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Applied Surface Science (v.258, #18)

Sensitivity analysis of nanoparticles manipulation based on different friction models by M.H. Korayem; M. Taheri; M. Zakeri (pp. 6713-6722).

► We model nanoparticle displacement using the friction models of HK and LuGre. ► We compare the effect of accurate friction modeling with the previous model. ► Increasing the surfaces energy increases the critical force and time of manipulation. ► Increasing the width and thickness lead to increase the force and decrease the time. ► Increasing the length and effective elastic module decrease the force and time.The advent of miniaturization and transition from the macro world to the micro/nano world has brought into existence materials with more ratio of area to volume. In transition from the macro world to the micro/nano world, surface forces such as friction and adhesion that were formerly less significant or even negligible are under solemn scrutiny. In this respect, various friction models have been developed by numerous researchers in an effort to model the governing conditions in the micro/nano manipulation. In this paper, nanoparticle displacement dynamic modeling and simulation in AFM-based manipulation is addressed using advanced friction models in the nano scale including HK and LuGre which are both on the basis of true contact surface. Moreover, the effect of accurate modeling on the process of manipulation is compared with the results of the previous model. In addition, critical force and time variations by using different friction models are analyzed under the influence of model parameters. Previous research entailed a simplification of nanoparticles manipulation modeling using modified Coulomb friction model and assuming apparent contact surface while in reality, true contact surface is much less than apparent contact surface due to the raggedness of surfaces. This causes a significant decrease in friction force and hence manipulation critical parameters. Implementing an accurate friction model upgrades the precision of the prior less complex models. Simulation results show that the predicted critical force necessary for the initiation of particle movement by HK and LuGre models are reduced by 15.87% and 22.22% respectively and the critical time by 50% and 75% respectively compared to Coulomb model.

Keywords: Modeling; Nanomanipulation; Atomic Force Microscopy; Friction models

Effect of UV exposure on the surface chemistry of wood veneers treated with ionic liquids by Silvia Patachia; Catalin Croitoru; Christian Friedrich (pp. 6723-6729).

► Treating poplar wood veneers with four types of alkylimidazolium-based ionic liquids. ► Wood wettability is increased by ionic liquid treatment. ► Wood resistance to UV light exposure is increased by ionic liquid treatment. ► Decreasing the crystallinity and improving the flexibility of the cellulose matrix. ► Preservation of cellulose crystallinity at higher UV irradiation duration.In this paper, the influence of four types of imidazolium-based ionic liquids (ILs) on the chemical alteration of the surface of wood veneers exposed to 254nm UV irradiation have been studied by using image analysis, Fourier transform infrared spectroscopy and surface energy calculation. The wood treated with ionic liquids showed better stability to UV light, as demonstrated by the low lignin, carbonyl index and cellulose crystallinity index variation, as well as very small color modification of the surface with the increase of the UV exposure period, by comparing to non-treated wood. The results show that the tested ionic liquids could be effective as UV stabilizers.

Keywords: Ionic liquids; Wood veneers; UV irradiation; Image analysis; FTIR spectroscopy; Surface energy

Nanoindentation response of zinc titanate thin films deposited by co-sputtering process by Shyh-Chi Wu; Yeau-Ren Jeng; Wei-Hung Yau; Kuan-Te Wu; Chien-Huang Tsai; Chang-Pin Chou (pp. 6730-6734).

► We evaluated the nanoindentation response of zinc titanate films. ► The H, M, R_ms, and R_a were altered based on grain growth and recovery. ► The annealing treatment induces weaker bonds and lower resistance at the film.In this study, ZnTiO₃ films were grown by radio frequency magnetron co-sputtering using a sintered ceramic target on silicon substrates, we used nanoindenter techniques under a CSM mode to evaluate the hardness ( H) and elastic modulus ( E) of the films after annealing in temperature range of 520–820°C. The measured values of hardness and elastic moduli of the ZnTiO₃ films were in the range from 8.5±0.4 to 5.6±0.4GPa and from 171±2.3 to 155±2.5GPa, respectively. It is evident that an increase in the roughness due to high annealing temperature using atomic force microscopy. The XRD patterns were observed that as-deposited films are mainly amorphous, however, the hexagonal ZnTiO₃ phase was observed with the ZnTiO₃ (104), (110), (116), and (214) peaks from 620 to 820°C, indicating that there is highly (104)-oriented ZnTiO₃ on the silicon substrate. The X-ray photoelectron spectroscopy core level analysis of the ZnTiO₃ films have been measured for O 1s that can be attributed the weaker bonds and lower resistance at the film based on the higher annealed temperature. The H, M, R_ms, and R_a were altered due to the grain growth and recovery to result in a relax crystallinity at ZnTiO₃ films.

Keywords: Radio frequency magnetron co-sputtering; Hardness; Atomic force microscopy; X-ray photoelectron spectroscopy

Enhanced UV emission of Y-doped ZnO nanoparticles by J.H. Zheng; J.L. Song; Q. Jiang; J.S. Lian (pp. 6735-6738).

► Rare earth element Y was doped in ZnO nanoparticles and the saturation concentration of Y in ZnO lattice is 6.12at%. ► The UV emission of ZnO can be significantly increased by Y doping in ZnO lattice. ► The deep level emission of ZnO was suppressed by Y doping and a high intensity ratio (32) of UV to DLE was obtained.Y-doped ZnO (Zn1−_xY_xO) nanoparticles with different Y concentrations were synthesized by sol–gel method. The effects of Y concentration on the optical properties of the as-synthesized Zn1−_xY_xO nanoparticles were investigated. Photoluminescence (PL) measurements revealed that doping of Y in ZnO induced an evidence increase of UV emission. At Y concentration x=0.07, the UV emission intensity reached maximum, which is about 9 times higher than that of the compared pure ZnO nanoparticles. Exceeding this concentration, the formation of Y₂O₃ causes a decrease in the UV emission intensity. This enhanced UV emission enables Zn1−_xY_xO system potential applications in supersensitive UV detector sinimaging, photosensing, and intrachip optical interconnects.

Keywords: Semi-conductors; Zn; 1−; _x; Y; _x; O nanoparticals; Optical properties

Fabrication and characterization of superhydrophobic surface by using water vapor impingement method by Kok Deng Han; C.P. Leo; Siang Piao Chai (pp. 6739-6744).

Display Omitted► New fabrication method to produce superhydrophobic coating has been successfully developed. ► This method requires less than an hour of processing time and uses simple fabrication processes. ► Measured average static contact angle is 166° while hysteresis is 10° with sliding angle of 2.6°.In this research, superhydrophobic coating with average static contact angle of 166° has been successfully prepared by using a new surface roughening method. Discussion on the applicability of Cassie and Wenzel equations used to determine surface parameters from experimental data is being included as well. This new surface roughening method uses accelerated water vapor to impinge wet film forming crater-like structure surface; analogous to meteor striking earth forming crater. Wet film is comprised of aluminium tri-sec butoxide, propan-2-ol, and ethyl acetoacetate according to molar ratio of 1:10:1. Craters with diameter distribution of 1–20μm were formed on the roughened surface. It was then subjected to 10min of immersion in boiling water, 20min of immersion in fluoroalkylsilane solution, and 10min of 100°C hot air treatment producing superhydrophobic coating. This superhydrophobic crater-like structure surface has approximately 8% solid-to-liquid area fraction and high roughness value of 6.4. These values were obtained from both Cassie and Wenzel equations but with some minor modification in order to fit them into experimental data. Average sliding angle of 2.6° and hysteresis value of 10° were recorded.

Keywords: Superhydrophobic; Water vapor impingement; Crater-like structure; Cassie; Wenzel

Titania/zinc oxide nanocomposite coatings on glass or quartz substrate for photocatalytic degradation of direct blue 71 by Mohammad Hossein Habibi; Maryam Mikhak (pp. 6745-6752).

► We have coated zinc titanate nanocomposite was coated on glass and quartz substrate. ► We have studied optical properties of composite films. ► We have studied the effect of heat-treatment on the structure evolution. ► We have studied the photocatalytic activity of the nanocomposite toward photodegradation of direct blue 71.Zinc titanate nanocomposite was coated on glass and quartz substrate by sol–gel method. Powder X-ray diffraction (XRD) patterns of the nanocomposite coatings demonstrate that heat treatment change crystalline phase of zinc titanate nanocomposite. Higher temperature led to higher purity of the hexagonal zinc titanate phase. Scanning electron microscope/energy dispersive X-ray spectrometry (SEM/EDX) images demonstrate that size of the nanoparticles decreases with increasing of calcination temperature with an average grain size of 68nm. UV–vis diffuse reflectance spectra (DRS) of the nanocomposites show that the absorption edge of zinc titanate thin films is shifted to higher wavelengths at higher annealing temperatures which is probably due to the atomic inter diffusion between titania nanoparticles and zinc oxide. Photocatalytic activity of the nanocomposites toward photodegradation of direct blue 71 (DB71) was evaluated under UV visible light irradiation. The results indicate that hexagonal zinc titanate nanocomposite exhibit highest photocatalytic activity among the prepared samples.

Keywords: Nanocomposite; Titania/zinc oxide; Direct blue 71 (DB71); Composite coatings; Thin films; Photocatalysts

Treatment for GaSb surfaces using a sulphur blended (NH₄)₂S/(NH₄)₂SO₄ solution by D.M. Murape; N. Eassa; J.H. Neethling; R. Betz; E. Coetsee; H.C. Swart; J.R. Botha; A. Venter (pp. 6753-6758).

► ([(NH₄)₂S/(NH₄)₂SO₄]+S) treatment improved the morphology of (100) n-GaSb surface. ► ([(NH₄)₂S/(NH₄)₂SO₄]+S) found to be most effective at removing SbO and partially removes GaO. ► Higher solubility of SbO in S-based solution accounts for its efficient removal. ► Ga is a “harder” base compared to Sb and therefore GaO is not as efficiently removed as SbO.A sulphur based chemical, [(NH₄)₂S/(NH₄)₂SO₄] to which S has been added, not previously reported for the treatment of (100) n-GaSb surfaces, is introduced and benchmarked against the commonly used passivants Na₂S·9H₂O and (NH₄)₂S. The surfaces of the treated material were studied by scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It has been found that the native oxides present on the GaSb surface are more effectively removed when treated with ([(NH₄)₂S/(NH₄)₂SO₄]+S) than with (NH₄)₂S or Na₂S·9H₂O, as evidenced by the ratio of the O506_eV to Sb457_eV AES peaks. XPS results reveal that Sb₂S₃/Sb₂S₅ “replaces” Sb₂O₃/Sb₂O₅, suggesting that sulphur atoms substitute oxygen atoms in Sb₂O₃/Sb₂O₅ to form SbS. It seems sulphurization only partially removes Ga₂O₃. Treatment with ([(NH₄)₂S/(NH₄)₂SO₄]+S) also results in a noteworthy improvement in the current–voltage ( I– V) characteristics of Au/ n-GaSb Schottky contacts compared to those fabricated on as-received material.

Keywords: Auger electron spectroscopy; X-ray photoelectron spectroscopy; Sulphurization; Native oxides; GaSb surfaces

Study of mixed Ca–Zn hydroxyapatite surface modified by lactic acid by Thouraya Turki; Abdallah Aissa; Christophe Goze Bac; Férid Rachdi; Mongi Debbabi (pp. 6759-6764).

► New hybrid compounds Ca(10− x₎Zn_xHAp-(Lacid) n with 0≤ x≤2; n=5, 10, 20 or 40 were prepared. ► For treated Ca₈Zn₂HAp, DRX and¹³C MAS NMR confirm the appearance of new crystalline phase; zinc phosphate (ZnP₂O₇). ► These obtained results display that the presence of some amount of zinc exalts the reactivity of the apatitic surface.The new hybrid inorganic–organic composites, Ca(10− x₎Zn_x(PO₄)₆(OH)₂-lactic acid, at different amounts of zinc and lactic acid were prepared by dissolution of the organic compound in an hydroxyapatite suspension. They were characterized by XRD, IR, MAS NMR (¹³C and¹H) and chemical analysis. The crystallinity was slightly affected by the presence of organic fragments. IR and (¹³C and¹H) MAS NMR measurements indicate that the carboxylic groups of the acid interact with calcium and zinc ions of hydroxyapatite surface. Chemical analysis displays that zinc promotes the acid grafting. A mechanism of surface modification is proposed based on the obtained results.

Keywords: Hydroxyapatite; Lactic acid; Grafting, Hybrid compounds

Biodegradability study and pH influence on growth and orientation of ZnO nanorods via aqueous solution process by P. Suresh Kumar; P. Paik; A. Dhayal Raj; D. Mangalaraj; D. Nataraj; A. Gedanken; S. Ramakrishna (pp. 6765-6771).

FESEM image of synthesized (a) vertical ZnO nanorods at pH 7 and (b) bio-degradation behavior of ZnO nanorods.Display Omitted► A simple two step method was adopted to fabricate vertical ZnO nanorod onto seedlayer glass and Si substrates. ► The optimum vertical ZnO rod growth occur within the pH range of 6–7. ► Biodegradability studies reveal that the grown ZnO rods are found to be dissolving in bioﬂuids.In the present work, a simple and cost effective successive ionic layer absorption and reaction (SILAR) method was adopted for the first time to grow well oriented crystalline ZnO seed layer films. The highly oriented ZnO hexagonal micro/nanorods were grown over seeded glass and Si (100) substrates by a simple chemical bath deposition (CBD) process at various pH. The surface morphology studies found that the diameters and orientation of the ZnO micro/nanorods has been tailored by varying the pH of the solution. The SEM analysis reveals that the ZnO rods were grown vertically with perfect wurtzite hexagonal shape and their diameter ranges from 300nm to 1μm at optimized pH concentration. The XRD patterns of both ZnO seed layer and micro/nanorods grown films exhibit highly crystalline orientation of ZnO wurtzite structure with a (002) plane orientation, preferentially. The Raman spectra provide evidence for the presence of defects and oxygen vacancies in these nanostructures, which are responsible for the photoluminescence (PL) in the visible region. Biodegradability study on ZnO rods confirms the etching and dissolving behavior of rods over a time period which could act as the Zn ions nutrition. This simple and integrated approach, could lead to a cost effective and convenient way to large scale growth of ZnO rods with subsequent huge interest in future nano-based biosensor applications.

Keywords: ZnO; pH; SILAR method; Chemical bath deposition; Photoluminescence; Biodegradability

Fe₃O₄@ZrO₂ nanoparticles magnetic solid phase extraction coupled with flame atomic absorption spectrometry for chromium(III) speciation in environmental and biological samples by Yi-Wei Wu; Jing Zhang; Jun-Feng Liu; Lin Chen; Zhen-Li Deng; Mu-Xian Han; Xiao-Shu Wei; Ai-Min Yu; Hai-Li Zhang (pp. 6772-6776).

► Fe₃O₄@ZrO₂ nanoparticles were simply prepared by sol–gel method. ► Speciation of Cr(VI) and Cr(III) in different matrix have been easily and cheaply realized by using Fe₃O₄@ZrO₂ nanoparticles magnetic solid phase extraction and FAAS. ► A magnetic separation mode with speediness and convenience was carried out under an extra magnetic field in SPE techniques. ► The analytical performance established by this work is superior to other methods.A new method for Cr(III) speciation in seven kinds of environmental and biological samples by Fe₃O₄@ZrO₂ nanoparticles magnetic solid phase extraction (MSPE) and flame atomic absorption spectrometry (FAAS) has been developed. Fe₃O₄@ZrO₂ nanoparticles were simply prepared by sol–gel method, and the adsorptive behaviors of Cr(III) and Cr(VI) on Fe₃O₄@ZrO₂ nanoparticles were assessed. At pH 8.0–9.0, Fe₃O₄@ZrO₂ nanoparticles were selective towards Cr(III) but hardly Cr(VI). The retained Cr(III) was subsequently eluted with 3.0mL of 0.5molL⁻¹ HNO₃ followed by magnetic decantation. Total chromium was determined after reduction of Cr(VI) to Cr(III) by ascorbic acid. Various parameters affecting Fe₃O₄@ZrO₂ nanoparticles MSPE were optimized systematically. Under the optimum conditions, the adsorption capacity of Fe₃O₄@ZrO₂ nanoparticles for Cr(III) is 24.5mgg⁻¹. With an enrichment factor (EF) of 25, detection limit of Cr(III) was 0.69ngmL⁻¹, and the proposed method has been successfully applied for Cr(III) speciation in seven kinds of environmental and biological samples with satisfactory results.

Keywords: Chromium speciation; Environmental and biological samples; FAAS; Magnetic solid phase extraction; Magnetic nanoparticles

A DFT study on the Cu (111) surface for ethyl acetate synthesis from ethanol dehydrogenation by Ruzhen Li; Minhua Zhang; Yingzhe Yu (pp. 6777-6784).

Display Omitted► Adsorption of ethanol and some other species on Cu (111) surface were presented. ► Most stable configurations of all species and surface properties were presented. ► We find the transitional states for each step. ► Two mechanisms were validated and the route proposed by Colley is favorable. ► The barrier of ethanol dehydrogenation should be the rate-determining step.Copper-based catalysts have shown excellent catalytic performances. Despite extensive studies in the field, the microscopic mechanism of ethanol dehydrogenation to ethyl acetate (EA) on Cu-based catalysts remains controversial. Aiming to provide insight into the catalytic roles of Cu, density functional theory (DFT) calculations have been performed to study the elementary reactions involved in ethanol dehydrogenation to EA on Cu surfaces. In this work, the adsorption properties of ethanol, ethoxy, acetaldehyde, acetyl and EA on the Cu (111) catalyst surface were investigated. Based on two pathways, many transition states involved are located. The results show that the route proposed by Colley is more likely to happen.

Keywords: Cu-based catalyst; Cu (1; 1; 1) surface; Ethanol; Ethyl acetate; DFT

DFT study of 2-butyne-1,4-diol adsorption on Ni(111) or Ni(100) clusters by Takeshi Sakamoto; Hiroto Tachikawa; Kazuhisa Azumi (pp. 6785-6792).

.Display Omitted► DFT calculation was applied to 2-butyne-1,4-diol adsorbed on an Ni(111) or Ni(100) model cluster surface. ► The 2s orbital of carbon atoms contribute to the adsorption energy more than that of the 2p orbital. ► A two-stage interaction of 2-butyne-1,4-diol with the substrate surface was clarified. ► Two-stage interaction includes a weak interaction due to oxygen atoms in a long-range and a strong interaction due to a triple bond in a short-range.Density functional theory (DFT) calculation was applied to acetylene (AC) and 2-butyne-1,4-diol (BD) adsorbed on an Ni(111) or Ni(100) model cluster surface in order to elucidate the relationship between their electronic states and geometry in the adsorption process. Adsorption energy of AC calculated using BSSE correction and binding structure were in good agreement with the experimental data. The geometry and adsorption energy of AC or BD on the Ni(111) surface in the optimized adsorption condition differ from those on the Ni(100) surface. Analysis of a natural electron configuration of adsorbates before and after adsorption on Ni clusters clarified that the 2s orbital rather than other orbitals such as 2p contributed mainly to the adsorption energy.

Keywords: Adsorption; 2-Butyne-1,4-diol; Ni cluster model surface; Density functional theory (DFT) calculation; Natural bond orbital (NBO) method; Natural electron configuration (NEC)

Self assembled film based on hexane-1,6-diamine and 2-mercapto-ethanol on copper by Tunç Tüken; Nur Kıcır; N. Tuğba Elalan; Gökmen Sığırcık; Mehmet Erbil (pp. 6793-6799).

► Inhibition efficiencies of hexane-1,6-diamine, 2-mercapto-ethanol was investigated. ► Their mixture exhibited extra ordinary protection efficiency. ► A self-assembled film is performed on the surface. ► The film thickness can get higher than 0.50μm. ► The protection efficiency of 98.22% is obtained after 7 days.The inhibition efficiencies of hexane-1,6-diamine (HMDA), 2-mercapto-ethanol (ME) and a mixture of these two compounds have been investigated against copper corrosion, in acidic chloride solution. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), atomic force microscopy (AFM), Fourier transformed infrared (FT-IR) and atomic absorption spectroscopy (AAS) measurements were utilized to study the inhibition mechanism. ME was shown to have higher efficiency than HMDA, also their mixture could exhibit extra ordinary protection efficiency. It was shown that this excellent efficiency is a result of self-assembled film on the surface. The surface analysis showed that the film has high surface roughness and its thickness can get higher than 0.50μm. After 7 days exposure time to corrosive environment, the corrosion current ( i_corr) values were calculated and it was shown that self assembled film had 98.22% protection efficiency.

Keywords: 2-Mercapto-ethanol; Hexane-1,6-diamine; Copper; Thin film

Grain-size effect on the preferred orientation of TiC/α-C:H thin films by Yadong Su; Xiangming Wang; Huaming Wang; Mao Wen; Weitao Zheng (pp. 6800-6806).

► The grain-size effect on the preferred orientation has been revealed. ► The preferred orientation of films is significantly affected by the grain size. ► The change in the preferred orientation is governed by the size-dependent Gibbs free energy.The grain-size effect on the preferred orientation has been revealed in TiC/α-C:H nanocomposite films grown by magnetron sputtering, in which the grain size of TiC can be adjusted through changing C content in films. The finding is that the preferred orientation of films is significantly affected by the grain size, and the crystallographic orientation changes from face-centered cubic ( fcc) TiC(111) to (200) as the grain size of nanocrystallite TiC decreases from ∼22.3 to ∼4.7nm. This size-dependent preferred orientation is explained via thermodynamic calculations, from which the size-dependent Gibbs free energies are found to be a key factor that controls the texture development in thin films if the grain size in films is sufficient small.

Keywords: TiC/α-C:H nanocomposite films; Size dependences; Preferred orientation

Adsorption of 2-mercaptobenzothiazole on copper surface from phosphate solutions by L.P. Kazansky; I.A. Selyaninov; Yu.I. Kuznetsov (pp. 6807-6813).

► 2-Mercaptobenzothiazole (MBT) adsorbs on copper from phosphate solutions. ► MBT forming a complex with Cu removes phosphate from the surface film. ► The formed complex [CuMBT]_n completely suppresses the anodic current. ► The thickness of polymeric complex [CuMBT]_n may reach 10nm. ► The possible structure of the formed complex is discussed.Analysis of the electrochemical and XPS results has shown that adsorption of 2-mercaptobenzothiazole (MBT) on copper electrodes in neutral phosphate solutions proceeds through the formation of the chemical bonds by copper (I) cations with exo-sulfur and nitrogen atoms. A protection layer formed of Cu(I)MBT complex prevents precipitation of copper (II) phosphate on a copper surface. The thickness of the surface film consisting of a complex [Cu(I)MBT]_n (having probably polymeric nature), where MBT acts as at least three-dentate ligand, increases depending on the exposure time, reaching 8–9nm after immersing for 12h in test solution. Even in a case of the preliminary formation of copper (II) phosphate on the copper electrode at the anodic potential addition of small amounts of MBT results in complete removal of copper (II) phosphate from the surface.

Keywords: Copper; Inhibition; Phosphate; 2-Mercaptobenzothiazole; XPS

Rapid combustion method for surface modification of strontium aluminate phosphors with high water resistance by Qu Yang; Yingliang Liu; Caixia Yu; Guoxian Zhu; Lei Sha; Yunhua Yang; Mingtao Zheng; Bingfu Lei (pp. 6814-6818).

The XRD profiles of phosphors showed that SrAl₂B₂O₇ phase was formed by solid-state reaction between strontium aluminate and boracic acid in the process of surface modification.Display Omitted► Rapid combustion method was introduced into surface modification of SrAl₂O₄:Eu²⁺, Dy³⁺. ► SrAl₂B₂O₇ layer was formed on the surface of strontium aluminate phosphors. ► Water resistance of strontium aluminate phosphors was enhanced by surface modification.A rapid combustion method was introduced into surface modification of strontium aluminate phosphors, which improved the water resistance of phosphors. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), pH measurements and photoluminescence (PL) spectrophotometry were used to characterize the phosphors before and after modification respectively. Experimental results showed that compact layer of SrAl₂B₂O₇ substance was formed on the surface of strontium aluminate phosphors by direct chemical reaction between strontium aluminate and boracic acid. SrAl₂B₂O₇ substance is chemically stable in water and could improve water resistance of strontium aluminate phosphors effectively.

Keywords: Strontium aluminate phosphors; Rapid combustion method; Surface modification

Role of carbon in the formation of ohmic contact in Ni/4HSiC and Ni/Ti/4HSiC by M. Siad; M. Abdesslam; A.C. Chami (pp. 6819-6822).

► Structural characterisation of Ni and Ni/Ti contacts on n-type 4HSiC. ► Role of carbon in the Ni and Ni/Ti contacts on n-type 4HSiC. ► Raman spectroscopy (RS), X-ray diffraction (XRD) and Auger electron spectroscopy (AES).In this work, we focus on the role of carbon in the Ni and Ni/Ti contacts on n-type 4HSiC. The contacts, formed on the backside of the wafers C-face by electron gun evaporation and annealed at 950°C, were studied by Raman spectroscopy (RS), X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The results show that titanium acts as a diffusion barrier for Si and C preventing the formation of the unfavourable phase NiSi and interacts with carbon to form TiC. The transformation of carbon to graphitic structure (in Ni/Ti/SiC) considerably lowers the sheet resistance and greatly improves the ohmic contact.

Keywords: 4H; SiC; Ohmic contact; Nickel; Titanium; RS; XRD; AES

Hydroxyapatite–poly(l-lactide) nanohybrids via surface-initiated ATRP for improving bone-like apatite-formation abilities by Jiqing He; Xiaoping Yang; Jiaofu Mao; Fujian Xu; Qing Cai (pp. 6823-6830).

Display Omitted► A new strategy based on ATRP to prepare HA–poly(l-lactide) (PLLA) nanohybrids was developed. ► Dispersibility of HA nanoparticles in PLLA matrix was significantly improved by applying HA–PLLA nanohybrids. ► With the good dispersion of HA–PLLA nanohybrids, PLLA/HA–PLLA nanocomposites demonstrated improved bone-like apatite-formation ability in simulated body fluids (SBF).It is important to improve the compatibility of hydroxyapatite (HA) nanoparticles in biodegradable polyesters to obtain desirable nanocomposites for bone tissue engineering applications. Polymer grafting has been proven an efficient way to get nanohybrids with good dispersibility in polymeric matrixes. In this paper, a new strategy to prepare HA–poly(l-lactide) (PLLA) nanohybrids was developed, where PLLA oligomers were grafted from HA nanoparticle surfaces via surface-initiated atom transfer radical polymerization (ATRP) of methylacrylate group terminated PLLA macromonomers (PLLA-MA). HA with the derived ATRP initiators was obtained by (1) preparation of HA from precursors in the presence of 3-aminopropyl-triethoxysilane (APTS) to produce the HA surface with terminalNH₂ groups (HA–NH₂) and (2) reaction of theNH₂ groups of the HA–NH₂ nanoparticles with 2-bromoisobutyryl bromide (BIBB) to produce the 2-bromoisobutyryl-immobilized nanoparticles (HA–Br). The obtained HA–PLLA nanohybrids demonstrated good dispersibility in chloroform. With the good dispersion of HA–PLLA nanohybrids in PLLA matrix, the resultant PLLA/HA–PLLA nanocomposites could much faster induce bone-like apatite-formation in simulated body fluids (SBF) than the PLLA/HA counterparts where the HA nanoparticles aggregated heavily. With the versatility of ATRP, properly, grafting oligomeric PLLA chains from HA nanoparticle surfaces is an effective means for the design of novel HA–polymer biohybrids for future bone tissue engineering applications.

Keywords: Hydroxyapatite; PLLA; Nanohybrids; ATRP; Biomineralization

Numerical and experimental analysis of surface roughness generated by shot peening by Sara Bagherifard; Ramin Ghelichi; Mario Guagliano (pp. 6831-6840).

► Numerical simulation of shot peening is adopted to study surface roughness development. ► The numerical results correspond quiet well with the roughness values measured experimentally on shot peened specimens. ► Different analyses with a wide range of peening parameters have been performed to study the effect of peening condition. ► Each studied roughness parameter, including R_a, R_c and R_z, shows a diverse evolution trend vs. process time. ► The developed model can be used to assess the dependency of surface roughness on various process and material parameters.Shot peening, apart from its various projected effects, modifies also the surface state of treated components in terms of surface irregularities. Bearing in mind that both the macroscopic and the microstructure surface characteristics strongly affect the mechanical structures’ functionality, it is essential to carefully study the surface state of treated components. To assess the surface roughness evolution induced by shot peening, a 3D finite element model of the process is used to investigate surface topography alterations as a function of peening parameters and processing time.Discrete data obtained from the numerical simulations are subsequently elaborated to calculate the conventional roughness parameters. The results obtained from the numerical simulations, correspond quite well with the roughness values measured experimentally on shot peened specimens.It is indicated that the developed numerical model provides an efficient estimation of surface characteristics of shot peened specimens, in terms of surface roughness parameters and thus can be used to properly select the peening parameters considering the eventual surface roughness.

Keywords: Shot peening; Surface roughness; Numerical simulation

Influence of saliva-coating on the ultraviolet-light-induced photocatalytic bactericidal effects on modified titanium surfaces by Jeong-Eun Lee; So-Yoon Park; Young-Il Chang; Young-Jun Lim; Sug-Joon Ahn (pp. 6841-6845).

The purpose of this study was to investigate the ultraviolet-light-induced photocatalytic bactericidal effects of titanium surfaces on Streptococcus sanguinis in the presence of saliva-coating. Three different titanium disks were prepared: machined (MA), heat-treated (HT), and anodized surfaces (AO). Each disk was incubated with whole saliva or phosphate-buffered saline for 2h. Antibacterial tests were performed by incubating a S. sanguinis suspension with each disk for 90 or 180min under ultraviolet (UV) illumination. The viable counts of bacteria were enumerated from the cell suspension and the UV-light-induced photocatalytic bactericidal effects were determined by the bacterial survival rate. Without saliva-coating, AO disks exhibited significantly decreased bacterial survival rates compared to MA disks. The bacterial survival rates of the HT disks were intermediate between MA and AO in the absence of saliva-coating. However, saliva-coating significantly increased bacterial survival rates in all surface types. There was no significant difference in bacterial survival rates among the three surface types after saliva-coating. This study suggests that Ti-based antibacterial implant materials using TiO₂ photocatalyst may have a limitation for intraoral use.

Keywords: Abbreviations; MA; machined titanium surface; HT; heat-treated titanium surface; AO; anodized titanium surface; CFUs; colony forming unitsSaliva-coating; Ultraviolet light; Photocatalytic effect; Bactericidal effect; Titanium dioxide

Synthesis of bifunctional catalysts Al-SBA-15-NH₂ with high aluminum content and the catalytic application for different one-pot reactions by Chunhua Wang; Fanpeng Shang; Xiaofang Yu; Jingqi Guan; Qiubin Kan (pp. 6846-6852).

TEM images of the sample of 6-Al-SBA-15-NH₂ from parallel direction (a) and perpendicular direction (b). TEM images show a perfect hexagonal pore structure, indicating that the addition of organic function group to the materials has no distinct influence on the morphology of composition. The pore diameter of the functionalized materials estimated from the TEM is around 6–8nm.Display Omitted► Acid–base bifunctionalized Al-SBA-15-NH₂ catalysts. ► Synthesized by postsynthetic grafting. ► Possessing high catalytic activity for one-pot cascade reactions.Acid–base bifunctional mesoporous catalysts Al-SBA-15-NH₂ containing high content of Al and organic amine functional groups have been synthesized through the “pH-adjusting” method. The materials were characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM), transmission electron micrographs (TEM), Fourier-transform infrared spectroscopy (FTIR), IR spectra of pyridine adsorption, NH₃-TPD and elemental analysis. Catalytic results showed that 6-Al-SBA-15-NH₂ (Si/Al=6mol%) was more active than 10-Al-SBA-15-NH₂ (Si/Al=10mol%) in one-pot deacetalization–Knoevenagel and deacetalization–nitroaldol (Henry) reactions.

Keywords: pH-adjusting; Acid and base; Mesoporous; One-pot reaction

Role of electrolyte additives on in-vitro electrochemical behavior of micro arc oxidized titania films on Cp Ti by Venkateswarlu K.; Rameshbabu N.; Sreekanth D.; Bose A.C.; Muthupandi V.; Babu N.K.; Subramanian S. (pp. 6853-6863).

► Effect of electrolyte chemistry on the properties of micro arc oxidized titania films was studied. ► The role of oxygen abundance in the electrolyte on anatase-to-rutile phase transformation was studied. ► The corrosion mechanism was explained by EIS equivalent circuit modeling. ► An appropriate electrolyte system was identified to develop corrosion resistant titania films on Cp Ti.The present work is aimed at studying the influence of electrolyte chemistry on the voltage–time ( V– T) response characteristics, phase structure, surface morphology, film growth rate and corrosion properties of titania films fabricated by micro arc oxidation (MAO) on Cp Ti. The titania films were developed with a sodium phosphate based reference electrolyte comprising the additives such as sodium carbonate (Na₂CO₃), sodium nitrite (NaNO₂) and urea (CO(NH₂)₂). The phase composition, surface morphology, elemental composition and thickness of the films were assessed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The corrosion characteristics of the fabricated films were studied under Kokubo simulated body fluid (SBF) condition by potentiodynamic polarization, long term potential and linear polarization resistance (LPR) measurements and electrochemical impedance spectroscopy (EIS) methods. In addition, the corrosion characteristics of the grown films were analyzed by EIS curve fitting and equivalent circuit modeling. Salt spray test (SST) as per ASTMB 117 standard was also conducted to verify the corrosion resistance of the grown films. The XRD results showed that the titania films were composed of both anatase and rutile phases at different proportions. Besides, the films grown in carbonate and nitrite containing electrolyte systems showed an enhanced growth of their rutile phase in the [101] direction which could be attributed to the modifications introduced in the growth process by the abundant oxygen available during the process. The SEM–EDX and elemental mapping results showed that the respective electrolyte borne elements were incorporated and distributed uniformly in all the films. Among all the grown films under study, the film developed in carbonate containing electrolyte system exhibited considerably improved corrosion resistance due to suitable modifications in its structural and morphological characteristics. The rate of anatase to rutile phase transformation and the rutile growth direction were strongly influenced by the abundant oxidizing species available during the film growth process.

Keywords: Cp Ti; Micro arc oxidation; Titania; Corrosion; EIS; Salt spray test

Papillaes-enhanced hydrophobicity of large-sized polytetrafluoroethylene-polyphenylene sulfite soft film prepared by layer-by-layer construction by Cheng Cheng Hou; Wen Jun Wang; Yu Zhang; Zi Sheng Guan (pp. 6864-6869).

Large-sized superhydrophobic film with hierarchical structures were prepared by combining the papillaes on the polytetrafluoroethylene-polyphenylene sulfite surface via layer-by-layer loading on the glass substrate and heat treatment processes. The papillaes formed by 0.1μm-PTFE-coated pollen grains with micro/nanostructures play a key role in formation of the superhydrophobic surfaces.Display Omitted► We reported a low-cost and economical method to fabricate a large size of superhydrophobic soft film ► Our method may be developed into a good strategy to construct special functional surfaces ► Our manuscript shows a novel method to prepare Cassie-type surface by combining natural micro-nanostructure units.Large-sized superhydrophobic soft film with hierarchical structures were prepared by combining papillaes on the polytetrafluoroethylene-polyphenylene sulfite (PTFE-PPS) surface via layer-by-layer construction on the glass substrate and heat treatment processes, therein, the papillaes were formed by 0.1μm PTFE coated on the pollen grains. The water contact angles (CAs) and sliding angles (SAs) of the films are strongly dependent on the number density of the papillaes on the PTFE-PPS surface. A superhydrophobic surface with a water CA=151.5° and SA=4° was obtained when the number density was about 649mm⁻². The papillaes with micro/submicroscale structures play an important role in the formation of the superhydrophobic surface and can change Wenzel-type surface into Cassie–Baxter-type surface. The condensation of water vapor on the Cassie–Baxter-type PTFE-PPS film is much more difficult than that of on the Wenzel-type film. Our method may develop into a facile method to prepare large-sized soft film with low cost, which limited only by the size of the loading substrates.

Keywords: Superhydrophobic; Polytetrafluoroethylene; Polyphenylene sulfite; Soft Film; Pollen Grain

Role of pH of precursor solution in taming the material properties of spray pyrolysed SnS thin films by T.H. Sajeesh; K.B. Jinesh; C. Sudha Kartha; K.P. Vijayakumar (pp. 6870-6875).

► Investigated the effect of pH of the precursors in CSP technique on the material properties of SnS films for the first time. ► Drastic change in crystalline size is achieved. ► Could deposit very low resistive SnS films with photosensitivity. ► Optimized the pH of the precursors for depositing device quality SnS films using CSP technique. ► Engineered the optical band gap of SnS thin films.Samples were deposited using chemical spray pyrolysis technique by varying the pH of the starting precursor solution from 0.8 to 3.2. These samples were analyzed using X- ray diffraction, optical absorption spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy, and electrical measurements in order to investigate the role of pH of the precursor solution on structural, morphological, electrical and optical properties of the SnS films. From the study we could optimize the pH of precursor solution required for the deposition of device quality SnS thin films. Resistivity of the films was brought down by three orders (to 6×10⁻²Ωcm) along with enhancement in grain size as well as photosensitivity by optimizing the pH of the precursor solution alone. Band gap of the films could also be tailored by controlling the pH of the precursor solution.

Keywords: Chemical spray pyrolysis; Photovoltaic, Compound semiconductors; Thin films; Opto-electronic properties; Structural properties

A model for diffusion-driven hydrophobic recovery in plasma treated polymers by Mehdi Mortazavi; Michael Nosonovsky (pp. 6876-6883).

Display Omitted► We propose a model for the hydrophobic recovery of plasma-treated polymers. ► The model takes into account different mechanisms involved in hydrophobic recovery. ► A good agreement between the proposed model and the experimental data is achieved. ► The proposed model can be used in the industries where plasma treatment is used.Plasma treatment is widely used for polymer surface modification and, in particular, for the improvement of its adhesive properties. After such treatment the surface energy increases and therefore adhesion increases. However, the change of surface properties is not permanent. Following the treatment, the surface undergoes a relaxation process, called hydrophobic recovery, after which it restores, at least partially, its original low surface energy. Different mechanisms can be responsible for the observed hydrophobic recovery including the diffusion of polar groups and molecular reorientation. We propose a model for the hydrophobic recovery due to a combination of two thermodynamically non-equilibrium processes: diffusion and molecular reorientation. The model explains the mechanism of the hydrophobic recovery and fits well the available experimental data.

Keywords: Plasma treatment; Hydrophobic recovery; Diffusion; Contact angle

Magnetic property and corrosion resistance of electrodeposited nanocrystalline iron–nickel alloys by G.P. Pavithra; A. Chitharanjan Hegde (pp. 6884-6890).

► The present work describes the electrochemical deposition of Fe–Ni coatings. ► The micro-hardness and magnetization enhanced with increasing current density. ► The alloys show good corrosion resistance in alkaline media. ► These alloys can find applications in the field of hydrogen fuel cells.In the present investigation we have galvanostatically synthesized nanocrystalline Fe–Ni alloys on copper substrate. The effect of current density (c.d.) on composition, surface morphology and phase structure were studied for explaining the magnetic and electrochemical properties of the nanocrystalline alloy. The bath found to exhibit the preferential deposition of less noble Fe than Ni, and at no conditions of c.d., the deposition has changed from anomalous to normal type. Surface morphology and structural characteristics of the deposits were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. As composition of the alloy varied, consequent to the current density a change of body centered cubic structure (bcc) to face centered cubic structure (fcc) was observed for nanocrystalline materials. Finally, the conditions responsible for peak magnetic property and corrosion resistance were optimized. Factors responsible for improved functional properties were explained in terms of surface morphology and crystalline grain size of the coatings.

Keywords: Nanocrystalline Fe–Ni alloy deposition; SEM; XRD; Magnetic property; Corrosion behavior

Hydrothermal synthesis spherical TiO₂ and its photo-degradation property on salicylic acid by Wenlu Guo; Xiaolin Liu; Pengwei Huo; Xun Gao; Di Wu; Ziyang Lu; Yongsheng Yan (pp. 6891-6896).

► We prepared anatase TiO₂ spheres using hydrothermal synthesis via a simple way. ► The TiO₂ had better photocatalytic activity for degradation of salicylic acid. ► We analyzed the degradation process of mechanism of TiO₂. ► We analyzed the kinetics of photocatalytic degradation and the kinetics of adsorption.Anatase TiO₂ spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectra (UV–vis DRS). The TiO₂ consisted of well-defined spheres with size of 3–5μm. The photocatalytic activity of spherical TiO₂ was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO₂ which was processed at 150°C for 48h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716S⁻¹ of the salicylic acid onto TiO₂ (temperature: 150, time: 48h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695gmg⁻¹ of the salicylic acid onto TiO₂ (temperature: 150, time: 48h).

Keywords: Hydrothermal synthesis; Spherical TiO; ₂; Salicylic acid; Degradation rate

Effect of negative substrate bias on the microstructure and mechanical properties of Ti–Si–N films deposited by a hybrid filtered cathodic arc and ion beam sputtering technique by Yujuan Zhang; Yingze Yang; Yuhao Zhai; Pingyu Zhang (pp. 6897-6901).

► A new technique of hybrid MFCA and IBS was used to deposit TiSiN films. ► TiSiN superhard films were synthesized without intentional heating system. ► Negative bias had a wide influence on structure and properties of TiSiN films. ► 100V negative bias was the optimal condition. ► Severe oxidation occurred in films deposited under 200V and 300V negative bias.A hybrid cathodic arc and ion beam sputtering method was employed to synthesize Ti–Si–N films. The influence of negative substrate bias on the structure and mechanical properties was investigated by using XRD, XPS, HRTEM, nanoindentor and so on. With the increasing of negative bias there is a decrease in the TiN crystallite size from 36nm to 10nm. Negative substrate bias promoted the conformation of nc–TiN/a–Si₃N₄ nanocomposite structure with complete phase separation and uniform crystallite size. Superhard TiSiN films with a maximum hardness of 46GPa were successfully synthesized under 100V negative bias. Severe oxidation occurred in films deposited under 200V and 300V negative substrate bias due to the decreasing of deposition rate, which led to the hardness of films reduced to the value of 26GPa and 22GPa respectively.

Keywords: Filtered arc; Ion beam sputtering; Ti–Si–N; Nanocomposite; Hardness

Microstructure and tribological behavior of amorphous and crystalline composite coatings using laser melting by Peilei Zhang; Hua Yan; Peiquan Xu; Zhishui Yu; Chonggui Li (pp. 6902-6908).

► The amorphous and crystal composite coatings were formed by laser melting casting alloy. ► The hardness was increased greatly due to the amorphous phase and grain refinement. ► The elements Nb and Si show obvious positive effects on improving the GFA of coatings.Four composite coatings were fabricated by laser melting. Amorphous phase appeared in the Fe_43.2Ni_28.8B_19.2Si_4.8Nb₄ and Fe_43.2Co_14.4Ni_14.4B_19.2Si_4.8Nb₄ coatings but not in the Fe₃₀Co₃₀Ni₁₅B₁₇Si₈ and Fe₃₉Ni₃₆Mo₂B₁₈Si₅ coatings. The growth of crystalline grain in the coatings was suppressed greatly due to the large cooling rates caused by fast laser scanning. But the crystallization in the coatings cannot be avoided completely and an amorphous and crystalline composite coating was formed in melted zone. Amorphous phase can increase the hardness of coatings greatly and the highest hardness is related to the amount of amorphous phase in the coatings. The amorphous and crystalline composite coatings exhibit excellent performance of abrasion.

Keywords: Coating; Laser melting; Amorphous

The influence of boron doping level on quality and stability of diamond film on Ti substrate by J.J. Wei; Ch.M. Li; X.H. Gao; L.F. Hei; F.X. Lvun (pp. 6909-6913).

► The influence of boron doping on diamond quality was discussed in detail. ► The film adhesion was systematic analyzed. ► Electrode inactivation mechanism was discussed. ► Boron doping level can be optimized based on this study.In this study, we investigate the influence of boron doping level on film quality and stability of boron doped diamond (BDD) film deposited on titanium substrate (Ti/BDD) using microwave plasma chemical vapor deposition system. The results demonstrate that high boron concentration will improve the film conductivity, whereas the diamond film quality and adhesion are deteriorated obviously. The increase of total internal stress in the film and the variation of components within the interlayer will weaken the coating adhesion. According to the analysis of electrode inactivation mechanism, high boron doping level will be harmful to the electrode stability in the view of diamond quality and adhesion deterioration. In this study, 5000ppm B/C ratio in the reaction gas is optimized for Ti/BDD electrode preparation.

Keywords: Boron-doped diamond film; Titanium; Interface; Adhesion; Electrode stability

Cellular response to poly(vinyl alcohol) nanofibers coated with biocompatible proteins and polysaccharides by So Young Lee; Da Hyun Jang; Yun Ok Kang; O Bok Kim; Lim Jeong; Hyun Ki Kang; Seung Jin Lee; Chong-Heon Lee; Won Ho Park; Byung-Moo Min (pp. 6914-6922).

Display Omitted► PVA nanofibers were coated with biopolymers to construct biomimetic scaffolds. ► The effect of biopolymers coating was examined by cytocompatibility in vitro. ► This approach may be useful in the design of novel matrices for skin regeneration.A PVA nanofibrous matrix was prepared by electrospinning an aqueous 10wt% PVA solution. The mean diameter of the PVA nanofibers electrospun from the aqueous PVA solution was 240nm. The water resistance of the as-spun PVA nanofibrous matrix was improved by physically crosslinking the PVA nanofibers by heat treatment at 150°C for 10min. In addition, the heat-treated PVA nanofibrous matrix was coated with biocompatible polysaccharides (chitosan (CHI) or hyaluronic acid (HA)) and proteins (collagen (COL) or silk fibroin (SF)) to construct biomimetic nanofibrous scaffolds. The coating of proteins or polysaccharides on the PVA nanofibrous matrix was confirmed by ATR-IR spectra, and the degree of coating was determined by elemental analysis based on nitrogen content. The coated PVA matrices exhibited less hydrophilicity, except for the HA coating, and better tensile properties than the pure PVA nanofibrous matrix. The increase in tensile properties was due to interfiber bonds formed by the coating. The effect of protein and polysaccharide coating on normal human keratinocytes (NHEKs) and fibroblasts (NHEFs) was examined by cytocompatibility assessment in vitro. Among the CHI-, COL-, HA- and SF-coated PVA matrices, the SF-coated PVA nanofibrous matrix was found to be the most promising scaffold for the attachment and spreading of NHEKs and NHEFs as compared to the pure PVA matrix. This approach to controlling the surface properties of nanofibrous structures with SF may be useful in the design and tailoring of novel matrices for skin regeneration.

Keywords: Poly(vinyl alcohol) (PVA); Electrospinning; Nanofiber; Chitosan; Collagen; Hyaluronic acid; Silk fibroin; Coating; Cell

Hydrothermal derived Li₂SnO₃/C composite as negative electrode materials for lithium-ion batteries by Qiufen Wang; Ying Huang; Juan Miao; Yan Wang; Yang Zhao (pp. 6923-6929).

► We synthesized nanocomposite Li₂SnO₃/C by hydrothermal route. ► Amorphous carbons are distributed among the Li₂SnO₃ nanoparticles. ► The first discharge–charge capacities are 2045.8 and 1756.6mAhg⁻¹. ► Its retain capacity is higher than Li₂SnO₃ after 50th cycles.Composite Li₂SnO₃/C with good cycle performance for lithium-ion batteries was synthesized by a hydrothermal route. The structure, morphology and electrochemical properties of the as-prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and electrochemical measurements. Results show that the length of the Li₂SnO₃ nanorods are in the range of 40–60nm while the average diameter is approximately 30nm. Amorphous carbons are distributed among the Li₂SnO₃ nanoparticles. The first discharge–charge capacities of Li₂SnO₃/C are 2045.8mAhg⁻¹ and 1756.6mAhg⁻¹. After the 50th cycles, the capacity retained is 598.3mAhg⁻¹ at a constant current density of 60mAg⁻¹ in the voltage range of 0.05–2.0V. The composite Li₂SnO₃/C exhibits a better electrochemical property than Li₂SnO₃.

Keywords: Li; ₂; SnO; ₃; /C; Hydrothermal route; Lithium-ion batteries; Electrochemical properties

Field emission properties of vertically aligned thin-graphite sheets/graphite-encapsulated Cu particles by S.M. Wang; H.W. Tian; Q.N. Meng; C.M. Zhao; L. Qiao; Y.F. Bing; C.Q. Hu; W.T. Zheng; Y.C. Liu (pp. 6930-6937).

The insert of Cu particles with larger inter-particle distance can significantly improve the field emission properties of the VGs, which can be attributed to the enhanced local fields at the tip of VGs/GC as well as the electron conductivity enhancement due to the existence of Cu particles.Display Omitted► VGs/GC material was synthesized to improve the FE property of thin-graphite sheets. ► The insert of Cu has significantly improved the FE property of thin-graphite sheets. ► Inter-particle distance and size of Cu particles affect the FE property of VGs/GC. ► FE properties in the low- and high-field region have different emission mechanisms.The field emission from planar graphene sheets is usually limited by the morphological features. To overcome this problem, we grow vertically aligned thin-graphite sheets on graphite-encapsulated Cu particles (VGs/GC) using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Field emission measurements show that the insert of Cu particles can substantially improve the field emission properties of the VGs, which can be attributed to the enhanced local fields at the tip of VGs/GC as well as the electron conductivity enhancement due to the existence of Cu particles. The effects of size and inter-particle distance of Cu particles on field emission for the VGs/GC hybrid material have been revealed.

Keywords: Thin-graphite sheets; Graphite-encapsulated Cu; RF-PECVD; Field emission

Surface adhesion and its dependence on surface roughness and humidity measured with a flat tip by Arzu Çolak; Herbert Wormeester; Harold J.W. Zandvliet; Bene Poelsema (pp. 6938-6942).

► Adhesion force between a surface and large flat atomic force microscope tip. ► Dependence of adhesion on relative humidity and roughness. ► Decrease of the adhesion force beyond 70% relative humidity.The adhesion force between a surface and the tip of an atomic force microscope cantilever has been determined by recording force–distance curves with an atomic force microscope. Flat tips with a diameter of 2μm were used to mimic the adhesion between two parallel surfaces. In such a configuration, the location for the formation and breaking of the capillary water neck is a stochastic by nature, significantly different from that of a spherical tip. The adhesion force is measured as a function of relative humidity for smooth and chemically etched Si(100) surfaces. The roughness of the etched substrate reduces the adhesion by more than an order of magnitude, depending on the exact value of the relative humidity. The adhesion force increases with increasing humidity until a relative humidity of about 70%. Beyond a relative humidity of 70% a decrease of the adhesion force is observed. We anticipate that the latter is due to a decrease of the cross section of the water neck at the snap off point with increasing relative humidity.

Keywords: Adhesion force; Capillary force; Surface roughness; Relative humidity; Flat tip

Pilot-scale production of mesoporous silica-based adsorbent for CO₂ capture by Hou Chuan Wang; Chungsying Lu; Hsunling Bai; Jyh Feng Hwang; Hsiu Hsia Lee; Wang Chen; Yuhao Kang; Shing-Ting Chen; Fengsheng Su; Shih-Chun Kuo; Fang-Chun Hu (pp. 6943-6951).

► A pilot-scale spray drying designed to manufacture mesoporous silica particles. ► The amine-modified MSP exhibited a high adsorption capacity. ► The physicochemical properties of TEPA-MSP were preserved after 20 cycles.This study presents a pilot-scale spray drying system designed to manufacture spherical mesoporous silica particles (MSP) that is capable of producing up to 100g per hour. The MSP fabricated via a nozzle pressure of 4kg/cm² and a drying temperature of 200°C possess a high specific area of 1012m²/g, a narrow pore size distribution with an average pore diameter of 2.4nm, and large pore volume of 0.81cm³/g. They were further modified with a tetraethylenepentamine (TEPA-MSP) to enhance CO₂ adsorption selectivity from gas streams. The adsorption capacity of 15% CO₂ on TEPA-MSP was significantly influenced by adsorption temperature and water vapor of air streams, and reached a maximum of 87.05mg/g (1.98mmol/g) at 60°C and 129.19mg/g (2.94mmol/g) at a water vapor of 6.98%. The adsorption capacities and the physicochemical properties of TEPA-MSP were preserved through 20 cycles of adsorption–desorption operation. A comparative study revealed that the TEPA-MSP had better adsorption performance of 15% CO₂ than the TEPA-modified granular activated carbon and zeolite. These results suggest that the TEPA-MSP can be stably employed in the prolonged cyclic CO₂ adsorption and that they possess good potential for CO₂ capture from flue gas.

Keywords: Amine modification; CO; ₂; adsorption; Spherical mesoporous silica particles; Pilot-scale

Photocatalytic characteristics of TiO₂ films deposited by magnetron sputtering on polycarbonate at room temperature by C.G. Kuo; C.Y. Hsu; S.S. Wang; D.C. Wen (pp. 6952-6957).

► Anatase TiO₂ films were successfully grown at room temperature on PC substrates. ► An optimal sputtering parameters for high photocatalytic activity was proposed. ► RF power was the factor that most affected the contact angle of TiO₂ films. ► The photocatalytic performance is improved by increasing RF power.Anatase TiO₂ thin films were successfully grown at room temperature on polycarbonate substrates, using RF magnetron sputtering under various conditions. The deposition parameters used to examine the photocatalytic activity of TiO₂ films included RF power, sputtering pressure, argon/oxygen ratio (O₂/(Ar+O₂)) and deposition time. An orthogonal array and analysis of variance (ANOVA) were used to determine the performance of the deposition process. The effects of the deposition parameters on the structure, morphology and photocatalytic performance of TiO₂ films were analyzed using scanning electron microscopy (SEM), X-ray diffraction, a contact angle meter and UV/vis/NIR spectroscopy. The RF power was found to be the factor that most affected the water droplet contact angle and the sputtering pressure was found to be the second ranking factor. The results indicate that the photocatalytic performance is improved by increasing RF power, but an increase in sputtering pressure has an adverse effect. Higher photocatalytic activity is achieved for TiO₂ films using an RF power of 210W, sputtering pressure of 0.93Pa, argon/oxygen ratio of 30% and a deposition time of 2h.

Keywords: Photocatalytic TiO; ₂; films; RF magnetron sputtering; Polycarbonate substrates; Hydrophilicity; Methylene blue

Characterization and field emission properties of multi-walled carbon nanotubes with fine crystallinity prepared by CO₂ laser ablation by Ryota Yuge; Kiyohiko Toyama; Toshinari Ichihashi; Tetsuya Ohkawa; Yasushi Aoki; Takashi Manako (pp. 6958-6962).

► Multi-walled carbon nanotubes (MWNTs) were synthesized by irradiating a CO₂ laser onto a boron-containing graphite target. ► A large quantity of MWNTs with fine crystalline structure has been obtained at the condition of 760Torr and room temperature. ► Field emission device with MWNT cathodes indicated sufficient reliability for long term operations.Multi-walled carbon nanotubes (MWNTs) were synthesized by irradiating of a CO₂ laser in continuous wave mode onto a boron-containing graphite target at room temperature. The pressure of Ar atmosphere was controlled in 50, 150, 400, or 760Torr. The diameter of obtained MWNTs was in the range of 5–40nm. The quantity and degree of graphitization of synthesized MWNTs increased with the Ar gas pressure. A large quantity of MWNTs with fine crystalline structure has been synthesized preferentially at the condition of 760Torr. The MWNTs with the fine crystalinity indicated highly oxidative stability in O₂. We also found that a large area field emission device with MWNT cathodes indicated good β value of 3.6×10⁴cm⁻¹, and sufficient reliability for long term operations over 150h, suggesting promising application to field emission devices.

Keywords: Carbon nanotube; CO; ₂; laser ablation; Field emission

White light interferometry for quantitative surface characterization in ion sputtering experiments by S.V. Baryshev; A.V. Zinovev; C.E. Tripa; R.A. Erck; I.V. Veryovkin (pp. 6963-6968).

► Ion beam profiles and crater shapes, yielding accurate sputtering yields, are quantitatively characterized by white light interferometry. ► A dual-beam mass spectrometric system utilizing overlap of multiple ion beams is precisely aligned by means of white light interferometry. ► Time-to-depth calibration in sputter depth profiling experiments is performed by white light interferometry. ► Precise characterization of shallow (∼10nm in depth) surface processing of a Si Genesis collector coupon by a gas clusterAr2000+ ion beam is carried out by white light interferometry.White light interferometry (WLI) can be used to obtain surface morphology information on dimensional scale of millimeters with lateral resolution as good as ∼1μm and depth resolution down to 1nm. By performing true three-dimensional imaging of sample surfaces, the WLI technique enables accurate quantitative characterization of the geometry of surface features and compares favorably to scanning electron and atomic force microscopies by avoiding some of their drawbacks.In this paper, results of using the WLI imaging technique to characterize the products of ion sputtering experiments are reported. With a few figures, several example applications of the WLI method are illustrated when used for (i) sputtering yield measurements and time-to-depth conversion, (ii) optimizing ion beam current density profiles, the shapes of sputtered craters, and multiple ion beam superposition and (iii) quantitative characterization of surfaces processed with ions.In particular, for sputter depth profiling experiments of²⁵Mg,⁴⁴Ca and⁵³Cr ion implants in Si (implantation energy of 1keV per nucleon), the depth calibration of the measured depth profile curves determined by the WLI method appeared to be self-consistent with TRIM simulations for such projectile-matrix systems. In addition, high depth resolution of the WLI method is demonstrated for a case of a Genesis solar wind Si collector surface processed by gas cluster ion beam: a 12.5nm layer was removed from the processed surface, while the transition length between the processed and untreated areas was 150μm.

Keywords: PACS; 06.30.Bp; 07.60.Ly; 61.80.Jh; 79.20.RfWhite light interferometry; Ion sputtering; Depth profiling; Mass spectrometry; Genesis

Surface modification of thermoplastic poly(vinyl alcohol)/saponite nanocomposites via surface-initiated atom transfer radical polymerization enhanced by air dielectric discharges barrier plasma treatment by Weijun Zhen; Canhui Lu (pp. 6969-6976).

Display Omitted► Thermoplastic PVA/saponite nanocomposites were prepared by melting processing. ► Covalent immobilization of ATRP initiators on the TPVA surfaces was enhanced by air DBD plasma treatment. ► The hydrophobic network PMMA brushes were grafted onto the TPVA surfaces via SI-ATRP. ► The water resistance of TPVA substrate after SI-ATRP was significantly enhanced.To improve the water resistance of thermoplastic poly(vinyl alcohol)/saponite nanocomposites (TPVA), a simple two-step method was developed for the covalent immobilization of atom transfer radical polymerization (ATRP) initiators on the TPVA surfaces enhanced by air dielectric barrier discharges (DBD) plasma treatment, and hydrophobic poly(methyl methacrylate) (PMMA) brushes were then grafted onto the surface of TPVA via surface-initiated atom transfer radical polymerization (SI-ATRP). The chemical composition, morphology and hydrophobicity of the modified TPVA surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The water resistance of the surface-functionalized PMMA was evaluated by the contact angle and water adsorption method. It was shown that air DBD plasma treatment activated the TPVA surface and accelerated the immobilization of ATRP initiator on the TPVA surface. Compared with TPVA control, TPVA modified by SI-ATRP can be grafted well-defined and covalently tethered network PMMA brushes onto the surface and the hydrophobicity of TPVA were significantly enhanced.

Keywords: Thermoplastic poly(vinyl alcohol); Saponite; Air dielectric barrier discharges plasma; Surface-initiated atom transfer radical polymerization; Water resistance

Direct radiative recombination in the Se-terminated nanoscale Si porous structure by L.H. Lin; Z.C. Li; J.Y. Feng; Z.J. Zhang (pp. 6977-6981).

► We attain ultrafast recombination lifetimes of 0.49 and 2.68ns in the Se-treated Si porous structure. ► The fast recombination rate is considered to origin from the direct radiative recombination induced by surface modification. ► Excitation wavelength- and temperature-dependent PL spectra are carried out. ► A near-infrared emission band with wavelength around the optimal energy region of light-transfer in optical fiber is observed. ► PLE spectrum indicates the near-infrared PL band is due to recombination in defect states.We prepared vertical porous silicon nanowire (SiNW) arrays using the silver-assisted electroless etching method. The post-selenization treatment was carried out to passivate the surface of the nanostructure with Se-related bonds. Besides the great enhancement of the photoluminescence (PL) intensity and stability, the slow red emission band from the untreated porous SiNWs disappears and the new PL bands blue-shift to the higher energy, with the recombination rate more than three orders of magnitudes faster than that of the red emission band. The lifetime of 0.49 and 2.68ns are attributed to the recombination in the Si nanostructures passivated with SiSe, and SiSeO bonds, respectively. The fast recombination rates indicate that surface modification induced by selenization treatment could lead to the direct radiative recombination of Si nanostructure. Furthermore, a broad near-infrared emission band located at around ∼1300nm is also observed. These results are thought useful in the band gap engineering of Si.

Keywords: Nanoscale Si porous structure; Selenization treatment; Recombination lifetime; Near-infrared emission; Direct radiative recombination

Synthesis of nickel oxide nanoparticles using pulsed laser ablation in liquids and their optical characterization by M.A. Gondal; Tawfik A. Saleh; Q.A. Drmosh (pp. 6982-6986).

► NiO nanoparticles were prepared by pulsed laser ablation technique. ► The structural properties were investigated by XRD, FE-SEM, EDX spectroscopy. ► Optical properties were studied by HR spectrofluorometery, UV–Vis and FTIR spectroscopy. ► XRD analysis confirms lattice parameter=0.4203nm and 8nm grain size. ► Photoluminescence emission spectrum showed strong peak at 3.62eV attributed to band edge transition.Nanomaterials are of great interest due to their applications in many fields. The structural and efficacy of nano-materials depend strongly on the method applied for their synthesis. In this work, nanosized nickel oxide (NiO) particles were prepared by pulsed laser ablation (PLA) technique in 3% H₂O₂ aqueous solution The structural and optical properties of the NiO were investigated by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscope (EDX), UV–Vis spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). XRD analysis confirms that the phase is pure nickel oxide with lattice parameter=0.42033nm and 8nm grain size while photoluminescence emission spectrum showed strong peak at 3.62eV attributed to the band edge transition. FT-IR spectra depicts a strong band at ∼450cm⁻¹ which corresponds to the bending vibration of Ni–O bond. This work demonstrates that PLA is an effective method to control the size, impurity and minimal chemical waste generation which is the major problem with other wet chemical methods.

Keywords: Nickle oxide; Nanoparticles; Pulsed laser ablation; Metal oxides; Optical properties

First-principles study on the electronic structure and optical properties for SnO₂ with oxygen vacancy by Donglin Guo; Chenguo Hu (pp. 6987-6992).

► The electronic structure of SnO₂ with an oxygen vacancy is calculated by DFT. ► The electron and hole effective masses for Sn₁₆O₃₁ are analyzed in detail. ► Various optical properties are calculated and the results agree with experimental data. ► An additional absorption band (588nm) is found for Sn₁₆O₃₁ compared with that of pure SnO₂.The electronic structure and optical properties of SnO₂ with consideration of oxygen vacancy are computed using the first-principles plane-wave pseudopotential method based on the density functional theory. The results show that SnO₂ with oxygen vacancy has a band gap of 1.03eV, and the Fermi level shift upward to the conduction band, showing a typical n-type character; besides oxygen vacancy would introduce a new electronic state within the band gap compared with that of pure SnO₂. Moreover, certain impurity levels are located near the top of the valence band, which narrows the band gap of the compound. Optical properties, including the dielectric function, reflectivity, absorption coefficient and the energy-loss spectrum are calculated and the results are in good agreement with the experiments. The calculated absorption coefficient shows that SnO₂ with oxygen vacancy exhibits an absorption band in the visible region, centered at 2.10eV (588nm). It is demonstrated that oxygen vacancy causes the visible light absorption band.

Keywords: SnO; ₂; crystal; Oxygen vacancy; Electronic structure; Optical properties

Correlation between molecular secondary ion yield and cluster ion sputtering for samples with different stopping powers by A. Heile; C. Muhmann; D. Lipinsky; H.F. Arlinghaus (pp. 6993-6999).

► Power dependency of secondary ion yield on sputtering yield. ► Yield enhancement per primary ion constituent decreases with increasing cluster size. ► Prediction of secondary ion yield enhancement as a function of primary ion species. ► Prediction of degree of fragmentation of sputtered molecules from different samples.In static SIMS, the secondary ion yield, defined as detected ions per primary ion, can be increased by altering several primary ion parameters. For many years, no quantitative predictions could be made for the secondary ion yield enhancement of molecular ions. For thick samples of organic compounds, a power dependency of the secondary ion yield on the sputtering yield was shown. For this article, samples with thick molecular layers and (sub-)monolayers composed of various molecules were prepared on inorganic substrates such as silicon, silver, and gold, and subsequently analyzed. For primary ion bombardment, monoatomic (Ne⁺, Ar⁺, Ga⁺, Kr⁺, Xe⁺, Bi⁺) as well as polyatomic (Bi_n⁺, Bi_n⁺⁺) primary ions were used within an energy range of 10–50keV. The power dependency was found to hold true for the different samples; however, the exponent decreased with increasing stopping power. Based on these findings, a rule of thumb is proposed for the prediction of the lower limit of the secondary ion yield enhancement as a function of the primary ion species. Additionally, effects caused by the variation of the energy deposition are discussed, including the degree of molecular fragmentation and the non-linear increase of the secondary ion yield when polyatomic primary ions are used.

Keywords: Abbreviations; PEI; polyethylene imine; PI; primary ion; PS; polystyrene; SI; secondary ion; SIY; secondary ion yield; SpN; sputtering numberStatic SIMS; Cluster bombardment; Fragmentation; Non-linear yield enhancement; Near-surface energy deposition; Stopping power

Experimental and numerical study of the chemical composition of WSe_x thin films obtained by pulsed laser deposition in vacuum and in a buffer gas atmosphere by S.N. Grigoriev; V.Yu. Fominski; A.G. Gnedovets; R.I. Romanov (pp. 7000-7007).

► WSe_x films were obtained by PLD in vacuum and at various Ar gas pressures up to 10Pa. ► The stoichiometric coefficient x was 1.3 in vacuum, and increased from 1.5 to 2.2 with Ar pressure rise from 2 to 10Pa. ► TOF experiments were used to measure the energy distributions of W and Se atoms in vacuum. ► Collision Monte Carlo model was used to calculate the energy distributions of W and Se atoms in Ar gas. ► Influence of the buffer gas on the preferential sputtering of Se is revealed as a result of modeling.WSe_x thin films were obtained by pulsed laser deposition in vacuum and at various Ar gas pressures up to 10Pa. Stoichiometry and chemical state of the WSe_x films were studied by means of Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. In the case of pulsed laser deposition of WSe_x films in vacuum the value of stoichiometric coefficient x was 1.3. During the deposition in argon at pressures of 2–10Pa the value of x varied from 1.5 to 2.2. To explain the influence of the buffer gas, a model was used that takes into account the following processes: (1) congruent pulsed laser evaporation of the WSe_2.2 target; (2) scattering of laser-evaporated W and Se atoms in Ar; (3) sputtering of the deposited film by high-energy atoms from the laser plume. Experimentally, the velocity distributions of laser-evaporated W and Se atoms in vacuum were determined by the time-of-flight measurements. Collision Monte Carlo simulations were used to quantify the impact of the buffer gas on the energy and the incidence angle distributions of the deposited W and Se atoms. Model distributions were used to determine the chemical composition of the WSe_x films, depending on the efficiency of the preferential sputtering of Se atoms.

Keywords: Pulsed laser deposition; Tungsten diselenide thin films; Monte Carlo simulations; Laser plume dynamics; Chemical composition; Selective sputtering

Preparation of heteropolyacid/TiO₂/fly-ash-cenosphere photocatalyst for the degradation of ciprofloxacin from aqueous solutions by Di Wu; Pengwei Huo; Ziyang Lu; Xun Gao; Xiaolin Liu; Weidong Shi; Yongsheng Yan (pp. 7008-7015).

► The fly-ash cenospheres for carrier are able to solve the problem of hard recycling. ► The photocatalyst modified with H₄SiW₁₂O₄₀ shows superior photocatalytic activity. ► The photocatalyst could represent some selectivity for target pollutants.The TiO₂/fly-ash cenosphere photocatalysts modified with heteropolyacid were synthesized by sol–gel followed solvothermal method at 40°C. Their chemical composition and optical absorption were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), Fourier Transform Infra Red spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that heteropolyacid modification could facilitate the absorption edge of TiO₂/fly-ash cenosphere photocatalyst to shift the visible light region. Heteropolyoxanion could be loaded on the titanium dioxide surface, by which could hinder the recombination rate of excited electron holes. The photocatalytic activity of TiO₂/fly-ash cenospheres modified with heteropolyacid was observed for the degradation of ciprofloxacin (CPFX) under visible light irradiation. The result from degradation of CPFX suggested that the photocatalytic activity of TiO₂/fly-ash cenospheres modified with silicotungstic acid was superior. The synergistic effects of heteropolyacid in modified TiO₂/fly-ash cenospheres photocatalyst particles were responsible for improving visible light photocatalytic activity. Besides, the novel photocatalyst was easy to recycle during post treatment because the fly-ash cenosphere was adopted for carrier.

Keywords: Photocatalysis; Heteropolyacid; TiO; ₂; /fly-ash cenospheres; Ciprofloxacin

Nanometer-scale sharpening and surface roughening of ZnO nanorods by argon ion bombardment by Shyamal Chatterjee; Akshaya K. Behera; Amarabha Banerjee; Lokesh C. Tribedi; Tapobrata Som; Pushan Ayyub (pp. 7016-7020).

► A single crystalline ZnO nanorod array was bombarded by a beam of 50keV argon ions. ► Ion bombardment produces a nanoscale roughening of the nanorod sidewalls. ► It also causes the flat nanorod tips to get sharpened to ultrafine points. ► Both effects are expected to favorably impact a wide variety of applications.We report the effects of exposing a hydrothermally grown, single crystalline ZnO nanorod array to a beam of 50keV argon ions at room temperature. High resolution electron microscopy reveals that the ion bombardment results in a nanometer-scale roughening of the nanorod sidewalls, which were almost atomically flat in the pristine sample. Ion bombardment further causes the flat, ≈100nm diameter nanorod tips to get sharpened to ultrafine points less than 10nm across. While tip sharpening is attributed to preferential sputtering, the formation of crystalline surface protuberances can be ascribed to surface instability due to curvature dependent sputtering and surface diffusion under argon-ion bombardment. Both the nanoscale roughening as well as the tip sharpening are expected to favorably impact a wide variety of applications, such as those involving catalysis, gas sensing, solar cells, field emission and gas discharge.

Keywords: Ion bombardment; Nanorod array; Surface roughening; HREM

Electrochemical depositions of fluorohydroxyapatite doped by Cu²⁺, Zn²⁺, Ag⁺ on stainless steel substrates by F. Bir; H. Khireddine; A. Touati; D. Sidane; S. Yala; H. Oudadesse (pp. 7021-7030).

► Electrochemical deposition process has been successfully used for synthesis of metal ions-doped fluorohydroxyapatite coatings. ► The metal ions reduce the crystallinity of the coatings and improve the surface structure which contributes to the formation of thin and homogeneous layers. ► The solubility of fluorohydroxyapatite layers varies with syntheses temperature. ► The differences in working conditions affect the degree of fluoridation in the coatings. ► The antimicrobial efficiency of biomaterials is improved.Fluoridated hydroxyapatite (FHA, Ca₁₀(PO₄)₆(OH)2−_xF_x where 0< x<2 is the degree of fluoridation) and inorganic ions (Zn²⁺, Cu²⁺, Ag⁺) substituted fluoridated hydroxyapatite coatings (M-FHA) were deposited on the surface of medical grade 316L stainless steel samples by electrochemical deposition technique. The FHA coatings were co-substituted with antibacterial ions (Zn²⁺, Cu²⁺ or Ag⁺) by co-precipitation and ion-exchange methods. Characterization studies of coatings from X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) showed that the obtained layers are monophase crystals FHA and did not contain any discernible crystalline impurity. The particles of all samples are of nano size that gives thin layers. The surface morphology, microstructure and Ca/P atomic ratio of the FHA coatings can be regulated by varying electrolyte temperature. This later affects the porosity of the coating surface and the chemical compositions of the deposits.Quantitative elemental analysis indicates that the copper, zinc and silver ions are incorporated into the Fluorohydroxyapatite.The antimicrobial effects of doped fluorohydroxyapatite coatings against pathogen bacterial strains Staphylococcus aureus were tested in liquid media. The results are promising and demonstrated that all doped FHA samples exhibit excellent antimicrobial activity “in vitro” against the microorganism, so the antimicrobial properties of the coatings developed are improved.

Keywords: Biomaterials; Electrodeposition; Calcium phosphate; Hydroxyapatite (HA); Fluorohydroxyapatite (FHA); Infection; Antimicrobials

Optimal conditions for the preparation of superhydrophobic surfaces on al substrates using a simple etching approach by Min Ruan; Wen Li; Baoshan Wang; Qiang Luo; Fumin Ma; Zhanlong Yu (pp. 7031-7035).

► The superhydrophobic surfaces on an Al substrate were prepared by a simple etching method. ► Effects of etching time, modifiers, and modification concentration and time were investigated. ► The optimal conditions for the best superhydrophobicity were obtained.Many methods have been proposed to develop the fabrication techniques for superhydrophobic surfaces. However, such techniques are still at their infant stage and suffer many shortcomings. In this paper, the superhydrophobic surfaces on an Al substrate were prepared by a simple etching method. Effects of etching time, modifiers, and modification concentration and time were investigated, and optimal conditions for the best superhydrophobicity were studied. It was demonstrated that for etching the aluminum plate in Beck's dislocation, if the etching time was 15s, modifier was Lauric acid–ethanol solution, and modification concentration and time was 5% and 1.5h, respectively, the surface exhibited a water contact angle as high as 167.5° and a contact angle hysteresis as low as 2.3°.

Keywords: Superhydrophobic; Etching; Contact angle

Effects of sintering temperatures on the infrared emissivity of La_0.7Sr_0.3MnO₃ by Shuyuan Zhang; Quanxi Cao; Xiaohua Ma; Zhimin Li (pp. 7036-7038).

► La_0.7Sr_0.3MnO₃ powders were synthesized by the conventional solid state reaction. ► The infrared normal emissivity of La_0.7Sr_0.3MnO₃ powders was studied. ► The resistivity of La_0.7Sr_0.3MnO₃ powders was measured. ► Effects of sintering temperatures on the infrared normal emissivity were discussed.La_0.7Sr_0.3MnO₃ powders were fabricated by the traditional solid state reaction at different temperatures. The crystal structure, infrared transmittance spectra, resistivity and infrared normal emissivity ɛ_N in the range of 8–14μm were examined using different methods. Effects of sintering temperatures on the infrared emissivity were investigated. It is found that the emissivity of La_0.7Sr_0.3MnO₃ powders decreased first and increased then with the sintering temperature's increase from 1273K to 1523K, and the lowest infrared emissivity was obtained when calcined at 1473K. The trend of the variation of the infrared normal emissivity with sintering temperature's increase was opposite to that of crystallite size and similar to that of resistivity.

Keywords: Infrared emissivity; La; _0.7; Sr; _0.3; MnO; ₃; Sintering temperatures

Photocatalytic degradation of an aqueous sulfamethoxazole over the metallic silver and Keggin unit codoped titania nanocomposites by Lei Xu; Geriletu Wang; Fengya Ma; Yahui Zhao; Nan Lu; Yihang Guo; Xia Yang (pp. 7039-7046).

Display Omitted► H₃PW₁₂O₄₀/Ag–TiO₂ was prepared by a single step sol–gel-hydrothermal route. ► H₃PW₁₂O₄₀/Ag–TiO₂ exhibited excellent photocatalytic activity. ► H₃PW₁₂O₄₀/Ag–TiO₂ exhibited excellent recyclability. ► Photocatalytic degradation pathway of sulfamethoxazole was proposed.A series of metallic silver and Keggin unit codoped titania nanocomposites (H₃PW₁₂O₄₀/Ag–TiO₂) were prepared through a single step sol–gel-hydrothermal method. The composites mainly exhibited an anatase phase, featuring micro–meso dual porosity with metallic Ag nanoparticles homogeneously dispersed on the surface of the H₃PW₁₂O₄₀/Ag–TiO₂; meanwhile, they showed photoresponses to both the UV- and visible-light regions. As the novel composite photocatalysts, the materials were used to degrade a light-insensitive target compound, sulfamethoxazole (SMZ), under Xe lamp irradiation (320nm< λ<680nm). The influences of the experimental parameters such as the initial acidity of the reaction system, the initial concentration of SMZ, and the amount of the catalyst on the photocatalytic activity of the H₃PW₁₂O₄₀/Ag–TiO₂ were studied; additionally, the photocatalytic degradation pathway of an aqueous SMZ over H₃PW₁₂O₄₀/Ag–TiO₂ was proposed by analyzing the reaction intermediates and final products identified during the photcatalytic process. Finally, the recyclability of the photocatalyst was evaluated.

Keywords: Polyoxometalate; Silver; Codoped titania; Photocatalysis; Sulfamethoxazole

In vitro assessments on bacterial adhesion and corrosion performance of TiN coating on Ti6Al4V titanium alloy synthesized by multi-arc ion plating by Naiming Lin; Xiaobo Huang; Xiangyu Zhang; Ailan Fan; Lin Qin; Bin Tang (pp. 7047-7051).

► Continuous and compact TiN coating was formed on TC4 by multi-arc ion plating. ► The obtained coating consisted of pure TiN. ► TiN coating could significantly reduce bacterial adhesion. ► TiN coating showed better corrosion resistance than TC4.TiN coating was synthesized on Ti6Al4V titanium alloy surface by multi-arc ion plating (MIP) technique. Surface morphology, cross sectional microstructure, elemental distributions and phase compositions of the obtained coating were analyzed by means of scanning electron microscope (SEM), optical microscope (OM), glow discharge optical emission spectroscope (GDOES) and X-ray diffraction (XRD). Bacterial adhesion and corrosion performance of Ti6Al4V and the TiN coating were assessed via in vitro bacterial adhesion tests and corrosion experiments, respectively. The results indicated that continuous and compact coating which was built up by pure TiN with a typical columnar crystal structure has reached a thickness of 1.5μm. This TiN coating could significantly reduce the bacterial adhesion and enhance the corrosion resistance of Ti6Al4V substrate.

Keywords: In vitro; Bacterial adhesion; Corrosion; TiN; Coating; Titanium alloy

Effect of hydrothermal reaction time on morphology and photocatalytic activity of H₂Ti₃O₇ nanotubes obtained via a rapid synthesis route by Pengyu Dong; Yuhua Wang; Bin Liu; Linna Guo; Yongji Huang; Shu Yin (pp. 7052-7058).

Display Omitted► The conventional method for preparing H₂Ti₃O₇ nanotubes was modified. ► The time of forming a matured network of H₂Ti₃O₇ nanotubes was decreased by 50%. ► The obtained multi-walled nanotubes showed large BET surface area. ► Methyl orange can be degraded effectively in the presence of H₂Ti₃O₇ nanotubes.The traditional hydrothermal method for synthesis of H₂Ti₃O₇ nanotubes was modified, and the total hydrothermal reaction time of forming a matured network of H₂Ti₃O₇ nanotubes was successfully decreased by 50%. The effect of hydrothermal reaction time on morphology and photocatalytic activity of H₂Ti₃O₇ nanotubes was investigated and discussed. Various morphologies can be observed in the as-prepared samples with different hydrothermal reaction times. The photocatalytic activity of the as-prepared samples was evaluated for degradation of methyl orange (MO) under simulated solar irradiation. It was found that the sample treated in the hydrothermal condition for 36h with a matured network of H₂Ti₃O₇ nanotubes showed excellent photocatalytic activity. The photocatalytic activity results were discussed in detail. The stronger absorption in the ultraviolet (UV) range, the increasing crystallization of H₂Ti₃O₇ phase, and larger surface area and pore volume contributed to the enhancement of photocatalytic activity of the as-prepared samples.

Keywords: Nanostructures; Hydrothermal process; Dispersant; Photocatalytic degradation

Morphology on 3D ordered macroporous metals associated to deposition depth by Wuhong Xin; Lili Yang; Jiupeng Zhao; Yao Li (pp. 7059-7063).

► The relationship between the morphology of 3DOM metals and the deposition depth is discussed. ► Poorly ordered templates allow different diffusion rates and result in uneven metal deposits. ► 3DOM FeNi has been fabricated through electrodeposition in a two-electrode system assisted by colloidal templates. ► The product is confirmed to be a pure cubic phase according to XRD analysis.High quality three-dimensionally (3D) ordered macroporous FeNi has been fabricated using the electrodeposition method assisted by colloidal crystal templates. The architectures are composed of highly ordered close-packed spherical pores interconnected. The material of this characteristic structure has potential applications in the fields of catalysts, electrodes, and sensors. The morphology of 3D ordered macroporous metals along the (111) direction is determined by the deposition depth (film thickness). In this work, the observed surface morphology is discussed in terms of subsequently increasing film thickness. Models are set up to help with full understanding of the evolution of the morphology (the shapes of the pore mouths and pore walls).

Keywords: Three-dimensionally (3D) ordered macroporous materials; Morphology; FeNi; Electrodeposition

Size effect on shape recovery and induced strain of NiTi nanowires by Po-Hsien Sung; Cheng-Da Wu; Te-Hua Fang; Cheng-I Weng (pp. 7064-7069).

► The occurrence of initial adhesion deformation depends on the nanowire diameter. ► The nanomechanical strength can be enhanced by decreasing NiTi nanowire diameter. ► During deformation, dislocations glide along the {110} planes inside the nanowire. ► The shape recovery after loading on the (100) surface is faster than that on the (110) surface.The nanomechanical properties, the mechanism of fracture, and the shape recovery of NiTi nanowires under the nanobending test by an atomic force microscope tip are studied using molecular dynamics simulations. The effects of the nanowire diameter and heat treatment are evaluated in terms of atomic trajectories, loading force, adhesion, stress, slip vector, centro-symmetry parameter, Young's modulus, and yield strength. Simulation results show that the occurrence of initial adhesion deformation depends on the nanowire diameter. The nanomechanical strength of a NiTi nanowire can be enhanced by decreasing its diameter. NiTi nanowires in the high-temperature austensite phase have better nanomechanical strength than those of nanowires in the low-temperature martensite phase. During deformation, dislocations glide along the {110} planes inside the nanowire. The shape recovery after loading on the (100) surface is faster than that on the (110) surface.

Keywords: Nanobending; NiTi nanowire; Shape recovery; Nanomechanical properties; Molecular dynamics

Investigation of microstructures and optical properties in Mn-doped SiC films by Yukai An; Lingshen Duan; Xiang Li; Zhonghua Wu; Jiwen Liu (pp. 7070-7074).

► Local structure and optical properties of Mn-doped SiC films were investigated. ► Mn₄Si₇ compounds result in the formation of the C clusters. ► Mn₄Si₇ compounds strongly affect the photoluminescence properties. ► The 413-nm PL peak origins from C cluster centers.Mn-doped SiC films were prepared on Si(100) substrates by RF-magnetron sputtering technique. The microstructures and composition of films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The XRD results show that the Mn-doped SiC films form a 3C–SiC crystal structure and some doped Mn atoms occupy the C sites of SiC lattice. The XPS results suggest that there exist SiC, CC and SiMn bonds in the films, but the signal of SiC bond decreases and that of CC bond increases with the increase of Mn concentration. The Mn K-edge XANES and EXAFS measurements show that the majority of Mn atoms form Mn₄Si₇ secondary phase compounds and the existence of Mn metal and MnO can be safely excluded. Then the photoluminescence (PL) properties of films are observed at room temperature. The origin of 413-nm PL peak is associated with C cluster centers, which obviously correlates with the Mn-doped concentration.

Keywords: SiC film; Mn-doped; Microstructures; Photoluminescence

Wettability modification of rock cores by fluorinated copolymer emulsion for the enhancement of gas and oil recovery by Chunyan Feng; Ying Kong; Guancheng Jiang; Jinrong Yang; Chunsheng Pu; Yuzhong Zhang (pp. 7075-7081).

► The fluorinated copolymer emulsion was successfully fabricated by emulsion polymerization. ► The fluorine side chains of the fluorinated copolymer predominantly moved to the air-polymer interface. ► The prepared copolymer emulsion could alter the wettability of reservoirs rock from strong liquid-wetting to gas-wetting.The fluorine-containing acrylate copolymer emulsion was prepared with butyl acrylate, methacrylic acid and 1H, 1H, 2H, 2H-perfluorooctyl acrylate as monomers. Moreover, the structure of the copolymer was verified by Fourier transform infrared (FTIR), nuclear magnetic resonance (¹H NMR and¹⁹F NMR) and X-ray photoelectron spectroscopy (XPS) analyses. The results showed that all the monomers had been copolymerized and the presence of fluorine moieties. The contact angle (CA) analyses, capillary rise and imbibition spontaneous tests were used to estimate the influence of the copolymer emulsion on the wettability of gas reservoirs. It was observed that the rock surface was of large contact angles of water, oilfield sewage, hexadecane and crude oil after treatment with the emulsion. The capillary rise results indicated that the contact angles of water/air and oil/air systems increased from 60° and 32° to 121° and 80°, respectively, due to the emulsion treatment. Similarly, because of wettability alteration by the fluoropolymer, the imbibition of water and oil in rock core decreased significantly. Experimental results demonstrated that the copolymer emulsion can alter the wettability of porous media from strong liquid-wetting to gas-wetting. This work provides a cost-effective method to prepare the fluoropolymer which can increase gas deliverability by altering the wettability of gas-condensate reservoirs and mitigating the water block effect.

Keywords: Fluorine-containing acrylate copolymer; Contact angle; Liquid-wetting; Gas-wetting; Gas reservoirs rock

Hybrid dimension based modeling of part surface topography and identification of its characteristic parameters by Chan Qiu; Zhenyu Liu; Wanghui Bu; Jianrong Tan (pp. 7082-7093).

► The concept of hybrid dimension is proposed based on integral and fractal dimensions. ► A hybrid dimensional modeling method is presented to describe the surface topography. ► Hybrid dimensional models preserve controllable regular shape and irregular detail. ► Characteristic parameters are constructed and identified to evaluate surface quality. ► Correlation is established between macro and micro surface topographies.Since the complete description of complex part surface is difficult to achieve using the existing integral dimensional or fractal dimensional approaches, the novel concept of hybrid dimension and its modeling method of part surface topography are proposed in this paper. The hybrid dimensional model of part surface topography is established based on the deflection method of surface correlation coefficient, which associates the integral dimensional and fractal dimensional surface topographies. Superimposing the normalized fractal dimensional surface altitude field on the B-spline surface, the hybrid dimensional model can express the integral dimensional information of part surface in macro level, and the fractal dimensional detail in micro level. And the correlation of part surface topographies among different scales and different dimensions is established by the Hybrid Dimensional Surface Correlation Coefficient. Moreover, the characteristic parameter identification method for the hybrid dimensional model of part surface topography is proposed. The component information of integral dimension and fractal dimension is separated and extracted by wavelet analysis, and hybrid dimensional characteristic parameters are identified by the generalized surface structure function method and the roughness mapping method. Finally, the proposed method is applied to design and manufacture of turbo expander.

Keywords: Surface characteristic; Hybrid dimensional modeling; Integral dimensional model; Fractal dimensional model; Wavelet analysis; Characteristic parameter identification

Temperature dependent field emission performances of carbon nanotube arrays: Speculation on oxygen desorption and defect annealing by Jian-hua Deng; Yu-mei Yang; Rui-ting Zheng; Guo-an Cheng (pp. 7094-7098).

► Systematic study of field emission (FE) of CNT arrays at different temperatures. ► Influence of oxygen desorption on field emission of CNT arrays at temperatures. ► Influence of defect annealing on field emission stability of CNT arrays.We report here a systematic study of the field emission (FE) properties of highly ordered carbon nanotube (CNT) arrays at different temperatures. The FE characteristics of the CNT arrays are significantly improved with temperature increasing from 298K to 473K, as evidenced by the decreases of turn-on electric field at 10μA/cm² from 1.064 to 0.774V/μm and threshold field at 10mA/cm² from 1.628 to 1.418V/μm, respectively. Moreover, the stability behavior of the CNT arrays is ameliorated at or after suffering to temperatures. Raman, EDS, XPS, and photoelectron spectrometer were employed to characterize the CNT arrays before and after the FE-Temperature measurements for comparison. Our results demonstrate that the oxygen desorption induced work function decrease (from 4.89 to 4.68eV) of the CNT arrays after longtime exposure to temperature is responsible for the improved FE behavior, while the annealing of defects on CNTs is the main reason for the improved FE stability, which provides an effective approach to stabilizing emitters by temperature processing.

Keywords: Multi-walled carbon nanotubes; Temperature; Field emission; Oxygen desorption; Annealing

Fabrication and surface photovoltage study of hematite microparticles with hollow spindle-shaped structure by Hong Li; Qidong Zhao; Xinyong Li; Yong Shi; Guohua Chen (pp. 7099-7104).

Display Omitted► Hollow α-Fe₂O₃ microparticles with spindle-shaped microstructure were fabricated. ► The hollow α-Fe₂O₃ microparticles mainly grew along the (104) crystal plane. ► The α-Fe₂O₃ microparticles exhibited pronounced surface photovoltage response.Hematite (α-Fe₂O₃) particles with hollow spindle-shaped microstructure were successfully synthesized by a one-pot hydrothermal approach in large scale. The structural properties of the sample were systematically investigated by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectrum, high resolution transmission electron microscopy, selected-area electron diffraction techniques, UV–vis diffuse reflectance spectroscopy and infrared spectroscopy techniques. The characterization results revealed that the α-Fe₂O₃ microparticles with a single-domain crystalline structure was mainly grown along the (104) crystal plane. The valence states and the surface chemical compositions of α-Fe₂O₃ were further identified by X-ray photoelectron spectroscopy. The feature of photo-induced charge separation on spectrum was demonstrated by the surface photovoltage measurement under different external biases. The observed photoelectric characteristics of the as-fabricated material are beneficial for various optical and electronic applications.

Keywords: α-Fe; ₂; O; ₃; microparticles; Hollow structure; Optical properties; Surface photovoltage

Facile synthesis of silver nanoparticles-modified PVA/H₄SiW₁₂O₄₀ nanofibers-based electrospinning to enhance photocatalytic activity by Chunhong Sui; Chao Li; Xiaohong Guo; Tiexin Cheng; Yukun Gao; Guangdong Zhou; Jian Gong; Jianshi Du (pp. 7105-7111).

► Silver nanoparticles are deposited on the surface of PVA/SiW₁₂ nanofibers by using electrospinning and photoreduction methods. ► The as-electrospun PVA/SiW₁₂ nanofibers are regarded as particular precursor. ► Higher photocatalytic activity of tri-component nanohybrids was measured.Regarding poly(vinyl alcohol)/silicotungstic acid (PVA/H₄SiW₁₂O₄₀) gel as precursor, the silver nanoparticles (NPs) were selectively deposited on the surface of the PVA/H₄SiW₁₂O₄₀ nanofibers by using electrospinning and photoreduction methods. X-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy, and UV–vis diffuse reflectance spectroscopy were used to affirm the structure and formation of tri-component nanohybrids. Field environmental scanning electron microscope and transmission electron microscopy indicate that the average diameter of silver NPs was changed from 25nm to 50nm, with decreasing the relative concentration of SiW₁₂ in the as-electrospun nanofibers. The nanocomposites exhibit excellent photocatalytic activity in degradation of Rhodamine B. This result arises from the synergistic effects and the large specific surface areas of Ag/PVA/H₄SiW₁₂O₄₀ tri-component nanohybrids.

Keywords: Electrospinning; Silicotungstic acid; Silver nanoparticles; Photocatalytic activity

Growth of vertically aligned carbon nanotubes over self-ordered nano-porous alumina films and their surface properties by Kuldeep Rana; Gokce Kucukayan-Dogu; Erman Bengu (pp. 7112-7117).

► Anodic aluminum oxide with self-organized arrays of nanopores has been synthesized. ► Wetting behavior of water on AAO surfaces is investigated. ► AAO was used as a template for vertically aligned carbon nanotube array synthesis. ► Super-hydrophobic behavior of AAO/VACNT hybrid structures was examined.Nanoporous anodic aluminum oxide (AAO) with self-organized arrays of uniform nanopores have been used for various applications in the fields of sensing, storage, separation and template-based fabrication of metal nanowires, carbon nanotubes, oxides and polymers. The work presented here involves the production and use of AAO templates for growth of aligned multi walled carbon nanotube arrays. AAO templates were formed by electrochemical oxidation of aluminum in different electrolyte solutions containing sulfuric, oxalic and phosphoric acid. SEM was used for the analysis of the surface morphology of the AAO films. The porous structures with pore size in the range of 25–120nm were observed. Pore sizes were correlated with the type of acidic solutions used as the electrolyte. Finally, AAO surfaces have been used as substrates for the growth of vertically aligned carbon nanotubes through chemical vapor deposition technique, which showed super-hydrophobic behavior as confirmed by contact angle measurements.

Keywords: Anodization; Porous alumina film; Chemical vapor deposition; Carbon nanotube; Contact angle

Effect of Cu ions on the morphology, structure and luminescence properties of ZnO nanorod arrays prepared by hydrothermal method by Jianping Xu; Pei Liu; Shaobo Shi; Xiaosong Zhang; Lishi Wang; Zhirui Ren; Lin Ge; Lan Li (pp. 7118-7125).

Display Omitted► The diameter sizes of ZnO nanorod arrays can be tuned by Cu ion additions. ► The effects of Cu ions and annealing on luminescence properties are investigated. ► PL and PLE spectra were used to investigate the excitation process of the visible emissions.Well-aligned ZnO nanorod arrays with different average diameters were grown by hydrothermal method in the presence of Cu ions in the deposition solution. Cu ions significantly inhibit diameter growth of ZnO nanorods and influence the luminescence properties. Quantitative analyses reveal that Cu ions were not incorporated into the synthesized nanorods. Photoluminescence spectra show that a weak ultraviolet emission and a strongly broad visible emission band in yellow region under ultraviolet light excitation for as-grown ZnO nanorods. The intensity of yellow emission bands decreases with Cu ions concentration increasing and the peak position has a blue-shift after low temperature thermal treatment. Photoluminescence spectra under different excitation energies and photoluminescence excitation spectra reveal that the yellow emission bands and green (blue) emission bands are associated with zinc interstitial related shallow donor level and oxygen vacancies related deep donor level as initial states, respectively. A plausible growth mechanism has been proposed to explain the narrowed diameter for ZnO nanorods in the presence of Cu ions based on crystallographic habits of wurtzite hexagonal.

Keywords: PACS; 62.23.St; 61.72.uj; 81.10.Aj; 78.67.−n; 73.20.−rNanostructures; Cation additions; Crystal growth; Luminescence properties; Surface states

Functionalized periodic mesoporous organosilicas for selective adsorption of proteins by Ling Zhu; Xiaoyan Liu; Tong Chen; Zhigang Xu; Wenfu Yan; Haixia Zhang (pp. 7126-7134).

Display Omitted► Amino or carboxylic group periodic mesoporous organosilicas (PMO) was synthesized. ► Modified materials showed selective adsorption of proteins with the different pI. ► The adsorption of proteins was influenced by the interaction of mixture protein.The periodic mesoporous organosilicas (PMO) with an organobridged (CH₂) was synthesized and functionalized with amino or carboxylic groups by post-synthesis methods. The functionalized PMO by changing the hydrophilic/hydrophobic property and the net charge could be used to selectively adsorb and purify proteins with different shapes and different isoelectric points (pI). The experimental result showed that Bovine serum albumin (BSA) was adsorbed quicker than hemoglobin (Hb) on the materials, and lysozyme (Lys) could not be adsorbed on these PMO materials at all. The adsorption capacity of amino groups modified PMO (PMO-(NH₂)₂) for BSA was 44.67mg/g and 300.0mg/gfor Hb on carboxylic groups modified PMO (PMO-(COOH)₂). The adsorption behavior of proteins was affected strongly by the interaction among different constituents in the mixture of proteins. In addition, it is found that the adsorption rate of (PMO-(NH₂)₂ for adsorption of proteins was much slower than PMO-(COOH)₂.

Keywords: Protein; PMO; Amino group; Carboxylic group

Atmospheric pressure diffuse plasma in ambient air for ITO surface cleaning by Tomáš Homola; Jindřich Matoušek; Veronika Medvecká; Anna Zahoranová; Martin Kormunda; Dušan Kováčik; Mirko Černák (pp. 7135-7139).

► Unique filament-free high-energy diffuse plasma in ambient air. ► Considerable decrease of carbon contamination after plasma treatment. ► Significant reduction of water contact angle after plasma treatment.Effects of atmospheric filament-free diffuse plasma in ambient air and oxygen by Diffuse Coplanar Surface Barrier Discharge (DCSBD) on surface of indium tin oxide (ITO) were studied. The DCSBD plasma treatment resulted in significant reduction of water contact angles (even for 1s long treatment). The decrease can be explained by the chemical changes on surface. These were studied by XPS which shows considerable decrease in the carbon surface concentration. The detailed analysis of C1s peak indicates the increase of the highest binding energy component of the C1s peak that corresponds to polar bonds with oxygen, which may be also related to decrease of water contact angle. AFM measurement showed no significant effect of plasma on ITO surface morphology.

Keywords: Atmospheric diffuse plasma; DCSBD; Filament-free plasma; ITO surface; Cleaning; XPS

Investigation on the coupling effect of thermochromism and microstructure on spectral properties of structured surfaces by Junfei Fang; Yimin Xuan; Qiang Li; Desong Fan; Jinguo Huang (pp. 7140-7145).

► Experimental investigation on radiative properties of structured surfaces of thermochromic materials has been conducted. ► The emittance of the structured surfaces dramatically increases. ► A novel approach is proposed for enhancing the spectral features of the thermochromic materials.This paper is aimed at studying the coupling effect of thermochromism and surface microstructure on the spectral properties of structured surfaces. We prepare the samples of structured surfaces of perovskite-type manganese thermochromic materials by patterning one-dimensional gratings and two-dimensional cavity arrays by means of the photolithographic technique. Experiment on radiative properties of these samples indicates that the emittance of the structured surfaces dramatically increases compared with that of the bulk thermochromic materials. It is demonstrated the adjustable emittance range of the thermochromic materials can be effectively enlarged by designing the surface morphology. This implies a novel approach for improving the thermochromic effect of the perovskite-type manganese materials.

Keywords: Emittance; Thermochromic effect; Structured surface

Bismuth titanate microspheres: Directed synthesis and their visible light photocatalytic activity by Xue Lin; Peng Lv; Qingfeng Guan; Haibo Li; Hongjv Zhai; Chunbo Liu (pp. 7146-7153).

Display Omitted► BIT microspheres were synthesized through hydrothermal method. ► BIT samples were characterized by various characterization technologies. ► BIT samples presented outstanding visible-light-induced photocatalytic performance. ► The photoactivity of BIT microspheres is highly affected by its crystal size. ► BIT microspheres prepared at OH⁻ concentration of 3M showed the highest photocatalytic activity.Bismuth titanate, Bi₄Ti₃O₁₂ (BIT), with a well-defined spherical structure, was synthesized by a facile hydrothermal process without using any surfactant or template. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) showed that BIT spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a key role in controlling the formation of seeds and growth rates of BIT particles. Ultraviolet–visible (UV–vis) absorption spectra demonstrated that the band gap of BIT samples was about 2.79eV. In addition, based on the structural analysis of samples obtained at different conditions, a possible mechanism for the formation of these distinctive morphologies was proposed. The as-prepared BIT microspheres exhibited higher photocatalytic activities in the degradation of methyl orange (MO) under visible light irradiation than that of N–TiO₂. Furthermore, BIT microspheres which prepared at OH⁻ concentration of 3molL⁻¹ showed the highest photocatalytic activity.

Keywords: Bi; ₄; Ti; ₃; O; ₁₂; Microspheres; Hydrothermal synthesis; Photocatalytic degradation; Visible light irradiation

Insight into the adsorption and dissociation of CH₄ on Pt( h k l) surfaces: A theoretical study by Riguang Zhang; Luzhi Song; Yuhan Wang (pp. 7154-7160).

Display Omitted► CH is the most abundant species for CH₄ dissociation on Pt catalyst. ► CH dissociation on Pt is unfavorable both kinetically and thermodynamically. ► Pt catalyst can resist the carbon deposition in the CH₄ dissociation.A density functional theory slab calculations of CH₄ dissociation on Pt( h k l) surfaces have been systematically presented. On the basis of the energetic analysis, the favorable adsorption sites and stable configurations of CH_x( x=0–4) and H species on Pt(111), Pt(110) and Pt(100) surfaces are first obtained, respectively. Afterwards, the most stable configurations of coadsorbed CH_x/H( x=0–3) are located. Further, the kinetic and thermodynamical results of CH₄ dissociation on Pt( h k l) surface suggest that CH is the most abundant CH_x species. Our results mean that Pt catalyst can resist the carbon deposition in the CH₄ dissociation, which can give a microscopic reason that why Pt catalyst can lead to lower carbon deposition and show a high activity in the reaction related to CH₄.

Keywords: CH; ₄; Dissociation; Pt(; h; k; l; ) surface; Density functional theory

Existence of ferromagnetism and structural characterization of nickel doped ZnO nanocrystals by R. Varadhaseshan; S. Meenakshi Sundar (pp. 7161-7165).

► The DMS nanoparticles are prepared by microwave irradiated solvothermal process. ► The grain size estimation using transmission electron microscope is less than 20nm. ► RTFM was confirmed in Zn_0.9Ni_0.1O combination. ► RTFM was induced by Ni ions, not for secondary phase or defects in the crystal.Ni doped ZnO (Zn1−_xNi_xO, in which 0.1≤ x≤0.4) diluted magnetic semiconductor nanoparticles are prepared by microwave irradiated solvothermal process. The structural properties are studied using X-ray diffraction. It is evident from the XRD spectrum that the Ni doped ZnO nanocompounds exhibit single phase hexagonal wurtzite structure with strong c-axis orientation. To improve the crystalline quality the samples are annealed at 400°C. The effects of annealing temperature and dopant concentration on the structural properties are also discussed. Unit cell expansion is clearly observed in Ni doped ZnO nanocrystals. The TEM images confirm that the particle size is 20nm and the particles are well dispersed. The magnetic property of the nanocrystals was measured using vibrational sample magnetometer. According to the magnetization measurements ferromagnetic behavior was found in Zn_0.9Ni_0.1O combination. However, for the other higher dopant ratios paramagnetism is observed.

Keywords: Metal oxide; Solvothermal method; Single phase; DMS

Synthesis of acid-functionalized composite via surface deposition of acid-containing amorphous carbon by Bin Du; Xuan Zhang; Lan-Lan Lou; Yanling Dong; Gaixia Liu; Shuangxi Liu (pp. 7166-7173).

► A facile process was developed to synthesize acid-functionalized composite. ► A hydrothermal treatment was employed to prepare the composite. ► All manipulations were carried out at relatively lower temperatures. ► The resultant composite performed high catalytic activity in the test.A synthetic procedure, including two steps: a hydrothermal treatment using H₂SO₄ solution and a thermal treatment with concentrated H₂SO₄ in Teflon-lined stainless autoclaves was developed to synthesize acid-functionalized composite. In this process, the carbonization of glucose which contributed to the formation of carbon species with acid functional groups occurred on the silica surface. The resultant composite, investigated by powder XRD, low temperature N₂ sorption and TEM, possessed well-defined mesostructure. And it was determined by XPS that amorphous carbon was deposited at the silica surface of SBA-15. The presence of multi-functional groups in the composite was confirmed by FT-IR results. Furthermore, carboxylic and sulfonic groups could be incorporated into the composite material via the covalent bond. The composite was employed as the catalyst for the acetalization of carbonyl compounds. It was suggested that acid sites were well dispersed, which was responsible for the good performance in the catalytic test. According to these facts, a synthesis route for mesostructured composite with acid functional groups has been proposed.

Keywords: Acid-functionalized composite; Carboxylic and sulfonic groups; Hydrothermal; Acetalization of carbonyl compounds

Preparation and characterization of carbon/nickel oxide nanocomposite coatings for solar absorber applications by Kittessa T. Roro; Ngcali Tile; Andrew Forbes (pp. 7174-7180).

► We presented a sol–gel synthesis process of C/NiO nanocomposites, and studied the effect of process parameters on structural and optical properties. ► Spectroscopic measurements have shown that the absorption edge shifts to the higher wavelength with increase in heating temperature due to an increase in carbon content in the material. ► The present study demonstrates the potential of nanocomposite surfaces as solar thermal conversion materials.Nanocomposite materials have wide range of applications in solar energy conversion. In this work, C/NiO nanocomposite solar energy absorbing surfaces were prepared using sol–gel synthesis and deposited on aluminium substrates using a spin coater. The coatings were prepared from alcoholic sols based on Ni-acetate using diethalonamine as a chelating agent and polyethylene glycol (PEG) as organic template. Sucrose was used as a carbon source. Sols with different heating temperature and PEG concentrations were fabricated. Thermal analysis on the gel revealed that the xerogels weight loss stabilized at around 430°C. It was found that the absorption edge shifts to the higher wavelength with an increase in the heating temperature in the temperature range studied, 300–550°C, due to an increase in carbon content in the material. The main features of Raman spectra obtained from the composite films are the D and G bands, characteristic of graphitic carbon films. The G peak width narrowed while the ratio of the integrated intensities of the D and G peaks, I_D/ I_G, increased with the heating temperature, suggesting a progressive increase of the graphitic domain within the films. The solar absorption property of the films was enhanced with the increase of PEG concentrations in the sols from 0 to 2g and decreases with further increase of PEG. The best solar absorption, α_sol, and the surface thermal emittance, ɛ_therm, at 100°C obtained were 85% and 5% for a single layer, respectively, yielding an optical selectivity S= α_sol/ ɛ_therm of 17.1.

Keywords: Thin films; Sol–gel preparation; Selective surfaces; Nanocomposite

One-pot aqueous synthesis of near infrared emitting PbS quantum dots by Yaxin Yu; Kexin Zhang; Shuqing Sun (pp. 7181-7187).

► L-Cysteine capped PbS QDs were first successfully synthesized in aqueous solution. ► The synthesized PbS QDs exhibit higher photoluminescent intensity. ► The PbS QDs were still keeping highly PL properties in different environment.In this study, we report the synthesis of PbS quantum dots (QDs) using an aqueous route withl-cysteine (l-Cys) as the capping ligands. The as-prepared PbS QDs were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), the results indicated that the QDs were about 7nm in size and dispersed well. There wasl-Cys on the surface of QDs, which was confirmed by Fourier transform infrared (FT-IR) spectrometry. Various synthesis parameters affecting on the photoluminescent (PL) properties of the PbS QDs were discussed in detail. These parameters include the reaction time, the molar ratio ofl-Cys/Pb or S/Pb, pH value and different sulfur source compounds. Furthermore, we found the as-synthesized QDs were still keeping highly PL properties not only in their original solution but also in deinoized (DI) water and phosphate buffer saline (PBS) solution during the period of 30 days, which indicated that thel-Cys capped PbS QDs could be important to the application in biomedical field in the future.

Keywords: PbS quantum dots; Aqueous synthesis; l; -Cysteine; Luminescence characteristics

Effect of calcination temperature on the adsorption and photocatalytic activity of hydrothermally synthesized TiO₂ nanotubes by Fang Jiang; Shourong Zheng; Lichao An; Huan Chen (pp. 7188-7194).

► The calcination temperature has a crucial effect on photocatalytic activity of TNTs. ► The adsorption amount and crystallinity determine the photocatalytic activity. ► TNTs calcinated at 400°C exhibited a good effect for the mineralization of MB.TiO₂ nanotubes (TNTs) were synthesized by modified hydrothermal method and characterized by the X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermogravimetric (TG) analysis, BET surface area analysis and Raman spectroscopy. The effects of calcinations temperature on the morphology, textural properties, adsorption amount and photocatalytic activity of TiO₂ nanotubes were investigated. The results showed that the adsorption behavior and photocatalytic activity of TiO₂ nanotubes strongly depended on the calcination temperature. Photocatalytic MB degradation on TiO₂ nanotubes surface followed first-order kinetics and the photocatalytic activity of TiO₂ nanotube calcined at 400°C was higher compared to other TiO₂ nanotube catalysts. The higher photocatalytic activity was mainly ascribed to the adsorption amount of MB on the TiO₂ nanotubes and the intrinsic rate constant, a factor of reflecting the crystalline phases and crystallinity on the photocatalytic rate of TiO₂ nanotubes. In addition, the change of the total organic carbon (TOC) of MB photocatalytic-reduction was examined, it was found that nanotubes calcinated at 400°C exhibited a good effect for the mineralization of MB.

Keywords: TiO; ₂; nanotube; Calcination; Adsorption; Photocatalytic activity

Infrared ellipsometry as an investigation tool of thin layers grown into plasma immersion N⁺ implanted silicon by M. Gartner; A. Szekeres; S. Alexandrova; P. Osiceanu; M. Anastasescu; M. Stoica; A. Marin; E. Vlaikova; E. Halova (pp. 7195-7201).

► SiO_xN_y layers were synthesized by high-temperature (1050°C) annealing in oxidizing ambient of plasma immersion N⁺ ion implanted Si substrates. ► The IRSE spectra analysis of the dielectric functions showed that, depending on N⁺ fluence (10¹⁶–10¹⁸N⁺/cm²) and annealing duration (10 and 20min) the grown layers were either as silicon oxynitride with considerably low N content or silicon dioxide enriched with nitrogen. ► SiN, SiNO and SiSi chemical bonds in the silicon oxide network were identified by Infrared ellipsometry and confirmed by X-ray Photoelectron Spectroscopy.By applying ellipsometry and extending the measurements from visible to mid infrared spectral range we examined the complex dielectric function of thin layers grown into silicon. The layers were synthesized by high-temperature (1050°C) annealing in oxidizing ambient of plasma immersion N⁺ ion implanted Si substrates. SiN, SiNO and SiSi chemical bonds in the silicon oxide network were identified and confirmed by X-ray photoelectron spectroscopy (XPS). Depending on N⁺ fluence (10¹⁶–10¹⁸N⁺/cm²) and annealing duration (10 and 20min) the grown layers were identified either as silicon oxynitride with considerably low N content or silicon dioxide enriched with nitrogen.

Keywords: Annealing of N; ⁺; ion implanted Si; Silicon oxynitride; VIS and IR ellipsometry; XPS measurements

Cell adhesion to cathodic arc plasma deposited CrAlSiN thin films by Sun Kyu Kim; Vuong-Hung Pham; Chong-Hyun Kim (pp. 7202-7206).

► We examined osteoblast cell response to CrN, CrAlSiN and Ti thin films in vitro. ► Cell adhesion, actin stress fibers and microtubule organization depended on the film composition. ► Results showed good focal contact adhesion and cell proliferation on the CrAlSiN and Ti thin films but not on the CrN thin films.Osteoblast cell response (cell adhesion, actin cytoskeleton and focal contact adhesion as well as cell proliferation) to CrN, CrAlSiN and Ti thin films was evaluated in vitro. Cell adhesion and actin stress fibers organization depended on the film composition significantly. Immunofluorescent staining of vinculin in osteoblast cells showed good focal contact adhesion on the CrAlSiN and Ti thin films but not on the CrN thin films. Cell proliferation was significantly greater on the CrAlSiN thin films as well as on Ti thin films than on the CrN thin films.

Keywords: Cell adhesion; CrAlSiN thin films; Focal contact adhesion; Cell proliferation; Actin cytoskeleton

Surface characterization of polyethylene terephthalate films treated by ammonia low-temperature plasma by Zhiwen Zheng; Li Ren; Wenjiang Feng; Zhichen Zhai; Yingjun Wang (pp. 7207-7212).

► In order to study the surface characterization and protein adhesion behavior of polyethylene terephthalate film, low temperature ammonia plasma was used to modify the film. ► The surface hydrophilicity of polyethylene terephthalate was significantly improved by ammonia plasma treatment and FTIR spectra showed that some new bonds such asNO and NH which could result in the improvement of the surface hydrophilicity were successfully grafted on the film surface. ► AFM and SEM experiments indicated that more protein or cells adsorbed on hydrophobic surfaces than hydrophilic ones. ► Timeliness experiments showed that the plasma treatment gave the material a certain performance only in a short period of time and the hydrophobicity recovered after 12 days.In order to study the surface characterization and protein adhesion behavior of polyethylene terephthalate film, low temperature ammonia plasma was used to modify the film. Effects of plasma conditions of the surface structures and properties were investigated. Results indicated that surface hydrophilicity of polyethylene terephthalate was significantly improved by ammonia plasma treatment. Ammonia plasma played the role more important than air treatment in the process of modification. Furthermore, by Fourier Transform Infrared spectra some new bonds such asNO and NH which could result in the improvement of the surface hydrophilicity were successfully grafted on the film surface. Atom force microscope experiments indicated that more protein adsorbed on hydrophobic surfaces than hydrophilic ones, and the blobs arranged in a straight line at etching surface by plasma. Modified membrane after ammonia plasma treatment had a good cell affinity and could be effective in promoting the adhesion and growth of cells on the material surface. Timeliness experiments showed that the plasma treatment gave the material a certain performance only in a short period of time and the hydrophobicity recovered after 12 days.

Keywords: Polyethylene terephthalate; Ammonia plasma; Surface treatment; Hydrophilicity; X-ray photoelectron spectroscopy

The improvement of adhesive properties of PEEK through different pre-treatments by Lubica Hallmann; Albert Mehl; Nuno Sereno; Christoph H.F. Hämmerle (pp. 7213-7218).

Display Omitted► Airborne abrasion. ► Etching with piranha solution. ► Primers. ► Self-adhesive luting resin.The purpose of this in vitro study was the evaluation of the bond strength of the adhesives/composite resin to Poly Ether Ether Ketone (PEEK) based dental polymer after using different surface conditioning methods. PEEK blanks were cut into discs. All disc specimens were polished with 800 grit SiC paper and divided into 6 main groups. Main groups were divided into 2 subgroups. The main groups of 32 specimens each were treated as follow: (1) control specimens (no treatment), (2) piranha solution etching, (3) abraded with 50μm alumina particles and chemical etching, (4) abraded with 110μm alumina particles and chemical etching, (5) abraded with 30μm silica-coated alumina particles and chemical etching, (6) abraded with 110μm silica-coated alumina particles and chemical etching. Plexiglas tubes filled with a composite resin (RelyX Unicem) were bonded to the specimens. The adhesives used were Heliobond and Clearfil Ceramic Primer. Each specimen was stored in distilled water (37°C) for 3 days. Tensile bond strength was measured in a universal testing machine and failure methods were evaluated. Abraded surface with 50μm alumina particles followed by etching with piranha solution lead to the highest bond strength of 21.4MPa when Heliobond like adhesive was used. Tribochemical silica coated/etched PEEK surfaces did not have an effect on the bond strength. Non-treated PEEK surface was not able to establish a bond with composite resin. The proper choice of adhesive/composite resin system leads to a strong bond.Airborne particle abrasion in combination with piranha solution etching improves the adhesive properties of PEEK.

Keywords: Airborne abrasion; Bond strength; Chemically etching; Adhesive/composite resin system; PEEK

Effects of nano-fluorocarbon coating on icing by Hong Wang; Guogeng He; Qiqi Tian (pp. 7219-7224).

► Expand the application of surface modifier in the nano-scale. ► The nano-fluorocarbon film is in the thickness of about 10nm. ► The superhydrophobic surface has a good anti-icing performance. ► The results provide a good guidance for designing a dynamic ice-making system using supercooled water.Icing is a common phenomenon in many fields, from aeronautics to power lines. Recently, researchers have paid much attention on the superhydrophobic surface as one of the favorable anti-icing techniques. In the present study, we investigated the performance of water icing on a superhydrophobic surface with a nano-fluorocarbon film in the average thickness around 10nm. The surface topographies and wettabilities were characterized by a scanning electron microscopy system and a video-based contact angle measurement system respectively. To investigate the effects of this nano-fluorocarbon coating on water icing, the water droplet shape, the starting icing time and the whole icing process were observed on both the coated and uncoated surface. It was found that the coated surface has a good ability to retard the starting time of icing while the whole icing time on the coated surface was longer compared the uncoated one under the experimental conditions. The test results showed that the nano-fluorocarbon coating expresses a good anti-icing performance and can be used as a coating material to avoid ice-blocking in the dynamic ice-making system.

Keywords: Ice blocking; Anti-icing; Superhydrophobic surface; Nano-fluorocarbon coating

Ultrathin Cr added Ru film as a seedless Cu diffusion barrier for advanced Cu interconnects by Kuo-Chung Hsu; Dung-Ching Perng; Jia-Bin Yeh; Yi-Chun Wang (pp. 7225-7230).

Display Omitted► 5nm thick RuCr alloy is developed as a Cu diffusion barrier layer. ► RuCr film reveals a glassy microstructure and exhibits high thermal stability. ► RuCr film shows great barrier performance against Cu diffusion up to 650°C.A 5nm thick Cr added Ru film has been extensively investigated as a seedless Cu diffusion barrier. High-resolution transmission electron microscopy micrograph, X-ray diffraction (XRD) pattern and Fourier transform-electron diffraction pattern reveal that a Cr contained Ru (RuCr) film has a glassy microstructure and is an amorphous-like film. XRD patterns and sheet resistance data show that the RuCr film is stable up to 650°C, which is approximately a 200°C improvement in thermal stability as compared to that of the pure Ru film. X-ray photoelectron spectroscopy depth profiles show that the RuCr film can successfully block Cu diffusion, even after a 30-min 650°C annealing. The leakage current of the Cu/5nm RuCr/porous SiOCH/Si stacked structure is about two orders of magnitude lower than that of a pristine Ru sample for electric field below 1MV/cm. The RuCr film can be a promising Cu diffusion barrier for advanced Cu metallization.

Keywords: RuCr alloy; Diffusion barrier; Cu interconnect; Cu metallization

Synthesis and characterization of photochromic Ag-embedded TiO₂ nanocomposite thin films by non-reactive RF-magnetron sputter deposition by J. Zuo; P. Keil; G. Grundmeier (pp. 7231-7237).

► Ag-embedded TiO₂ nanocomposite with reversible photochromic properties. ► No oxidation of the embedded Ag deposited in pure Ar plasma confirmed by XAS. ► No change of the electronic and optical properties of TiO₂ film as well. ► Ag diffuses from the film volume to the outer surface in the oxidizing plasma. ► The non-reactive RF-magnetron method avoids the attack of energetic oxygen ions to Ag.Ag-embedded TiO₂ nanocomposite thin film with reversible photochromic properties were prepared by layer-by-layer non-reactive RF-magnetron sputtering. Films were produced in Ar/O₂ and pure Ar atmospheres. In the oxidizing regime, a diffusion of Ag from the film volume to the outer film surface was observed. Therefore, pure Ar plasma was applied in the deposition of TiO₂. The electronic and optical properties of the TiO₂ film were almost not affected by the presence of oxygen. Transmission electron microscopy (TEM) and reflection mode X-ray absorption spectroscopy (XAS) were performed to study the morphology, crystal structure and chemical state of the embedded Ag nanoparticles before and after the annealing step. Annealing of the film led to the crystallization of the TiO₂ matrix. Moreover, the Ag nanoparticles in the film underwent Ostwald ripening leading to particle agglomerate. No oxidation of the embedded Ag during the sputter deposition and subsequent annealing process was found as confirmed by XAS measurements. The non-reactive RF-magnetron method is believed to avoid the energetic oxygen ions attack to Ag during the deposition of Ag-embedded TiO₂ nanocomposite and thus the films are expected to have better optical properties and long-term stability.

Keywords: Ag-embedded TiO; ₂; Nanocomposite; RF magnetron sputtering; Photochromic

Effect of copper concentration in the electrolyte on the surface morphology and the microstructure of CuInSe₂ films by Pin-Kun Hung; Ting-Wei Kuo; Kuo-Chan Huang; Na-Fu Wang; Po-Tsung Hsieh; Mau-Phon Houng (pp. 7238-7243).

► The relation between surface morphology and [Cu²⁺] concentration is considered in terms of electrodeposition nucleation mechanisms. ► The higher [Cu²⁺] concentrations can provide more numbers of nucleation sites on the surface of the electrode. ► The decreasing dCu_Se is related to charge transfer from interstitial copper atoms and can affect the film microstructure. ► The formation of secondary phases does not relate significantly to the copper content in the precursor films.The surface morphology and the microstructure of CuInSe₂ precursor films have been investigated by co-electrodeposition with different [Cu²⁺] concentrations from 2mM to 4mM. The characteristic of the precursor films was examined using field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), glancing incidence angle X-ray diffraction (GIXRD) and micro-Raman spectrometer, respectively. The surface morphology of the precursor films become more smoother and compact with choice of appropriate [Cu²⁺] concentration (3–3.5mM) in the electrolyte. The relation between surface morphology and [Cu²⁺] concentration is also considered in terms of electrodeposition nucleation mechanisms using the mathematical models of Scharifker and Hills. It is suggested that the higher [Cu²⁺] concentrations can provide more numbers of nucleation sites on the surface of the electrode. Results simulated from the Rietveld refinement method suggest that decreasing dCu_Se is related to charge transfer from interstitial copper atoms and can affect the film microstructure. Micro-Raman spectrum also shows that the excess Cu atoms in the precursor films does not contribute significantly to large amounts of secondary phases but rather exists in the crystallite structure as other defect types.

Keywords: CuInSe; ₂; Electrodeposition; Nucleation; Microstructure

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Applied Surface Science (v.258, #18)