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Applied Surface Science (v.257, #13)

The effect of SiO₂ buffer layer on the electrical and structural properties of Al-doped ZnO films deposited on soda lime glasses by K.H. Ri; Y.B. Wang; W.L. Zhou; J.X. Gao; X.J. Wang; J. Yu (pp. 5471-5475).

► We studied influence of SiO₂ buffer layer on property of AZO films on soda lime glasses by sputtering. ► Electrical property of film deposited at high temperature is enhanced by introducing SiO₂ layers. ► Optical absorption edge is blue shifted due to increase of carrier concentration. ► SiO₂ layer prepared at 400°C is more effective compared with that at room temperature. ► Stress dependence of band gap is linear for AZO films on quartz but deviates for soda lime glasses.In this paper, the influence of SiO₂ buffer layer on electrical and structural properties of AZO films on soda lime glasses has been investigated. The results showed that the Hall mobility and carrier concentration of AZO films deposited on soda lime glasses at high temperature could be enhanced by introducing SiO₂ layers. The optical absorption edges of AZO films with SiO₂ buffer layer are blue shifted compared with that of buffer layer free due to the increase of carrier concentration. SiO₂ layers prepared at 400°C more effectively suppress the diffusion of Na atoms into AZO films compared with that prepared at room temperature. On the other hand, the in-plane stress dependence of optical band gap is linear for AZO films deposited on quartz glass substrates, but is deviated from linearity in the case of soda lime glass substrates.

Keywords: Al doped zinc oxide; Transparent conducting film; Sputtering; Soda lime glass; Buffer layer

Addition of surfactants in ozonated water cleaning for the suppression of functional group formation and particle adhesion on the SiO₂ surface by Jahyun Yang; Kyungtaek Im; Sangwoo Lim (pp. 5476-5479).

Display Omitted► Effect of surfactant addition in ozonated water on the suppression of organic function group formation and particle adhesion to SiO₂ surface. ► Introduction of multi-internal reflection Fourier transform infrared spectroscopy for the analysis. ► Addition of anionic glycolic acid ethoxylate 4-tert-butylphenyl ether in ozonated water prevents particle adhesion and organic group formation on the SiO₂ surface.Various kinds of surfactants were added to a cleaning solution and deionized (DI) water, and their effect on the suppression of organic function group formation and particle adhesion to a SiO₂ surface was analyzed using multi-internal reflection Fourier transform infrared spectroscopy. The results implied that attached organic functional groups are affected by the chemical structure of a surfactant in DI water. Furthermore, the addition of anionic glycolic acid ethoxylate 4-tert-butylphenyl ether (GAE4E) is the most effective in terms of preventing organic group attachment and particle adhesion to the SiO₂ surface, whether it was added to the cleaning solution or post-cleaning rinse water, with or without polystyrene latex particles. Moreover, it was possible to completely prevent particle adhesion to the SiO₂ surface with the proper addition of GAE4E in DIO₃ solution.

Keywords: Photomask; Cleaning; Particle; DIO; ₃; Surfactant; FT-IR

Behavior of oxygen in zinc oxide films through thermal annealing and its effect on sheet resistance by Takahiro Hiramatsu; Mamoru Furuta; Tokiyoshi Matsuda; Chaoyang Li; Takashi Hirao (pp. 5480-5483).

► Improvement of the crystallinity of ZnO film by Post-deposition annealing. ► Decrease of resistivity of ZnO film by post-deposition annealing. ► Formation of oxygen vacancy in ZnO film with desorption of O₂. ► Recover of the resistivity by annealing in O₂. ► The oxygen vacancies are compensated by annealing in O₂ with diffusing into the film.Behavior of oxygen in sputtering deposited ZnO films through thermal annealing and its effect on sheet resistance of the films were investigated. The crystallinities of the ZnO film were improved by post-deposition annealing in vacuum. However, the sheet resistance of ZnO film was dramatically decreased after post-deposition annealing in vacuum at more than 300°C, while O₂ desorbed from the film. The oxygen vacancies which acted as donors were formed by the thermal annealing in vacuum. The sheet resistance of the films was recovered by annealing in oxygen ambient. In this paper,¹⁸O₂ gas as an oxygen isotope was used as the annealing ambient in order to distinguish from¹⁶O, which was constituent atom of the ZnO films. SIMS analysis revealed that¹⁸O diffused into the ZnO film from the top surface by¹⁸O₂ annealing. Therefore oxygen vacancies formed by the post-deposition annealing in vacuum could be compensated by the annealing in oxygen ambient.

Keywords: Oxide semiconductor; Zinc oxide; Thermal desorption spectroscopy (TDS); X-ray diffraction (XRD); Post-annealing

Comparative evaluation of UV–vis–IR Nd:YAG laser cleaning of beeswax layers on granite substrates by A. Pan; S. Chiussi; P. González; J. Serra; B. León (pp. 5484-5490).

► Effect of laser cleaning at four Nd:YAG laser wavelengths. ► Irradiation of beeswax layers on granite samples representing real surfaces. ► Laser cleaning is not a layer by layer removal process. ► Wax–granite interface plays a fundamental role in laser cleaning. ► Wax weakened by absorption of radiation at 266nm increases the cleaning efficiency.The beeswax treatment applied in the sixties to prevent rain water from penetrating the outer stone surface of valuable granitic Galician monuments is contributing to the acceleration of the superficial degradation process of these monuments. At present, the northern sector of the renaissance frieze in the Cloister of the Cathedral of Santiago de Compostela is one of the most representative examples.Conventional wax removal methods (water, chemical and mechanical cleaning) can possibly destruct important details of the relief. Therefore laser removal is considered as a good alternative.In this work, we report systematic investigations of the effect of laser cleaning at different Nd:YAG laser wavelengths (266, 355, 532 and 1064nm) on representative samples of the real historical surfaces.Laser removal of beeswax on granite at neither of the four wavelengths of the Nd:YAG laser is not a layer by layer removal process. For each irradiance and wavelength there is a maximum thickness that can be completely removed by a single pulse. Above this thickness the waxy material is not removed, although it undergoes thermal modifications; since the fraction of radiation that reaches the granite substrate is not enough to trigger the ejection of material.Our results show that the wax–granite interface plays a fundamental role in granite cleaning, and when the wax is weakened by absorption of radiation at 266nm, the removal process becomes more efficient.

Keywords: Nd:YAG laser; Beeswax; Granite; Laser cleaning; Cultural heritage

Fabrication of superhydrophobic cotton fabrics by silica hydrosol and hydrophobization by Lihui Xu; Wei Zhuang; Bi Xu; Zaisheng Cai (pp. 5491-5498).

Display Omitted► Superhydrophobic cotton was prepared by SiO₂ hydrosol and HDTMS hydrophobization. ► We prepared silica hydrosols in the alcohol-free sol–gel system. ► The catalyst and surfactant concentrations affected the SiO₂ particle size. ► SEM, SPM, XPS, and TGA confirmed grafting of SiO₂ and HDTMS on the treated cotton. ► The superhydrophobic cotton had a WCA of 151.9̊ and a WSA of 13̊.Superhydrophobic cotton fabrics were prepared by the incorporation of silica nanoparticles and subsequent hydrophobization with hexadecyltrimethoxysilane (HDTMS). The silica nanoparticles were synthesized via sol–gel reaction with methyl trimethoxy silane (MTMS) as the precursor in the presence of the base catalyst and surfactant in aqueous solution. As for the resulting products, characterization by particle size analyzer, scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) were performed respectively. The size of SiO₂ nanoparticles can be controlled by adjusting the catalyst and surfactant concentrations. The wettability of cotton textiles was evaluated by the water contact angle (WCA) and water shedding angle (WSA) measurements. The results showed that the treated cotton sample displayed remarkable water repellency with a WCA of 151.9° for a 5μL water droplet and a WSA of 13° for a 15μL water droplet.

Keywords: Superhydrophobicity; Silica hydrosol; Cotton fabrics; Hydrophobization; Sol–gel reaction

Adsorption of O₂ on the CaO and SrO (100) surfaces: A first-principles study by Lizhi Wang (pp. 5499-5502).

► The bridge-top site for both the CaO and SrO (100) surfaces is the most favorable site for O₂ adsorption, with predicted adsorption energies of 1.437eV and 1.236eV, respectively. ► Detailed analysis of density of states, Mullikan population and vibration frequency are performed. ► The calculated results imply the possible formation of a peroxo (O₂²⁻) when O₂ is adsorbed with the bridge-top mode on both CaO and SrO (100) surfaces.First-principles calculations based on density functional theory (DFT) have been performed to investigate the adsorption of O₂ on the CaO and SrO (100) surfaces. The present results indicate that the bridge-top site for both the CaO and SrO (100) surfaces is the most favorable site for O₂ adsorption, with predicted adsorption energies of 1.437eV and 1.236eV, respectively. Detailed analysis of density of states, Mullikan population and vibration frequency are performed. The calculated results imply the possible formation of a peroxo (O₂²⁻) when O₂ is adsorbed with the bridge-top mode on both CaO and SrO (100) surfaces.

Keywords: First-principles calculations; Adsorption energy; Mullikan population; Vibration frequency

Structural and surface features of multiwall carbon nanotube by K.P.S.S. Hembram; G. Mohan Rao (pp. 5503-5507).

► The distorted portions of MWCNT are relatively separated at larger distance than the regular portion. ► The alignment of the inner layers are more ordered, than outer layers of MWCNT. ► Disordered portion of the MWCNT possess defects. ► These defects sites retain amorphous carbons, and are suitable places for functionalization.We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the π orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.

Keywords: Carbon nanotube; Surface; Defects; Functionalization

Research of microstructural characteristics on nanocrystalline diamond by microwave plasma CVD by Jing-Ming Hung; Li-Hsiang Lin; Yung-Hsun Shih; Chung-Ming Liu; Hsin-Chung Cheng; Keng-Liang Ou (pp. 5508-5512).

► A less amount of H₂ content additive has improved the aggregation of the nucleation film to form the NCD films. ► The average grain sizes of the diamond film increases as the H₂ concentration increased. ► The microstructure of diamond films were transited from microcrystalline structure to nanocrystalline structure as the concentration of H₂ decreases. ► The NCD film possessed a highly hydrophobic property.In this study, the nanocrystalline diamond (NCD) films were carried out by microwave plasma chemical vapor deposition (CVD) with CH₄/Ar/H₂ gas concoction on Si substrate at moderate temperatures. The characteristics of NCD films were evaluated using scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, optical emission spectroscopy and optical contact angle meter. The analytical results revealed that C₂ radial was the dominant species in the deposited process. From TEM observation, the NCD films were formed via the etching of hydrocarbons and a small amount of H₂ content additive into gas mixture has improved the aggregation of the nucleation film to form the NCD films. The more hydrophobic surfaces imply that NCD films are the potential biomaterial in the application of article heart valve or stent.

Keywords: Nanocrystalline diamond; Microwave plasma; Chemical vapor deposition; Microstructure; Wettability

Investigation on fluorescence quenching of dyes by graphite oxide and graphene by Yan Liu; Chun-yan Liu; Yun Liu (pp. 5513-5518).

► We have studied the electron transfer from the excited dyes molecules to GO, G. ► We have varied different parameters such as the concentration of GO, G and the charge of dyes to study their effect on the fluorescence quenching. ► The possible mechanism leading to fluorescence quenching was proposed.Rhodamine B (Rh B), eosin (E) and methylene blue (MB) were used as a probe to investigate the molecular structure and charge of the dyes on the sensitized efficiency of graphite oxide (GO) and graphene (G). The structure of the prepared GO and G were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. To study the electron transfer between dyes and GO or G, UV–vis absorption spectra (UV–vis), steady state fluorescence spectra (FL) and time resolved fluorescence spectra have been determined. It has been found that the electron transfer from the excited dyes to G was more efficient than to GO, and the transfer from excited MB to G was easier than to Rh B and E, because of the different electrostatic attraction between the dye and G.

Keywords: Graphite oxide; Graphene; Electron transfer; Fluorescence quenching

Galvanic deposition of ZnO nanorods and thermal annealing effects on their optical properties by Lida Wang; Guichang Liu; Longjiang Zou; Dongfeng Xue (pp. 5519-5523).

► Driving force for galvanic deposition of ZnO is related to NaCl concentration. ► Increase of NaCl concentration promotes blue shift of UV emission of ZnO. ► Air thermal annealing at 300° improves ZnO quality and increases their UV emission. ► Air thermal annealing at above 400° decreases UV emission and enhances visible emission. ► Visible emission is related to surface defect induced by thermal annealing.The effects of NaCl electrolyte concentrations in the range 6–48mM on the galvanic deposition of ZnO in Zn(Ac)₂ electrolyte is presented. Effects of thermal annealing on their structural and optical properties have been investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) microanalysis and photoluminescence (PL). The results show that the increase of NaCl electrolyte concentration not only results in the increase of the diameter of ZnO nanorods, but also promotes the blue-shift of UV emission of ZnO. After air annealing at 200°C, 300°C and 400°C, the UV emission is first enhanced then quenched sharply, while the visible emission tends to be enhanced tremendously. It can be ascribed to the new defect states introduced in ZnO after annealing at high temperature.

Keywords: ZnO; Galvanic deposition; Supporting electrolyte; Annealing; Photoluminescence

A variable hydrophobic surface improves corrosion resistance of electroplating copper coating by Xiuqing Xu; Liqun Zhu; Weiping Li; Huicong Liu (pp. 5524-5528).

► The copper/liquid microcapsules composite coating was prepared by electroplating method. ► The composite coating surface exhibits the variable super-hydrophobic property due to the release of liquid core material from microcapsules. ► The hydrophobic surface of composite improves the corrosion resistance and oxygen resistance greatly.In this paper, Cu/liquid microcapsule composite coating was prepared by electroplating method. And a variable hydrophobic surface was obtained due to the slow release of microcapsules and the rough surface. The hydrophobic property and corrosion resistance of the composite was investigated by means of water contact angle instrument and electrochemical technique, respectively. The results suggest that the contact angle (CA) of composite increases gradually with the increasing storing time, and the stable super-hydrophobic property was exhibited after storing in air for 15 days. Meanwhile, the excellent corrosion resistance was displayed, which could be ascribed to the good stability of hydrophobic film on composite surface.

Keywords: Electroplating; Super-hydrophobic; Copper; Microcapsule; Corrosion resistance

Annealing temperature effect on the properties of mercury-doped TiO₂ films prepared by sol–gel dip-coating technique by R. Mechiakh; N. Ben Sedrine; M. Karyaoui; R. Chtourou (pp. 5529-5534).

► Elaboration and characterization of structural and optical properties. ► Sol–gel. ► Nano materials, nano systems, thin films, surfaces and interfaces, applications.This work presents the annealing temperature effect on the properties of mercury (Hg)-doped titanium dioxide (TiO₂). Thin films and polycrystalline powders have been prepared by sol–gel process. The structure, surface morphology and optical properties, as a function of the annealing temperature, have been studied by atomic force microscopy (AFM), Raman, reflectance and ellipsometric spectroscopies. In order to determine the transformation points, we have analyzed the xerogel-obtained powder by differential scanning calorimetry (DSC). Raman spectroscopy shows the crystalline anatase and rutile phases for the films annealed at 400°C and 1000°C respectively. The AFM surface morphology results indicate that the particle size increases from 14 to 57nm by increasing the annealing temperature. The complex index and the optical band gap ( E_g) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreases by increasing the annealing temperature.

Keywords: TiO; ₂; Thin films; Sol–gel; Hg-doped; Anatase; Band gap; Annealing temperature

Influence of reactive gas and temperature on structural properties of magnetron sputtered CrSiN coatings by Hetal N. Shah; R. Jayaganthan; Davinder Kaur (pp. 5535-5543).

► CrSiN coatings were deposited on two substrates under different process condition using reactive magnetron sputtering technique. ► The coatings with low nitrogen content, 40% N₂ has formed a crystalline structure consisting of nano-crystalline CrN, separated by an amorphous SiN phase. ► A less columnar growth is observed in CrSiN coatings deposited at low argon content, and with 3.67at.% Si in the coatings. ► The morphology of the coatings becomes dense with increasing nitrogen content.CrSiN coatings were deposited on stainless steel (Grade: SA304) and silicon Si(100) substrates, with varying argon–nitrogen gas proportions and deposition temperature, using reactive magnetron sputtering technique in the present work. The influence of sputtering (Ar) and reactive gas proportions (N₂) and temperature on the structural properties of the CrSiN coating was investigated. A small amount of silicon content (3.67at.% Si) plays a crucial role in addition to the nitrogen content for the formation of different phases in the CrSiN coatings as observed in the present work. For example, the coating with comparatively low nitrogen content, 40% N₂, during deposition, formed a crystalline structure consisting of nano-crystalline CrN which is separated by an amorphous SiN phase, as evident from X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The formation of CrN(111) and Cr₂N(111) phases has occurred at 30% N₂ with 3.67% Si content, which transformed in to CrN(111) and CrN(200) with increase in N₂ content but with same Si content. The surface topography and morphology of the coatings were analyzed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), respectively. A less columnar growth is observed in CrSiN coatings deposited at low argon content, Ar:N₂ (20:80), and with 3.67at.% Si in the coatings. However, it becomes dense with increase in nitrogen content and temperature. The XRD analysis showed that the intensity of a dominating peak (111) is decreasing from (80:20) to (60:40) argon:nitrogen environment. With a further increase of nitrogen content, from (60:40), in the sputtering gas mixture, to (40:60) argon–nitrogen, there is a sudden increase in (111) peak and above (40:60), the peak reduction rate is very slow than the previous one. The (111) and (200) peak intensity variations are very limited due to high nitrogen content, above 50%, and considerable amount of Si atoms, 3.67at.%, present in the CrN coatings.

Keywords: Reactive sputtering; CrSiN coatings; Microstructural characterizations; Electron microscopy

Synthesis of S/Cr doped mesoporous TiO₂ with high-active visible light degradation property via solid state reaction route by Liu Shao-You; Tang Qun-Li; Feng Qing-Ge (pp. 5544-5551).

► This study demonstrates the successful preparation of S and Cr co-doped mesoporous TiO₂ material via a simple solid state reaction route. ► Research illustrates that the series of the S-Cr-TiO₂ samples show strong absorptions to light irradiation in the visible light and near infrared region, which can greatly promote the utilization of the major part of the solar spectrum, such as in the form of photocatalyst. ► The Raman spectra from the S and Cr co-doped TiO₂ sample are determined, generating the overlapping of the vibrational peaks. ► The high photocatalytic activity results from the cooperative effect of S and Cr co-doped TiO₂, as well as the nanoparticle size effect, large surface area and mesostructure. ► Within 50min, ∼82.6% of the initial BCG is degraded for the S-Cr-TiO₂ (6S-4Cr) photocatalyst, which displays an application feasibility of industrialization.S/Cr doped mesoporous TiO₂ (S-TiO₂, Cr-TiO₂, S-Cr-TiO₂) were successfully synthesized via a simple, effective and environmental benign solid state reaction route. The low angle XRD patterns demonstrated that the resulting samples possess mesostructures. The further characterizations via N₂ adsorption–desorption and XPS showed that the typical S/Cr co-doped mesoporous TiO₂ (S-Cr-TiO₂(5S-5Cr)) possesses mesopore with the high specific surface area of 118.4m²/g and narrow pore size distribution, and both S and Cr have been incorporated into the lattice of TiO₂ with the amounts of 4.16% sulfur and 7.88% chromium, respectively. And Raman spectroscopy shows that the surface of S-Cr-TiO₂ (5S-5Cr) material possesses stretching vibrational peaks at ∼709, ∼793cm⁻¹ are assignable to the Ti-O-Cr, O-Cr (Ti)-OH bonds, respectively. Interestingly, the UV–vis displayed that the absorption regions of S/Cr doped mesoporous TiO₂ cover the visible light region. As for the series of S-Cr-TiO₂ samples, the absorption region even extends to near infrared region with strong adsorption. Moreover, compared with the pure titanium dioxide (P25-TiO₂), the photodegradation properties of bromocresol green (BCG) on the S/Cr doped mesoporous TiO₂ showed excellent photocatalytic properties under visible light irradiation. Within 50min visible light irradiation, 82.6% of the initial BCG was degraded for the S-Cr-TiO₂ (6S-4Cr) photocatalyst.

Keywords: S/Cr doped; Mesoporous; Solid state reaction route; Bromocresol green; Visible light degradation

Organosilane grafted acid-activated beidellite clay for the removal of non-ionic alachlor and anionic imazaquin by Blain Paul; Wayde N. Martens; Ray L. Frost (pp. 5552-5558).

► We prepared clay adsorbents via two-step method to remove nonionic alachlor and anionic imazaquin herbicides from water. ► Layered beidellite clay was treated with acid in hydrothermal process with common silane coupling agents. ► It was found that the selective modification of clay samples displayed higher adsorption capacity for herbicides compared with acid activated clay. ► Clay grafted with 3-chloro-propyl trimethoxysilane is an excellent adsorbent for both alachlor and imazaquin. ► Triethoxy (octyl) silane grafted clay is more efficient only for alachlor removal.Clay adsorbents were prepared via two-step method to remove nonionic alachlor and anionic imazaquin herbicides from water. Firstly, layered beidellite clay, a member of smectite family, was treated with acid in hydrothermal process; secondly, common silane coupling agents, 3-chloro-propyl trimethoxysilane or triethoxy silane, were grafted on the acid treated samples to prepare adsorbent materials. The organically modified clay samples were characterized by powder X-ray diffraction, N₂ gas adsorption, and FTIR spectroscopy. It was found that the selective modification of clay samples displayed higher adsorption capacity for herbicides compared with acid activated clay. And the amount of adsorption is increased with increasing the grafting amount of silane groups. Clay grafted with 3-chloro-propyl trimethoxysilane is an excellent adsorbent for both alachlor and imazaquin but triethoxy (octyl) silane grafted clay is more efficient only for alachlor removal.

Keywords: Adsorption; Beidellite; Silanation; Herbicide removal

Shape controlled flower-like silicon oxide nanowires and their pH response by Qi Shao; Rong-hui Que; Ming-wang Shao; Qing Zhou; Dorothy Duo Duo Ma; Shuit-Tong Lee (pp. 5559-5562).

Display Omitted▶ Silicon oxide flowers with petals composed of nanowires were synthesized using tin and gallium as bicatalysts. ▶ Their pH response reveals excellent linear relation due to their vast surface area.Silicon oxide nanowires were synthesized with high-temperature evaporation using silicon monoxide as starting materials and tin and gallium as catalysts. The products take the shape of flowers with petals composed of silicon oxide nanowires. The pH response of the products reveals excellent linear relation due to their vast surface area.

Keywords: Key words; Silicon oxide; Nanomaterials; pH sensor

Hydrothermal synthesis and characterization of ZnO films with different nanostructures by Jiaoxian Yu; Baibiao Huang; Xiaoyan Qin; Xiaoyang Zhang; Zeyan Wang; Haixia Liu (pp. 5563-5565).

► ZnO films with morphologies of nanorods, nanowires and nanosheets were grown on F-doped SnO₂ glass substrate. ► ZnO preferentially oriented along the c-axis had the best photocurrent density, which may have potential use in solar cells. ► The photocurrent density for ZnO nanorods is as high as 60μA/cm².ZnO films with morphologies of nanorods, nanowires and nanosheets were grown on F-doped SnO₂ glass substrate, which may have potential application in solar cells. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the structures and morphologies of the as-synthesized samples. The photoluminescence (PL) and the photoelectrochemical properties of ZnO films were also measured. The results showed that ZnO nanorods preferentially oriented along the c-axis and had the largest photocurrent density which is as high as 60μA/cm².

Keywords: Semiconductor; ZnO; Thin films; Luminescence; Photocurrent

Effect of spraying power on microstructure and bonding strength of MoSi₂-based coatings prepared by supersonic plasma spraying by Heng Wu; He-jun Li; Qing Lei; Qian-gang Fu; Chao Ma; Dong-jia Yao; Yong-jie Wang; Can Sun; Jian-feng Wei; Zhi-hai Han (pp. 5566-5570).

► MoSi₂-based oxidation protective coatings were prepared using supersonic plasma spraying. ► Effects of spraying power on microstructure and bonding strength of the coatings were studied. ► The coatings become more and more compact and the bonding strength increases when the spraying power increases from 40kW to 50kW. At 50kW, the coatings were dense and the bonding strength reached a maximum value of 14.5MPa. However, when the spraying power reaches 55kW, cracks and pores will reappear in the coatings and the bonding strength also decreases.MoSi₂-based oxidation protective coatings for SiC-coated carbon/carbon composites were prepared using a supersonic plasma spraying at the power of 40kW, 45kW, 50kW and 55kW, respectively. Effect of spraying power on the microstructure and bonding strength of MoSi₂-based coatings was studied. The results show that coatings become more and more compact and the bonding strength increases when the spraying power increases from 40kW to 50kW. At the power of 50kW, the coatings were dense and the bonding strength reached a maximum value of 14.5MPa. As the spraying power is of sufficient magnitude, many cracks and pores reappaer in coatings and the bonding strength between coating and substrate also decreases.

Keywords: MoSi; ₂; -based coatings; Carbon/carbon composites; Bonding strength; Supersonic plasma spraying

Preparation, structure and photo-catalytic performances of hybrid Bi₂SiO₅ modified Si nanowire arrays by Xiang Feng; Xiang Qi; Jun Li; Liwen Yang; Mengchun Qiu; Jinjie Yin; Fang Lu; Jianxin Zhong (pp. 5571-5575).

► Bi₂SiO₅ modified Si nanowire array films were fabricated via dip-coating Bi(NO₃)₃ on electroless-etched Si nanowires and subsequently annealing. ► About 42.2% and 74.8% of methyl orange molecules were degraded in the first 30min and 5h with the aid of the hybrid Bi₂SiO₅ modified Si nanowire arrays, respectively. ► The hybrid Bi₂SiO₅ modified Si array structures are proposed to be resulted in the improvement for efficient electron–hole separation and photo-catalytic stability, thereby possessing superior photo-degradation performance.Bi₂SiO₅ modified Si nanowire array films were fabricated as photo-catalysts via dip-coating Bi(NO₃)₃ on silver-assisted electroless wet chemical etching Si nanowires and subsequently annealing. The structures and morphologies of as-prepared samples are characterized by X-ray diffraction, Fourier transform infrared spectrum, scanning electron microscopy and transmission electron microscopy. The results of photocatalytic experiments indicated that the Bi₂SiO₅ modified Si nanowire arrays benefit the improvement for efficient electron–hole separation and photo-catalytic stability, thereby possessing superior photo-degradation performance. These hybrid nanowire arrays will be promising materials for photo-catalysts and degradation agents.

Keywords: Photo-catalysis; Hybrid nanowire array; Bi; ₂; SiO; ₅; Silicon; Electroless-etching

Preparation and properties of titanium oxide film on NiTi alloy by micro-arc oxidation by H.R. Wang; F. Liu; Y.P. Zhang; D.Z. Yu; F.P. Wang (pp. 5576-5580).

► Titanium oxide coatings were produced on the NiTi alloy by micro-arc oxidation. ► The coatings were tightly adhesive to the substrates. ► The corrosion resistance of NiTi alloy was significantly improved by micro-arc oxidation.Titanium oxide ceramic coatings were prepared by micro-arc oxidation (MAO) in galvanostatic regime on biomedical NiTi alloy in H₃PO₄ electrolyte using DC power supply. The surface of the coating exhibited a typical MAO porous and rough structure. The XPS analysis indicated that the coatings were mainly consisted of O, Ti, P, and a little amount of Ni, and the concentration of Ni was greatly reduced compared to that of the NiTi substrate. The TF-XRD analysis revealed that MAO coating was composed of amorphous titanium oxide. The coatings were tightly adhesive to the substrates with the bonding strength more than 45MPa, which was suitable for medical applications. The curves of potentiodynamic porlarization indicated that the corrosion resistance of NiTi alloy was significantly improved due to titanium oxide formation on NiTi alloy by MAO.

Keywords: NiTi alloy; Titanium oxide coating; Micro-arc oxidation; Corrosion resistance

Corrosion properties of aluminium coatings deposited on sintered NdFeB by ion-beam-assisted deposition by Shoudong Mao; Hengxiu Yang; Jinlong Li; Feng Huang; Zhenlun Song (pp. 5581-5585).

► The effects of Ar⁺ ion-beam-assisted deposition on Al coating were investigated. ► IBAD-Al-coating had fewer voids and better corrosion resistance than Al-coating. ► Pitting corrosion of Al coatings always began at the grain boundaries.Pure Al coatings were deposited by direct current (DC) magnetron sputtering to protect sintered NdFeB magnets. The effects of Ar⁺ ion-beam-assisted deposition (IBAD) on the structure and the corrosion behaviour of Al coatings were investigated. The Al coating prepared by DC magnetron sputtering with IBAD (IBAD-Al-coating) had fewer voids than the coating without IBAD (Al-coating). The corrosion behaviour of the Al-coated NdFeB specimens was investigated by potentiodynamic polarisation, a neutral salt spray (NSS) test, and electrochemical impedance spectroscopy (EIS). The pitting corrosion of the Al coatings always began at the voids of the grain boundaries. Bombardment by the Ar⁺ ion-beams effectively improved the corrosion resistance of the IBAD-Al-coating.

Keywords: NdFeB; Aluminium coatings; Magnetron sputtering; IBAD; Corrosion resistance

Effect of growth parameters on the structure and magnetic properties of thin polycrystalline Fe films fabricated on Si〈100〉 substrates by A. Javed; N.A. Morley; M.R.J. Gibbs (pp. 5586-5590).

This paper deals with the experimental investigation of the structure and magnetic properties of thin polycrystalline Fe films. Two sets of 50±2nm thick Fe films were fabricated on Si〈100〉 substrates with native oxides in place by varying (i) the sputter pressure p_Ar and (ii) the Fe sputter power P_Fe. X-ray diffraction (XRD) study revealed that all films grew with strong 〈110〉 texture normal to the film plane. No higher order peaks were observed in any of the films studied. For both film sets, the lattice constant ( a) was less than the bulk Fe lattice constant ( a₀=2.866Å), which suggested the existence of compressive strain in all films. Two regions of homogeneous strain were observed over the range of p_Ar studied. Magneto-optical Kerr's effect (MOKE) measurements showed that all films exhibited magnetically isotropic behaviour. The magnetic properties were observed to be influenced strongly by p_Ar. The film grown at p_Ar=4μbar was the most softest ( H_s=100±8kAm⁻¹, M_r/ M_s=0.87±0.02) film among all the films studied. The magnetic properties were found to be independent of P_Fe. The effective saturation magnetostriction constant λ_eff determined (using the Villari method) was positive (4±1ppm) and observed to vary within the calculated error.Display Omitted► In this study we examined the microstructure and magnetic properties of thin Fe films. ► The film thickness was fixed to 50nm and the effect of sputter parameters (such as sputter pressure p_Ar and Fe power P_Fe) on the film properties was investigated. ► It was found that the film grown at 4μbar was the softest film among all the films studied in this work. ► Over the range of P_Fe investigated in this work, the magnetic properties were observed to be unaffected by P_Fe. ► It was also found that the Fe films grown on Si〈100〉 substrates had positive magnetostriction constant (4±1ppm).This paper deals with the experimental investigation of the structure and magnetic properties of thin polycrystalline Fe films. Two sets of 50±2nm thick Fe films were fabricated on Si〈100〉 substrates with native oxides in place by varying (i) the sputter pressure p_Ar and (ii) the Fe sputter power P_Fe. X-ray diffraction (XRD) study revealed that all films grew with strong 〈110〉 texture normal to the film plane. No higher order peaks were observed in any of the films studied. For both film sets, the lattice constant ( a) was less than the bulk Fe lattice constant ( a₀=2.866Å), which suggested the existence of compressive strain in all films. Two regions of homogeneous strain were observed over the range of p_Ar studied. Magneto-optical Kerr effect (MOKE) measurements showed that all films exhibited magnetically isotropic behaviour. The magnetic properties were observed to be influenced strongly by p_Ar. The film grown at p_Ar=4μbar was the most softest ( H_s=100±8 kAm⁻¹, M_r/ M_s=0.87±0.02) film among all the films studied. The magnetic properties were found to be independent of P_Fe. The effective saturation magnetostriction constant λ_eff determined (using the Villari method) was positive (4±1ppm) and observed to vary within the calculated error.

Keywords: Growth parameters; Fe thin films; X-ray diffraction; Texture; Surface morphology; Magnetic properties

Surface plasmon enhanced light emission of silicon-rich silicon nitride: Dependence on metal island size by Peihong Cheng; Dongsheng Li; Jingxia Wang; Deren Yang (pp. 5591-5594).

► Light emission of silicon-rich silicon nitride was coupled with surface plasmon of Ag island films. ► Both emission intensity and spectral shape were found dependent on the metal island size. ► Surface plasmon scattering and absorption efficiency of the metal islands decide the photoluminescence changes including emission intensity enhancement and band position shift.Surface plasmon coupled light emission of silicon-rich silicon nitride (SRSN) was investigated as a function of metal island size. It was found that the emission intensity was enhanced by surface plasmon (SP) and the enhancement factors increase greatly with the increase of metal island size. Moreover, SP coupled emission spectral shape was found also correlating with Ag island size. By calculating the extinction characteristics of the Ag islands, it was believed that SP scattering and absorption efficiency of the metal islands decide the photoluminescence (PL) changes including emission intensity enhancement and band position shift.

Keywords: Surface plasmon; Silicon-rich silicon nitride; Light emission

Comparison study on structure of Si and Cu doping CrN films by reactive sputtering by Shuyong Tan; Xuhai Zhang; Xiangjun Wu; Feng Fang; Jianqing Jiang (pp. 5595-5600).

► We compare the microstructure of the copper and silicon doping CrN films under the same deposition conditions, and thus we can get a better understanding of nanocomposite films. ► The different variation in the preferred orientation with substrate bias of CrN, CrCuN and CrSiN films is considered in the manuscript. ► The TEM observation combined with the XPS results shows that the CrSiN film is composed of nanocrystallites distributed in amorphous Si₃N₄, while no amorphous phase exists in CrCuN films.CrN, CrSiN and CrCuN films were deposited by DC magnetron reactive sputtering with hot pressed pure Cr, CrSi, and CrCu targets, respectively. As substrate bias increased from −50V to −200V, the preferred orientation of CrN films changed from (111) to (200). And the Si doping did not change this condition. However, the Cu doping films kept (200) orientation all along. CrN films presented typical columnar structure, and the alloying of Si and Cu could restrain columnar growth leading to dense structure. The CrSiN film was composed of nanocrystallites distributed in amorphous Si₃N₄, while no amorphous phase existed in CrCuN films.

Keywords: CrN; CrSiN; CrCuN; Nanocrystallite; Amorphous

Nanosecond multi-pulse damage investigation of optical coatings in atmosphere and vacuum environments by XiuLan Ling (pp. 5601-5604).

► We comparatively investigated the cumulative effect of multi-pulse irradiation of the dielectric mirror coatings in atmosphere and vacuum environments. ► For both environments, the laser-induced damage (LIDT) of the dielectric mirror coatings will decrease when shot number increase. ► The fatigue effect under repetitive shots in two environments will lead to different speeds of degradation. ► The formation of the sub-stoichiometry defect in the course of laser irradiation and air-vacuum effect is attributed to the different fatigue effect and degradation speed in two environments.The cumulative effect of nanosecond multi-pulse irradiation on the dielectric coatings in atmosphere and vacuum environments was investigated. The laser-induced damage thresholds (LIDT) and the life span submitted to multi-pulse irradiation in two environments were compared. For both environments, we observe a decrease in laser-induced damage thresholds (LIDT) when shot number increase. However, the fatigue effect under repetitive shots under atmosphere environments and vacuum cases leads to different speeds of degradation. The correlative theory models were built to explain the experimental results.

Keywords: PACS; 42.79.Wc; 81.70.Fy; 68.37.HkVacuum; Laser-induced damage; Fatigue effect; Defect statistical model; Air–vacuum effect

Stability of phosphonic self assembled monolayers (SAMs) on cobalt chromium (Co–Cr) alloy under oxidative conditions by Rahul Bhure; Tarek M. Abdel-Fattah; Carl Bonner; Felicia Hall; Anil Mahapatro (pp. 5605-5612).

► Phosphonic acid self assembled monolayers (SAMs) on cobalt chromium (Co–Cr) alloy. ► Oxidative stability determined by X-ray Photoelectron Spectroscopy (XPS), uniformity and surface coverage confirmed by contact angle measurements, topographical confirmation by Atomic Force Microscope (AFM). ► Detailed high energy elemental XPS scans indicated presence the organic layer after exposure under oxidative conditions. ► The SAMs were stable under oxidative conditions over a period of 14 days.Cobalt chromium (Co–Cr) alloys have been widely used in the biomedical arena for cardiovascular, orthopedic and dental applications. Surface modification of the alloy allows us to tailor the interfacial properties to address critical challenges of Co–Cr alloy in medical applications. Self assembled monolayers (SAMs) of Octadecylphosphonic acid (ODPA) have been used to form thin films on the oxide layer of the Co–Cr alloy surface by solution deposition technique. The SAMs formed were investigated for their stability to oxidative conditions of ambient laboratory environment over periods of 1, 3, 7 and 14 days. The samples were then characterized for their stability using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and contact angle measurements. Detailed high energy XPS elemental scans confirmed the presence of the phosphonic monolayer after oxidative exposure which suggested that the SAMs were firmly attached to the oxide layer of Co–Cr alloy. AFM images gave topographical data of the surface and showed islands of SAMs on Co–Cr alloy surface, before and after SAM formation and also over the duration of the oxidative exposure. Contact angle measurements confirmed the hydrophobicity of the surface over 14 days. Thus the SAMs were found to be stable for the duration of the study. These SAMs could be subsequently tailored by modifying the terminal functional groups and could be used for various potential biomedical applications such as drug delivery, biocompatibility and tissue integration.

Keywords: Surface modification; Self assembled monolayers (SAMs); Phosphonic acids; Cobalt chromium alloy

Paper coatings with multi-scale roughness evaluated at different sampling sizes by Pieter Samyn; Jürgen Van Erps; Hugo Thienpont; Gustaaf Schoukens (pp. 5613-5625).

Display Omitted► Paper coating with micro- to nanoscale roughness pattern. ► Roughness measurements by atomic force microscopy and non-contact profilometry are complimentary. ► Correlation length and spectral densities can be linearly extrapolated between different sampling sizes.Papers have a complex hierarchical structure and the end-user functionalities such as hydrophobicity are controlled by a finishing layer. The application of an organic nanoparticle coating and drying of the aqueous dispersion results in an unique surface morphology with microscale domains that are internally patterned with nanoparticles. Better understanding of the multi-scale surface roughness patterns is obtained by monitoring the topography with non-contact profilometry (NCP) and atomic force microscopy (AFM) at different sampling areas ranging from 2000μm×2000μm to 0.5μm×0.5μm. The statistical roughness parameters are uniquely related to each other over the different measuring techniques and sampling sizes, as they are purely statistically determined. However, they cannot be directly extrapolated over the different sampling areas as they represent transitions at the nano-, micro-to-nano and microscale level. Therefore, the spatial roughness parameters including the correlation length and the specific frequency bandwidth should be taken into account for each measurement, which both allow for direct correlation of roughness data at different sampling sizes.

Keywords: Paper; Coating; Surface; Roughness; Scaling

Magnesium nitride phase formation by means of ion beam implantation technique by Daniel Höche; Carsten Blawert; Matthieu Cavellier; Denis Busardo; Thierry Gloriant (pp. 5626-5633).

▶ Nitrogen implantation for improving Mg surface properties. ▶ Formation of stable Mg₃N₂ nanocrystalline phase. ▶ Decrease of corrosion potential for about 100mV. ▶ Al containing alloys lead to improvement of properties due to AlN.Nitrogen implantation technique (Hardion⁺) has been applied in order to modify the surface properties of magnesium and Mg-based alloys (AM50, AZ31). Nitrogen ions with an energy of approximately 100keV were used to form the Mg₃N₂ phase leading to improved surface properties. The samples were investigated using various characterization methods. Mechanical properties have been tested by means of nanoindention, the electrochemical behavior was measured by potentiodynamic polarization and impedance spectroscopy, phase formation by using grazing incidence Xray diffraction, the chemical state was determined by means of Xray induced photoelectron spectroscopy (XPS) and depth profiling by using secondary ions mass spectroscopy (SIMS). Additionally, the results were compared to calculated depth profiles using SRIM2008. The correlation of the results shows the nitride formation behavior to a depth of about 600nm.

Keywords: Magnesium nitride; Ion implantation; XPS; Corrosion

Enhanced in vitro biocompatibility of ultrafine-grained titanium with hierarchical porous surface by C.Y. Zheng; F.L. Nie; Y.F. Zheng; Y. Cheng; S.C. Wei; R.Z. Valiev (pp. 5634-5640).

► A new hierarchical porous surface was produced on the ultrafine-grained titanium. ► The hierarchical porous surface increased the apatite forming ability and promoted osteoblast-like cells attachment and proliferation. ► Ultrafine-grained titanium with hierarchical porous surface exhibited low corrosion rate in simulated body fluid.Bulk ultrafine-grained Ti (UFG Ti) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study, and to further improve its surface biocompatibility, surface modification techniques including sandblasting, acid etching and alkali treatment were employed to produce a hierarchical porous surface. The effect of the above surface treatments on the surface roughness, wettability, electrochemical corrosion behavior, apatite forming ability and cellular behavior of UFG Ti were systematically investigated with the coarse-grained Ti as control. Results show that UFG-Ti with surface modification had no pitting corrosion and presented low corrosion rate in simulated body fluids (SBF). The hierarchical porous surface yielded by surface modification enhanced the ability of UFG Ti to form a complete apatite layer when soaked in SBF and promoted osteoblast-like cells attachment and proliferation in vitro, which promises to have a significant impact on increasing bone-bonding ability and reducing healing time when implanted due to faster tissue integration.

Keywords: Ultrafine-grained titanium; Biocompatibility; Surface modification; Bioactivity; Corrosion

Studies on certain physical properties of modified smectite nanocatalysts by Ming Ching Wu; Shu Lung Kuo; Jao Chuan Lin; Chih Ming Ma; Gui Bing Hong; Chang Tang Chang (pp. 5641-5646).

► This study used smectite as the carrier to exchange with Ag⁺, Zn²⁺ and Ti⁴⁺ to modify the surface and form smectite catalysts. ► The transmission electron microscopy (TEM), FT-IR spectrum, and DSC–TGA instrument were applied to characterize their physical properties. ► The result indicating crystals formed of smectite–Ag are more comprehensive and stable than the other smectite or modified smectite catalysts at high temperature.Most volatile organic compounds (VOCs) are toxic to humans in some manner. Generally, transitional metal catalysts have better conversion rates for controlling VOCs. However, catalyst activity will decay at high temperature, though the oxidizing catalyst is cheap. This study used smectite as the carrier to exchange with Ag⁺, Zn²⁺ and Ti⁴⁺ to modify the surface and form smectite catalysts. In addition, the transmission electron microscopy (TEM), FT-IR spectrum, and DSC–TGA instrument were applied to characterize their physical properties. After the FT-IR analysis of the modified smectite catalyst (smectite–Ag, smectite–Zn and smectite–Ti), both smectite and smectite catalyst had significant and complicated wave crests between the fingerprint area with the wave numbers of 415–600cm⁻¹ and 750–1170cm⁻¹, that indicated the existence of a strong bond between impure silicates (Si–O) and silicates (O–Si–O). TEM observation proved that sintering at 350°C results in the distribution of catalyst ions on clay carrier with a nanoscale. As thermal analysis reveals, the smectite reached endothermic peaks at the temperatures of 920°C and 1057°C, respectively, and shows the decomposition in a non-crystal form. Besides, the disappearance of the endothermic peak of smectite–Ag occurs at 920.5°C and the exothermic peak occurs at 950°C. The results indicating crystals formed of smectite–Ag are more comprehensive and stable than the other smectite or modified smectite catalysts at high temperature.

Keywords: Smectite; Carrier; Heavy metal; VOCs

Surface modification of highly oriented pyrolytic graphite by reaction with atomic nitrogen at high temperatures by Luning Zhang; Dušan A. Pejaković; Baisong Geng; Jochen Marschall (pp. 5647-5656).

► Highly oriented pyrolytic graphite etched by N atoms at temperatures 500–1000°C. ► Hexagonal etch pits are observed, indicating anisotropic etching. ► Shallow and deep etch pits are formed via different mechanisms.Dry etching of {0001} basal planes of highly oriented pyrolytic graphite (HOPG) using active nitridation by nitrogen atoms was investigated at low pressures and high temperatures. The etching process produces channels at grain boundaries and pits whose shapes depend on the reaction temperature. For temperatures below 600°C, the majority of pits are nearly circular, with a small fraction of hexagonal pits with rounded edges. For temperatures above 600°C, the pits are almost exclusively hexagonal with straight edges. The Raman spectra of samples etched at 1000°C show the D mode near 1360cm⁻¹, which is absent in pristine HOPG. For deep hexagonal pits that penetrate many graphene layers, neither the surface number density of pits nor the width of pit size distribution changes substantially with the nitridation time, suggesting that these pits are initiated at a fixed number of extended defects intersecting {0001} planes. Shallow pits that penetrate 1–2 graphene layers have a wide size distribution, which suggests that these pits are initiated on pristine graphene surfaces from lattice vacancies continually formed by N atoms. A similar wide size distribution of shallow hexagonal pits is observed in an n-layer graphene sample after N-atom etching.

Keywords: HOPG; Graphene; Dry etching; Anisotropic etching; Hexagonal pits; Nitridation; N atoms

Structural, optical and electrical properties of Zn1−_xCd_xO thin films prepared by PLD by B.J. Zheng; J.S. Lian; L. Zhao; Q. Jiang (pp. 5657-5662).

► Zn1−_xCd_xO films were deposited on quartz substrates by pulse laser deposition. ► All films possess polycrystalline hexagonal wurtzite structure. ► The photoluminescence spectra show substantial red shift to visible light range. ► The resistivity of the films decreases for higher Cd content.Ternary polycrystalline Zn1−_xCd_xO semiconductor films with cadmium content x ranging from 0 to 0.23 were obtained on quartz substrate by pulse laser deposited (PLD) technique. X-ray diffraction measurement revealed that all the films were single phase of wurtzite structure grown on c-axis orientation with its c-axis lattice constant increasing as the Cd content x increasing. Atomic force microscopy observation revealed that the grain size of Zn1−_xCd_xO films decreases continuously as the Cd content x increases. Both photoluminescence and optical measurements showed that the band gap decreases from 3.27 to 2.78eV with increasing the Cd content x. The increase in Cd content x also leads to the broadening of the emission peak. The resistivity of Zn1−_xCd_xO films decreases evidently for higher values of Cd content x. The shift of PL emission to visible light as well as the decrease of resistivity makes the Zn1−_xCd_xO films potential candidate for optoelectronic device.

Keywords: Zn; 1−; _x; Cd; _x; O films; Pulse laser deposition; Transparent conductor oxide; Hall effect

Functional and unmodified MWNTs for delivery of the water-insoluble drug Carvedilol – A drug-loading mechanism by Yuting Li; Tianyi Wang; Jing Wang; Tongying Jiang; Gang Cheng; Siling Wang (pp. 5663-5670).

► We use MWNTs and functional MWNTs to use as a drug delivery system to load with a poorly water-soluble drug. ► We used three methods to load the model drug. ► We studied the drug loading mechanism through many detection means. ► The drug loading capacity and the solubility of the drug were improved by MWNTs and functional MWNTs.The purpose of this study was to develop carboxyl multi-wall carbon nanotubes (MWNTs) and unmodified MWNTs loaded with a poorly water-soluble drug, intended to improve the drug loading capacity, dissolubility and study the drug-loading mechanism. MWNTs were modified with a carboxyl group through the acid treatment. MWNTs as well as the resulting functionalized MWNTs were investigated as scaffold for loading the model drug, Carvedilol (CAR), using three different methods (the fusion method, the incipient wetness impregnation method, and the solvent method). The effects of different pore size, specific surface area and physical state were systematically studied using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The functional MWNTs allowed a higher drug loading than the unmodified preparations. The methods used to load the drug had a marked effect on the drug-loading, dissolution, and physical state of the drug as well as its distribution. In addition, the solubility of the drug was increased when carried by both MWNTs and functional MWNTs, and this might help to improve the bioavailability.

Keywords: Drug delivery; MWNTs; Carboxyl MWNTs; Poorly water-soluble drugs; Drug-loading mechanism

Theoretical calculations on the adhesion, stability, electronic structure, and bonding of Fe/WC interface by Yefei Li; Yimin Gao; Bing Xiao; Ting Min; Shengqiang Ma; Dawei Yi (pp. 5671-5678).

► The present work calculate the electronic structure, adhesion energy, optimal geometry, and the interface stability of the polar Fe (110)/WC(0001) interface by using first-principles method. ► The preferred stacking sequence is HCP structure with Fe atoms above the metallic W atoms, as this structure has the lowest interfacial free energy; the effects of the interface on the electronic structures of both the metal Fe and ceramic are mainly localized within the first and second layer. ► The formation of interface will reduce the magnetic moment of interfacial Fe atoms both for C-HCP and W-HCP interfaces. ► Calculations of the interfacial energies provide theoretical evidence for the excellent wear behaviors of Fe/WC composites.The adhesion, stability, electronic structure, and bonding of Fe/WC interfaces were studied using first-principles calculations. The preferred stacking sequence is HCP structure that Fe atoms continue the natural stacking sequence of the bulk WC. For two different interfaces with HCP stacking geometry (C-HCP and W-HCP), the work of adhesion of the optimized Fe/WC interfaces are 9.7Jm⁻² for C-HCP and 5.1Jm⁻² for W-HCP, respectively. The effects of the interface on the electronic structures of both the metal Fe and ceramic WC are mainly localized within the first and second layers of the interface. C-HCP interface has strong covalency and W-HCP interface is dominated by metallic bonds. The magnetic moments of Fe atoms at interface are decreased in both interfaces. Calculations of the interfacial energies provide theoretical evidence for the excellent wear behaviors of Fe/WC composites. Besides, the chemical bonding properties for the interfacial atoms are also discussed in this paper based on Milliken population method.

Keywords: Composite; Tungsten carbides; Interface; Electronic structure; Stability

Nanoplasmonic sensing and QCM-D as ultrasensitive complementary techniques for kinetic corrosion studies of aluminum nanoparticles by Markus Schwind; Christoph Langhammer; Bengt Kasemo; Igor Zorić (pp. 5679-5687).

► QCM-D and nanoplasmonic sensing enable submonolayer, in situ, real-time sensing of Al corrosion. ► Nanoplasmonic sensing results can be quantized by correlation to model calculations. ► Oxidation of Al nanodisks proceeds by two mechanisms: (i) growth of a homogeneous oxide layer, (ii) fragmentation and roughening.Corrosion (oxidation) kinetics of Al nanodisks, 262nm in diameter and 20nm in height, was measured in degassed Milli-Q water at 23°C and neutral pH by quartz crystal microbalance with dissipation monitoring (QCM-D) and nanoplasmonic sensing. The former detects the changes of the resonance frequency and the damping of the oscillation of a piezoelectric quartz crystal resonator. The latter detects the changes of the localized surface plasmon resonance (LSPR) in the metallic part of the Al nanoparticle, caused both by the shrinking metallic core and the changes in the dielectric environment as the oxide grows. Highly resolved kinetic data were obtained which show different corrosion stages. The two techniques yield complementary information not obtainable with one technique alone. Two main corrosion mechanisms, namely homogeneous oxide growth and nanoparticle fragmentation and roughening, are distinguished. The time dependence of the corrosion kinetics, determined using QCM-D, is in agreement with weight gain studies of bulk Al found in literature. The nanoplasmonic sensing measurements are compared to analytical model calculations of LSPR shifts which yield an estimate for the increase of oxide thickness during homogeneous oxide growth.

Keywords: Corrosion; Metal oxidation in water; Aluminum nanoparticles; Localized surface plasmon resonances; Nanoplasmonic sensing; Quartz crystal microbalance with dissipation monitoring

Fabrication of durable hydrophobic surfaces through surface texturing by Samuel Beckford; Nicholas Langston; Min Zou; Ronghua Wei (pp. 5688-5693).

► We study the durability of hydrophobic surfaces by rubbing test. ► Durability is measured by surface water contact angle change with rubbing cycles. ► Textured samples retain hydrophobic property after many cycles of rubbing. ► Textured samples have much lower static and kinetic coefficients of friction.Low surface energy polymer thin-films can be applied to surfaces to increase hydrophobicity and reduce friction for a variety of applications. However, wear of these thin films, resulting from repetitive rubbing against another surface, is of great concern. In this study, we show that highly hydrophobic surfaces with persistent abrasion resistance can be fabricated by depositing fluorinated carbon thin films on sandblasted glass surfaces. In our study, fluorinated carbon thin films were deposited on sandblasted and as-received smooth glass using deep reactive ion etching equipment by only activating the passivation step. The surfaces of the samples were then rubbed with FibrMet abrasive papers in a reciprocating motion using an automatic friction abrasion analyzer. During the rubbing, the static and kinetic friction forces were also measured. The surface wetting properties were then characterized using a video-based contact angle measuring system to determine the changes in water contact angle as a result of rubbing. Assessment of the wear properties of the thin films was based on the changes in the water contact angles of the coated surfaces after repetitive rubbing. It was found that, for sandblasted glass coated with fluorinated carbon film, the water contact angle remained constant throughout the entire rubbing process, contrary to the smooth glass coated with fluorinated carbon film which showed a drastic decrease in water contact angle with the increasing number of rubbing cycles. In addition, the static and kinetic friction coefficients of the sandblasted glass were also much lower than those of the smooth glass.

Keywords: Fluorinated carbon film; Durability; Hydrophobic; Water contact angle; Friction

Synthesis of titanium nitride thin films deposited by a new shielded arc ion plating by Yanhui Zhao; Guoqiang Lin; Jinquan Xiao; Wenchang Lang; Chuang Dong; Jun Gong; Chao Sun (pp. 5694-5697).

► A new shielded arc ion plating method with double layers and vicarious circular holes, were developed, we called DL-SAIP. ► When the distance between the double-layered shield plates is 10mm, the film surface is smooth and homogeneous, and almost no particles are seen. ► Because of their low droplet particles number and uniform deposition rate, the TiN films prepared by this technique can be expected to perform well in applications.Thin films of titanium nitride (TiN) were deposited on stainless steel substrates by a modified deposition technique, double-layered shielded arc ion plating with vicarious circular holes (DL-SAIP). The results show that the TiN film with the distance of 10mm between the double-layered shield plates had the least droplets. The deposition rate of the films prepared with the new technique was more homogeneous than that of all the other shielded arc ion plating. The film/substrate adhesion and microhardness values of the TiN films were higher than 40N and 18GPa, respectively. Thus such TiN thin films can be expected in applications.

Keywords: Shielded arc ion plating; TiN; Thin films; Deposition rate; Droplet particles; Adhesion

Influence of spin-glass-like phase on magnetic and electrical transport properties of reactive sputtered Al1−_xFe_xN films by W.B. Mi; X.C. Wang; H.L. Bai (pp. 5698-5704).

Display Omitted► Nano-scale Al1−_xFe_xN grains form in the reactive sputtered films. ► A large amount of spin-glass-like moments exist in the films. ► The coercivity increases below 50K due to the frozen spin-glass-like moments. ► The low-temperature transport mechanism turns from tunneling to hopping as x increases. ► MR follows the relation oflogMR=a+bT−1, and the spin polarization satisfies the relation ofP(T)=P0e−βTα.Nanocrystalline Al1−_xFe_xN films were fabricated using the reactive sputtering method. A large amount of spin-glass-like moments are in the films. With the decrease of temperature, the films turn from the spin-glass-like behavior to ferromagnetism. At low temperatures, the saturation magnetization increases and the coercivity decreases with the increase of x. The coercivity increases significantly below 50K due to the pinning effect of the frozen disordered spin-glass-like moments. All of the films are semiconducting. The low-temperature transport mechanism turns from tunneling to hopping as x increases. Magnetoresistance (MR) shows weak saturation trend with the applied field because of the hard alignment of the frozen moments. Meanwhile, MR follows the relation oflogMR=a+bT−1, and the spin polarization satisfiesP(T)=P0e−βTα, related with the disordered spin-glass-like moments.

Keywords: PACS; 73.50.−h; 73.63.Bd; 73.43.Qt; 75.70.−iNanocrytalline films; Magnetoresistance; Magnetic properties; Electrical properties

A stable superhydrophobic and superoleophilic Cu mesh based on copper hydroxide nanoneedle arrays by Duc-Duong La; Tuan Anh Nguyen; Sungho Lee; Jeong Won Kim; Yong Shin Kim (pp. 5705-5710).

► Prepare a stable superhydrophobic and superoleophilic copper mesh. ► Perfluoroalkylsilane-modified Cu(OH)₂ nanoneedle surface maintains superhydrophobic property after the wet treatment in pH 2–14. ► Dynamic permeation behaviors exhibit a potential use in oil/water separation.A superhydrophobic and superoleophilic copper mesh was prepared via a simple electrochemical route. Copper substrates were anodized in a 1mol/L NaOH aqueous solution to produce a rough thin film of Cu(OH)₂ nanoneedle arrays and then the film was reacted with 1H,1H,2H,2H-perfluorooctyltriethoxysilane to form a very thin and stable hydrophobic coating layer. X-ray photoelectron spectroscopy (XPS) data revealed the coordination of silicon atoms with cuprate (CuO) molecules present on the anodized substrate. The water contact angle of the perfluoroalkylsilane-modified nanoneedle surface was approximately 170°. Furthermore, the superhydrophobicity was maintained after wet treatments in aqueous solutions with a wide pH range of 2−14 and after a long storage time of 4 months. This excellent durability and long-term reliability, which was unattainable in comparable samples modified with n-dodecanethiol or n-dodecanoic acid, could be interpreted with the formation of a stable and dense surface modification layer via a condensation reaction between –SiOEt and –CuOH and subsequent polymerization among the ethoxysilane adsorbates. Preliminary studies of the dynamic permeation behaviors of water and non-polar solvents exhibited a potential use of the hybrid copper mesh as a filtering layer for oil and water separation.

Keywords: Superhydrophobicity; Copper mesh; Electrochemical anodization

Investigations of Co/Cu(110) by AES and DEPES by D. Turko; I. Morawski; M. Nowicki (pp. 5711-5714).

► In this study we examined the growth mechanism and crystalline structure of Co on Cu(110). ► Both experimental (DEPES) and theoretical (MS) approaches were used. ► We conclude that Co forms subsequent layers before the completion of the previous one. ► Co layers reflect the crystalline structure of the Cu(110) substrate.Auger electron (AES) and directional elastic peak electron spectroscopies (DEPES) were used to find the growth mode of Co on Cu(110) and the crystalline structure within the first few atomic layers. The Co growth at RT is characterized by the at first linear and then exponential decay of the Auger signal from the substrate h_Cu (CuM_2,3VV, 66eV). A detailed analysis of the Auger signal suggests that at an early stage of the Co growth the formation of the second layer occurs before the completion of the first monolayer. Further deposition leads to the simultaneous nucleation of subsequent layers before the complete covering of the substrate. The DEPES profiles recorded along the two Cu[100] andCu1¯10 azimuths at the primary electron beam energy Ep=1.0keV for equivalent quantities of 3ML and 5ML of Co show distribution of the intensity maxima similar to that for the clean Cu(110) sample, which indicates the epitaxial growth of Co. Theoretical DEPES profiles obtained by using the multiple scattering (MS) formalism at the maximal scattering order s=3 reflect the intensity maxima associated with the100,110,112 and111 directions, as it was observed in experiment.

Keywords: PACS; 91.60Ed, 91.55.Nc, 61.05.jdCopper; Cobalt; Primary electron beam scattering; Crystalline structure; Directional elastic peak electron spectroscopy (DEPES)

P-doped TiO₂ nanoparticles film coated on ground glass substrate and the repeated photodegradation of dye under solar light irradiation by Yingying Lv; Leshu Yu; Xiaolan Zhang; Jinyan Yao; Ruyi Zou; Zheng Dai (pp. 5715-5719).

► Loading of photocatalyst. ► P-doped TiO₂ nanoparticles coating on ground glass. ► Recycle of photocatalyst. ► A compact TiO₂ film showed high photacatalytic reaction efficiency in the degradation of dye.The convenient reuse of photocatalysts is essential to the practical application in the degradation of organic pollutant. In this study, compact P-doped TiO₂ film coated on ground glass substrate was easily achieved by layer-by-layer assembly technique. Thus such an elaborate complex system exhibited very convenient in recycling photocatalyst in the degradation of dye with high catalytic activity. The excellent performance of P-TiO₂ film coated on ground glass substrates endows the assembled route potential in purifying waste water.

Keywords: Photocatalyst; Coating materials; Nanostructured materials; Oxide materials; Solar light

The tribology properties of alumina/silica composite nanoparticles as lubricant additives by Da Jiao; Shaohua Zheng; Yingzi Wang; Ruifang Guan; Bingqiang Cao (pp. 5720-5725).

The modified Al₂O₃/SiO₂ composite nanoparticles dispersed homogenously in mineral oil as lubricating additives can reduce the friction coefficient by ∼20% under optimized concentration.Display Omitted► By surface modification, Al₂O₃/SiO₂ composite nanoparticles can dispersed in mineral oil homogenously. ► The modified Al₂O₃/SiO₂ nanoparticles as lubricating oil additives can greatly reduce the friction coefficient. ► The oil lubricating performance using composite nanoparticles as additives was better than pure Al₂O₃ or SiO₂ particles.The as-prepared alumina/silica (Al₂O₃/SiO₂) composite nanoparticles were synthesized with a hydrothermal method and modified by silane coupling agent. The tribological properties of the modified Al₂O₃/SiO₂ composite nanoparticles as lubricating oil additives were investigated by four-ball and thrust-ring tests in terms of wear scar diameter, friction coefficient, and the morphology of thrust-ring. It is found that their anti-wear and anti-friction performances are better than those of pure Al₂O₃ or SiO₂ nanoparticles. When the optimized concentration of nanoparticle additive is 0.5wt.%, the diameters of wear scar and friction coefficients are both smallest. Such modified composite nanoparticles can adsorb onto the friction surfaces, which results in rolling friction. Therefore, the friction coefficient is reduced.

Keywords: Composite nanoparticles; Lubricating oil additives; Nanotribology

Assembly of tungsten oxide nanobundles and their electrochromic properties by Xueting Chang; Shibin Sun; Zhenjiang Li; Xiao Xu; Yanyan Qiu (pp. 5726-5730).

Display Omitted► Lenticular W18O49 nanobundles were synthesized by a solvothermal method. ► Electrochromic films were prepared by assembling the nanobundles onto ITO glass. ► The nanobundles exhibited excellent electrochromic stability and reversibility.Lenticular W₁₈O₄₉ nanobundles composed of ultra-thin nanowires with diameters of 5–10nm have been synthesized through a simple solvothermal method with hexachloride as precursor and mixed cyclohexanol and ethanol as solvent. Electrochromic films were prepared by assembling the W₁₈O₄₉ nanobundle suspension onto tin-doped indium oxide (ITO) coated glass. Results showed that self-assembly of the W₁₈O₄₉ nanobundles was strongly influenced by the solvents employed to disperse the nanobundles. The W₁₈O₄₉ nanobundles coated films exhibited excellent electrochromic stability and reversibility. The W₁₈O₄₉ nanobundle films also showed much higher charge-insertion density compared with the WO₃ nanorod film, which may be due to the ultrathin feature of single nanowires constituting the nanobundles, unique oxygen vacancies of monoclinic W₁₈O₄₉, and the highly ordered assembly of the nanobundles.

Keywords: Tungsten oxide; Nanobundles; Self-assembly; Electrochromic; Charge-insertion density

Deposition and characterization of layer-by-layer sputtered AgGaSe₂ thin films by H. Karaagac; M. Parlak (pp. 5731-5738).

► Sputtering technique has been used for the deposition of AgGaSe₂ thin films. ► There was a pronounce effect of post-annealing on chemical composition of samples. ► Mono phase AgGaSe₂ was obtained at 600°C annealing temperature. ► Band gap values were found to be varying between 1.55 and 1.77eV. ► The crystal-field and spin-orbit splitting levels were resolved.Sputtering technique has been used for the deposition of AgGaSe₂ thin films onto soda-lime glass substrates using sequential layer-by-layer deposition of GaSe and Ag thin films. The analysis of energy dispersive analysis of X-ray (EDXA) indicated a Ga-rich composition for as-grown samples and there was a pronounce effect of post-annealing on chemical composition of AgGaSe₂ thin film. X-ray diffraction (XRD) measurements revealed that Ag metallic phase exists in the amorphous AgGaSe₂ structure up to annealing temperature 450°C and then the structure turned to the single phase AgGaSe₂ with the preferred orientation along (112) direction with the annealing temperature at 600°C. The surface morphology of the samples was analyzed by scanning electron microscopy (SEM) measurements. The structural parameters related to chalcopyrite compounds have been calculated. Optical properties of AgGaSe₂ thin films were studied by carrying out transmittance and reflectance measurements in the wavelength range of 325–1100nm at room temperature. The absorption coefficient and the band gap values for as-grown and annealed samples were evaluated as 1.55 and 1.77eV, respectively. The crystal-field and spin-orbit splitting levels were resolved. These levels (2.03 and 2.30eV) were also detected from the photoresponse measurements almost at the same energy values. As a result of the temperature dependent resistivity and mobility measurements in the temperature range of 100–430K, it was found that the decrease in mobility and the increase in carrier concentration following to the increasing annealing temperature attributed to the structural defects (tetragonal distortion, vacancies and interstitials).

Keywords: Chalcopyrite compounds; AgGaSe; ₂; X-ray diffraction; Scanning electron microscopy; Transmission–reflection; Photoresponse

Immobilization of glucose oxidase using CoFe₂O₄/SiO₂ nanoparticles as carrier by Hai Wang; Jun Huang; Chao Wang; Dapeng Li; Liyun Ding; Yun Han (pp. 5739-5745).

► The immobilized GOD enhances the thermal stability and exhibits a strong endurance to the variation of solution pH, high temperature, and long-term storage. ► A facile chemical method was developed to prepare monodisperse CoFe₂O₄/SiO₂ NPs with desired size and narrow size distributions. ► As-prepared CoFe₂O₄/SiO₂ NPs have superparamagnetism, indicating that the CoFe₂O₄/SiO₂ NPs can be used as an effective carrier for the GOD immobilization.Aminated-CoFe₂O₄/SiO₂ magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. Glucose oxidase (GOD) was immobilized on CoFe₂O₄/SiO₂ NPs via cross-linking with glutaraldehyde (GA). The optimal immobilization condition was achieved with 1% (v/v) GA, cross-linking time of 3h, solution pH of 7.0 and 0.4mg GOD (in 3.0mg carrier). The immobilized GOD showed maximal catalytic activity at pH 6.5 and 40°C. After immobilization, the GOD exhibited improved thermal, storage and operation stability. The immobilized GOD still maintained 80% of its initial activity after the incubation at 50°C for 25min, whereas free enzyme had only 20% of initial activity after the same incubation. After kept at 4°C for 28 days, the immobilized and free enzyme retained 87% and 40% of initial activity, respectively. The immobilized GOD maintained approximately 57% of initial activity after reused 7 times. The K_M (Michaelis–Menten constant) values for immobilized GOD and free GOD were 14.6mM and 27.1mM, respectively.

Keywords: CoFe; ₂; O; ₄; /SiO; ₂; Nanoparticles; Immobilization; Glucose oxidase

Effects of dodecylamine and dodecanethiol on the conductive properties of nano-Ag films by Lixin Mo; Dongzhi Liu; Wei Li; Luhai Li; Lichang Wang; Xueqin Zhou (pp. 5746-5753).

► Nano-Ag film's conductive property is related to the bonding and configuration of PAs. ► Higher bonding of Ag–S and ordering of DDT lead to higher T_c of Ag–DDT film. ► Ag–DDA film is thermodynamically unstable and the sintering could occur at R.T. ► The morphology and resistivity of nano-Ag film are also affected by the PAs.Nano-Ag particles, with dodecylamine (DDA) and dodecanethiol (DDT) as the protective agent, were prepared and studied in order to investigate the effect of protective agent in the post heat-treatment of nano-Ag films. Results of electrical resistivity, micro-structural evolution and thermal analysis showed that the Ag–DDA films require a lower treatment temperature to convert into conductive materials compared to that of the Ag–DDT films. And the Ag–DDA films also have lower final electrical resistivity as well as more uniform and dense microstructure in comparison with the Ag–DDT films. Further study indicated that Ag–DDA films are thermodynamically unstable and the sinter of Ag–DDA particles could occur spontaneously even at room temperature. FT-IR,¹H NMR and X-ray diffraction determinations revealed that both DDA and DDT molecules coordinate to the surface of nano-Ag particles through their head-groups. The bonding energy of Ag–S is higher than that of Ag–N and the alkyl chains ordering of chemisorbed DDT is also higher than that of chemisorbed DDA. It is implied that the post heat-treatment temperature and final resistivity of nano-Ag films are associated with the bonding energy and configuration of different capping molecules. Finally the conductive ink was prepared with well dispersed Ag–DDA nanoparticles and the ink-jet printed patterns on PI films show a sheet resistance of 166mΩ/□ after heat-treating at 140°C for 60min.

Keywords: Silver nanoparticles; Conductive ink; Protective agents; Heat-treatment

Graphene oxide monolayers as supporting films for high resolution transmission electron microscopy by Bing Yuan; Zexin Zhang; Kun Zhou (pp. 5754-5758).

Display Omitted► A novel kind of TEM support was fabricated with graphene oxide (GO) monolayers. ► Such GO support was prepared by a facile solution-cast method. ► It induced less disturbance to object imaging compared to conventional carbon films.A novel kind of TEM support composed of graphene oxide monolayers was fabricated by a facile solution-cast method. Compared to the conventional carbon supporting films, such graphene oxide film (GO-film) performed better stability under high-energy electron beams and better dispersion effect for water-soluble nanoparticles. Quantitative improvement in TEM imaging resolution for nanomaterials on such GO-films compared to the commercial ultrathin carbon films was demonstrated.

Keywords: Graphene oxide; Transmission electron microscopy (TEM); Specimen support

Microstructure, hydrogenation and optical behavior of Mg–Ni multilayer films deposited by magnetron sputtering by H. Zhang; X.L. Wang; Y.Q. Qiao; X.H. Xia; J.P. Tu (pp. 5759-5765).

► The interdiffusion between Mg and Ni adjacent layers is seriously affected by the deposition temperature. ► The film deposited at 473K exhibits amorphous/nanocrystalline composite structure. ► Without the Pd-cap catalysis layer, the film can still switch from metallic state to transparent state after hydrogenation. ► The optical transmittance modulation of the film reaches up to 19% in visible light region, and it nearly approaches the results of the Mg–Ni films with a Pd-cap layer.Mg–Ni multilayer films with sequential Mg and Ni layers were prepared by direct current magnetron sputtering. The substrate temperature influences the microstructure of the films greatly. The film deposited at 298K exhibits multilayered structure, while the film shows nanocrystalline/amorphous composite structure at the deposition temperature of 473K. The optical properties between hydrogenation/dehydrogenation states of the films were performed using spectrophotometer in visible light region. The film deposited at 473K can switch from mirror-like metallic state towards brownish yellow transparent state under 0.6MPa H₂ at 298K, and the optical transmittance modulation reaches up to 20% both at a wavelength of 770nm and IR region, while the film deposited at 298K exhibits low optical change, and the optical switching behavior can hardly be found. The extra free energy stored in the boundary of the nanocrystallines benefits the formation of magnesium-based hydride, resulting in the enhancement of the optical switching properties of the Mg–Ni film deposited at 473K.

Keywords: Mg–Ni alloy; Multilayer film; Interdiffusion; Optical switching property

X-ray photoelectron spectroscopic analysis of the surface chemistry of silica nanowires by Miles F. Beaux II; Nathan J. Bridges; Morgan DeHart; Thomas E. Bitterwolf; David N. McIlroy (pp. 5766-5771).

► Silica nanowires are capable of very high surface hydroxyl concentrations. ► Surface hydroxyl concentration corresponds to the pH of aqueous storage media. ► Storage in DI water and basic solution results in a decrease in surface hydroxyls. ► Storage in acidic solution results in an increase in surface hydroxyls. ► Fibronectin binding is inhibited by storage in water or basic solution.A thorough analysis of the surface chemistry of silica nanowires has been performed by X-ray photoelectron spectroscopy to investigate unexpected surface changes. Examination of the Si 2p, O 1s, and C 1s core level states before and after exposure of the nanowires to various liquid media showed that silica nanowires are capable of much higher surface hydroxyl concentrations than planar native oxides. It is further demonstrated that the nanowire surface hydroxyl concentration corresponds to the pH of the aqueous media to which the nanowires are exposed. Spectral feature changes due to water exposure similar to those observed for fibronectin binding suggests that fibronectin binding is competitively inhibited by slow changes in surface chemistry resulting from water exposure.

Keywords: Nanowire; Surface chemistry; Silica; XPS

Mechanically stable and corrosion resistant superhydrophobic sol–gel coatings on copper substrate by A. Venkateswara Rao; Sanjay S. Latthe; Satish A. Mahadik; Charles Kappenstein (pp. 5772-5776).

Display Omitted► The coating showed the water contact angle of 155° and the water sliding angle of 7°. ► Superhydrophobic coatings are stable against humidity even for 90 days of exposure. ► The water drops maintained the spherical shape on the bent copper substrate.Development of the anticorrosion coatings on metals having both passive matrix functionality and active response to changes in the aggressive environment has raised tremendous interest in material science. Using a sol–gel deposition method, superhydrophobic copper substrate could be obtained. The best hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7M NH₄OH) at a molar ratio of 1:19.1:4.31 respectively. The surface morphological study showed the ball like silica particles distributed on the copper substrate with particle sizes ranging from 8 to 12μm. The coatings showed the static water contact angle as high as 155° and the water sliding angle as low as 7°. The superhydrophobic nature was maintained even though the deposited copper substrate was soaked for 100h in 50% of HCl solution. The coatings are stable against humidity and showed superhydrophobic behavior even after 90 days of exposure. The coatings are mechanically stable and water drops maintained the spherical shape on the bent copper substrate, which was bent more than 90°.

Keywords: Coatings; Corrosion; Superhydrophobic; Wetting; Contact angle

Effect of TiO₂/Al₂O₃ film coated diamond abrasive particles by sol–gel technique by Weida Hu; Long Wan; Xiaopan Liu; Qiang Li; Zhiqi Wang (pp. 5777-5783).

► The diamond abrasive grains were coated with the TiO₂/Al₂O₃ film via sol-gel route. ► The incipient oxidation temperature of the coated diamonds in air atmosphere was higher 175°C than that of the uncoated diamonds. ► The coated diamonds had better the mechanical properties than that of uncoated diamonds after sintering at 750°C. ► For the vitrified bond grinding wheels, replacing the uncoated diamonds with the coated diamonds, the properties of the grinding wheels were improved.The diamond abrasive particles were coated with the TiO₂/Al₂O₃ film by the sol–gel technique. Compared with the uncoated diamonds, the TiO₂/Al₂O₃ film was excellent material for the protection of the diamonds. The results showed that the incipient oxidation temperature of the TiO₂/Al₂O₃ film coated diamonds in air atmosphere was 775°C, which was higher 175°C than that of the uncoated diamonds. And the coated diamonds also had better the diamond's single particle compressive strength and the impact toughness than that of uncoated diamonds after sintering at 750°C. For the vitrified bond grinding wheels, replacing the uncoated diamonds with the TiO₂/Al₂O₃ film coated diamonds, the volume expansion of the grinding wheels decreased from 6.2% to 3.4%, the porosity decreased from 35.7% to 25.7%, the hardness increased from 61.2 H_RC to 66.5 H_RC and the grinding ratio of the vitrified bond grinding wheels to carbide alloy (YG8) increased from 11.5 to 19.1.

Keywords: Diamond; Sol–gel; TiO; ₂; Al; ₂; O; ₃; Vitrified bond

Twinned tabour-like ZnO: Surfactant-, template-free synthesis and gas sensing behaviors by Yanyan Zhang; Wuyou Fu; Yongming Sui; Haibin Yang; Jing Cao; Minghui Li; Yixing Li; Xiaoming Zhou; Yan Leng; Wenyan Zhao; Hui Chen; Lina Zhang; Qiang Jing; Hui Zhao (pp. 5784-5788).

► We synthesized twinned tabour-like ZnO microstructures via a solvothermal method without the assistant of any additive and template. ► We found every single ZnO tabour is composed by many single crystal units. ► The gas sensors based on these ZnO microstructures show good gas sensing properties. ► The response of the sensor to 200ppm ethanol is about 24.64 with the response time of 3s.The twinned tabour-like ZnO microstructures have been successfully synthesized via a solvothermal method without the assistant of any additive and template. The as-prepared products are characterized by X-ray diffraction, field emission scanning electron microscope, and high-resolution transmission electron microscope. The ZnO microcrystals grow symmetrically, and are wurtzite structure. The tabour, with a diameter of about 8.5μm, grows along the c axis. The time-dependent morphology evolution of the ZnO microcrystal presents every single ZnO tabour is composed by many single crystal units. A possible formation mechanism of these complex hierarchical structures is investigated by adjusting the reaction time. In addition, the twinned ZnO tabours exhibit excellent ethanol-sensing properties at 250°C. The highest response is 6.4–20ppm ethanol. The response of the sensor rapidly increases with the increasing concentration of ethanol, until the ethanol reaching 200ppm. The response of the sensor to 200ppm ethanol is about 24.64 with the response time of 3s.

Keywords: Zinc oxide; Crystal growth; Microcrystal; Gas sensing; Solvothermal synthesis

Optical emission spectroscopy by Ar³⁺ ion sputtering of Ti surface under O₂ environment by Kenji Motohashi; Yuichi Saitoh; Shin-iti Kitazawa (pp. 5789-5792).

► Intensity of Ti I and Ti II changed with O₂ pressure. ► The pressure dependences are completely opposite. ► Local band structure model is appropriate for understanding the finding.Visible light emission from atoms and ions sputtered on a polycrystalline Ti surface was observed under irradiation of 30keV Ar³⁺ ions. A number of atomic lines of Ti I and II were observed in the wavelength of 250–850nm. The intensity of Ti II emission increased 1.3–5.6 times by introducing oxygen molecules at a pressure of 5.8×10⁻⁵Pa, whereas that of Ti I decreased 0.5–0.8 times. Factors enhancing or reducing photon intensities were plotted as a function of energy of the corresponding electrons in the excited states for Ti atoms and Ti⁺ ions.

Keywords: Ion bombardment; Sputtering; Photon emission

An XPS study of Au alloyed Al–O sputtered coatings by N.M. Figueiredo; N.J.M. Carvalho; A. Cavaleiro (pp. 5793-5798).

► Nanocomposite films of Au clusters in an Al–O matrix were reactive-sputtered. ► The chemical bonding and the Au clusters size were studied by X-ray photoelectron spectroscopy (XPS). ► In the as-deposited films the Au is present from individual atoms to small clusters up to 1–2nm. ► With annealing temperature, Au clustering in the dielectric matrix was observed.The focus of this research is the X-ray photoelectron spectroscopy (XPS) analysis of thin films consisting of Au metal clusters embedded in a dielectric matrix of Al–O coatings. The coatings were deposited by co-sputtering an Al+Au target in a reactive atmosphere with Au contents up to 8at.%. The Al–O matrix was kept amorphous even after annealing at 1000°C. In the as-deposited films the presence of Au clusters with sizes smaller than 1–2nm (not detected by XRD) was demonstrated by XPS. With increasing annealing temperature, Au clustering in the dielectric matrix was also confirmed by XPS, in agreement with XRD results.

Keywords: XPS; Al; ₂; O; ₃; –Au; Au clusters; Alumina; Charging effect

Crystallization of amorphous Si₃N₄ and superhardness effect in HfC/Si₃N₄ nanomultilayers by Guanqun Li; Yuge Li; Geyang Li (pp. 5799-5802).

► Si₃N₄ does not react with C₂H₂ in the sputtering condition. ► Transitional metal carbide (HfC) could force as-deposited amorphous materials (Si₃N₄) to crystallize as nitride due to “template effect” in multilayer growth. ► The carbide-based HfC/Si₃N₄ nanomultilayer can also exhibit coherent growth and get superhardness effect.HfC/Si₃N₄ nanomultilayers with various thicknesses of Si₃N₄ layer have been prepared by reactive magnetron sputtering. Microstructure and mechanical properties of the multilayers have been investigated. The results show that amorphous Si₃N₄ is forced to crystallize and grow coherently with HfC when the Si₃N₄ layer thickness is less than 0.95nm, correspondingly the multilayers exhibit strong columnar structure and achieve a significantly enhanced hardness with the maximum of 38.2GPa. Further increasing Si₃N₄ layer thickness leads to the formation of amorphous Si₃N₄, which blocks the coherent growth of multilayer, and thus the hardness of multilayer decreases quickly.

Keywords: HfC/Si; ₃; N; ₄; nanomultilayer; Superhardness effect; Coherent growth; Crystallization of amorphous

Nanoscale semiconductor Pb1−_xSn_xSe ( x=0.2) thin films synthesized by electrochemical atomic layer deposition by Shaoxiong Lin; Xin Zhang; Xuezhao Shi; Jinping Wei; Daban Lu; Yuzhen Zhang; Huanhuan Kou; Chunming Wang (pp. 5803-5807).

.Display Omitted► The semiconductor is synthesized at room temperature by electrochemical atomic layer deposition (EC-ALD) ► The SEM demonstrates that the EC-ALD methodology is promising in controlling the Pb1−_xSn_xSe ( x=0.2) compounds’ growth and forming homogeneous deposits at nanometer scale. ► The excellent photoelectric performance of the compound is verified with a light on–off test.In this paper the fabrication and characterization of IV–VI semiconductor Pb1−_xSn_xSe ( x=0.2) thin films on gold substrate by electrochemical atomic layer deposition (EC-ALD) method at room temperature are reported. Cyclic voltammetry (CV) is used to determine approximate deposition potentials for each element. The amperometric I– t technique is used to fabricate the semiconductor alloy. The elements are deposited in the following sequence: (Se/Pb/Se/Pb/Se/Pb/Se/Pb/Se/Sn …), each period is formed using four ALD cycles of PbSe followed by one cycle of SnSe. Then the deposition manner above is cyclic repeated till a satisfactory film with expected thickness of Pb1−_xSn_xSe is obtained. The morphology of the deposit is observed by field emission scanning electron microscopy (FE-SEM). X-ray diffraction (XRD) pattern is used to study its crystalline structure; X-ray photoelectron spectroscopy (XPS) of the deposit indicates an approximate ratio 1.0:0.8:0.2 of Se, Pb and Sn, as the expected stoichiometry for the deposit. Open-circuit potential (OCP) studies indicate a good p-type property, and the good optical activity makes it suitable for fabricating a photoelectric switch.

Keywords: Pb; 1−; _x; Sn; _x; Se; Gold substrate; EC-ALD; UPD; Photoelectric switch

The field emission of vacuum filtered graphene films reduced by microwave by Kai Wang; Tao Feng; Min Qian; Hui Ding; Yiwei Chen; Zhuo Sun (pp. 5808-5812).

► Field emission of graphene film produced by microwave reduction is better. ► By examining the surface of graphene films by SEM and the detail of graphene by TEM, we conclude that larger size of microwave reduced graphene sheet can produce more natural rolls and tips by higher surface tension. It leads to the better field emission performance of microwave-reduced graphene film. ► The reduction level by microwave radiation is similar to reduced by hydrazine.A green, convenient, and inexpensive approach to producing graphene field emitters has been developed. Graphite oxide (GO) produced by hummer method was reduced to graphene in a microwave synthesis system. The vacuum filtration method made it possible to form pure and uniform graphene thin films without any additives and it's easy to transfer to other substrates. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV–vis diffuse reflectance spectroscopy (UV–vis) measurements proved that the graphene prepared by microwave has nearly the same reduction level as that prepared by hydrazine. The results of field emission testing demonstrated that graphene films reduced by microwave are more suitable as field emitters than those reduced by hydrazine, which pave a way to mass-produce low-cost graphene emitter for field emission applications.

Keywords: Field emission; Vacuum filtered graphene films; Microwave-synthesis

Preparation and characterization of visible light responsive Fe₂O₃–TiO₂ composites by Hong Liu; H.K. Shon; Xuan Sun; S. Vigneswaran; Hao Nan (pp. 5813-5819).

► Optimal synthesis method of a Fe₂O₃–TiO₂ composite photocatalyst from Fe₂(SO₄)₃ and Ti(SO₄)₂ by a ethanol-assisted hydrothermal method. ► Detailed physical and chemical characterization of the Fe₂O₃–TiO₂ composites. ► Superior photocatalytic activity of the new Fe₂O₃–TiO₂ composite photocatalyst for the degradation of auramine under visible light irradiation.In this study we present the effects of iron oxide (Fe₂O₃) on titanium dioxide (TiO₂) in synthesising visible-light reactive photocatalysts. A Fe₂O₃–TiO₂ composite photocatalyst was synthesized from Fe₂(SO₄)₃ and Ti(SO₄)₂ by a ethanol-assisted hydrothermal method. The preparation conditions were optimized through the investigation of the effects of hydrothermal temperature and time as well as molar ratio of Ti to Fe on the photocatalytic activity. The visual, physical and chemical properties of the Fe₂O₃–TiO₂ composites were investigated. The results showed that α-Fe₂O₃ and anatase TiO₂ were present in the composites. The Fe₂O₃–TiO₂ synthesized under optimum condition consisted of mesoporous structure with an average pore size of 4nm and a surface area of 43m²/g. Under visible and solar light irradiation, the photocatalytic activity of optimized sample was significantly higher than that of pure TiO₂. This sample led to a photodegradation efficiency of 90% and 40% of auramine under visible light and solar light, respectively.

Keywords: Fe; ₂; O; ₃; –TiO; ₂; composites; Hydrothermal synthesis; Photocatalytic activity; Auramine; Degradation efficiency

Recombination of hydrogen atoms on fine-grain graphite by Aleksander Drenik; Alenka Vesel; Arkadi Kreter; Miran Mozetič (pp. 5820-5825).

► Neutral H atoms recombine on solid surfaces with certain probability. ► We investigate the recombination probability for graphite at different values of roughness. ► The recombination probability exhibits a non-linear response to surface roughness.The probability of recombination of hydrogen atoms on surfaces of fine-grain graphite EK98 was investigated as a function of surface roughness. The source of hydrogen atoms used in this experiment was weakly ionised plasma created with an inductively coupled radiofrequency generator at pressures from 30Pa to 175Pa in hydrogen. Hydrogen atom density was measured by means of fibre optic catalytic probes. The recombination coefficient of the graphite samples was determined by observing their impact on the spatial distribution of the atom density in a closed side-arm of the reactor. Smith's diffusion model was used to calculate the values of the recombination coefficient. The measured recombination coefficient was found to increase much faster than the measured effective surface. This discrepancy is explained by the fact that on a surface which is not perfectly flat, there is a finite probability for multiple collisions. Impinging atoms collide more than once with the surface before they are reflected into the surface, which results in a larger probability of recombination.

Keywords: Recombinaton; Fine grain graphite; Fibre optic catalytic probe; Weakly ionised plasma; Hydrogen; Neutral atoms

Surface modification of hard alloy by Y ion implantation under different atmosphere by Shixing Wang; Cong Li; Bijun Xiong; Xiubo Tian; Shiqin Yang (pp. 5826-5830).

► Rare-earth Y was implanted into hard alloy surface by MEVVA technology under different atmosphere. ► New phases of C, YC₂, Y₂O₃, and WN appear in the implanted sample surface. ► Nnitrogen atmosphere can farther promote the performance of the implanted sample surface. ► Surface modification is the comprehensive action result of all involved aspects. ► Introducing atmosphere factor may develop the using scope of ion implantation in certain degree.To enhance the properties of hard alloy, rare-earth metal yttrium (Y) was implanted into its surface by using Metal Vapor Vacuum Arc (MEVVA) source implantor. The experiments were finished under different vacuum conditions with/without aerating nitrogen in the chamber. The metallograph and phase formation of sample were characterized and analyzed with metallurgical microscope and X-ray diffraction. The results show that there exist new phases of C, YC₂, Y₂O₃, and WN in the sample surface. Moreover, it can be found that the performances of sample surface (such as microhardness, friction coefficient and corrosion resistance) are evidently improved, and that nitrogen atmosphere plays a very important role in farther promoting these performances. The surface modification of hard alloy is not only affected by the implantation itself, but also related to the microstructure transformation, which can be partly induced by the atmosphere.

Keywords: Surface modification; Hard alloy; Y ion implantation; Nitrogen atmosphere

Facile fabrication of superhydrophobic surface with micro/nanoscale binary structures on aluminum substrate by Yonggang Guo; Qihua Wang; Tingmei Wang (pp. 5831-5836).

► Simple method to produce a zinc–aluminum layered double hydroxide (ZnAl-LDH) film. ► Complex micro/nanoscale binary structures similar to that of lotus leaf. ► After a simple modification, the wettability of as-prepared film changed from superhydrophilic to superhydrophobic.The present work reports a simple method to produce the aluminum superhydrophobic surface based on an interface reaction between an aluminum foil and zinc aqueous solution. The products were characterized by field-emission scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectrum. The field-emission scanning electron microscopy images show that the coating surface is composed of micro/nanoscale binary structure, which is similar to the structure of lotus leaf. The wettability of the coating surface was also investigated. It was found that after treatment with stearic acid, the wettability of the aluminum foil changed from superhydrophilic to water-repellent superhydrophobic. The complex micro/nanoscale binary structures along with the low surface energy lead to the high surface superhydrophobicity.

Keywords: Aluminum; Micro/nanoscale binary structure; Superhydrophobicity

Investigation of chemical mechanical polishing of zinc oxide thin films by Sushant Gupta; Purushottam Kumar; A. Arul Chakkaravathi; Doina Craciun; Rajiv K. Singh (pp. 5837-5843).

► Highly smooth zinc oxide thin films were demonstrated. ► Chemical mechanical polishing process for zinc oxide was developed. ► Chemical and mechanical aspect of CMP process synergistically work to demonstrate high removal rates with high surface finish. ► Modified Preston's equation was proposed.Zinc oxide has become an important material for various applications. Commercially available zinc oxide single crystals and as-grown zinc oxide thin films have high surface roughness which has detrimental effects on the growth of subsequent layers and device performance. A chemical mechanical polishing (CMP) process was developed for the polishing of zinc oxide polycrystalline thin films. Highly smooth surfaces with RMS roughness <6Å (as compared to the initial roughness of 26±6Å) were obtained under optimized conditions with removal rates as high as 670Å/min. Effects of various CMP parameters on removal rate and surface roughness were evaluated. The role of pH on the polishing characteristics was investigated in detail.

Keywords: Transparent conducting oxide; Zinc oxide; Chemical mechanical polishing; Thin films

Surface modification of HMS material with silica sol leading to a remarkable enhanced catalytic performance of Cu/SiO₂ by Anyuan Yin; Chao Wen; Wei-Lin Dai; Kangnian Fan (pp. 5844-5849).

Display Omitted► Silica sol leads to the surface modification of HMS material. ► Great enhancement of catalytic performance could be obtained via the surface modified catalyst. ► The yield of the ethylene glycol could be improved at least 2 times higher after the surface modification. ► Surface modification could improve the dispersion of copper species, stabilize the particle size and strengthen the interaction between the active copper species and support.Cu/SiO₂ catalysts with different bimodal pore structures adjusted by the ratio of HMS and silica sol were prepared via modified impregnation method. Structure evolutions of the catalyst were systematically characterized by N₂-physisorption, X-ray diffraction, H₂ temperature-programmed reduction, N₂O titration and X-ray photoelectron spectroscopy. The results show that the composite silica supported copper catalysts showed remarkably enhanced catalytic performance in the selective hydrogenation of dimethyl oxalate to ethylene glycol compared to the individual silica supported ones obtained by the same method. The dimethyl oxalate conversion and the ethylene glycol selectivity can reach 100% and 98% at 473K with 2.5MPa H₂ pressure and 1.5h⁻¹ liquid hour space velocity of dimethyl oxalate over the optimized Cu/SiO₂ catalyst. The remarkably enhanced catalytic performance of Cu/SiO₂ catalysts might be attributed to the homogeneous dispersion and uniformity of the active copper species and to the larger copper surface areas attained on the HMS supports with large pore diameters and surface areas.

Keywords: Surface modification; Cu/HMS catalyst; Hydrogenation of dimethyl oxalate; Ethylene glycol; Hierarchical pore structure

The effect of multi-walled carbon nanotube pretreatments on the electrodeposition of Ni–MWCNTs coatings by S. Khabazian; S. Sanjabi (pp. 5850-5856).

► In the current research, MWCNTs are pretreated by two different chemical treatments and then electrodeposited with nickel from a modified Watt's plating bath. The main results are as bellows ► In similar plating condition, shortened nanotubes were more co-deposited than elongated ones. ► Shortened nanotubes are behaved as inert ceramic particles, and embedded into the nickel matrix, whilst the long functionalized nanotubes showed metallic behavior and incorporated into the nickel matrix. ► SMWCNTs enhance more effectively the hardness of matrix due to their smaller length and higher co-deposition in comparison with LMWCNTs. ► Inclusion of nanotubes into the nickel matrix modifies grain orientation from (100) soft mode toward (111) direction. ► As LMWCNTs are more tightly incorporated into the nickel matrix than SMWCNTs, the dissention of them from the matrix posterior is more occurred results in lower corrosion current density in comparison with Ni-SMWCNTs coating.Two different chemical treatments were performed on multi-walled carbon nanotubes (MWCNTs), namely functionalization, and shortening-functionalization processes. Then, nickel–MWCNTs coatings were co-electrodeposited. The results showed that the chemically shortened nanotubes were behaved as inert particles, and embedded into the nickel matrix, whilst the long functionalized nanotubes showed metallic behavior and during electrodeposition, they were incorporated into the nickel matrix. In similar plating condition, the amount of co-deposited shortened nanotubes was more than elongated ones. Furthermore, it was revealed that the pretreatment of nanotubes significantly affected the microstructure, surface morphology, hardness and corrosion resistance of deposited coatings.

Keywords: Electrodeposition; Microstructure; Multi-walled carbon nanotubes; Nickel coating

Hydrothermal synthesis of Sb₂O₃ nanorod-bundles via self-assembly assisted oriented attachment by Qingyao Wang; Xiuchun Yang; Junwei Hou; Min Huang; Yuhua Zhao (pp. 5857-5862).

. It is speculated that the Sb₂O₃ nanorod-bundles are formed mainly via a three-step sequence, i.e. nucleation, self-assembly and 1D oriented attachment growth. The nucleated grains first grow into small nanoparticles, and were absorbed by PVA molecules. After this, PVA self-assembled into micelles with the layered structures and these Sb₂O₃ nanoparticles aggregated into microdisks of ∼230nm in diameter. Furthermore, the remaining seeds attached on the surface of the microdisks and grew into short rods. The arms were elongated by oriented attachment on the end of each rod, which led to the formation of a long rod. Finally, product with bundle-like structures is obtained with the growth of arms along the [001] direction. The whole formation of Sb₂O₃ nanorod-bundles can be summarized in the schematic illustration as shown in the figure.Display Omitted► We report the fabrication of uniform Sb₂O₃ nanorod-bundles via a facile hydrothermal synthetic method. ► Morphology, composition, microstructure and optical property of Sb₂O₃ nanorod-bundles were researched. ► The self-assembly assisted oriented attachment mechanism was proposed.Sb₂O₃ nanorod-bundles with length of about 4μm were fabricated in the presence of polyvinyl alcohol (PVA) by a simple hydrothermal method. The composition, morphology, microstructure and optical property of the as-prepared bundles were characterized by XRD, XPS, SEM, TEM and Raman spectrum. The results showed that the nanorod-bundles were composed of massive orthorhombic phase Sb₂O₃ nanorods grown along [001] direction. It was speculated that the nanorod-bundles developed through self-assembly of initially scattered nuclei into microdisks and subsequent oriented attachment process. PVA played a crucial role in the formation of Sb₂O₃ nanorod-bundles.

Keywords: Nanostructures; Hydrothermal crystal growth; Growth mechanism

Product analysis of partial discharge damage to oil-impregnated insulation paper by Jiaming Yan; Ruijin Liao; Lijun Yang; Jian Li; Bin Liu (pp. 5863-5870).

► During PD damage, surface of insulation paper was investigated by optical microscope and SEM. ► Surface products and their components were studied by IR and XPS. ► Volume variation of cavity gas was also analyzed. ► Gas constituents and their relevant contents were studied by GC–MS. ► Formation mechanism of damage products was also explored.Surface products of oil-impregnated insulation paper during the damage process caused by partial discharge (PD), as well as gas within the cavity, were studied. An optical microscope and a scanning electron microscope (SEM) were used to investigate surface morphology, while an infrared spectroscopy (IR) and an X-ray photoelectron spectroscopy (XPS) were used to study surface products and their components. The volume variation in cavity gas was also analyzed. Furthermore, gas constituents and their relevant contents were studied using a gas chromatography–mass spectrometer (GC–MS). The study results reveal the following: during the PD damage process, the total gas volume and the content of electronegative gasses alternately decline and increase, while discharge types alternate between pulse type and pseudo-glow type (or glow type); “surface droplets” and “crystalline solids” appear on the insulation surface one after another; surface droplets mainly consist of (CO)-group-containing compounds, whereas crystalline solids are mainly carboxylic acids, with carboxyl groups also found in cellulose chains; and the discharge type related to the oxidization of decomposition products is the main factor that determines the state (liquid or solid) of the surface products.

Keywords: IR; XPS; GC–MS; Surface droplets; Crystalline solids; Electronegative gases

Selective oxidation of dual phase steel after annealing at different dew points by Vanessa de Freitas Cunha Lins; Laureanny Madeira; Jose Mario Carneiro Vilela; Margareth Spangler Andrade; Vicente Tadeu Lopes Buono; Juliana Porto Guimarães; Evandro de Azevedo Alvarenga (pp. 5871-5878).

► Selective oxidation of a dual phase steel after annealing at different dew points. ► External selective oxidation of phosphorus occurred on steel surface annealed at 0°C dp. ► External selective oxidation of Mn, Si, and Al occurred on steel annealed at −60°C dp. ► Mo content increased as the depth from the surface of steels increased.Hot galvanized steels have been extensively used in the automotive industry. Selective oxidation on the steel surface affects the wettability of zinc on steel and the grain orientation of inhibition layer (Fe–Al–Zn alloy) and reduces the iron diffusion to the zinc layer. The aim of this work is to identify and quantify selective oxidation on the surface of a dual phase steel, and an experimental steel with a lower content of manganese, annealed at different dew points. The techniques employed were atomic force microscopy, X-ray photoelectron spectroscopy, and glow discharge optical emission spectroscopy. External selective oxidation was observed for phosphorus on steel surface annealed at 0°C dp, and for manganese, silicon, and aluminum at a lower dew point. The concentration of manganese was higher on the dual phase steel surface than on the surface of the experimental steel. The concentration of molybdenum on the surface of both steels increased as the depth increased.

Keywords: Selective oxidation; Hot galvanized steel; Dual phase steel; X-ray photoelectron spectroscopy; Glow discharge optical emission spectroscopy

Synthesis of fluorinated TiO₂ hollow microspheres and their photocatalytic activity under visible light by Li Junqi; Wang Defang; Liu Hui; He Zuoli; Zhu Zhenfeng (pp. 5879-5884).

► Fluorinated TiO₂ hollow microspheres were prepared by solvothermally treatment. ► The sample exhibited unique three-dimensional hierarchical architecture. ► A significantly improved photocatalytic performance was demonstrated.Fluorinated TiO₂ hollow microspheres with three-dimensional hierarchical architecture were prepared by solvothermally treatment using solid microspheres as precursor. The obtained solid and hollow TiO₂ microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectrum (DRS) and photoluminescence (PL) spectra. The photocatalytic activity of as-prepared solid and hollow TiO₂ microspheres was determined by degradation of methyl orange (MO) under visible light irradiation. The results showed that the surface fluorination, the existence of accessible mesopores channels, and the increased light harvesting abilities could remarkably improve the photocatalytic activity of TiO₂ hollow microspheres.

Keywords: Fluorinated TiO; ₂; Hollow microspheres; Photocatalysis

Microstructure and tribological properties of TiCu₂Al intermetallic compound coating by Chun Guo; Jiansong Zhou; Jierong Zhao; Linqian Wang; Youjun Yu; Jianmin Chen; Huidi Zhou (pp. 5885-5892).

► TiCu₂Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding with aluminum bronze powder. ► Microstructre of the prepared TiCu₂Al intermetallic compound coating was systematically analyzed by XRD, SEM and TEM. ► Tribological properties of the TiCu₂Al intermetallic compound coating were systematically investigated.TiCu₂Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu₂Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu₂Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu₂Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15N.

Keywords: Coating; Intermetallics; Friction; Wear

Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene by K. Ozeki; K.K. Hirakuri; T. Masuzawa (pp. 5893-5898).

► Polypropylene was coated with diamond-like carbon (DLC)/titanium dioxide (TiO₂) multilayer thin films using the CVD and sputtering techniques for application of food container. ► The DLC film coated PP effectively prevented flavour retention to PP. ► The DLC/TiO₂ film coated PP actively decomposed flavour compounds adsorbed to the film under UV radiation.Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO₂) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers.For the flavour removal test, two types of multilayer films were prepared, DLC/TiO₂ films and DLC/TiO₂/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO₂-coated and the DLC/TiO₂/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO₂ coated plates were 0.8%, 65.2% and 75.0% after 40h of UV radiation, respectively. For the DLC/TiO₂/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40h of UV radiation, respectively. The DLC/TiO₂/DLC film had a photocatalytic effect even though the TiO₂ film was covered with the DLC film.

Keywords: Diamond-like carbon; Photocatalyst; Polypropylene; Prevention of flavour retention; Flavour removal

Surface modification of pure titanium by pulsed electron beam by X.D. Zhang; S.Z. Hao; X.N. Li; C. Dong; T. Grosdidier (pp. 5899-5902).

► LEHCPEB surface treatment was performed on commercial purity Ti. ► Ultrafine α’ martensite has formed on cooling during LEHCPEB treatment. ► Hardness and corrosion properties have been improved due to ultrafine structure.The microstructure, hardness and corrosion resistance of commercially pure Ti treated by low energy high current pulsed electron beam (LEHCPEB) have been investigated. The thin near-surface melted layer rapidly solidified into β and subsequently transformed into ultrafine α′ martensite. This has led to a drastic improvement of the corrosion properties and a significant increase (more than 60%) in hardness of the top surface.

Keywords: Low energy high current pulsed electron beam; Surface treatment; Ti; Microstructure; Hardness; Corrosion

Electrochromic properties of WO₃ thin film onto gold nanoparticles modified indium tin oxide electrodes by Jiajia Deng; Ming Gu; Junwei Di (pp. 5903-5907).

► Gold nanoparticle (GNP) thin films were electrodeposited onto indium tin oxide coated glass. ► The color of GNP film can vary from pale red to blue. ► The WO₃/GNPs composite films were fabricated by sol–gel method. ► Their electrochromic performance was improved in comparison with a single component system of WO₃.Gold nanoparticles (GNPs) thin films, electrochemically deposited from hydrogen tetrachloroaurate onto transparent indium tin oxide (ITO) thin film coated glass, have different color prepared by variation of the deposition condition. The color of GNP film can vary from pale red to blue due to different particle size and their interaction. The characteristic of GNPs modified ITO electrodes was studied by UV–vis spectroscopy, scanning electron microscope (SEM) images and cyclic voltammetry. WO₃ thin films were fabricated by sol–gel method onto the surface of GNPs modified electrode to form the WO₃/GNPs composite films. The electrochromic properties of WO₃/GNPs composite modified ITO electrode were investigated by UV–vis spectroscopy and cyclic voltammetry. It was found that the electrochromic performance of WO₃/GNPs composite films was improved in comparison with a single component system of WO₃.

Keywords: Tungsten oxide; Electrochromic; Gold nanoparticles; Electrodeposition

Characterization of DC reactive magnetron sputtered NiO films using spectroscopic ellipsometry by T.C. Peng; X.H. Xiao; X.Y. Han; X.D. Zhou; W. Wu; F. Ren; C.Z. Jiang (pp. 5908-5912).

► Ni-rich NiO films and relatively pure NiO film were prepared by magnetron sputtering. ► The partial pressure of oxygen is a key condition for growing NiO films. ► Optical properties of the NiO films were investigated by spectroscopic ellipsometry. ► The partial pressure of oxygen influences the thickness and roughness of NiO films. ► Direct gap energy and indirect gap energy of the NiO films are also influenced.Thin NiO films were deposited at 500°C on n-type Si(111) by a DC reactive magnetron sputtering in a gas mixture of oxygen and argon. The ratio between the flow rates of oxygen and argon was respectively set at 1:4, 1:2, and 1:1. The dependence of structures and optical properties of NiO films were investigated using grazing incidence X-ray diffraction and spectroscopic ellipsometry in the spectral region of 1.5–5.0eV. Ni-rich NiO films were obtained when the ratio between the flow rates of oxygen and argon was 1:4 and 1:2 in sputtering process. And when the ratio was 1:1, a relatively pure NiO film was formed. The partial pressure of oxygen could significantly influence the thickness and roughness of films. Refractive index n, extinction coefficient k, and direct gap energy and indirect gap energy of the NiO films were also subject to the influence of the partial pressure of oxygen.

Keywords: NiO films; Spectroscopic ellipsometry; Tauc–Lorentz dispersion function

Enhanced corrosion resistance and cellular behavior of ultrafine-grained biomedical NiTi alloy with a novel SrO–SiO₂–TiO₂ sol–gel coating by C.Y. Zheng; F.L. Nie; Y.F. Zheng; Y. Cheng; S.C. Wei; Liqun Ruan; R.Z. Valiev (pp. 5913-5918).

► A novel, homogeneous and smooth SrO–SiO₂–TiO₂ sol–gel coating without cracks was fabricated on ultrafine-grained NiTi surface. ► The sol–gel coating significantly increased the corrosion resistance and decreased the release of nickel ions of ultrafine-grained NiTi. ► Ultrafine-grained NiTi with sol–gel coating enhanced osteoblast-like cell attachment, spreading and proliferation.NiTi alloy has a unique combination of mechanical properties, shape memory effects and superelastic behavior that makes it attractive for several biomedical applications. In recent years, concerns about its biocompatibility have been aroused due to the toxic or side effect of released nickel ions, which restricts its application as an implant material. Bulk ultrafine-grained Ni50.8Ti49.2 alloy (UFG NiTi) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study. A homogeneous and smooth SrO–SiO₂–TiO₂ sol–gel coating without cracks was fabricated on its surface by dip-coating method with the aim of increasing its corrosion resistance and cytocompatibility. Electrochemical tests in simulated body fluid (SBF) showed that the pitting corrosion potential of UFG NiTi was increased from 393mV(SCE) to 1800mV(SCE) after coated with SrO–SiO₂–TiO₂ film and the corrosion current density decreased from 3.41μA/cm² to 0.629μA/cm². Meanwhile, the sol–gel coating significantly decreased the release of nickel ions of UFG NiTi when soaked in SBF. UFG NiTi with SrO–SiO₂–TiO₂ sol–gel coating exhibited enhanced osteoblast-like cells attachment, spreading and proliferation compared with UFG NiTi without coating and CG NiTi.

Keywords: Ultrafine-grained NiTi; Sol–gel coating; Cytocompatibility; Corrosion resistance

Effects of Co and W alloying elements on the electrodeposition aspects and properties of nanocrystalline Ni alloy coatings by M.A. Farzaneh; M.R. Zamanzad-Ghavidel; K. Raeissi; M.A. Golozar; A. Saatchi; S. Kabi (pp. 5919-5926).

► Corrosion resistance of Ni coatings is under direct control of surface structure. ► Co content and surface structure affect the corrosion resistance of Ni–Co coatings. ► Surface structure strongly determines the corrosion resistance of Ni–W coatings. ► Surface structure and grain size of Ni–Co–W coatings do not change by current density.Depending on deposition current density and alloying elements, various types of surface structure (surface morphology and grain orientation) were observed for Ni and Ni alloy nanocrystalline coatings. It was found that the variation of surface morphology with current density is in a good agreement with the variation of grain orientation. An increase in the current density produced larger grains and also reduced the charge transfer resistance and growth inhibition intensity which may change the surface structure of the coatings. For Ni coatings, the effect of surface structure on the corrosion resistance was detected to be superior to that of grain size. In the case of Ni–Co coating and at different deposition current densities, Co content and surface structure were recognized as the major factors influencing the corrosion resistance. Surface structure was also a more important factor determining the corrosion resistance of Ni–W coatings. In Ni–Co–W coatings, surface structure and grain size of the coatings were found to be independent of deposition current density. This is believed to be due to the simultaneous contrary effects of Co and W elements.

Keywords: Ni; Ni–Co; Ni–W; Ni–Co–W; Electrodeposit; Nanocrystalline; Coating

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Applied Surface Science (v.257, #13)

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Applied Surface Science (v.257, #13)