubic spinel structure. The presence of possible functional group was confirmed through FTIR analysis. The FE-SEM images showed the particles to be polyhedral in shape with uniform size distribution. It was also revealed that there was a particle size reduction with the effect of Mn⁴⁺ dopant ions. The electrochemical studies performed using cyclic voltammogram (CV), charge–discharge, and electrochemical impedance analysis (EIS) indicate that Li₄Ti_4.9Mn_0.1O₄ possesses a better discharge capacity (305mAh/g), cycling stability, and charge carrier conductivity than both Li₄Ti_4.95Mn_0.05O₁₂ (265mAh/g) and Li₄Ti₅O₁₂ (240mAh/g). The cycling stability reveals that the acceptable capacity fading was observed even after 20th cycle. The results of electrochemical studies infer that Li₄Ti_4.9Mn_0.1O₄ could be utilized as a suitable anode material for Li-ion batteries.

Keywords: Ceramics; Anodes; Lithium titanate; X-ray diffraction; Li-ion batteries

A comparative study on wear behavior of TiN and diamond coated WC–Co substrates against hypereutectic Al–Si alloys by Chakravarthy G.V.; Maneesh Chandran; S.S. Bhattacharya; M.S. Ramachandra Rao; M. Kamaraj (pp. 520-527).

► Wear behaviors of diamond/WC–Co, TiN/WC–Co and WC–Co against Al–Si were studied. ► Both TiN and diamond coatings were done using chemical vapor deposition technique. ► Friction and sliding wear properties were characterized using a pin-on-disc method. ► Diamond coated WC–Co pins showed one order less wear loss than bare WC–Co pins. ► A weight gain was observed for the TiN coated WC–Co pins. ► Average coefficient of friction was lowest for the diamond coated WC–Co pins.The demand for better tools for machining hypereutectic aluminum–silicon (Al–Si) alloys are increasing day by day since the extensive use of these alloys in internal combustion engines. In addition to the lifetime of the machining tool, surface finish of the machined piece is also equally important, as it directly affects the performance of the engine. In this paper, we compared the wear behavior of bare tungsten carbide (WC–Co), titanium nitride (TiN) coated WC–Co and diamond coated WC–Co substrates against Al–Si alloys using pin-on-disc method. Both TiN and diamond coatings were done using chemical vapor deposition technique. Diamond coated WC–Co substrates show one order less wear loss compared to the bare WC–Co substrates. Instead of weight loss, a weight gain was observed for the TiN coated WC–Co substrates. Average coefficient of friction was lowest for the diamond coated WC–Co substrates due to the different wear behavior of diamond coated tribological system, which is explained in detail.

Keywords: Diamond films; CVD TiN; Hot filament CVD; Wear; Al–Si alloys

Manipulating poly(lactic acid) surface morphology by solvent-induced crystallization by Jian Gao; Lingyan Duan; Guanghui Yang; Qin Zhang; Mingbo Yang; Qiang Fu (pp. 528-535).

Display Omitted► PLA crystal morphologies can be tuned by adjusting acetone/ethanol ratio. ► Beautiful PLA shish–kebab crystals can be easily observed using SEM. ► Fractured surface is important for the morphological evolution of PLA surface.Here, we report some unique crystalline morphologies of poly(lactic acid) (PLA) via organic solvent-induced crystallization. It was revealed that the surface morphology of PLA can be fine tuned by simply varying the volume ratio of a mixed solvent (acetone/ethanol). By increasing the ethanol content in the mixed solvent, we observed a morphological evolution of PLA surface from spherulite to shish–kebab and bamboo-cage-like structure. It was also interesting to find that the initial surface structure of PLA plays an important role to determine the final solvent-induced crystalline morphology. This work provides a new method for manipulating PLA crystal morphology through a simple solvent-induced crystallization.

Keywords: Poly(lactic acid); Solvent-induced crystallization; Morphology; Surface structure

Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants by Abdalla Abdal-hay; Montasser Dewidar; Jae Kyoo Lim (pp. 536-546).

► The corrosion behavior of magnesium for orthopedic applications is extremely poor. ► The solvent (DCM, THF and DMF) had a strong effect on the coatings performance. ► Mg bar alloy coated with PVAc/DCM layers provided an excellent bonding strength. ► Treated samples indicated significant damping for the degradation rate. ► Cytocompatibility on MC3T3 cells of the PVAc/DCM samples revealed a good behavior.The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc–solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

Keywords: Polyvinyl acetate; Adhesion; Dip-coatings process; Cytotoxicity; Degradation

Fractal and multifractal analysis of LiF thin film surface by R.P. Yadav; S. Dwivedi; A.K. Mittal; M. Kumar; A.C. Pandey (pp. 547-553).

► Fractal and multifractal analysis of surface morphologies of the LiF thin films. ► Complexity and roughness of the LiF thin films increases as thickness increases. ► LiF thin films are multifractal in nature. ► Strength of the multifractality increases with thickness of the film.Fractal and multifractal analysis is performed on the atomic force microscopy (AFM) images of the surface morphologies of the LiF thin films of thickness 10nm, 20nm, and 40nm, respectively. Autocorrelation function, height–height correlation function, and two-dimensional multifractal detrended fluctuation analysis (MFDFA) are used for characterizing the surface. It is found that the interface width, average roughness, lateral correlation length, and fractal dimension of the LiF thin film increase with the thickness of the film, whereas the roughness exponent decreases with thickness. Thus, the complexity and roughness of the LiF thin films increases as thickness increases. It is also demonstrated that the LiF thin films are multifractal in nature. Strength of the multifractality increases with thickness of the film.

Keywords: LiF thin film; Height–height correlation; MFDFA; Fractal analysis; Multifractal analysis

Inkjet printing of silver citrate conductive ink on PET substrate by Xiaolei Nie; Hong Wang; Jing Zou (pp. 554-560).

► A direct synthesis method of silver conductive film on PET substrate was presented. ► A stable particle-free conductive ink was prepared. ► Formation of silver-amine complex reduced the thermal decomposition temperature. ► Conductive patterns for flexible electronics were fabricated by inkjet printing. ► Silver film on PET substrate possessed highest adhesion rating even without polymer.Direct synthesis of silver conductive film on PET substrate by inkjet printing silver citrate conductive ink was presented in this paper. This kind of conductive ink contained silver citrate as silver precursor, 1,2-diaminopropane as complex agent dissolving the silver salt and methanol and isopropanol as a media adjusting the viscosity and surface tension. The formation of silver-amine complex reduced the decomposition temperature from 180°C to 135°C, thus the ink could be cured at relatively low temperature. The film reached the lowest resistivity of 17μΩcm after cured at 150°C for 50min, 3.1μΩcm at 230°C and possessed high reflection and excellent adhesive property. Electrical conductivity, surface morphology and composition were investigated by four-point probe method, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). It is demonstrated how the cured condition affects the silver film. Moreover, radio-frequency identification (RFID) antenna was fabricated by inkjet printing, which opens up routes for the flexible electronics fabrication.

Keywords: Silver citrate; Conductive ink; Inkjet printing; Flexible electronics

A facile method to fabricate superhydrophobic cotton fabrics by Ming Zhang; Shuliang Wang; Chengyu Wang; Jian Li (pp. 561-566).

. The superhydrophobic cotton fabric surface was synthesized by layer-by-layer self-assembly deposition of cationic Poly(dimethyldiallylammonium chloride) and negative charged silica particles, followed with the modification of (heptadecafluoro-1,1,2,2-tetradecyl)trimethoxysilane reagent. The water contact angle of the superhydrophobic cotton fabric surface reached the maximum of 157°.Display Omitted► The fabrication route of superhydrophobic cotton fabric is facile and novel. ► The cotton fabric surface with superhydrophobicity was obtained by a layer-by-layer self-assembly procedure. ► The wettability of cotton fabric surface has been transformed from superhydrophilic to superhydrophobic. ► Superhydrophobic cotton surface showed an excellent stability after exposure, immersion and washing tests. ► The superhydrophobic method may contribute to accelerate the large-scale usage of cotton fabrics resource.A facile and novel method for fabricating superhydrophobic cotton fabrics is described in the present work. The superhydrophobic surface has been prepared by utilizing cationic poly (dimethyldiallylammonium chloride) and silica particles together with subsequent modification of (heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane. The size distribution of silica particles was measured by Particle Size Analyzer. The cotton textiles before and after treatment were characterized by using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The wetting behavior of cotton samples was investigated by water contact angle measurement. Moreover, the superhydrophobic durability of coated cotton textiles has been evaluated by exposure, immersion and washing tests. The results show that the treated cotton fabrics exhibited excellent chemical stability and outstanding non-wettability with the WCA of 155±2°, which offers an opportunity to accelerate the large-scale production of superhydrophobic textiles materials for new industrial applications.

Keywords: Superhydrophobic; Layer-by-layer self-assembly deposition; Cotton fabrics; Poly-DMDAAC aqueous solution; Silica nanoparticles

Effects of minor elements in Al alloy on zincate pretreatment by Shinnosuke Egoshi; Kazuhisa Azumi; Hidetaka Konno; Ken Ebihara; Yoshihiro Taguchi (pp. 567-573).

► Contribution of Cu and Si in Al alloy to the plating process was clarified. ► 55ppm Cu and a small % of Si considerably improves the zincate process. ► Cu pretreatment significantly improves the zincate process of Al–Si alloy.The effects of minor elements in Al alloys on Zn deposition during double zincate pretreatment were investigated using four Al alloys: Al foil containing ca. 55ppm Cu (Al(Cu)), Al–1%Si (Al(Si)), 99.99% Al (Al(4N)) and 99.999% Al (Al(5N)). SEM images showed that a uniform Zn layer was deposited on Al(Cu) and Al(Si) but not on Al(4N) or Al(5N) after the double zincate process. Immersion potential during the zincate process indicated that the duration of substitution reaction of Zn deposition and Al dissolution on Al(Cu) was shorter than that on the other alloys. These results suggest that a small amount of Cu increases the efficiency of the zincate process and the density of Zn deposition. Etching pretreatment of alloys in sulfuric acid containing Cu²⁺ ions before zincate pretreatment dramatically improved the uniformity and efficiency of Zn deposition on Al(Si) but not on Al(4N) or Al(5N), indicating that small and dispersed Cu particles were deposited efficiently on the Al(Si) alloy and provided Zn nucleation sites. From the results, it was concluded that the activity level of native Al for the zincate process is considerable low and is thus dramatically affected by alloying or surface modification with a small amount of electrochemically active elements.

Keywords: Double zincate; Cu pretreatment; Alloy composition

Sulfonated mesoporous silica–carbon composites and their use as solid acid catalysts by Patricia Valle-Vigón; Marta Sevilla; Antonio B. Fuertes (pp. 574-583).

.Display Omitted► Sulfonic functionalized mesoporous silica–carbon composites have been synthesized. ► The silica pores are uniformly coated by a thin SO₃H doped carbon layer. ► These materials contain a large number of strong acid sites situated in accessible mesopores. ► The usefulness of these solid acids as catalysts has been demonstrated for esterification reactions.The synthesis of highly functionalized porous silica–carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica ( i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica–carbon composites contain ∼30wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon ( i.e.SO₃H,COOH andOH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica–carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

Keywords: Silica; Carbon; Composite; Mesoporous; Sulfonation; Solid acid; Catalyst; Esterification

Composition versus friction and wear behavior of plasma sprayed WC–(W,Cr)₂C–Ni/Ag/BaF₂–CaF₂ self-lubricating composite coatings for use up to 600°C by Jianmin Chen; Guoliang Hou; Jie Chen; Yulong An; Huidi Zhou; Xiaoqin Zhao; Jie Yang (pp. 584-592).

► WC–(W,Cr)₂C–Ni/Ag/BaF₂–CaF₂ self-lubricating coatings can be used up to 600°C. ► Optimum content of solid lubricants is 15wt.% Ag and 15wt.% eutectic. ► Solid lubricants can reduce friction coefficient ( μ) over a wide temperature range. ► Wear volume of counterpart ball is closely related to μ and transfer film.This paper reports the composition optimization of self-lubricating composite coatings containing WC–(W,Cr)₂C–Ni, silver and fluoride eutectics. Various ingredients obtained by powder blending were studied to determine their optimum content in as-prepared composite coatings. An atmospheric plasma spraying (APS) system was used to deposit promising WC–(W,Cr)₂C–Ni/Ag/BaF₂–CaF₂ self-lubricating composite coatings. The friction and wear behavior of the composite coatings sliding against Si₃N₄ ball was investigated from room temperature to 600°C. Results show that silver and fluoride eutectics can effectively reduce the friction coefficient of the coatings and the wear volume loss of counterpart balls over the whole temperature range. Thanks to the highest hardness, WC–(W,Cr)₂C–Ni coating without silver and fluoride eutectics has the lowest wear rate at room temperature and 600°C. However, it has a high friction coefficient and a very high wear rate at 200 and 400°C, due to severe adhesion wear and fatigue wear thereat. Fortunately, introducing appropriate amount of silver and fluoride eutectics contributes to effectively reduce the wear rate of the composite coatings at 200 and 400°C. The optimized composite coating consists of 70wt.% WC–(W,Cr)₂C–Ni, 15wt.% Ag and 15wt.% BaF₂/CaF₂, and it has excellent friction and wear performance over a wide range of temperature.

Keywords: Atmospheric plasma spraying; WC–(W,Cr); ₂; C–Ni; BaF; ₂; /CaF; ₂; Ag; Self-lubricating composite coating; Composition optimization; Friction and wear behavior

Preparation, characterization and photocatalytic activities of ZrWMoO₈/Ag composites with core–shell structure by Qinqin Liu; Shuai Sun; Haohua Li; Xiaofei Yang; Hao Shen; Xiaonong Cheng; Shubin Dong (pp. 593-597).

. ZrWMoO₈ rods with negative thermal expansion and ZrWMoO₈/Ag composites with core–shell structure were first proved to exhibit photocatalytic activity under UV-irradiation.Display Omitted► ZrWMoO₈ rods with negative thermal expansion property were first studied for its photocatalytic activity. ► ZrWMoO₈/Ag composites with core–shell structure were prepared using a simple reduction method. ► Improved photocatalytic activity was found in the ZrWMoO₈/Ag heterostructures. ► The ZrWMoO₈/Ag heterostructure promotes the separation of electron–hole pairs and enhances the photocatalytic activity.A novel photocatalytic ZrWMoO₈/Ag composite with core–shell structure was prepared. The composites were composed of ZrWMoO₈ rods with negative thermal expansion (NTE) property as cores and Ag nanoparticles as shell. The resulting products were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–visible spectrophotometer (UV–vis DRS). The results showed that ZrWMoO₈ rods displayed not only negative thermal expansion but also photocatalytic efficiency toward Rhodamine B (RB) degradation under UV-irradiation. The as-prepared ZrWMoO₈/Ag composites exhibited a higher photocatalytic activity than that of pure ZrWMoO₈, thereby implying that the ZrWMoO₈/Ag interfaces promote the separation of photogenerated electron–hole pairs and enhance the photocatalytic activity.

Keywords: ZrWMoO; ₈; /Ag composites; Core–shell; Negative thermal expansion; Photocatalysis

Chemical and biochemical activities of sonochemically synthesized poly(N-isopropyl acrylamide)/silica nanocomposite by Pranesh Chowdhury; Swadhin Kr Saha; Arun Guha; Samar Kr Saha (pp. 598-604).

Display Omitted► Synthesized novel polymer mesoporous silica nanocomposite sonochemically.► Minimized organic solvents and additives (Green approach).► Encapsulation increased the stability, functionality and utility of the product.► Nanocomposite exhibits pH sensitivity, antibacterial activity and biocompatibility.Poly(N-isopropyl acrylamide) (PNIPA) grafted mesoporous silica nanoparticles (MPSNP) leading to novel inorganic/organic core–shell nanocomposite has been synthesized sonochemically in an aqueous medium without additives like cross-linker, hydrophobic agent, organic solvent. The colloidal stability of MPSNP is enhanced significantly due to encapsulation of the polymer. The composites are characterized by TEM, FTIR and TGA. The chemical and biochemical activities of the sonochemically synthesized materials have been studied in the light of reaction with acid–base, protein adsorption, antimicrobial activity, biocompatibility and nonthrombogenic property. Advantages of sonochemical synthesis compared to other techniques have been evaluated.

Keywords: Silica nanoparticles; Ultrasound; Polymer grafting; Nanocomposite; Bioactivity

Hot spots engineering in hierarchical silver nanocap array for surface-enhanced Raman scattering by Jun Wang; Liqing Huang; Lipeng Zhai; Lin Yuan; Lihua Zhao; Weiwei Zhang; Dongzhi Shan; Aiwen Hao; Xuehong Feng; Jian Zhu (pp. 605-609).

Display Omitted► Rapid and room-temperature method to fabricate hierarchical Ag array is proposed. ► Arrays consist of submicrosized ordered caps with nanoscale Ag particles on surface. ► Controlling Ag deposition thickness leads to various surface roughnesses. ► Both optical property and SERS activity display non-monotonic behaviors. ► Hot spots engineering on three-dimensional curved surface is facilely achieved.We proposed a rapid, simple and room-temperature method to fabricate hierarchical silver nanocap arrays, in which hot spots could be facilely engineered on three-dimensional curved surface. Both optical property and surface-enhanced Raman scattering (SERS) activity displayed non-monotonic Ag thickness dependence. Furthermore, the simulation results obtained by finite-difference time-domain (FDTD) method reveal that hot spots intensity and density on three-dimensional curved surface significantly vary and strongly depend on deposited Ag thickness. The investigation opens a possibility for facile fabrication of SERS substrate with promising hot spot engineering on three-dimensional surface and extremely high SERS activity.

Keywords: Surface-enhanced Raman scattering (SERS); Hot spots; Finite-difference time-domain (FDTD); Hard anodization (HA); Nanocap arrays

Effect of the nanoscratch resistance of indium nitride thin films in the etching duration by Wen-Nong Hsu; Teng-Shih Shih (pp. 610-615).

► We evaluated the tribological properties of InN films/AlN buffer/Si. ► The measured values of friction upon increasing the etching duration. ► Low In–N density of InN films at longer etching duration to decay resistance and plastic deformation.This study present the nanotribological behavior of single-crystalline indium nitride (InN) films onto aluminum nitride (AlN) buffer layers on Si(111) substrates. The surface morphology and friction ( μ) were analyzed using atomic force microscopy and nanoscratch system. It is confirmed that the normal force ( F_n) measured values of μ of the InN films, from 10 to 60min of etching duration, were in the range from 0.2 to 0.43 for F_n=2000μN; 0.25 to 0.58 for F_n=6000μN, respectively. It is suggested that the measured values of μ is slightly increased based on the etching duration due to the etching effect on the grain boundary and reduce film quality of InN films. From morphological observations, we compared the sliding resistance against contact-induced damage of the InN films in the presented ploughed of the area. It is confirmed that the contact sliding line is observable due to the increased F_n, the following investigation with friction curve and lateral force is studied.

Keywords: Indium nitride; Molecular beam epitaxy; Friction; Nanoscratch

The study of palladium ions incorporation into the mesoporous ordered silicates by M. Zienkiewicz-Strzałka; S. Pikus (pp. 616-622).

Display Omitted► Palladium containing mesoporous ordered silica were synthesized and characterized. ► Detailed analysis of chemical bonding between palladium and silica was performed. ► Proposed procedure allows to obtain materials where palladium is binding with silicon and oxygen atoms.In this work mesoporous ordered silica materials containing palladium species were prepared using of tetraammine palladium chloride ([Pd(NH₃)₄]Cl₂) complex as a palladium source during synthesis and by wetness impregnation of pure support by solution containing dissolved metal salt. The ammonia ligands from tetraammine palladium chloride were removed during calcination or during thermal treatment at 300°C in oxygen atmosphere. For reduction of palladium ions to metallic state as prepared materials were treated by hydrogen at high temperature. In this work the locations of palladium atoms in silica lattice were considered by study of binding energy changes of cardinal atoms of mesoporous ordered silica.Ordered mesoporous silicates (MCM-41 and SBA-15) are very promising materials for a wide range of industrial applications due to their unique properties as well-defined ordered structure and excellent textural properties. They exhibit high surface area with high pore volume. Such supports ensure a high dispersion of the metal nanoparticles or other active phases providing the high activity of solid catalysts.The obtained materials were characterized primarily by X-ray diffraction (XRD) technique, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms, and infrared spectroscopy. The proportional content of palladium was controlled by X-ray fluorescence technique.

Keywords: Palladium; Pd/SBA-15; Mesoporous silica; Tetraammine palladium

Synthesis of PbSO₄ crystals by hydrogel template on postprocessing strategy for secondary pollution by Bing Han; Anjian Xie; Qingbo Yu; Fangzhi Huang; Yuhua Shen; Ling Zhu (pp. 623-627).

► A postprocessing strategy for Pb²⁺ ions secondary pollution was proposed. ► Hydrogel was introduced to capture Pb²⁺ ions at suitable conditions. ► The Pb²⁺-adsorbed hydrogel was used as template to induce the formation of PbSO₄. ► The branch-type PbSO₄ crystals were synthesized successfully.Pb²⁺ ions pose a significant threat to the environment and public health. Removal and reuse of Pb²⁺ ions from the environment are major focuses of waste treatment. Here the poly(acrylonitrile-acrylamide-acrylic acid) hydrogel prepared via crosslinking polymerization was introduced to capture Pb²⁺ ions, then as an in situ template to induce the formation of PbSO₄ crystals with special morphology successfully. The absorption efficiency of Pb²⁺ ions by hydrogel was tested. The results show at the conditions of initial pH 5, 25°C, 1.578mg Pb²⁺ ions was removed by per unit hydrogel mass. PbSO₄ crystals were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, transmission electron microscopy, and fluorescence spectrometer. The results indicate that the branch-type structure crystals were excellent crystalline and mainly oriented along (101) and (231) plane. The PL spectrum show emission peaks at 380 and 400nm and indicate that the product may have applications in an electronic light device. This approach provides an inspiration on the post-processing of the secondary pollution.

Keywords: Postprocessing; Hydrogel; Adsorption; PbSO; ₄; Template

Facile approach in fabricating superhydrophobic SiO₂/polymer nanocomposite coating by Hengzhen Chen; Xia Zhang; Pingyu Zhang; Zhijun Zhang (pp. 628-632).

► Fluorine-free superhydrophobic SiO₂/polymer composite coatings are fabricated by a simple spin-coating method without any surface chemical modification. ► The SiO₂/polymer coatings show long-term stability in the condition of continuous contact with corrosive water. ► The coating can be fabricated on various metal substrates to prevent metal from corrosion.We have developed a facile spin-coating method to prepare water-repellent SiO₂/polymer composite coating without any surface chemical modification. The wettability can be adjusted by controlling the content of SiO₂ nanoparticles. The coating demonstrates sustainable superhydrophobicity in the condition of continuous contact with corrosive liquids. Importantly, the coating can be fabricated on various metal substrates to prevent metal from corrosion.

Keywords: Superhydrophobic; Polymer; SiO; ₂; Coating

Effects of ultrathin layers on the growth of vertically aligned wurtzite ZnO nanostructures on perovskite single-crystal substrates by Yuan-Chang Liang; Chia-Yen Hu; Hua Zhong (pp. 633-639).

► ZnO nanostructures with various degrees of vertical alignment were grown on (100) SrTiO₃ substrates by thermal evaporation. ► The as-synthesized ZnO nanostructures have a hexagonal facet. ► The metal catalysis plays a crucial role in the synthesis of high-quality vertically aligned ZnO nanostructures on SrTiO₃ substrates.In this study, ZnO nanostructures were grown on various ultra-thin layers coated (100)-oriented SrTiO₃ (STO) single-crystal substrates using thermal evaporation of metallic zinc at 600°C. This study used the ZnO seed layer and/or metal catalyst layer to grow high-density ZnO nanostructures on STO substrates. X-ray diffraction and scanning electron microscopy (SEM) measurements showed that the use of Au and Ag catalysts is crucial in producing ZnO nanostructures with a preferential c-axis direction. The as-grown ZnO nanostructures had a hexagonal facet. Among various STO substrates (Au/STO, Ag/STO, ZnO/STO, Au/ZnO/STO, and Ag/ZnO/STO), the ZnO nanostructures grown on the Au/STO substrate had the highest degree of vertical alignment, and the intensity ratio of the UV to visible emission band reached 55. Conversely, the ZnO nanostructures grown on the ZnO seed layer-coated STO substrate were more randomly oriented, and the intensity ratio of the UV to visible emission band was only 9.5. The cathodoluminescence (CL) results showed that higher vertically aligned ZnO nanostructures have lower-density crystal defects. The current–voltage measurements supported the structural analysis.

Keywords: Perovskite; Thin films; Morphology; Microstructure

Can methanol be synthesized from CO by direct hydrogenation over Cu/ZnO catalysts? by Zhi-Jun Zuo; Pei-De Han; Zhe Li; Jian-Shui Hu; Wei Huang (pp. 640-646).

► DFT method was used to examine methanol synthesis from low Cu coverage on ZnO. ► The charge of Cu transfers into the ZnO carrier with low Cu coverage on ZnO. ► Cu valency is greater than zero and less than one. ► The rate-limiting step of methanol formation is CHO hydrogenation.Methanol synthesis from CO by direct hydrogenation has been studied using the density-functional theory (DFT). The charge of Cu has been found to be transferred to the ZnO carrier having low Cu cover. Due to the electron-charge transfer between the metallic Cu and the ZnO carrier, the Cu valency is greater than zero and less than one. Consideration of the water-gas-shift reaction and hydrogenation of CO₂ to CHOO and COOH, the result shows that the active sites for the synthesis of methanol from CO₂ and CO are different. Methanol is synthesized from CO by direct hydrogenation over Cu δ⁺ (0< δ<1) species through the intermediates CHO, CH₂O, and CH₃O, and the rate-limiting step is the hydrogenation of CHO, indicating that the Cu δ⁺ (0< δ<1) species comprise the active sites for the synthesis of methanol from CO by direct hydrogenation.

Keywords: Density-functional theory; Cu/ZnO; (; 1; 0; 1; ¯; 0; ); CH; ₃; OH; CO hydrogenation

Peculiarities of iron-containing microplasma coating deposition on aluminum in homogeneous electrolyte by A.B. Rogov; A.I. Slonova; V.R. Shayapov (pp. 647-652).

► Alkaline homogeneous electrolyte with Fe–EDTA complexes. ► Changes of coating morphology and discharges collective during microplasma synthesis. ► Discharges spectral characterization.In this paper the dynamics of microplasma iron-containing coating synthesis on aluminum A1050 alloy is reported. It is found that formation of iron-containing phases in the coating occurs with participation of microarc discharges rather than sparks. Comparison of the coating and corresponding microdischarges collective at different process duration is reported. It is shown that during the process the coating contains two regions with different morphology and composition. Discharge light was investigated by emission spectroscopy. Coatings were characterized by X-ray phase analysis, SEM with energy dispersive analyzer as well as by total iron chemical analysis.

Keywords: Microplasma; Iron-containing coating; Homogeneous electrolyte; Fe–EDTA complexes

Photoluminescence and reflectivity of polymethylmethacrylate implanted by low-energy carbon ions at high fluences by Jun Wang; Fei Zhu; Bei Zhang; Huixian Liu; Guangyi Jia; Changlong Liu (pp. 653-658).

► Photoluminescence was studied in carbon implanted polymethylmethacrylate (PMMA). ► A significant photoluminescence enhancement occurred at ion fluence of 5×10¹⁶cm⁻². ► Photoluminescence and Raman responses revealed carbon nanoclustered structures. ► Reflectivity of carbon implanted PMMA depended on both ion fluence and wavelength. ► A noticeable reflectivity modification appeared at ion fluence of 1×10¹⁶cm⁻².Polymethylmethacrylate (PMMA) specimens were implanted with 30keV carbon ions in a fluence range of 1×10¹⁶ to 2×10¹⁷cm⁻², and photoluminescence (PL) and reflectivity of the implanted samples were examined. A luminescent band with one peak was found in PL spectra excited by 480nm line, but its intensity did not vary in parallel with ion fluence. The strongest PL occurred at the fluence of 5×10¹⁶cm⁻². Results from visible-light-excited micro-Raman spectra indicated that the formation of hydrogenated amorphous carbon structures in subsurface layer and their evolutions with ion fluence could be responsible for the observed PL responses. Measurements of the small-angle reflectance spectra from both the implanted and rear surfaces of samples in the ultraviolet–visible (UV–vis) range demonstrated a kind of both fluence-dependent and wavelength-related reflectivity variations, which were attributed to the structural changes induced by ion implantation. A noticeable reflectivity modification, which may be practically used, could be found at the fluence of 1×10¹⁶cm⁻².

Keywords: Carbon ion implantation; Polymethylmethacrylate; Photoluminescence; Reflectivity; Micro-Raman; Hydrogenated amorphous carbon

Density functional study of adsorption properties of NO and NH₃ over CuO/γ-Al₂O₃ catalyst by Fan Cao; Sheng Su; Jun Xiang; Lushi Sun; Song Hu; Qingsen Zhao; Pengying Wang; Siyuan Lei (pp. 659-664).

► The adsorption behaviours of NO and NH₃ on the dry and partially hydroxylated γ-Al₂O₃ (110) surfaces are different. ► NH₃ could be adsorbed on Lewis and Brønsted acid sites and undergo hydrogen abstraction. ► NO could be adsorbed as bidentate nitrates or bridged nitrites. ► CuO supported on the partially hydroxylated γ-Al₂O₃ (110) surface could hardly affect the adsorption of NH₃ on the nearby active sites.Currently, selective catalytic reduction (SCR) of NO_x with NH₃ has been widely applied to reduce the emission of nitrogen oxides from mobile and stationary sources. But the detailed SCR reaction mechanism is still controversial and lacks the related comparative study of molecule modeling. The SCR reaction belongs to the gas–solid multiphase reaction, in which the adsorption of NH₃ and NO by the catalysts plays an important role. In the present study, the adsorption properties of NH₃ and NO on both the dry and partially hydroxylated γ-Al₂O₃ (110) surfaces supported CuO were revealed using the density-function theory (DFT) calculations. The results showed that NH₃ could be adsorbed strongly on the dry (110) surface in the form of coordinated NH₃ and NH₄⁺. Some of the coordinated NH₃ could then undergo H-abstraction and form the –NH₂ species. NO could be adsorbed weakly on the dry surface, and could also be adsorbed as bidentate nitrates or bridged nitrites. However, the adsorption activation of NH₃ and NO on the partially hydroxylated surface was much weaker. The results of the DFT calculations are in good agreement with the experimental results and provided detailed clues to understand the adsorption mechanism of NH₃ and NO on the CuO/γ-Al₂O₃ catalysts.

Keywords: CuO/γ-Al; ₂; O; ₃; SCR; Adsorption; Density functional theory (DFT)

The preparation and cathodoluminescence of ZnS nanowires grown by chemical vapor deposition by Meng-Wen Huang; Yin-Wei Cheng; Ko-Ying Pan; Chen-Chuan Chang; F.S. Shieu; Han C. Shih (pp. 665-670).

► ZnS nanowires have been achieved by thermal evaporation. ► The nanowires were 20–50nm in diameter and up to tens of nanometers in length. ► Single-crystalline wurtzite and sphalerite ZnS phase are coexist in the nanowires. ► The ZnS nanowires showed almost identical blue luminescence at room temperature. ► ZnS nanowires may be appropriate for use in UV/blue LED phosphor materials.Single crystal ZnS nanowires were successfully synthesized in large quantities on Si (100) substrates by simple thermal chemical vapor deposition without using any catalyst. The morphology, composition, and crystal structure were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and cathodoluminescence (CL) spectroscopy. SEM observations show that the nanowires have diameters about 20–50nm and lengths up to several tens of micrometers. XRD and TEM results confirmed that the nanowires exhibited both wurtzite and zinc blende structures with growth directions aligned along [0002] and [111], respectively. The CL spectrum revealed emission bands in the UV and blue regions. The blue emissions at 449 and ∼581nm were attributed to surface states and impurity-related defects of the nanowires, respectively. The perfect crystal structure of the nanowires indicates their potential applications in nanotechnology and in the fabrication of nanodevices.

Keywords: Zinc sulfide; Nanowires; X-ray photoelectron spectrometer; Cathodoluminescence

Characterization of Pd catalyst-electrodes deposited on YSZ: Influence of the preparation technique and the presence of a ceria interlayer by Carmen Jiménez-Borja; Florina Matei; Fernando Dorado; José Luis Valverde (pp. 671-678).

► Impregnation of palladium over YSZ led to more dispersed films. ► XPS spectra indicated electron deficient Pd²⁺ species on the surface of palladium films. ► Impregnated palladium films were more active than those prepared by paste deposition ► The addition of a CeO₂ interlayer enhanced the catalytic rate for the impregnated samples.Palladium catalyst-electrodes supported on Y₂O₃-stabilized-ZrO₂ (YSZ) prepared either by paste deposition or wet impregnation technique were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found a strong dependence of the catalytic film preparation technique as well as of the presence of a ceria interlayer between the palladium film and the solid electrolyte on the catalytic activity towards methane oxidation. Impregnated palladium films were found to be more active than films prepared by paste deposition. Besides, the addition of ceria allowed stabilizing the palladium active phase for methane oxidation.

Keywords: Palladium catalyst-electrodes; YSZ; Ceria interlayer; Metal–support interactions; Methane combustion; EPOC

Polishing and local planarization of plastic spherical capsules using tumble finishing by T.I. Suratwala; W.A. Steele; M.D. Feit; K. Moreno; M. Stadermann; J. Fair; K. Chen; A. Nikroo; K. Youngblood; K. Wu (pp. 679-689).

► Tumble finishing method for achieving local planarization on capsules is performed. ► Domes surface defects were observed to locally planarize after polishing. ► A material removal model based on spherical–spherical Hertzian contacts is described. ► A dome convergence model based on workpiece–lap mismatch is described. ► The calculated evolution of isolated domes compare well with the experimental data.A new method (a variant of tumble finishing) for polishing and achieving local planarization on precision spherical, plastic capsules is described. Such capsules have niche applications, such as ablators used in high-peak-power laser targets for fusion energy research. The as-manufactured ablators contain many shallow domes (many 100's of nm high and a few 10's of μm wide) on the outer surface which are undesirable due to contributions to instabilities during implosion. These capsules were polished (i.e., tumble finished) by rotating a cylindrical vial containing the capsule, many borosilicate glass or zirconia media, and an aqueous-based colloidal silica polishing slurry. During tumble finishing, the relative media/capsule motions cause multiple, random sliding spherical–spherical Hertzian contacts, resulting in material removal, and possibly plastic deformation, on the capsule. As a result, the domes were observed to locally planarize (i.e., converge to lower heights). Utilizing the correct kinematics (i.e., the characteristics of the media/capsule motions), as controlled by the vial rotation rate and the fill fraction of media and slurry, the high velocity downward circumferential media motions were avoided, preventing fracturing of the fragile capsules. Also, the resulting post-polished surface roughness on the capsule was found to scale with the initial media surface roughness. Hence, pre-polishing the media greatly reduced the roughness of the media and thus the roughness of the polished capsule. A material removal model is described based on the Preston model and spherical–spherical Hertzian contacts which shows reasonable agreement with measured average removal rates of 35±15nm/day and which serves as a valuable tool to scale the polishing behavior with changes in process variables. Narrow domes were observed to planarize more rapidly than wider domes. A local planarization convergence model is also described, based on the concept of workpiece–lap mismatch where the local pressure, and hence removal, varies with the gap at the interface contact. The calculated rate and shape evolution of various size isolated domes compares well with the experimental data.

Keywords: Polishing; Material removal; Plastic hollow spheres; Ablators; Convergence model; Tumble finishing; Local planarization

Growth and properties of Cu thin film deposited on Si(001) substrate: A molecular dynamics simulation study by Jun Zhang; Chong Liu; Yonghua Shu; Jing Fan (pp. 690-696).

► Deposition and growth of Cu thin film on Si(001) substrate is studied using molecular dynamics simulations. ► Tersoff potential parameters for the interaction of Cu and Si atoms are fitted. ► Growth mode, crystalline structure and orientation, and surface morphology of Cu thin film are investigated. ► Effect of substrate temperature on crystalline orientation and surface roughness of Cu thin film is analyzed.Molecular dynamics simulations are used to study the growth and properties of Cu thin film deposited on Si(001) substrate. In particular, growth mode, crystalline structure and orientation, and surface morphology of Cu thin film are investigated in detail. Our simulation results predict that the growth of Cu thin film on Si substrate is three-dimensional island growth mode. In the growth process, interspecies mixing occurs at the interface between Cu film and Si substrate, and the mixing length increases as the increasing of substrate temperature. Based on the common neighbor analysis of atoms, three crystalline structures in the deposited Cu films are indentified. More important, the formed face-centered cubic (fcc) structure of Cu thin film is (001) oriented with a rotation by 45° along 〈001〉 axis when the substrate temperature is 300K, while the fcc structure of Cu thin film becomes to be (111) oriented when the substrate temperature is 900K. The crystalline orientation of deposited film could be explained based on the surface free energy of different crystalline planes as well as the geometrical lattice match rule. In addition, surface roughness of Cu thin film decreases as the increasing of substrate temperature due to the enhancement of surface diffusion.

Keywords: Thin film deposition and growth; Crystalline structure and orientation; Surface roughness; Molecular dynamics method

Pt-decorated graphene as superior media for H₂S adsorption: A first-principles study by Masoud Darvish Ganji; Narges Sharifi; Mahdi Ardjmand; Morteza Ghorbanzadeh Ahangari (pp. 697-704).

► We report the first DFT study in the H₂S/Pt–graphene system. ► The adsorption properties of H₂S at different possible site on the surface of pristine graphene are slightly stable presenting energies from 0.02 to 0.06eV. ► When Pt decorates the graphene sheet on the single and double sides the H₂S adsorption energy increase to −3.2eV. ► A single Pt atom can locate up to seven H₂S molecules stably binded with energies from −6.73 to −0.95eV. ► The DOS plot indicates strong hybridization between H₂S molecules and Pt–graphene sheet.The adsorption mechanism of hydrogen sulfide (H₂S) molecules on pristine and Pt-decorated graphene sheets was studied using density functional theory calculations based on local density approximation and generalized gradient approximation methods. Our calculations show that a Pt-decorated graphene system has much higher binding energy, higher net charge transfer values and shorter connecting distances than pristine graphene due to chemisorption of the H₂S molecule. Furthermore, the calculated density of states show that orbital hybridization is visible between the H₂S and Pt-decorated graphene sheets, while there is no evidence for hybridization between the H₂S molecule and the pristine graphene sheet. Interestingly, we find that up to seven H₂S molecules can stably bind to a Pt atom on each side of the graphene sheet with desirable binding energy.

Keywords: H; ₂; S molecule; Graphene; Density functional theory; Adsorption

Femtosecond laser ablation of wide band-gap materials by Hidetoshi Takayama; Toshiro Maruyama (pp. 705-707).

A plasma model proposed by Jiang and Tsai was applied to the experimental results for wide band-gap materials. The model fairly well predicted the laser-fluence dependences of the hole depth and diameter. The analytical threshold fluence represented the pulse-duration dependence very well. However, the model was insufficient to express the crater shape and to predict the threshold fluence. Deviations from the measurements suggest that the effect of ponderomotive force should be taken into account to improve the expression for the crater shape and that the surface energy needed to be additionally taken into account to predict the threshold fluence quantitatively.

Keywords: Femtosecond laser; Laser ablation; Wide band-gap material

Carbon dioxide adsorption on polyacrylamide-impregnated silica gel and breakthrough modeling by Yi Zhao; Yanmei Shen; Lu Bai; Shiqing Ni (pp. 708-716).

► Polyacrylamide-impregnated silica gel with CO₂ capacity of 0.637mmolg⁻¹ at 60°C. ► Good thermal-stability at 250°C. ► Lower adsorption enthalpy than previous amine modified silica materials. ► Established breakthrough model successfully predicted the breakthrough curves.Polyacrylamide-impregnated silica gel was prepared to capture CO₂ from flue gas. The polymerization of acrylamide was carried out in AN solvent using AIBN as initiator and EGDMA as crosslinker. The adsorbents were characterized by N₂ adsorption, FTIR analysis, SEM analysis, and thermal gravimetric analysis. The results showed that the polymer was not only occupying the porosity of the silica, but necessarily surrounding silica particles, and the amide groups was successfully loaded on the support silica. The impregnated silica displayed good thermal-stability at 250°C. The CO₂ adsorption isotherms were measured to examine CO₂ adsorption on adsorbents, and the results showed that the capacity was increased significantly after modification. The CO₂ isosteric adsorption heats calculated from the isotherms showed that the adsorption interaction of CO₂ with the functionalized material may be mainly an intermolecular force or hydrogen bond. Fixed-bed breakthrough model of CO₂ adsorption on functionalized silica was successfully developed to describe the breakthrough curves under different adsorption temperature, CO₂ concentration, and gas flow rate. The mass transfer coefficients of CO₂ were calculated from the breakthrough model, the results showed that adsorption rate could be promoted by increasing temperature, flow rate and CO₂ concentration, among which the effect of gas flow rate is the most obvious.

Keywords: CO; ₂; adsorption; Acrylamide; Impregnated-silica; Breakthrough model; Mass transfer coefficients

TEA-assisted synthesis of single-crystalline Mn₃O₄ octahedrons and their magnetic properties by Li Li; Jun Liang; Hui Kang; Junzhuo Fang; Min Luo; Xiaoyong Jin (pp. 717-721).

Display Omitted► Mn₃O₄ octahedrons were obtained by a facile TEA-assisted route. ► A plausible mechanism of Mn₃O₄ octahedrons was suggested. ► The approach described is facile, reliable, and high-yield. ► The as-obtained sample exhibit ferrimagnetic and paramagnetic behavior.Well-defined Mn₃O₄ octahedrons were synthesized by a facile triethanolamine (TEA)-assisted route under mild hydrothermal conditions. The chemical compositions and morphologies of the as-prepared samples were characterized in detail by power X-ray diffraction (XRD), fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), and field emission scanning electron microscopy (FE-SEM). The possible reaction mechanism and growth mechanism was discussed to elucidate the formation of the single-crystalline Mn₃O₄ octahedrons. The amounts of TEA and NaOH played important roles in controlling the morphology of the final products. Besides, the magnetic property was tested by a vibrating sample magnetometer (VSM), and the as-obtained sample exhibit ferrimagnetic behavior at low temperature and normal paramagnetic behavior at room temperature. The method can be easily controlled and expected to be applicable for the large-scale preparation of the Mn₃O₄ octahedrons.

Keywords: Hydrothermal synthesis; Mn; ₃; O; ₄; Octahedron; Magnetic property

An alternative approach for femtosecond laser induced black silicon in ambient air by Yuncan Ma; Hai Ren; Jinhai Si; Xuehui Sun; Haitao Shi; Tao Chen; Feng Chen; Xun Hou (pp. 722-726).

► An alternative approach for femtosecond laser induced black silicon in ambient air is proposed. ► Energy dispersive X-ray spectroscopy analysis shows that incorporated oxygen is effectively eliminated via etching. ► Absorption measurement shows that the optical absorption of the black silicon is enhanced. ► The formation mechanism of black silicon and the enhancement mechanism of the optical absorption are discussed.An alternative approach for femtosecond laser induced black silicon in ambient air is proposed, in which, black silicon is fabricated on a tellurium coated silicon substrate via femtosecond laser irradiation in ambient air, and selectively etching with hydrofluoric acid is employed to remove the incorporated oxygen. Results of energy dispersive X-ray spectroscopy analysis and absorption measurement show that oxygen is effectively eliminated via etching, and the optical absorption of the black silicon is enhanced.

Keywords: Black silicon; Femtosecond laser; Selectively etching; Absorption; Ambient air

Phase transition in sputtered HfO₂ thin films: A qualitative Raman study by G.S. Belo; F. Nakagomi; A. Minko; S.W. da Silva; P.C. Morais; D.A. Buchanan (pp. 727-729).

► Results of Linear Raman Spectroscopy experiments on hafnium dioxide thin films deposited by magnetron sputtering. ► We examine changes in the crystalline phase as a function of the deposition conditions and annealing treatment. ► The HfO₂ sputtered thin films crystallization begins for temperatures greater than 400°C.In this work the results of Linear Raman Spectroscopy experiments on hafnium dioxide (HfO₂) thin films deposited by magnetron sputtering using different deposition conditions and post-deposition annealing are reported. Raman bands were identified considering the active symmetry modes expected from a tetragonal or monoclinic phase. The as-deposited HfO_x films sputtered from an Hf target exhibit a tetragonal phase, which may be due to a crystallite size effect. However, the as-deposited HfO_x films from the HfO₂ target is found to be amorphous. As these films are annealed, these films remain or begin to become amorphous. However, at 600°C they both begin to crystallize into a stable monoclinic phase.

Keywords: High-κ; Dielectrics; Hafnium dioxide; Sputtering; Raman scattering

Sunlight-initiated self-assembly of cyclodextrin networks by Sungmin Han; Sungkwon Yoon; William T. Nichols (pp. 730-734).

Display Omitted► Cyclodextrin networks of fibers created by sunlight initiated self-assembly. ► Hierarchically structured from molecular to centimeter scales. ► Identifies cyclodextrin as structure directing agent for organic and hybrid fiber networks. ► Biomimetic design is promising for environmental applications.We demonstrate sunlight initiated self-assembly of three-dimensional networks of β-cyclodextrin using simulated AM1.5 sunlight conditions. These all-organic networks display a highly porous hierarchical structure of interconnected fibers similar to the TiO₂–Cyclodextrin hybrid networks prepared previously. These results clearly identify cyclodextrin as the structure-directing agent providing important new insights into the network formation mechanism. Vibrational and thermal analysis suggest that the cyclodextrin molecules are dehydrated and their cone structure is broken to form a more stable molecular unit. From this data we introduce a formation model based on titania photocatalyzed reaction of cyclodextrin molecules. Subsequently, hydrophobic and surface tension forces drive the self-assembly into large networks of interconnected fibers resembling marine sponges. These results are significant because they demonstrate that cyclodextrin can be used to template the self-assembly of hierarchical networks of both organic and inorganic materials. More broadly, this technique represents a simple and eco-effective route to grow biomimetic structures directly using sunlight.

Keywords: Cyclodextrin; Titania; Self-assembly; Photocatalysis; Biomimetic

Characterisation of samarium and nitrogen co-doped TiO₂ films prepared by chemical spray pyrolysis by I. Oja Acik; V. Kiisk; M. Krunks; I. Sildos; A. Junolainen; M. Danilson; A. Mere; V. Mikli (pp. 735-741).

► The TiO₂:N:Sm thin films deposited by chemical spray pyrolysis have anatase structure. ► According to XPS, N is incorporated into the TiO₂ matrix. ► N-doping increases and Sm-doping reduces the crystallite size of the TiO₂:N:Sm films. ► Incorporation of N strongly suppresses the Sm³⁺ PL emission.The sol–gel chemical spray pyrolysis method was used to deposit samarium and nitrogen co-doped TiO₂ films onto a quartz substrate at a growth temperature of 450°C using pulsed spray solution feed, followed by annealing at 500°C for 2h in air. The obtained films exhibited anatase structure independent of the doping level. According to XRD analysis, the mean crystallite size of the undoped TiO₂, TiO₂:N(25) and TiO₂:N(5):Sm(5) films was 32, 38 and 20nm, respectively. According to AFM, the undoped TiO₂ film consisted of agglomerates with a size of 30–200nm. N-doping (25at%) transformed the agglomerates into individually distinctive grains with a size of ca. 30nm, while Sm doping (5at%) caused a significant decrease in the average diameter of the agglomerates to ca. 100nm. The RMS roughness of the undoped TiO₂ film was 1.7nm; doping resulted in the formation of smoother films with RMS roughness of 0.9–1.4nm. XPS data indicated that the Sm and N dopants were incorporated into the TiO₂ crystal lattice and/or adsorbed on the surface of the film. An increasing nitrogen concentration in the spray solution correlates to a systematic suppressing of the photoluminescence intensity of Sm³⁺.

Keywords: TiO; ₂; thin films; Doping; Chemical spray pyrolysis; XPS; AFM; Photoluminescence

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications by N. Saleema; D.K. Sarkar; R.W. Paynter; D. Gallant; M. Eskandarian (pp. 742-748).

Display Omitted► A very simple surface treatment method to achieve excellent and durable aluminum adhesive bonding. ► Our method involves simple immersion of aluminum in very dilute NaOH solution at room temperature with no involvement of strong acids or multiple procedures. ► Surface analysis via various surface characterization techniques showed morphological and chemical modifications favorable for obtaining highly durable bond strengths on the treated surface. ► Safe, economical, reproducible and simple method, easily applicable in industries.Structural adhesive bonding of aluminum is widely used in aircraft and automotive industries. It has been widely noted that surface preparation of aluminum surfaces prior to adhesive bonding plays a significant role in improving the strength of the adhesive bond. Surface cleanliness, surface roughness, surface wettability and surface chemistry are controlled primarily by proper surface treatment methods. In this study, we have employed a very simple technique influencing all these criteria by simply immersing aluminum substrates in a very dilute solution of sodium hydroxide (NaOH) and we have studied the effect of varying the treatment period on the adhesive bonding characteristics. A bi-component epoxy adhesive was used to join the treated surfaces and the bond strengths were evaluated via single lap shear (SLS) tests in pristine as well as degraded conditions. Surface morphology, chemistry, crystalline nature and wettability of the NaOH treated surfaces were characterized using various surface analytical tools such as scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), optical profilometry, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and contact angle goniometry. Excellent adhesion characteristics with complete cohesive failure of the adhesive were encountered on the NaOH treated surfaces that are comparable to the benchmark treatments such as anodization, which involve use of strong acids and multiple steps of treatment procedures. The NaOH treatment reported in this work is a very simple method with the use of a very dilute solution with simple ultrasonication being sufficient to produce durable joints.

Keywords: NaOH surface treatment; Infra-red reflection absorption spectroscopy (IRRAS); X-ray photoelectron spectroscopy (XPS); X-ray diffraction (XRD); Wettability; Aluminum adhesive bonding

Titanium nitride thin film as an adhesion layer for surface plasmon resonance sensor chips by W.M. Kim; S.H. Kim; K.-S. Lee; T.S. Lee; I.H. Kim (pp. 749-752).

► TiN_x thin film was proposed as an alternative adhesion layer for SPR sensor chip. ► TiN_x had lower resistivity and optical absorption loss than titanium thin film. ► TiN_x layer provided superior SPR characteristic to conventional Ti adhesion layer. ► TiN_x layer provided narrower line width of the SPR characteristic curve. ► TiN_x thin film could provide comparable adhesion strength with Ti thin film.Optical properties, surface plasmon resonance (SPR) response characteristics, and the adhesion properties of the plasmonic stacks with titanium nitride (TiN_x) adhesion layers were analyzed and compared with those of the Au single stack and the plasmonic stacks with conventional titanium adhesion layer. All the films were deposited by radio frequency magnetron sputtering. TiN_x single layer exhibited higher electrical conductivity and reflectance in long wavelength range than Ti single layer of similar thickness. When compared with the plasmonic stacks with Ti adhesion layer, the plasmonic stacks with TiN_x adhesion layer showed higher peak transmittance and less absorption loss in wavelength range longer than 500nm. Examination of the SPR response curves revealed that much improved SPR characteristics could be attained if conventional Ti adhesion layer were replaced by TiN_x layer, and it was attributed to the lower damping of TiN_x film than Ti film at corresponding thickness. Also, it was proved that TiN_x layer could provide sufficient adhesion strength at the glass/TiN_x and TiN_x/Au interfaces, which is comparable with that of Ti layer.

Keywords: Surface plasmon resonance; SPR sensor; Adhesion; Titanium nitride thin film; Titanium thin film

Green synthesis of graphene/Ag nanocomposites by Wenhui Yuan; Yejian Gu; Li Li (pp. 753-758).

A facile and green approach to synthesis of GNS/AgNPs is reported by employing sodium citrate as reductant, and this study represents the use of biocompounds for nontoxic and scalable production of GNS/AgNPs under a suitable concentration of silver ions and the prepared GNS/AgNPs can be used in the field of disinfection.Display Omitted► Graphene/Ag nanocomposites were prepared by a green and facile strategy based on sodium citrate. ► The influence of AgNO₃ amount on particle size and size range of AgNPs was studied. ► The surface plasmon resonance properties of AgNPs on graphene was investigated. ► The antibacterial activity of silver nanoparticles was retained in the nanocomposites.Graphene/Ag nanocomposites (GNS/AgNPs) were fabricated via a green and facile method, employing graphite oxide (GO) as a precursor of graphene, AgNO₃ as a precursor of Ag nanoparticles, and sodium citrate as an environmentally friendly reducing and stabilizing agent. The synthesized GNS/AgNPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectra (RS), respectively. The results indicated that graphite oxide was completely reduced to graphene, and the silver ion was reduced by sodium citrate simultaneously. Under a suitable dosage of silver ions, well-dispersed AgNPs on the graphene sheets mostly centralized at 20–25nm. The surface plasmon resonance property of AgNPs on graphene showed that there was a interaction between AgNPs and graphene supports. In addition, antibacterial activity of silver nanoparticles was retained in the nanocomposites, suggesting that they can be potentially used as a graphene-based biomaterial.

Keywords: Graphene; Graphene/Ag; Composites; Sodium citrate; Environment-friendly

Facile synthesis of ZnO micro-nanostructures with controllable morphology and their applications in dye-sensitized solar cells by Yi Zhou; Dang Li; Xiangchao Zhang; Jianlin Chen; Shiying Zhang (pp. 759-763).

► Different morphologies of ZnO micro-nanostructures were prepared at mild condition. ► ZnO's morphologies changed from wire to flower, urchin and wire with pH increased. ► The light scatterings of ZnO were studied upon diffuse reflectance spectra. ► The denser urchin-like ZnO exhibits the best photoelectric properties.Different morphologies of ZnO micro-nanostructures were successfully prepared by hydrothermal method at relatively mild conditions using ammonia to adjust the pH of the reaction system. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, optical reflectance spectra, and photocurrent–voltage curve. The results demonstrated that the morphologies of ZnO changed from “wire” to “flower”, “urchin” and “wire” with increase in the pH of the reaction system due to the increased concentration of ammonia. The diffused reflectance spectra illustrated that the reflectance of denser urchin-like ZnO was low at 18% in the visible region. When the as-synthesized ZnO micro-nanostructures were used as the anode of the dye sensitization solar cell, the denser urchin-like ZnO exhibited the best photoelectric properties. The short circuit current ( J_sc), open circuit voltage ( V_oc), and conversion efficiency ( η) were 6.50mA/cm², 0.682V, and 1.92%, respectively.

Keywords: ZnO; Micro-nanostructures; Urchin; Dye sensitization solar cell; Photoelectric properties

Fabrication of coral-like superhydrophobic coating on filter paper for water–oil separation by Ming Zhang; Chengyu Wang; Shuliang Wang; Yunling Shi; Jian Li (pp. 764-769).

The physics related to superhydrophobic surfaces has been investigated with attention of its potential applications in a variety of industrial and research fields. In the present study, a coralloid superhydrophobic coating with numerous nanometer-scale embossments has been fabricated on the filter paper surface by a simple, facile and inexpensive route. After treatment, the wettability of filter paper has been transformed from superhydrophilicity to superhydrophobicity with the WCA of 156°.Display Omitted► A coral-like superhydrophobic coating has been fabricated on the filter paper surface. ► Wettability of paper has been transformed from superhydrophilicity to superhydrophobicity. ► Superhydrophobic paper was obtained by a simple, facile and inexpensive drop-coating procedure. ► Superhydrophobic paper possesses some durability and the property in water–oil separation. ► This strategy offers an opportunity to extend the range of practical applications for filter paper.The physics related to superhydrophobic surfaces has been investigated with attention of its potential applications in a variety of industrial and scientific fields. In the present study, a coralloid superhydrophobic coating with numerous nanometer-scale embossments has been fabricated on the filter paper surface by a simple, facile and inexpensive route. The observations show that the wettability of paper sample has been transformed from superhydrophilicity to superhydrophobicity with the WCA of 156°, and had no significant change under ambient condition or in the water, oil and corrosive liquids, displaying an outstanding superhydrophobic stability. Importantly, the coated paper sample possesses not only superhydrophobicity but also superoleophobicity, and presents an excellent property in water–oil separation, which offers an opportunity to extend the range of practical applications for filter paper.

Keywords: Superhydrophobic filter paper; Drop-coating route; Nanocomposite coating; Water–oil separation

Fabrication of Gd₂O₃ nanofibers by electrospinning technique using PVA as a structure directing template by R. Thangappan; S. Kalaiselvam; A. Elayaperumal; R. Jayavel (pp. 770-773).

► The Gd₂O₃ fibers were prepared by electrospinning technique. ► The morphology of PVA/Gd₂O₃ nanofibers were investigated by SEM. ► The PVA/Gd₂O₃ nanofibers showed enhanced optical properties in the solid state. ► The promising nanofibers for multiple potential applications.Gd₂O₃ fibers from nano to submicron diameter were prepared by electrospinning technique. The polyvinyl alcohol (PVA) was used as a structure directing template for the synthesis of Gd₂O₃ fibers. The crystal structure and morphology of Gd₂O₃ fiber were studied by XRD and SEM analyses. The presence of functional groups was confirmed by FTIR spectroscopy. Thermal behavior of PVA/Gd₂(NO₃)₂ hybrid fibers were investigated by thermo-gravimetric analysis. Gd₂O₃ nanofibers exhibit bright down and upconversion luminescence under ultraviolet light excitation, with potential applications as of light-emitting phosphors, advanced flat panel displays and biological labeling.

Keywords: Nanofiber; Gd; ₂; O; ₃; FTIR; Structural

Characterization and mechanical properties of coatings on magnesium by micro arc oxidation by Salih Durdu; Metin Usta (pp. 774-782).

► The commercial pure magnesium was coated by MAO in sodium silicate and sodium phosphate. ► Coatings produced in the phosphate electrolyte are thicker than ones in the silicate electrolyte. ► Coatings in the silicate electrolyte are harder than ones in the phosphate electrolyte. ► Adhesion strength of coatings increases with increasing coating thickness. ► The wear resistance of the coated commercial pure magnesium is improved.The commercial pure magnesium was coated by micro arc oxidation method in different aqueous solution, containing sodium silicate and sodium phosphate. Micro arc oxidation process was carried out at 0.060A/cm², 0.085A/cm² and 0.140A/cm² current densities for 30min. The thickness, phase composition, morphology, hardness, adhesion strength and wear resistance of coatings were analyzed by eddy current, X-ray diffraction (XRD), scanning electron microscope (SEM), micro hardness tester, scratch tester and ball-on disk tribometer, respectively. The average thicknesses of the micro arc oxidized coatings ranged from 27 to 48μm for sodium silicate solution and from 45 to 75μm for sodium phosphate solution. The dominant phases formed on the pure magnesium were found to be a mixture of spinel Mg₂SiO₄ (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg₃(PO₄)₂ (Farringtonite) and MgO (Periclase) for sodium phosphate solution. The average hardnesses of the micro arc oxidized coatings were between 260HV and 470HV for sodium silicate solution and between 175HV and 260HV for sodium phosphate solution. Adhesion strengths and wear resistances of coatings produced in sodium silicate solution were higher than those of the ones in sodium phosphate solution due to high hardness of coatings produced in sodium silicate solution.

Keywords: Micro arc oxidation (MAO); Plasma electrolytic oxidation (PEO); Hardness; Adhesion strength; Wear resistance

Extruded expanded polystyrene sheets coated by TiO₂ as new photocatalytic materials for foodstuffs packaging by V. Loddo; G. Marcì; G. Palmisano; S. Yurdakal; M. Brazzoli; L. Garavaglia; L. Palmisano (pp. 783-788).

► An extruded polystyrene has been functionalised by TiO₂. ► A photocatalytic polymer has been developed via a sol–gel method. ► Thermoformed packagings for foodstuffs application have been prepared.Nanostructured, photoactive anatase TiO₂ sol prepared under very mild conditions using titanium tetraisopropoxide as the precursor is used to functionalise extruded expanded polystyrene (XPS) sheets by spray-coating resulting in stable and active materials functionalised by TiO₂ nanoparticles. Photocatalytic tests of these sheets performed in a batch reactor in gas–solid system under UV irradiation show their successful activity in degrading probe molecules (2-propanol, trimethylamine and ethene). Raman spectra ensure the deposition of TiO₂ as crystalline anatase phase on the polymer surface. The presence of TiO₂ with respect to polymer surface can be observed in SEM images coupled to EDAX mapping allowing to monitor the surface morphology and the distribution of TiO₂ particles. Finally thermoforming of these sheets in industrial standard equipment leads to useful containers for foodstuffs.

Keywords: Photoactive polymer; Polystyrene functionalised by TiO; ₂; Photocatalytic material for foodstuffs

Effect of nickel incorporation on microstructural and optical properties of electrodeposited diamond like carbon (DLC) thin films by B. Pandey; P.P. Pal; S. Bera; S.K. Ray; A.K. Kar (pp. 789-799).

► The growth process and optical properties of DLC and Ni-DLC thin films are studied. ► Contrary to DLC, with thickness number of particles increases in Ni-DLC film. ► The presence of Ni crystallites in an amorphous carbon network is revealed. ► With nickel incorporation the band gap of DLC films decreases. ► Optical studies confirm that nickel addition favors sp² bonding in the films.A simple electrodeposition technique was used to synthesize diamond like carbon (DLC) and nickel incorporated diamond like carbon (Ni-DLC) thin films on ITO coated glass substrates. Initial concentration of nickel in the electrolyte was kept fixed at 4.76×10⁻⁴M for all depositions of Ni-DLC films. Growth process of the films was studied by synthesizing films with variation of deposition time. With nickel addition to DLC the band gap and the Urbach energy varied from 2.67eV to 2.48eV and 1.0803eV to 1.452eV, respectively as estimated from UV-vis-NIR spectrophotometry of DLC and Ni-DLC. Results indicated that the metal incorporation effectively increased the graphitization of DLC films. Microstructural studies by SEM and AFM revealed that the particles in the Ni-DLC films were evenly distributed and the packing density of particles increased with increased time of deposition. XRD pattern exhibited the presence of Ni crystallites in an amorphous carbon network along with the phases of diamond and graphite in the Ni-DLC film. The FTIR spectrum showed peaks accountable for both CH₃ and CH₂ bonding. It was also apparent that nickel incorporation significantly modulated the FTIR spectrum of DLC film, as several new peaks appeared only in the case of Ni-DLC film at ∼776cm⁻¹, 745cm⁻¹ and 668cm⁻¹.

Keywords: Electrodeposition; Diamond-like carbon (DLC); Thin film; Nickel-incorporation; Microstructural property; Optical property

Cyclic oxidation behavior of plasma surface chromising coating on titanium alloy Ti–6Al–4V by Dong-Bo Wei; Ping-Ze Zhang; Zheng-Jun Yao; Jin-Tang Zhou; Xiang-Fei Wei; Peng Zhou (pp. 800-806).

► A chromising coating in gradient distribution was obtained on Ti–6Al–4V titanium alloy. ► The cyclic oxidation behavior of chromising coating was studied at 650–850°C. ► The Ti–Cr mutual diffusion layer changed into the Ti(Cr, Al)₂ laves phase layer, which prevented the inward diffusion of oxygen. ► A multi-layers structure of Cr₂O₃, TiO₂ and Al₂O₃ formed during oxidation. ► Ti, Al diffused toward the oxide-gas interface, Cr diffused predominantly outward.The cyclic oxidation behavior of plasma surface chromising coating on titanium alloy (Ti–6Al–4V) was researched in air at 650°C, 750°C and 850°C. A NiCrAlY coating was prepared by multi-arc ion plating as a comparison. The surface morphologies, microstructures and phases of both coatings before and after oxidation were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). The results show that the chromising coating consisted of an outer layer of loose Cr deposition, an intermediate layer of compact Cr deposition and an inner Ti–Cr mutual diffusion layer. The multilayer oxide scales formed in the oxidation process, which has the better cyclic oxidation resistance compared with NiCrAlY thermal barrier coating. However, the brittleness of Ti(Cr, Al)₂ laves phase resulted in spallation of oxide scales at 750°C and 850°C.

Keywords: Ti–6Al–4V alloy; Metal coatings; High-temperature oxidation; Diffusion

Surface studies on superhydrophobic and oleophobic polydimethylsiloxane–silica nanocomposite coating system by Bharathibai J. Basu; V. Dinesh Kumar; C. Anandan (pp. 807-814).

► Superhydrophobic coatings were rendered oleophobic by applying a topcoat of FAS. ► The coatings exhibited stable oleophobic property with oil CA of 79°. ► Fluoroalkyl groups have more affinity towards silica nanoparticles than for PDMS. ► Very small amount of fluorine was required to render oil repellency to the coating.Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)–silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158–160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

Keywords: Superhydrophobic; Oleophobic; PDMS; Nanocomposite; WCA; Oil CA

Influence of the substrate and nitrogen amount on the microstructural and optical properties of thin r.f.-sputtered ZnO films treated by rapid thermal annealing by Madalina Nicolescu; Mihai Anastasescu; S. Preda; H. Stroescu; M. Stoica; V.S. Teodorescu; E. Aperathitis; V. Kampylafka; M. Modreanu; M. Zaharescu; M. Gartner (pp. 815-823).

► ZnO:N films are crystallized in hexagonal wurtzite phase (XRD), (002) oriented. ► The presence of the Nitrogen in the RTA films is confirmed by EDX and XPS. ► All ZnO:N films are highly transparent (over 80%) in VIS to NIR spectral range. ► The frequency of the phonon modes, E₁(TO) and A₁(LO), were obtained by IRSE.N-doped ZnO (ZnO:N) thin films, intended to be used as one of the layers in solar cell applications were deposited by r.f. sputtering, using ZnN target (99.9% purity), on silicon and fused silica substrates. In the gas flow composition, Ar was kept constant (50%) and the O₂/N₂ ratio was varied as: 40%/10%, 25%/25% and 10%/40%. After deposition, rapid thermal annealing (RTA) at 400 and 550°C for 1min in N₂ ambient has been performed. The RTA impact on the optical and microstructural properties of ZnO:N thin films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX), UV–vis–NIR spectroscopy, UV–vis–NIR spectroscopic ellipsometry (SE) and infrared ellipsometry (IR-SE). The as-deposited (ad) ZnO:N films are polycrystalline with preferentially oriented columnar crystals. After RTA we found ZnO:N films with improved crystallinity and fewer boundary defects. We report optical constants of ZnO:N from UV to IR spectral range as well as the infrared active phononic modes.

Keywords: N-doped ZnO; AFM; XRD; TEM and SAED; Spectroscopic ellipsometry; Phonon modes

Experimental characterizations of non-seizing solutions for plastic moulding tools by P. Jacquet; M. Gołąbczak; P. Lourdin (pp. 824-829).

► Struggle against tools’ wear in the plastics moulding industry. ► Comparison between nitriding solutions and PVD coating. ► 2 solutions show an excellent behaviour: WC/C coating and salt bath nitriding followed by post-oxidation.In the plastics moulding industry many parts sustain movement in relation to other pieces: ejectors, slides, dies, etc. Some seizing or micro-welding may appear, especially when lubrication is not used. For many years, different kinds of hard coatings were developed to avoid such problems. In this paper, the investigation analyses these problems related with nitride layers which were obtained thanks to four different processes: salt bath nitriding, salt bath nitriding followed by a post-oxidation, gaseous low pressure nitriding and plasma nitriding. Several properties of the layers were investigated such as hardness, microstructure and constitution of the surface by means of X-ray diffraction (XRD), roughness, and friction coefficient at both room temperature and 100°C. Some important differences were pointed out between the different layers. The solution provided by a salt bath nitriding followed with an oxidation sequence gave, in terms of tribology, as good results as a physical vapour deposition (PVD) WC-C coating which was used as a reference for this study.

Keywords: Nitriding processes; PVD WC/C coating; Friction coefficient; X 38CrMoV5 steel; Mould tools

Synthesis and luminescence properties of ZnGa₂O₄ spinel doped with Co²⁺ and Eu³⁺ ions by Xiulan Duan; Fapeng Yu; Yuanchun Wu (pp. 830-834).

► ZnGa₂O₄ nanopowders doped with Co²⁺ and Eu³⁺ ions have been prepared by citrate sol–gel method. ► The samples have been characterized by XRD, XPS and fluorescence spectroscopy. ► The emission at 615nm is due to Eu³⁺, while the emission at 680nm is assigned to Co²⁺. ► The emission spectra are affected by the relative concentration of the two ions, and the annealing temperature.ZnGa₂O₄ nanopowders doped with Co²⁺ and Eu³⁺ ions, including dual doping, have been synthesized by citrate sol–gel method, and characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results show that ZnGa₂O₄ spinels were produced by calcining the gel above 500°C, with the crystallite size of 16–30nm in the temperature range of 500–900°C. Co²⁺ ions are located at the tetrahedral sites of ZnGa₂O₄ spinel by replacing Zn²⁺, and Eu³⁺ ions are incorporated in the defect regions at the grain boundaries. The emission spectra of Eu-doped ZnGa₂O₄ nanopowders display an intense emission at 615nm belonging to⁵D₀–⁷F₂ transition of Eu³⁺ ions. With the introduction of Co into Eu-doped ZnGa₂O₄, the emission intensity at 615nm decreases, while the luminescence at 680nm due to tetrahedral Co²⁺ increases. The result indicates that the energy transfer occurred from Eu³⁺ to Co²⁺ ions. The energy transfer was also studied by the luminescence decay behavior. The emission of Co and Eu Co-doped ZnGa₂O₄ also changed with annealing temperature. The luminescence properties of the doped ZnGa₂O₄ nanopowders can be controlled by the variation of Co and Eu doping concentration and annealing temperature.

Keywords: ZnGa; ₂; O; ₄; :Co, Eu; Citrate sol–gel method; Nanopowders; Luminescence

Photocatalytic activity and characterization of sol–gel-derived Ni-doped TiO₂-coated active carbon composites by R.R. Bhosale; S.R. Pujari; M.K. Lande; B.R. Arbad; S.B. Pawar; A.B. Gambhire (pp. 835-841).

Display Omitted► Nanocrystalline Ni-TiO₂/AC photocatalyst were prepared by sol–gel method. ► XRD, TEM, UV–vis, XPS measurements were used to catalysts characterization. ► Carbon in active carbon causes some of the Ti (IV) to reduce Ti (III). ► Doping of two kinds of atoms into TiO₂ results in higher photocatalytic activity than single one. ► Excellent visible-light photocatalytic activity and stability.Ni-doped, TiO₂-coated active carbon (Ni–TiO₂/AC) were prepared by a sol–gel method. The effect of supports, including TiO₂ and active carbon (AC), on the molecular structure and photocatalytic activity of nickel oxide for complete decomposition of methylene blue has been examined with respect to the content of Ni on the catalyst surface. The photocatalytic activities of the Ni–TiO₂/AC composites were evaluated in the decomposition of methylene blue solution under visible-light irradiation. The results indicate that Ni–TiO₂/AC has a higher efficiency in decomposition of methylene blue than TiO₂ and TiO₂/AC. This was attributed to the different functions of active carbon and nickel species. First, nanosize TiO₂ particles on composites were not reunited, possible because active carbon retards transformation of anatase into rutile and decrease the crystallite size. Second, production of high concentrations of organic compound near Ni–TiO₂. Third, carbon in active carbon causes some of the TiO₂ to reduce to Ti³⁺ ions, which prevents electron–hole pair recombination. It was found that the addition of Ni to TiO₂ sol could suppress the grain growth of TiO₂ crystals and increase the hydroxyl content on the surface of TiO₂/AC. The photocatalytic efficiency and activity of the composites remained good, even after three cycles.

Keywords: Sol–gel; Active carbon; Methylene blue; Photocatalytic activity; XPS

Surface modifications on InAs decrease indium and arsenic leaching under physiological conditions by Scott A. Jewett; Jeffrey A. Yoder; Albena Ivanisevic (pp. 842-850).

.Display Omitted► InAs was assessed under physiological conditions. ► A thiol-alcohol and a PEG-based polymer layers demonstrated the highest stability. ► Unmodified and modified InAs showed no toxicity to zebrafish up to 120h post fertilization.Devices containing III–V semiconductors such as InAs are increasingly being used in the electronic industry for a variety of optoelectronic applications. Furthermore, the attractive chemical, material, electronic properties make such materials appealing for use in devices designed for biological applications, such as biosensors. However, in biological applications the leaching of toxic materials from these devices could cause harm to cells or tissue. Additionally, after disposal, toxic inorganic materials can leach from devices and buildup in the environment, causing long-term ecological harm. Therefore, the toxicity of these materials along with their stability in physiological conditions are important factors to consider. Surface modifications are one common method of stabilizing semiconductor materials in order to chemically and electronically passivate them. Such surface modifications could also prevent the leaching of toxic materials by preventing the regrowth of the unstable surface oxide layer and by creating an effective barrier between the semiconductor surface and the surrounding environment. In this study, various surface modifications on InAs are developed with the goal of decreasing the leaching of indium and arsenic. The leaching of indium and arsenic from modified substrates was assessed in physiological conditions using inductively coupled plasma mass spectrometry (ICP-MS). Substrates modified with 11-mercapto-1-undecanol (MU) and graft polymerized with poly(ethylene) glycol (PEG) were most effective at preventing indium and arsenic leaching. These surfaces were characterized using contact angle analysis, ellipsometry, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Substrates modified with collagen and synthetic polyelectrolytes were least effective, due to the destructive nature of acidic environments on InAs. The toxicity of modified and unmodified InAs, along with raw indium, arsenic, and PEG components was assessed using zebrafish embryos.

Keywords: Abbreviations; ICP-MS; inductively coupled plasma mass spectrometry; PEG; poly(ethylene) glycol; AFM; atomic force microscopy; MU; 11-mercapto-1-undecanol; XPS; X-ray photoelectron spectroscopy; FET; field-effect transistor; TGA; thioglycolic acid; PAH; polyallylamine hydrochloride; PAA; poly(acrylic acid); dH; ₂; O; distilled water; PEGMEMA; poly(ethylene glycol) methyl ether methacrylate; RMS; root mean square; hpf; hours post-fertilization; LbL; layer-by-layer; MTD; maximum tolerable doseInAs; Zebrafish; Toxicity; Passivation; Surface modifications; ICP-MS

Die-casting effect on surface characteristics of thin-walled AZ91D magnesium components by Lifang Hu; Shaoping Chen; Yang Miao; Qingsen Meng (pp. 851-856).

► Depth profile of elements for the die-casting surface layer was studied. ► The content of C, Si and Fe increases along the molten magnesium filling trace. ► The outer skin of castings consists of more β-phase and less eutectic α-phase. ► The corrosion resistance decreases along the filling trace.Filling trace, filling time and temperature distribution during the die-casting process were simulated using commercial software (MAGMA). The surface microstructure and phase distribution in thin-walled AZ91D magnesium components cast on a hot-chamber die-casting machine were investigated by means of optical microscopy and scanning electron microscopy. The depth profile of alloying elements was examined using a glow discharge optical emission spectrometer. The outer skin microstructure consists of more β-phase and less eutectic α-phase than the interior region. The elemental content of C, Si, and Fe in the outer skin increased along the filling trace, and they decreased with increasing distance from the surface to the interior region, while the Al had an inverse trend. The corrosion resistance decreased along the filling trace.

Keywords: AZ91D; Magnesium alloys; Die casting; Surface; Corrosion

Zinc oxide (ZnO) grown on sapphire substrate using dual-plasma-enhanced metal organic vapor deposition (DPEMOCVD) and its application by Po-Hsun Lei; Hsiang-Ming Wu; Chia-Ming Hsu; Yuan-Chih Lee (pp. 857-862).

► We used a novel system to grow ZnO thin film on sapphire substrate. ► The undoped-ZnO thin film has very low resistivity of 6.5×10⁻³Ωcm. ► The optoelectrical characteristics of the InGaN/GaN LEDs with undoped ZnO TCL are similar to those with indium–tin-oxide (ITO) TCL.This study reports the use of dual-plasma-enhanced metal organic chemical vapor deposition (DPEMOCVD) in forming low-temperature-grown zinc oxide (ZnO). The proposed method uses a direct voltage (DC)-driven capacitor-coupled electrodes and a radio-frequency (RF) plasma system. The DC plasma system enhances the dissociation of oxygen gas (O₂), while the RF plasma system helps maintain the dissociated free radicals in the chamber. The optimum substrate temperature for undoped ZnO grown by DPEMOCVD system is 185°C, which yields the highest transmittance of 85%, and the lowest resistivity of 6.5×10⁻³Ωcm. The DPEMOCVD-deposited ZnO was used to the transparent conductive layer (TCL) of InGaN/GaN LED. As compared to the conventional InGaN/GaN light-emitting diode (LED), InGaN/GaN LED with DPEMOCVD-deposited ZnO TCL shows a lower turn-on voltage and higher light output intensity. This indicates that the DPEMOCVD-deposited ZnO can be the TCL for InGaN/GaN LEDs.

Keywords: Dual-plasma-enhanced chemical vapor deposition (DPEMOCVD); Zinc oxide (ZnO); Transparent conductive layer (TCL); InGaN/GaN light-emitting diodes (LEDs)

Investigation on hydrophobic films from a hydrophobic powder by Liqun Zhu; Guofang Hao; Yuan Chen; Yizhi Chen (pp. 863-867).

► A hydrophobic powder based on an organosiloxane and a corrosion inhibitor was synthesized. ► The hydrophobic films prepared from the hydrophobic powder showed excellent hydrophobic property. ► The hydrophobic films formed on steel greatly increased the corrosion resistance.A hydrophobic powder was prepared based mainly on an organosiloxane and a corrosion inhibitor with the addition of a reaction promoter. Structure and thermal stability of the hydrophobic powder were characterized by FTIR and TG/DSC, respectively. Hydrophobic property and corrosion resistance of the hydrophobic film formed on phosphatized steel by immersion in 3wt% NaCl aqueous solution were evaluated together with the electrochemical behavior. Results showed that the skeleton of the hydrophobic powder was composed mainly ofSiOSi which comprises longer and more hydrophobic groups ofSiR compared with the conventional BH-102 water-repellent agent. A thin hydrophobic film with a thickness of 15–20μm was formed on surface of the phosphatized steel after immersion in the solution of 5g/L of the hydrophobic powder in ethanol for 5min. The hydrophobic film exhibited excellent stability at a temperature below 135°C. Water contact angle on the film is about 117–132° and it was until 30h later when a corrosion spot occurred on the film covered on steel which revealed better water-repellent and corrosion resistant properties compared to that of the BH-102.

Keywords: Hydrophobic powder; Organosiloxane; Hydrophobic film; Contact angle; Corrosion resistance

Graphitization of boron predeposited 6H-SiC(0001) surface by Yuta Okonogi; Yuki Aoki; Hiroyuki Hirayama (pp. 868-872).

► We have tried to dope the B atoms into epitaxial graphene during the graphene growing process. ► The B induced changes in the surface were characterized by low-energy electron microscopy, auger electron spectroscopy, atomic force microscopy, and scanning tunneling icroscopy. ► No obvious B atoms doping evidence into the graphene was observed.We examined the substitutional doping of B atoms into epitaxial graphene on the SiC(0001) surface. B atoms were deposited on the SiC(0001) surface in advance of the growth of graphene. The B-induced changes in the surface morphology and chemical composition were characterized at the four thermal treatment stages in the growth of graphene (at 1120, 1370, 1520, and 1770K) by low-energy electron diffraction (LEED), auger electron spectroscopy (AES), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The B atoms were found to hinder the formation of a spatially uniform graphene layer. However, local deformation of the graphene lattice, which should be observed if B atoms are successfully doped substitutionally, was not observed in STM.

Keywords: Epitaxial graphene; Boron; Doping; STM; LEED; AES; AFM

Magic size effects of small Cu clusters diffusion on Ag (111) surface by Changqing Wang; Fei Wang; Yongsheng Zhang; Qiang Sun; Yu Jia (pp. 873-879).

Effective ( E_a) diffusion barriers for Cu clusters diffusion on Ag (111) surface have been plotted.Display Omitted► Diffusion behaviors of Cu clusters on Ag (111) surface have been studied by molecular dynamics. ► Binding energy and diffusion barrier of these clusters show significant magic size effect. ► The trimer and heptamer with relative higher diffusion barrier are more stable than other sizes. ► The dimer's and trimer's rotation mechanisms have been investigated in this paper as well.Using embedded-atom-method (EAM) potential of Ag/Cu heterogeneous system, structural stabilities and diffusion behaviors of small Cu clusters on Ag (111) surface have been investigated by molecular dynamics studies. The binding energies, the effective diffusion barriers and the corresponding prefactors for Cu clusters have been calculated. Structural stabilities and the diffusion properties of small Cu clusters show significant magic size effects: the trimer and heptamer clusters with relatively higher effective diffusion barriers are more stable than the other sizes. Moreover, the dimer's and trimer's rotation mechanism have been investigated in this paper as well.

Keywords: EAM potential; Molecular dynamics; Surface diffusion; Cluster; Magic size effect

Photo selective protein immobilization using bovine serum albumin by Wan-Joong Kim; Ansoon Kim; Chul Huh; Chan Woo Park; Chil Seong Ah; Bong Kyu Kim; Jong-Heon Yang; Kwang Hyo Chung; Yo Han Choi; Jongcheol Hong; Gun Yong Sung (pp. 880-889).

Display Omitted► A method for selectively immobilizing proteins onto a solid substrate using UV light has been developed. ► Bovine serum albumin is employed as the cross-linker and also as the blocker. ► This new photo-addressable immobilization method provides a new approach for developing novel protein microarrays.A simple and selective technique which immobilizes protein onto a solid substrate by using UV illumination has been developed. In protein immobilization, a Bovine serum albumin (BSA) performed bifunctional role as a cross-linker between substrate and proteins and as a blocker inhibiting a nonspecific protein adsorption. A new photo-induced protein immobilization process has been investigated at each step by fluorescence microscopy, ellipsometry, and Fourier transform infrared (FT-IR) spectroscopy. A UV photomask has been used to induce selective protein immobilization on target regions of the surface of the SiO₂ substrates under UV illumination with negligible nonspecific binding. The UV illumination also showed improved photostability than the conventional methods which employed bifunctional photo-crosslinker molecules of photo-reactive diazirine. This new UV illumination-based photo-addressable protein immobilization provides a new approach for developing novel protein microarrays for multiplexed sensing as well as other types of bio-immobilization in biomedical devices and biotechnologies.

Keywords: Photo-crosslinker; Protein immobilization; Bovine serum albumin (BSA)

Enhanced ethanol sensing properties of Zn-doped SnO₂ porous hollow microspheres by Wenchuang Wang; Yongtao Tian; Xinjian Li; Xinchang Wang; Hao He; Yurui Xu; Chuan He (pp. 890-895).

The Zn-doped SnO₂ porous hollow microsphere sensor showed enhanced ethanol sensing properties compared to ZnO and SnO₂ sensors. The response ( R_a/ R_g) of Zn-doped SnO₂ nanospheres was up to 3 when the sensor was exposed to 2ppm C₂H₅OH, with the response and recovery times of 7 and 4s, respectively.Display Omitted► Zn-doped SnO₂ porous hollow microspheres were synthesized for the gas sensing detection. ► The temperature-dependent and concentration-dependent sensing behaviors of the sensor to ethanol were studied. ► Zn-doped SnO₂ sensor showed enhanced ethanol gas sensing properties compared to the undoped ZnO and SnO₂ sensor. ► The good gas sensing performance of Zn-doped SnO₂ porous hollow microspheres sensor was based on the porous structure and doping.Zn-doped SnO₂ porous hollow microspheres with an average diameter of ∼180nm have been prepared by a direct precipitation method using colloidal carbon sphere as template. The XRD data disclosed that the structure of the Zn-doped SnO₂ microspheres was the same as pure SnO₂, while the crystallite size of Zn-doped SnO₂ microspheres (10.63nm) was smaller than SnO₂ (23.2nm). The sensing measurement showed that the response ( R_a/ R_g) increased near linearly with the ethanol gas concentration at the operating temperature of 240°C. Compared with SnO₂ microspheres, Zn-doped SnO₂ porous hollow spheres exhibited a significant improvement for the response towards ethanol at 240°C. The response of Zn-doped SnO₂ microspheres was up to 3 when the sensor was exposed to 2ppm C₂H₅OH, with the response and recovery times of 7 and 4s, respectively. Additionally, the response of Zn-doped SnO₂ sensor showed slight variation after 15 weeks storage. The results indicated that Zn-doped SnO₂ microspheres are of great potential for fabricating C₂H₅OH sensors with high performance.

Keywords: Zn-doped SnO; ₂; Hollow microspheres; C; ₂; H; ₅; OH; Gas sensor

Amorphous structure evolution of high power diode laser cladded Fe–Co–B–Si–Nb coatings by Yanyan Zhu; Zhuguo Li; Jian Huang; Min Li; Ruifeng Li; Yixiong Wu (pp. 896-901).

► Fabricated amorphous composited coating by high power diode laser cladding with single track. ► Lower dilution and higher scanning speed are desired to obtain higher amorphous phase fraction. ► White spots phase with high content of Nb embedded in the amorphous matrix.Fe–Co–B–Si–Nb coatings were fabricated on the surface of low carbon steel using high power diode laser cladding of [(Fe_0.5Co_0.5)_0.75B_0.2Si_0.05]_95.7Nb_4.3 amorphous powders at three different scanning speeds of 6, 17 and 50m/s. At each scanning speed, laser power was optimized to obtain low dilution ratio. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy with energy dispersive spectrometer and electron probe micro analysis were carried out to characterize the microstructure and chemical composition of the cladded coatings. Differential scanning calorimetry was also carried out to investigate the fraction of the amorphous phase. The results showed that dilution ratio and scanning speed were the two main factors for fabricating Fe–Co–B–Si–Nb amorphous coating by high power diode laser cladding. Low dilution ratio was crucial for the formation of amorphous phase. When the dilution ratio was low, the fraction of amorphous phase in the cladded coatings increased upon increasing the scanning speed.

Keywords: Laser cladding; Amorphous composite coating; Dilution ratio; Scanning speed

Adsorption properties and mechanism of mesoporous adsorbents prepared with fly ash for removal of Cu(II) in aqueous solution by Xiu-Wen Wu; Hong-Wen Ma; Lin-Tao Zhang; Feng-Jiao Wang (pp. 902-907).

Mesoporous materials were hydrothermally prepared from fly ash in an alkaline condition with cetyltrimethylammonium bromide as synthesis directing agent. The mean pore diameter was between 3.58nm and 3.96nm. The maximum adsorption capacity for Cu(II) was about 221mgg⁻¹.Display Omitted► Mesoporous adsorbents were hydrothermally prepared with fly ash. ► The equilibrium adsorption time was about 20min. ► The maximum adsorption capacity for Cu(II) was about 221mgg⁻¹. ► A chemical ion exchange mechanism.Mesoporous materials were hydrothermally prepared from fly ash in an alkaline condition with cetyltrimethylammonium bromide as synthesis directing agent. The structural properties of the mesoporous materials were characterized by X-ray powder diffraction, high-resolution transmission electron microscope, and N₂ adsorption. The chemical contents of SiO₂ in the mesoporous materials were determined by spectrometry of the silicone molybdenum and sulfosalicylic acid complexes, and Al₂O₃ determined by complexometry with Ethylene Diamine Tetraacetic Acid in the presence of KF-Zn(Ac)₂ tests. The removal of Cu(II) was studied under equilibrium and dynamic conditions, and the influence of the Al:Si molar ratio were also considered. The equilibrium data were fitted to Freundlich and Langmuir models and the models parameters were evaluated. The adsorption mechanism was clarified with the Dubnin–Radushkevich isotherm.

Keywords: Adsorption; Cu(II); Mesoporous materials; Fly ash; Adsorption mechanism

Solid-state densification of spun-cast self-assembled monolayers for use in ultra-thin hybrid dielectrics by Daniel O. Hutchins; Orb Acton; Tobias Weidner; Nathan Cernetic; Joe E. Baio; David G. Castner; Hong Ma; Alex K.-Y. Jen (pp. 908-915).

Display Omitted► Rapid processing of SAM in ambient conditions is achieved by spin coating. ► Thermal annealing of a bulk spun-cast molecular film is explored as a mechanism for SAM densification. ► High-performance SAM-oxide hybrid dielectric is obtained utilizing a single wet processing step.Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlO_x (2.5nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7×10⁻⁸Acm⁻² and capacitance density of 0.62μFcm⁻² at 3V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2V operation and charge carrier mobilites of up to 1.1cm²V⁻¹s⁻¹.

Keywords: Self assembled monolayer (SAM); SAM dielectric; Hybrid dielectric; SAM processing; Organic field effect transistor (OFET); Organic thin film transistor (OTFT)

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