Check out our New Publishers' Select for Free Articles

Applied Surface Science (v.258, #3)

Microscopic observation of lateral diffusion at Si–SiO₂ interface by photoelectron emission microscopy using synchrotron radiation by N. Hirao; Y. Baba; T. Sekiguchi; I. Shimoyama; M. Honda (pp. 987-990).

► PEEM combined with synchrotron soft X-ray was applied to investigate the chemical states in Si–SiO₂ interface at nanometer scale. ► The mechanism of diffusion by the annealing differs between in the lateral and longitudinal directions at the Si–SiO₂ interface. ► The lateral diffusion begins at lower temperature than the longitudinal diffusion. ► For the lateral diffusion, SiO is absent in the Si–SiO₂ interfaces. ► The observed differences between lateral and longitudinal diffusions are interpreted by the sublimated property of SiO.The lateral surface diffusion at Si–SiO₂ interface has been observed at nanometer scale using photoelectron emission microscopy (PEEM) combined with synchrotron soft X-ray excitation. The samples investigated were Si–SiO_x micro-patterns prepared by O₂⁺ ion implantation in Si (001) wafer using a mask. The lateral spacial resolution of the PEEM system was about 41nm. The brightness of each spot in the PEEM images changed depending on the photon energy around the Si K-edge, in proportion to the X-ray absorption intensity of the corresponding valence states. It was found that the lateral diffusion occurs by 400–450°C lower temperature than that reported for the longitudinal diffusion at the Si–SiO₂ interface. It was also found that no intermediate valence states such as SiO (Si²⁺) exist at the Si–SiO₂ interface during the diffusion. The observed differences between lateral and longitudinal diffusion are interpreted by the sublimated property of silicon monoxide (SiO).

Keywords: PEEM; NEXAFS; SOI; Si–SiO; ₂; interface; Diffusion

Organic–inorganic hybrid superhydrophobic surfaces using methyltriethoxysilane and tetraethoxysilane sol–gel derived materials in emulsion by Xiu-Fang Wen; Kun Wang; Pi-Hui Pi; Jin-Xin Yang; Zhi-Qi Cai; Li-juan Zhang; Yu Qian; Zhuo-Ru Yang; Da-feng Zheng; Jiang Cheng (pp. 991-998).

► A superhydrophobic surface was prepared by the sol-gel derived organic-inorganic hybrid emulsion. ► This hybrid emulsion can be achieved by alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) in organic siloxane modified polyacrylate emulsion (OSPA emulsion). ► The water contact angle (WCA) on the sol-gel derived hybrid film is determined to be 158°, and the contact angle hysteresis is 5° by keeping the mole ratio of TEOS:MTES:C₂H₅OH:NH₃·H₂O:AMP-95 at 1:4:30:10:0.63 and the mass percentage of OSPA emulsion at 25%. ► With the primer coating. ► The performance of superhydrophobic film achieve actual use standard.By applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) in organic siloxane modified polyacrylate emulsion (OSPA emulsion), we are able to demonstrate the potential for developing a sol–gel derived organic–inorganic hybrid emulsion for a superhydrophobic surface research. TEOS and MTES derived sol–gel moieties can be designed for a physical roughness and hydrophobic characteristic (Si–CH₃) of the hybrid superhydrophobic surface, while OSPA emulsion can be endowed for good film-forming property. The effect of formulation parameters on superhydrophobicity and film-forming property was analyzed. The water contact angle (WCA) on the sol–gel derived hybrid film is determined to be 156°, and the contact angle hysteresis is 5° by keeping the mole ratio of TEOS:MTES:C₂H₅OH:NH₃·H₂O:AMP-95 at 1:4:30:10:0.63 and the mass percentage of OSPA emulsion at 25%. The nanoparticle-based silica rough surface is observed as the mole ratio of MTES/TEOS at 4:1. The sol–gel derived organic–inorganic hybrid emulsion shows remarkable film-forming property when the mole ratio of MTES/TEOS reaches or exceeds 4:1. With the primer coating, the performance of superhydrophobic film achieve actual use standard. It reveals that this new procedure is an effective shortcut to obtain a superhydrophobic surface with potential applications.

Keywords: Superhydrophobic surface; Organic–inorganic hybrids; Sol–gel process; MTES/TEOS; Hydrophobic silica

Formation of α-Si1−_xC_x:H and nc-SiC films grown by HWCVD under different process pressure by Tianru Wu; Honglie Shen; Bin Cheng; Yuanyuan Pan; Bing Liu; Jiancang Shen (pp. 999-1003).

► The α-Si1−_xC_x:H films show the monotonously enhanced density of C–H_n and Si–C bonds and the atomic carbon content increases almost linearly with increasing C₂H₂ fraction. ► Process gas pressure is a key parameter for the preparation of nc-SiC thin films. The increase in the gas pressure enhances the generation of various radicals. ► The generation of H radicals is the most important factor and contributes not only to the inducement of the SiC nuclei formation but also to the etching of amorphous phases.In this work, hydrogenated amorphous silicon carbide (α-Si1−_xC_x:H) and nanocrystalline SiC (nc-SiC) thin films were deposited by hot wire CVD (HWCVD) using SiH₄/C₂H₂/H₂ gas mixtures. It was found that the films prepared under low gas pressure were α-Si1−_xC_x:H and those prepared under high gas pressure were nc-3C-SiC. The α-Si1−_xC_x:H films showed enhanced density of C–H_n and Si–C bonds with increasing C₂H₂ fraction, which induced an increase in optical gap from 1.8 to 3.0eV. For the deposition process of nc-SiC, the Eg_opt of the deposited films varied from 1.9eV to 2.5eV as the filament temperature increased from 1700 to 2100°C. The deposition rate decreased rapidly from 5.74nm/min to 0.8nm/min with increasing T_F.

Keywords: α-Si; 1−; _x; C; _x; :H; nc-SiC; Optical band gap; HWCVD; Fraction; Thin films

Formation of α-Si1−_xC_x:H and nc-SiC films grown by HWCVD under different process pressure by Tianru Wu; Honglie Shen; Bin Cheng; Yuanyuan Pan; Bing Liu; Jiancang Shen (pp. 999-1003).

Keywords: α-Si; 1−; _x; C; _x; :H; nc-SiC; Optical band gap; HWCVD; Fraction; Thin films

A novel simple approach to preparation of superhydrophobic surfaces of aluminum alloys by Degang Xie; Wen Li (pp. 1004-1007).

► A novel two-step methodology to fabricate superhydrophobic surfaces of aluminum alloys. ► Cheaper and more efficient than the fluorinated silane frequently adopted. ► A fast, low-cost, and reliable method for promising industrial applications.A novel two-step methodology is successfully developed to fabricate superhydrophobic surfaces of aluminum alloys. The essential procedure is that samples are first immersed and etched in a boiling aqueous solution of NaOH for 5min without preprocessing, and then they are modified for 30min in an ethanol solution of lauric acid, cheaper and more efficient than the fluorinated silane frequently adopted by other researchers. If the concentration of NaOH solution is larger than 5g/L, the contact angle of the prepared surfaces will be larger than 150° with a negligible hysteresis. Such a fast, low-cost, and reliable method for superhydrophobic surfaces implies significant promising industrial applications.

Keywords: Superhydrophobicity; Fatty acid

A novel simple approach to preparation of superhydrophobic surfaces of aluminum alloys by Degang Xie; Wen Li (pp. 1004-1007).

Keywords: Superhydrophobicity; Fatty acid

Preparation of porous super-hydrophobic and super-oleophilic polyvinyl chloride surface with corrosion resistance property by Yingke Kang; Jinyan Wang; Guangbin Yang; Xiujuan Xiong; Xinhua Chen; Laigui Yu; Pingyu Zhang (pp. 1008-1013).

► Porous super-hydrophobic and super-oleophilic PVC coatings were prepared via a facile solvent/non-solvent coating process below 20°C without addition of low-surface-energy compounds. ► The super-hydrophobic PVC coatings obtained from the mixed PVC solution containing 2.5:10.0 (volume ratio) of glacial acetic acid to THF and under a drying temperature of 17°C possess. ► The porous PVC coatings have good corrosion resistance against different corrosive mediums after being immersed in many solutions.Porous super-hydrophobic polyvinyl chloride (PVC) surfaces were obtained via a facile solvent/non-solvent coating process without introducing compounds with low surface energy. The microstructure, wetting behavior, and corrosion resistance of resultant super-hydrophobic PVC coatings were investigated in relation to the effects of dosage of glacial acetic acid and the temperature of drying the mixed PVC solution spread over glass slide substrate. As-prepared PVC coatings had porous microstructure, and the one obtained at a glacial acetic acid to tetrahydrofuran volume ratio of 2.5:10.0 and under a drying temperature of 17°C had a water contact angle of 150±1.5°, showing super-hydrophobicity. In the meantime, it possessed very small contact angles for liquid paraffin and diiodomethane and good corrosion resistance against acid and alkali corrosive mediums, showing promising applications in self-cleaning, waterproof for outer wall of building, seawater resistant coating, and efficient separation of oil and water.

Keywords: Polyvinyl chloride; Super-hydrophobic surface; Super-oleophilic; Corrosion resistance

Copper coated nickel foam as current collector for H₂S-containing syngas solid oxide fuel cells by Qing-Xun Low; Weishan Huang; Xian-Zhu Fu; Juri Melnik; Jing-Li Luo; Karl T. Chuang; Alan R. Sanger (pp. 1014-1020).

► Electrodeposition is a simple and effective method to form protective coating on Ni foam. ► Exposure to syngas and H₂S–syngas on uncoated Ni foam caused an increase in resistance and embrittlement. ► Cu-coated Ni foam showed a durable and steady resistance and did not show any destruction of the structure after exposure to H₂S-containing syngas. ► Cu coated Ni foam is a promising current collector for SOFC and further investigations are in progress.Copper coated nickel foam with Cu/Ni ratio of 2.5 was fabricated using electrochemical plating and characterized using XRD, SEM, EDS and Van der Pauw four point conductivity measurements. Copper coated nickel foam exhibited good stability of electronic conductivity and mechanical strength during more than 150h exposure to 500ppm H₂S-containing syngas at 750°C. In contrast, uncoated nickel foam readily underwent severe carbon deposition and brittle fracture resulting in dramatic increase of electronic resistance under the same testing conditions. Copper coated nickel foam is a promising current collector for H₂S-containing syngas solid oxide fuel cells (SOFCs).

Keywords: Copper coated nickel foam; Copper–nickel alloy; Carbon deposition; Sulfur corrosion; Current collector; SOFCs

Microstructure and mechanical properties of reactive magnetron sputtered Ti–B–C–N nanocomposite coatings by Q.H. Luo; Y.H. Lu (pp. 1021-1026).

► The study revealed that, in the studied composition range, the deposited Ti–B–C–N coatings exhibited nanocomposite based on TiN nanocrystallites. ► The following two results are new and beneficial for practical application. ► The first, incorporation of small amount of C promoted crystallization of Ti–B–C–N nanocomposite coatings, which resulted in increase of nano-grain size and mechanical properties of coatings. ► However, further increase of C content dramatically decreased not only grain size but also the mechanical properties of coatings. ► The second, we measured and calculated the fracture toughness of Ti–B–C–N nanocomposite coatings, which revealed that the fracture toughness was consistent with hardness/elastic modulus, however not consistent with the grain size.Ti–B–C–N nanocomposite coatings with different C contents were deposited on Si (100) and high speed steel (W18Cr4V) substrates by closed-field unbalanced reactive magnetron sputtering in the mixture of argon, nitrogen and acetylene gases. These films were subsequently characterized ex situ in terms of their microstructures by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), their nanohardness/elastic modulus and facture toughness by nano-indention and Vickers indentation methods, and their surface morphology using atomic force microscopy (AFM). The results indicated that, in the studied composition range, the deposited Ti–B–C–N coatings exhibit nanocomposite based on TiN nanocrystallites. When the C₂H₂ flow rate is small, incorporation of small amount of C promoted crystallization of Ti–B–C–N nanocomposite coatings, which resulted in increase of nano-grain size and mechanical properties of coatings. A maximum grain size of about 8nm was found at a C₂H₂ flux rate of 1sccm. However, the hardness, elastic modulus and fracture toughness values were not consistent with the grain size. They got to their maximum of 35.7GPa, 363.1GPa and 2.46MPam^1/2, respectively, at a C₂H₂ flow rate of 2sccm (corresponding to about 6nm in nano-grain size). Further increase of C content dramatically decreased not only grain size but also the mechanical properties of coatings. The presently deposited Ti–B–C–N coatings had a smooth surface. The roughness value was consistent with that of grain size.

Keywords: Ti–B–C–N coatings; Nanocomposite; Microstructure; Mechanical properties; Surface roughness

Microstructure and mechanical properties of reactive magnetron sputtered Ti–B–C–N nanocomposite coatings by Q.H. Luo; Y.H. Lu (pp. 1021-1026).

Keywords: Ti–B–C–N coatings; Nanocomposite; Microstructure; Mechanical properties; Surface roughness

A new strategy to assemble CdSe/ZnS quantum dots with multi-walled carbon nanotubes for potential application in imaging and photosensitization by Gi Beom Kim; B. Ramaraj; Kuk Ro Yoon (pp. 1027-1032).

► We have demonstrated a synthetic method for attachment of CdSe/ZnS quantum dots (QDs) on to the surface of sMWCNTs. ► The results reveal the attachment Q-dot with sMWCNTs surface through chlorobenzoic acid and 11-aminoundeccane-1-thiol is a successful one. ► This method could be used as a powerful tool to modify MWCNT into useful bio-sensors.With objective to enhance luminescence intensities of carbon nanotubes (CNTs), we hereby report the attachment of CdSe/ZnS quantum dots (QDs) on to the surface of shortened Multi Walled Carbon Nanotubes (sMWCNTs). The resultant QDs–sMWCNTs nanohybrid complex have been characterized by Fourier transform infrared (FT-IR) spectroscopy, optical microscopy (OM), ultraviolet (UV) light, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) diffraction spectroscopy and thermogravimetric analysis (TGA). Based on IR peaks characteristics of organic functional groups, optical brightness of sMWCNTs under polarized and UV light, the roughness of the sMWCNTs surface as observed in SEM images and black spots observed on the surface of sMWCNTs in TEM images, it is reasonable to conclude that CdSe/ZnS quantum dots (QDs) were attached on to the surface of sMWCNTs. Additionally, signals of Zn, S, Cd and Se along with carbon on the surface of sMWCNTs in EDX data and onset of thermal degradation of QDs–sMWCNTs nanohybrid complex at much lower temperature than that of sMWCNTs under TGA analysis further confirms the formation of QDs–sMWCNTs nanohybrid complex.

Keywords: Quantum dots; Carbon nanotubes; Nanohybrid complex

Effect of deposition and annealing temperature on mechanical properties of TaN film by X. Liu; G.J. Ma; G. Sun; Y.P. Duan; S.H. Liu (pp. 1033-1037).

► Hexagonal TaN were gotten by magnetron sputtering. With decreasing of deposition temperature, Ta phases are formed in TaN film. And Ta₂O₅ phases present with the increasing of annealing temperature after deposition. ► Films prepared at 573K show the highest hardness (34–39GPa), and the minimum value was 6GPa while the deposition temperature decreased to 373K, without annealing. ► The adhesion between films and substrates increases with deposition temperature. The post-annealing at 448K offers the highest adhesion (40GPa), and it reduces with the increase or decrease of annealing temperature.Tantalum nitride films (TaN) were synthesized by microwave ECR-DC sputtering. The effects of deposition and annealing temperature on mechanical properties of TaN films were investigated. Cross-section pattern, microstructure and binding energy of the films were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Mechanical properties were evaluated using nano-indentation and scratch tester. The results showed that the maximal hardness value of approximately 40GPa was deposited in the TaN sample at 573K. While the preparation temperature decreased, the hardness, modulus and adhesion of TaN film also decreased. Hardness and modulus also decreased with the increase in annealing temperature. Meanwhile the adhesion strength was also sensitive to the annealing temperature, with a maximum adhesion strength of 40N measured in the TaN film annealed at 448K. The results demonstrated that a desirable mechanical property of TaN films deposited by DC reactive magnetron sputtering can be obtained by controlling the deposition and annealing temperature.

Keywords: TaN film; Deposition temperature; Annealing temperature; Mechanical properties

Effect of deposition and annealing temperature on mechanical properties of TaN film by X. Liu; G.J. Ma; G. Sun; Y.P. Duan; S.H. Liu (pp. 1033-1037).

Keywords: TaN film; Deposition temperature; Annealing temperature; Mechanical properties

Improving protein resistance of α-Al₂O₃ membranes by modification with POEGMA brushes by Huating He; Wenheng Jing; Weihong Xing; Yiqun Fan (pp. 1038-1044).

Display Omitted► α-Al₂O₃ membrane was modified with POEGMA brushes to improve its protein resistance. ► The success of the modification was indicated by dynamic contact-angle measurements. ► POEGMA brushes resisted protein adsorption by restoring the compressed polymer chains. ► Protein deposition on POEGMA brushes layer was easier to remove.A kind of protein-resistant ceramic membrane is prepared by grafting poly(oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes onto the surfaces and pore walls of α-Al₂O₃ membrane (AM) by surface-initiated atom-transfer radical polymerization (SI-ATRP). Contact-angle, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and field-emission scanning electron microscopy (FESEM) were measured to confirm that the surfaces and pore walls of the ceramic porous membranes have been modified by the brushes with this method successfully. The protein interaction behavior with the POEGMA modified membranes (AM-POEGMA) was studied by the model protein of bovine serum albumin (BSA). A protein-resistant mechanism of AM-POEGMA was proposed to describe an interesting phenomenon discovered in the filtration experiment, in which the initial flux filtrating BSA solution is higher than the pure water flux. The fouling of AM-POEGMA was easier to remove than AM for the action of POEGMA brushes, indicated that the ceramic porous membranes modified with POEGMA brushes exhibit excellent protein resistance.

Keywords: Surface modification; α-Al; ₂; O; ₃; membrane; Polymer brushes; Protein resistance

Improving protein resistance of α-Al₂O₃ membranes by modification with POEGMA brushes by Huating He; Wenheng Jing; Weihong Xing; Yiqun Fan (pp. 1038-1044).

Keywords: Surface modification; α-Al; ₂; O; ₃; membrane; Polymer brushes; Protein resistance

Effect of reaction parameters on the growth of MWCNTs using mesoporous Sb/MCM-41 by chemical vapour deposition by R. Atchudan; A. Pandurangan; K. Subramanian (pp. 1045-1051).

The mesoporous Sb/MCM-41 (wt.% of Sb=1.0, 2.0, 3.0, 5.0, 10.0, 15.0 and 20.0) were used as a catalytic template and acetylene as a carbon precursor for the growth of MWNTs by CVD method. The 2wt.% of Sb/MCM-41 was found to produce MWCNTs with high quality and large quantity when compared with that obtained by other wt.% of Sb/MCM-41 at 800°C. Sb/MCM-41 produced MWCNTs having several internal compartments may induce the storage capacity in respective fields.Display Omitted► Synthesis and characterization of ordered mesoporous MCM-41 materials. ► The better formation of MWCNTs were obtained over 2wt.% of Sb/MCM-41 at 800°C. ► Sb loaded MCM-41 is one of the good catalytic support for the growth MWCNTs. ► Sb/MCM-41 produced MWCNTs having several internal compartments. ► These MWCNTs may induce the storage capacity in respective fields.Mesoporous Si-MCM-41 molecular sieve was synthesized hydrothermally and different wt.% of Sb (1.0, 2.0, 3.0, 5.0, 10.0, 15.0 and 20.0) was loaded on it by wet impregnation method. The Sb/MCM-41 materials were characterized by various physico-chemical techniques such as XRD, TGA and TEM. The TEM image showed a honeycomb structure of the host material. They were used as catalytic templates for the growth of MWCNTs by CVD method with different temperatures at 700, 800, 900 and 1000°C using acetylene as a carbon precursor. The reaction temperature was optimized for the better formation of MWCNTs and they were purified and then characterized by XRD, SEM, HR-TEM and Raman spectroscopy techniques. The formation of MWCNTs with diameter in the range of 4−6nm was observed from HR-TEM. The good thermal stability and high productivity of catalyst observed in this study revealed that the 2wt.% Sb loaded MCM-41 could be a promising support for the catalytic synthesis of MWCNTs at 800°C by CVD method.

Keywords: Mesoporous material; MCM-41; MWCNT; CVD; Acetylene; Sb/MCM-41

Effect of reaction parameters on the growth of MWCNTs using mesoporous Sb/MCM-41 by chemical vapour deposition by R. Atchudan; A. Pandurangan; K. Subramanian (pp. 1045-1051).

Keywords: Mesoporous material; MCM-41; MWCNT; CVD; Acetylene; Sb/MCM-41

Theoretical study of cisplatin adsorption on silica by S. Simonetti; A. Díaz Compañy; G. Brizuela; A. Juan (pp. 1052-1057).

Display Omitted► We present the main characteristics of the adsorption process showing a possible way for the molecule/fragments adsorption. ► We analyzed the nature of the drug–carrier bonding and the changes observed in the electronic structure upon adsorption. ► We computed the new bondings by the OP and COOP curves. The new interactions are formed at expenses of the OH bonds. ► The more important interactions are the Cl–H and the Pt–O bonds. ► The Cl p, Pt s, p, d orbitals and the H s, O s, p orbitals are the main contribution to the surface bonds.The adsorption of cisplatin and its complexes, cis-[PtCl(NH₃)₂]⁺ and cis-[Pt(NH₃)₂]²⁺, on a SiO₂(111) hydrated surface has been studied by the Atom Superposition and Electron Delocalization method. The adiabatic energy curves for the adsorption of the drug and its products on the delivery system were considered. The electronic structure and bonding analysis were also performed. The molecule–surface interactions are formed at expenses of the OH surface bonds. The more important interactions are the Cl–H bond for cis-[PtCl₂(NH₃)₂] and cis-[PtCl(NH₃)₂]⁺ adsorptions, and the Pt–O interaction for cis-[Pt(NH₃)₂]²⁺ adsorption. The Cl p orbitals and Pt s, p y d orbitals of the molecule and its complexes, and the s H orbital and, the s and p orbitals of the O atoms of the hydrated surface are the main contribution to the surface bonds.

Keywords: Cis; platin; Hydrated silica; Adsorption; Drug delivery

Theoretical study of cisplatin adsorption on silica by S. Simonetti; A. Díaz Compañy; G. Brizuela; A. Juan (pp. 1052-1057).

Keywords: Cis; platin; Hydrated silica; Adsorption; Drug delivery

Broadband antireflection of silicon nanorod arrays prepared by plasma enhanced chemical vapor deposition by Desheng Wang; Zhibo Yang; Fei Li; Dequan Liu; Peng Wang; Deyan He (pp. 1058-1061).

► Hydrogenated nanocrystalline Si nanorod structures were cost-effectively prepared by very high frequency plasma enhanced vapor deposition in combination with an electrodeposition technique. ► The nc-Si:H nanorod structures can be tuned by controlling the configuration of the Ni nanocone substrate. ► The well-separated nanorods show a reflectance value of <5% at normal incident over a wide wavelength of 400–1100nm.Hydrogenated nanocrystalline Si (nc-Si:H) nanorod arrays were cost-effectively prepared on electrodeposited nickel nanocones substrates by very high frequency plasma enhanced vapor deposition. The antireflection properties of the obtained Si nanorod arrays were investigated carefully for the possible application in solar cells. It was found that the structures of nc-Si:H nanorod arrays can be tuned to obtain a very low reflectance especially in the near infrared region. The obtained Si nanostructure with well-separated nanorods, each of which had an average diameter of 200nm and height of 700nm, showed a reflectance value of <5% at normal incident over a wide wavelength of 400–1100nm.

Keywords: Si nanorods; VHF-PECVD; Electrodeposition; Antireflection

Broadband antireflection of silicon nanorod arrays prepared by plasma enhanced chemical vapor deposition by Desheng Wang; Zhibo Yang; Fei Li; Dequan Liu; Peng Wang; Deyan He (pp. 1058-1061).

Keywords: Si nanorods; VHF-PECVD; Electrodeposition; Antireflection

Porous WO₃ from anodized sputtered tungsten thin films for NO₂ detection by Ming Hu; Jing Zeng; Weidan Wang; Huiqing Chen; Yuxiang Qin (pp. 1062-1068).

.Display Omitted► Porous WO₃ gas sensors were prepared by anodization of metallic tungsten films. ► Cracks appeared on the surface after anodization, which makes the films porous. ► The optimal operating temperature for porous WO₃ sensors to NO₂ was 150°C. ► The porous WO₃ showed high response values to different concentration of NO₂ gas. ► The porous WO₃ kept its gas sensing properties to NO₂ even after two weeks.In this paper, porous WO₃ films were prepared by anodic oxidation of metallic tungsten (W) films deposited on alumina substrates. The structural and morphological properties of the porous WO₃ films were investigated using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). A large number of cracks appeared on the surface of films after anodization, which makes the films porous. The porous WO₃ sensors achieved their maximum response values to NO₂ at a low operating temperature of 150°C. The porous WO₃ sensors showed high response values, great stability and fast response–recovery characteristics to different concentration of NO₂ gas due to the high specific surface area and special structural and morphological properties.

Keywords: NO; ₂; detection; Porous tungsten oxide; Anodization; Magnetron sputtering

Porous WO₃ from anodized sputtered tungsten thin films for NO₂ detection by Ming Hu; Jing Zeng; Weidan Wang; Huiqing Chen; Yuxiang Qin (pp. 1062-1068).

Keywords: NO; ₂; detection; Porous tungsten oxide; Anodization; Magnetron sputtering

Preparation of vertically aligned carbon nanotube arrays grown onto carbon fiber fabric and evaluating its wettability on effect of composite by Feng An; Chunxiang Lu; Jinhai Guo; Shuqing He; Huibin Lu; Yu Yang (pp. 1069-1076).

► Aligned carbon nanotubes were uniformly grown onto the carbon fiber fabric. ► The carbon nanotube-grafted carbon fiber shows a great hydrophobicity over 145. ► No obvious mechanical properties of carbon fiber were observed after CNT growth. ► A nearly 110% increase of interfacial shear strength has been identified.Vertically aligned carbon nanotube (CNT) arrays have been grown onto the carbon fiber fabric using a catalytic chemical vapor deposition (CCVD) method. The as-synthesized CNT arrays are about 20μm in height, and the nanotube has a mean inner and outer diameter of 2.6nm, 5.5nm, respectively. The CNT-grafted carbon fabric shows a hydrophobic property with a contact angle over 145°, and the single CNT-grafted carbon fiber shows a sharp increase of dynamic contact angle in de-ionized water from original 71.70° to about 103°, but a little increase does in diiodomethane or E-51 epoxy resin. However, the total surface energy of carbon nanotube-grafted carbon fiber is almost as same as that of as-received carbon fiber. After CNTs growth, single fiber tensile tests indicated a slight tensile strength degradation within 10% for all different lengths of fibers, while the fiber modulus has not been significantly damaged. Compared with the as-received carbon fibers, a nearly 110% increase of interfacial shear strength (IFSS) from 65 to 135MPa has been identified by single fiber pull-out tests for the micro-droplet composite, which is reinforced by as-received carbon fiber or CNT-grafted carbon fiber.

Keywords: Carbon fiber; Carbon nanotube; Surface energy; Wettability; Interfacial shear strength

Surface adhesion properties of graphene and graphene oxide studied by colloid-probe atomic force microscopy by Yan-Huai Ding; Ping Zhang; Hu-Ming Ren; Qin Zhuo; Zhong-Mei Yang; Xu Jiang; Yong Jiang (pp. 1077-1081).

► Surface adhesion properties of graphene and GO nanosheet were measured by colloid-probe AFM. ► Theoretical calculation of adhesion force was performed from water contact angle of graphene and GO. ► The difference of adhesion force can be used to monitor the change of surface properties of GO and graphene.Surface adhesion properties are important to various applications of graphene-based materials. Atomic force microscopy is powerful to study the adhesion properties of samples by measuring the forces on the colloidal sphere tip as it approaches and retracts from the surface. In this paper we have measured the adhesion force between the colloid probe and the surface of graphene (graphene oxide) nanosheet. The results revealed that the adhesion force on graphene and graphene oxide surface were 66.3 and 170.6nN, respectively. It was found the adhesion force was mainly determined by the water meniscus, which was related to the surface contact angle of samples.

Keywords: AFM; Surface adhesion; Graphene oxide; Graphene

Highly selective epoxidation of styrene over mesoporous Au–Ti–SBA-15 via photocatalysis process: Synthesis, characterization, and catalytic application by Yajie Guo; Zhengwang Liu; Guangjian Wang; Yanhog Huang; Fangfang Kang (pp. 1082-1090).

Highly ordered Au-Ti-SBA-15 mesoporous molecular sieves with one-dimensional channels for ca. 5.6 nm pore diameter were successfully synthesized by one-pot hydrothermal synthesis in acid medium. Important factors affecting the catalytic activity of Au-Ti-SBA-15 were explored in more detail. Highly selective epoxidation of styrene with H₂O₂ as the oxidant over Au-Ti-SBA-15 catalyst was performed only for ten minutes under photo-catalysis conditions.Display Omitted► The bifunctional catalyst of Au–Ti–SBA-15 was synthesized by one-pot hydrothermal method. ► Au–Ti–SBA-15 exhibited excellent photocatalytic properties in styrene epoxidation reaction. ► Highly efficient epoxidation was carried out perfectly for 10min with high TOF of 4.75×10³min⁻¹. ► The catalysts can be separated and reused for several times without significant loss in catalytic activity.Highly ordered Au–Ti–SBA-15 mesoporous molecular sieves were successfully synthesized by one-pot hydrothermal synthesis in acid medium, and were characterized by XRD, UV–vis, SEM, element-mapping, HRTEM, N₂ adsorption, XPS,²⁹Si MAS NMR, NH₃-TPD and FT-IR. The as-prepared Au–Ti–SBA-15 samples were possessed of highly ordered mesostructures with larger pore diameter, pore volume and uniform mesopore size distribution. In the oxidation of styrene with H₂O₂ as the oxidant over Au–Ti–SBA-15 catalyst under photo-irradiation, reaction parameters, such as molar ratio of H₂O₂ to styrene, reaction time, solvent, the amount of catalyst, catalyst species, and the amount of 3% NaOH, were conditioned at length. As a result, highly selective epoxidation of styrene over catalyst was carried out perfectly for 10min with high TOF of 4.75×10³min⁻¹.

Keywords: Au–Ti–SBA-15; Surface properties; Photo-catalysis; High selectivity; Epoxidation

Spray pyrolytic deposition of transparent aluminum oxide (Al₂O₃) films by Baban P. Dhonge; Tom Mathews; S. Tripura Sundari; C. Thinaharan; M. Kamruddin; S. Dash; A.K. Tyagi (pp. 1091-1096).

► Transparent thin films of alumina were synthesized by ultrasonic spray pyrolysis. ► The refractive index, film thickness and band gap were measured by ellipsometry and UV–vis spectroscopy. ► The compositional analysis and chemical bonding in the films were done using X-ray photoelectron and FTIR spectroscopy.Optically transparent Al₂O₃ films has been synthesized, on quartz substrates at 500, 600 and 700°C, from 0.02M aluminum acetyl acetonate (Al(acac)₃) in ethanol, by using ultrasonic spray pyrolysis technique. The films synthesized at 500, 600 and 700°C are amorphous having average particle sizes 27±6, 18±3 and 14±3, respectively. The films are found to be 95% optically transparent in the visible region. The optical transparency of the films in the ultraviolet region is found to increase with increase in deposition temperature. The observed increase in optical band gap and decrease in refractive index is attributed to the decrease in particle size with increase in deposition temperature. The stoichiometry and chemical bonding of the amorphous film studied using XPS and FTIR spectroscopy revealed the presence chemisorbed oxygen.

Keywords: Spray pyrolysis; Transparent Al; ₂; O; ₃; thin films; Refractive index and band gap

Spray pyrolytic deposition of transparent aluminum oxide (Al₂O₃) films by Baban P. Dhonge; Tom Mathews; S. Tripura Sundari; C. Thinaharan; M. Kamruddin; S. Dash; A.K. Tyagi (pp. 1091-1096).

Keywords: Spray pyrolysis; Transparent Al; ₂; O; ₃; thin films; Refractive index and band gap

Effects of proton and electron irradiation on the structural and tribological properties of MoS₂/polyimide by Baixing Liu; Xianqiang Pei; Qihua Wang; Xiaojun Sun; Tingmei Wang (pp. 1097-1102).

► The properties of PI composite irradiated by proton and electron have been studied. ► The structural changes of PI composite resulted from irradiation was explored. ► Irradiation decreased the friction coefficient and wear rate of PI composite.To study the structural and tribological properties of MoS₂/polyimide (MoS₂/PI) composite under the irradiation environment of proton and electron, the MoS₂/PI composites were investigated in a ground-based simulation facility, in which the energy of proton and electron was 25keV and the flux was 2.5×10¹⁴cm⁻²s⁻¹. The experimental results revealed that the simplex and combined irradiation of proton and electron induced bond break and cross-link, proton irradiation can break the PI bond easier than electron irradiation and then formed the graphite-like structure at surface area of the samples. Irradiation decreased the friction coefficient and wear rate remarkably of the composites comparing with the pristine one. The wear rate increased with the increasing of the proton and combined radiation time, and decreased with the electron radiation conditions.

Keywords: Polyimide; Proton irradiation; Electron irradiation; Tribological property

Effects of proton and electron irradiation on the structural and tribological properties of MoS₂/polyimide by Baixing Liu; Xianqiang Pei; Qihua Wang; Xiaojun Sun; Tingmei Wang (pp. 1097-1102).

Keywords: Polyimide; Proton irradiation; Electron irradiation; Tribological property

Improvement in micro-structural and mechanical properties of zinc film by surface treatment with low temperature argon plasma by Debadhyan Behera; Dilip K Mishra; Siddhartha K Pradhan; Ramasamy Sakthivel; Swagatika Mohanty (pp. 1103-1108).

Display Omitted► Deposition of Zinc thin film on gold coated borosilicate glass by rf plasma treatment. ► Improvement of crystalline ordering in rf plasma treated films at 200°C. ► Distinct grain growth and grain boundary with the increase in temperature. ► Improvement of the mechanical properties like hardness and Young's modulus.Nanocrystalline zinc films were deposited on gold coated borosilicate glass substrates by thermal evaporation method using zinc powders as the source material and then treated with argon plasma at various temperatures. From X-ray diffraction study, the as-deposited films are found to be metallic Zn and polycrystalline in nature. The crystalline nature improves with the increase of temperature up to 200°C and decreases with the further increase of temperature to 300°C. The binding energy observed for Zn 2p_3/2, and the binding energy separation between Zn 2p_3/2 and Zn 2p_1/2 in the X-ray photoelectron spectrum indicate that the films are metallic zinc films. Transmission electron microscopic study shows hexagonal shaped grains having size ∼58nm upon treatment with Ar plasma. It is clearly shown the grain growth and distinct grain boundary with the increase in temperature. The average Young's modulus ( E) and hardness ( H) are measured to be 84GPa and 4.0GPa for as-deposited film, whereas 98GPa and 5.8GPa for plasma treated film at 200°C. The enhancement in mechanical properties is attributed to improvement in crystalline nature of the film and better interlinking between grains and boundaries.

Keywords: Thermal evaporation; Zn film; Argon plasma treatment; X-ray photoelectron spectroscopy; Nanoindentation

A structured two-dimensional Au–Si alloy by Lin Tang; Fangsen Li; Quanmin Guo (pp. 1109-1114).

We report the formation of an ordered two-dimensional gold–silicon (Au/Si) alloy by deposition of a sub-monolayer of Si onto Au(111). Scanning tunneling microscope (STM) images show that at room temperature the Au/Si alloy consists of parallel rows with row-spacing 0.47nm. These rows appear to float on Au(111) in bundles. Each bundle of rows can bend quite freely forming arches of arbitrary curvature. By annealing to 300°C in ultra-high vacuum, the alloy changes its structure by forming straight rows with row spacing 0.35nm.

Keywords: Si; Au/Si alloy; Au(1; 1; 1); STM; Metallic glass; One-dimensional structures

A structured two-dimensional Au–Si alloy by Lin Tang; Fangsen Li; Quanmin Guo (pp. 1109-1114).

Keywords: Si; Au/Si alloy; Au(1; 1; 1); STM; Metallic glass; One-dimensional structures

Textural and electronic characteristics of mechanochemically activated composites with nanosilica and activated carbon by V.M. Gun’ko; Ya.V. Zaulychnyy; B.I. Ilkiv; V.I. Zarko; Yu.M. Nychiporuk; E.M. Pakhlov; Yu.G. Ptushinskii; R. Leboda; J. Skubiszewska-Zięba (pp. 1115-1125).

. Silica nanoparticles can penetrate into broad pores of activated carbon microparticles.Display Omitted► Characteristics of nanosilica and activated carbon composites depend on a silica type. ► USXE spectra show penetration of silica nanoparticles into broad pores of AC microparticles. ► 3s-electrons of Si atoms are more sensitive to formation of composites than 2p-electrons of O and C.Nanosilicas (A-50, A-300, A-500)/activated carbon (AC, S_BET=1520m²/g) composites were prepared using short-term (5min) mechanochemical activation (MCA) of powder mixtures in a microbreaker. Smaller silica nanoparticles of A-500 (average diameter d_av=5.5nm) can more easily penetrate into broad mesopores and macropores of AC microparticles than larger nanoparticles of A-50 ( d_av=52.4nm) or A-300 ( d_av=8.1nm). After MCA of silica/AC, nanopores of non-broken AC nanoparticles remained accessible for adsorbed N₂ molecules. According to ultra-soft X-ray emission spectra (USXES), MCA of silica/AC caused formation of chemical bonds Si–O–C; however, Si–C and Si–Si bonds were practically not formed. A decrease in intensity of O K_α band in respect to C K_α band of silica/AC composites with diminishing sizes of silica nanoparticles is due to both changes in the surface structure of particles and penetration of a greater number of silica nanoparticles into broad pores of AC microparticles and restriction of penetration depth of exciting electron beam into the AC particles.

Keywords: PACS; 61.43.−j; 67.30.hp; 71.20.−b; 71.23.−k; 73.20.At; 73.63.−bNanosilica; Activated carbon; Nanosilica/AC composites; Mechanochemical activation; USXES; Structural characteristics

Comparison of self-cleaning properties of three titania coatings on float glass by Minna Piispanen; Leena Hupa (pp. 1126-1131).

► Self-cleaning properties of three different TiO₂ coatings on float glass were characterized by a variety of techniques. ► Photocatalytic activation took different times for the three coated surfaces. ► The ability of the surfaces to degrade methylene blue and stearic acid correlated with the water contact angle.This work compares the self-cleaning properties of experimental TiO₂ and TiO₂–Ag coatings on float glass with a commercial self-cleaning glass. In the experimental surfaces, TiO₂ coating was applied to float glass via the sol–gel route, while TiO₂–Ag coating was applied by the liquid flame spray method, which deposits TiO₂–Ag composite nanoparticles on the surface. The effect of the coatings on the surface wettability and the activation time for achieving hydrophilicity was studied through water contact angle as a function of exposure time to UV light. The surface morphology was investigated by using scanning electron microscopy (SEM) and confocal optical microscopy. The photocatalytic activity of the coatings was examined with methylene blue and stearic acid degradation tests. Finally, the soil attachment to the surfaces was tested with a sebum-based model soil. The sol–gel TiO₂ coating became superhydrophilic within a few hours, while the activation time needed for the commercial titania coated glass was several days. The surface with the TiO₂–Ag nanoparticles did not show any marked changes in the water contact angle. The commercial titania coated and the sol–gel TiO₂ surfaces showed self-cleaning properties and clearly lower attachment of soil than the uncoated and TiO₂–Ag coated surfaces. The difference in the interaction of the surfaces with the organic contaminants was assumed to depend mainly on differences in the thickness of the coatings.

Keywords: Titania; Glass; Self-cleaning; Photocatalytic; Hydrophilic

Comparison of self-cleaning properties of three titania coatings on float glass by Minna Piispanen; Leena Hupa (pp. 1126-1131).

Keywords: Titania; Glass; Self-cleaning; Photocatalytic; Hydrophilic

One-step preparation of hierarchical superparamagnetic iron oxide/graphene composites via hydrothermal method by Lulu Ren; Shu Huang; Wei Fan; Tianxi Liu (pp. 1132-1138).

Graphene/magnetite composites with tunable size of Fe₃O₄ nanocrystals or nanocrystal clusters were synthesized via a one-step hydrothermal method. The size of the Fe₃O₄ nanocrystal and nanocrystal clusters can be easily controlled by altering reaction time and the starting mixed solvents ratio, respectively. Furthermore, Fe₃O₄ particles make the composites water-dispersible and can effectively load polyfluorene polyelectrolyte via electrostatic force. High magnetism, strong photoluminescence, and excellent water dispersibility make these composites ideal candidates for various important applications such as drug delivery, bioseparation and magnetic resonance imaging.Display Omitted► Superparamagnetic Fe₃O₄ nanocrystals and their clusters were grown on graphene oxide via a one-pot hydrothermal method. ► Size of the magnetite nanocrystals and nanocrystal clusters can be easily tuned. ► Polyacrylate modified Fe₃O₄ makes graphene–Fe₃O₄ composites water-dispersible. ► Positively charged polyfluorene polyelectrolyte can be adsorbed onto magnetite particles via electrostatic force. ► Polyfluorene endows interesting fluorescent property to graphene–Fe₃O₄ composites.In this paper, graphene/magnetite composites with hierarchical Fe₃O₄ structures were synthesized via a one-step hydrothermal method. The size of Fe₃O₄ nanocrystals and nanocrystal clusters can easily be controlled by altering reaction time and the starting mixed solvent ratio, respectively. Raman measurements evidenced that graphene oxide was simultaneously reduced to graphene during the deposition of magnetite particles. The deposition of Fe₃O₄ nanocrystals and nanocrystal clusters impedes graphene to restore the graphite structure. The composites showed a high crystallinity of magnetite and a considerable saturation magnetization. Furthermore, the acrylate modified Fe₃O₄ makes the composites water-dispersible and can effectively load polyfluorene polyelectrolyte via electrostatic force. The high magnetism, excellent water dispersibility and strong photoluminescence make these composites ideal candidates for various important applications such as magnetic resonance imaging, bioseparation, bioimaging, and optical devices fabrication.

Keywords: Graphene; Superparamagnetic; Iron oxide; Hydrothermal

One-step preparation of hierarchical superparamagnetic iron oxide/graphene composites via hydrothermal method by Lulu Ren; Shu Huang; Wei Fan; Tianxi Liu (pp. 1132-1138).

Keywords: Graphene; Superparamagnetic; Iron oxide; Hydrothermal

Lateral and vertical manipulations of single atoms on the Ag(111) surface with the copper single-atom and trimer-apex tips by Yi-Qun Xie; Tian-Xing Yang; Xiang Ye; Lei Huang (pp. 1139-1143).

► We dealt mainly with the hetero-system, i.e., study the lateral and vertical manipulations of single Ag and Cu atoms on the Ag(111) surface with the Cu single-atom and trimer-apex tips using molecular statics simulations. We find that in a wide tip-height range the reliability of the manipulation can be much better than for a homo-system. ► Secondly, with the Cu trimer-apex tip we show that a reversible vertical manipulation of single Ag atoms on the stepped Ag(111) surface is possible, which suggests a method to modify two-dimensional Ag nanostructures on the Ag(111) surface with the Cu trimer-apex tip. ► These results present a method to improve the reliability of the single-atom manipulation, and how to realize vertical single-atom manipulation on metal surface, which will be useful for the related experiments and the further applications in nanotechnology.We study the lateral and vertical manipulations of single Ag and Cu atoms on the Ag(111) surface with the Cu single-atom and trimer-apex tips using molecular statics simulations. The reliability of the lateral manipulation with the Cu single-atom tip is investigated, and compared with that for the Ag tips. We find that overall the manipulation reliability (MR) increases with the decreasing tip height, and in a wide tip-height range the MR is better than those for both the Ag single-atom and trimer-apex tips. This is due to the stronger attractive force of the Cu tip and its better stability against the interactions with the Ag surface. With the Cu trimer-apex tip, the single Ag and Cu adatoms can be picked up from the flat Ag(111) surface, and moreover a reversible vertical manipulation of single Ag atoms on the stepped Ag(111) surface is possible, suggesting a method to modify two-dimensional Ag nanostructures on the Ag(111) surface with the Cu trimer-apex tip.

Keywords: Single-atom manipulation; Single crystal surface; Adatom; Silver; Copper; Computing simulations

Lateral and vertical manipulations of single atoms on the Ag(111) surface with the copper single-atom and trimer-apex tips by Yi-Qun Xie; Tian-Xing Yang; Xiang Ye; Lei Huang (pp. 1139-1143).

Keywords: Single-atom manipulation; Single crystal surface; Adatom; Silver; Copper; Computing simulations

Fabrication and surface-enhanced Raman scattering (SERS) of Ag/Au bimetallic films on Si substrates by Chaonan Wang; Jinghuai Fang; Yonglong Jin; Mingfei Cheng (pp. 1144-1148).

► Ag films with island and dendritic morphologies were prepared by immersion plating. ► Numerous nano-scaled holes formed in the Ag/Au bimetallic films. ► Compared with Ag films, SERS intensity of bimetallic films enhanced significantly.Ag films on Si substrates were fabricated by immersion plating and served as sacrificial materials for preparation of Ag/Au bimetallic films by galvanic replacement reaction. The formation procedure of films on the surface of Si was studied by scanning electron microscopy (SEM), which revealed Ag films with island and dendritic morphologies experienced novel structural evolution process during galvanic replacement reaction, and nanostructures with holes were produced within the resultant Ag/Au bimetallic films. SERS activity both of sacrificial Ag films and resultant Ag/Au bimetallic films was investigated by using crystal violet as an analyte. It has been shown that SERS signals increased with the process of galvanic substitution and reached intensity significantly stronger than that obtained from pure Ag films.

Keywords: Surface-enhanced Raman scattering (SERS); Bimetallic; Nanostructure; Galvanic replacement

Fabrication and surface-enhanced Raman scattering (SERS) of Ag/Au bimetallic films on Si substrates by Chaonan Wang; Jinghuai Fang; Yonglong Jin; Mingfei Cheng (pp. 1144-1148).

Keywords: Surface-enhanced Raman scattering (SERS); Bimetallic; Nanostructure; Galvanic replacement

Cu-doped SiO_xC_y nanostructures induced by radio frequency plasma jet using hexamethyldisiloxane by B. Ke; M.D. Chen; F. Ding; S.J. Zheng; H. Li; X.D. Zhu (pp. 1149-1152).

► Cu-doped SiO_xC_y nanostructures were fabricated using radio frequency hexamethyldisiloxane (HMDSO)/H₂/Ar plasma jet. ► Tree-like nanostructures with spherical structures on sidewalls of nanowires were obtained at low concentration of HMDSO with vertical gas flow. ► Acaleph-like nanostructures were synthesized while a radio frequency bias was applied to the substrate.Formation of Cu-doped SiO_xC_y nanostructures has been studied by using hexamethyldisiloxane (HMDSO)/H₂/Ar radio frequency (RF) plasma, where a copper tube was utilized as power electrode to generate plasma jet. Tree-like nanostructures were obtained at low concentration of HMDSO. One can find the initial vertical growth of nanowires (NWs) and the spherical structures on sidewalls of the bended NWs, which were attributed to the vertical gas flow and secondary catalyzing due to copper from the ambience, respectively. However, the fragments with big mass were too many to synthesize nanostructure at high concentration of HMDSO. More Cu particles were transported to the substrate while an RF bias was applied to the substrate, which restrained the NWs growth catalyzed by Au and resulted in the formation of acaleph-like nanostructures.

Keywords: Cu-doped SiO; _x; C; _y; nanostructure; Radio frequency; Plasma jet

Cu-doped SiO_xC_y nanostructures induced by radio frequency plasma jet using hexamethyldisiloxane by B. Ke; M.D. Chen; F. Ding; S.J. Zheng; H. Li; X.D. Zhu (pp. 1149-1152).

Keywords: Cu-doped SiO; _x; C; _y; nanostructure; Radio frequency; Plasma jet

Direct-current electrodeposition and characterization of Ni₅Sb₂ nanowires array by Fei Liu; You-wen Yang; Yan-biao Chen; Tian-ying Li; Ming-guang Kong (pp. 1153-1156).

► Ni₅Sb₂ nanowires array was fabricated into AAM by DC electrodepostion. ► We discuss the influences of Sb content and the voltage value on the Ni–Sb alloy. ► The as-synthesized alloy grows highly along the [022] orientation. ► The resultant alloy is of a monoclinic structure.The fabrication of monocrystalline Ni₅Sb₂ nanowires array into porous anodic alumina membranes by using direct-current potentiostatic electrodeposition technique has been firstly reported. In this paper, the focus is on the effects of Sb content and the co-deposition voltage on the resultant. It was found that Ni₅Sb₂ nanowires array with a monoclinic structure could be successfully synthesized by regulating these two parameters. The analysis results displayed that the Ni₅Sb₂ nanowires array was highly filled and ordered, as well as around 80nm in diameter. Structure analysis indicated that the as-deposited nanowires had a highly preferential orientation grown along [022] direction.

Keywords: Electrodeposition; Ni; ₅; Sb; ₂; Nanowires; Intermetallics

Direct-current electrodeposition and characterization of Ni₅Sb₂ nanowires array by Fei Liu; You-wen Yang; Yan-biao Chen; Tian-ying Li; Ming-guang Kong (pp. 1153-1156).

Keywords: Electrodeposition; Ni; ₅; Sb; ₂; Nanowires; Intermetallics

The influences of plasma ion bombarded on crystallization, electrical and mechanical properties of Zn–In–Sn–O films by K.J. Chen; F.Y. Hung; S.J. Chang; J.D. Liao; C.C. Weng; Z.S. Hu (pp. 1157-1163).

► The quality of Zn–In–Sn–O (ZITO) films were adjusted by different gas (oxygen and argon) induced plasma ions bombarding (PIB) treatment. ► The contributions of PIB treatment on the structure, optoelectronic properties of ZITO film have been clearly defined. ► Briefly, PIB treatment can easily adjust the film quality in short time. ► Additionally, the film toughness not only was improved but also enhanced the structural stability by PIB treatment that was good for TCO film application in the flexible substrate.The quality of co-sputtering derived Zn–In–Sn–O (ZITO) film was adjusted by different gas (oxygen and argon) induced plasma ions bombarding (PIB) treatment. The result showed that the film conductivity could be improved after plasma bombardment. The increment of oxygen vacancies and plasma bombard-induced thermal energy were main reasons. Notably, the efficiency of Ar plasma bombarded for improved conductivity not only was better but also had a smoother surface morphology. Due to Ar ions will not react with metal atoms to form oxide and possessed a higher momentum. In addition, the O-rich layer on the ultra-surface not only was removed but also enhanced film reliability by plasma bombarded that could enhance the performance of optoelectronic devices.

Keywords: Co-sputtering; ZITO; Plasma ions bombarded (PIB); Toughness

Comparative study of titanium carbide and nitride coatings grown by cathodic vacuum arc technique by D.M. Devia; E. Restrepo-Parra; P.J. Arango (pp. 1164-1174).

► The TiN/TiC bilayer presents a strong interdiffusion at the interface. ► Substrate temperature has strong influence on structural, compositional and morphological properties of TiN, TiC and TiN/TiC. ► The TiN/TiC bilayer shows higher wear resistance than each monolayer.Titanium nitride (TiN), titanium carbide (TiC) thin films and TiC/TiN bilayers have been deposited on AISI 304 stainless steel substrates by plasma assisted physical vapor deposition technique—reactive pulsed vacuum arc method. The coatings were characterized in terms of crystalline structure, microstructure and chemical nature by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Tribological behavior was investigated using ball on disc technique. The average coefficient of friction was measured, showing lower values for the TiN/TiC bilayer. Dynamic wear curves were performed for each coating, observing a better wear resistance for TiN/TiC bilayers, compared to TiN and TiC monolayers. On the other hand, the TiCN formation in the TiN/TiC bilayer was observed, being attributed to the interdiffusion between TiN and TiC at the interface. Moreover, the substrate temperature influence was analysing observing a good behavior at T_S=115°C.

Keywords: Thin films; Pulsed arc; XPS; XRD; Wear; Bilayer; Tribology

Comparative study of titanium carbide and nitride coatings grown by cathodic vacuum arc technique by D.M. Devia; E. Restrepo-Parra; P.J. Arango (pp. 1164-1174).

Keywords: Thin films; Pulsed arc; XPS; XRD; Wear; Bilayer; Tribology

Periodic patterning of silicon by direct nanosecond laser interference ablation by T. Tavera; N. Pérez; A. Rodríguez; P. Yurrita; S.M. Olaizola; E. Castaño (pp. 1175-1180).

► Silicon solar grade wafers are processed to decrease their reflectivity. ► Direct ablation by laser interference is used as the structuring technique. ► Three different structures obtained: periodical bumps, nanoripples, microripples. ► Silicon reflectance diminishes probably due to the presence of nanoripples.The production of periodic structures in silicon wafers by four-beam is presented. Because laser interference ablation is a single-step and cost-effective process, there is a great technological interest in the fabrication of these structures for their use as antireflection surfaces. Three different laser fluences are used to modify the silicon surface (0.8Jcm⁻², 1.3Jcm⁻², 2.0Jcm⁻²) creating bumps in the rim of the irradiated area. Laser induced periodic surface structures (LIPSS), in particular micro and nano-ripples, are also observed. Measurements of the reflectivity show a decrease in the reflectance for the samples processed with a laser fluence of 2.0Jcm⁻², probably caused by the appearance of the nano-ripples in the structured area, while bumps start to deteriorate.

Keywords: Silicon; Laser ablation; Nanostructuring; Interference; Solar cells

Periodic patterning of silicon by direct nanosecond laser interference ablation by T. Tavera; N. Pérez; A. Rodríguez; P. Yurrita; S.M. Olaizola; E. Castaño (pp. 1175-1180).

Keywords: Silicon; Laser ablation; Nanostructuring; Interference; Solar cells

Modification of ferroelectric hysteresis in Pb(Nb,Zr,Ti)O₃ thin films induced by CO₂ adsorption by E. Ramos-Moore; D. Lederman; A.L. Cabrera (pp. 1181-1183).

► Manipulation of ferroelectric domains motivates exploration of surface reactivity. ► In situ ferroelectric characterization was performed in UHV under CO₂ dosage. ► Molecular adsorption on the top electrode was detected by AES. ► Remnant polarization shifted after different voltages were applied during dosing. ► Depolarizing field induced by molecular adsorption may lead to high-sensitivity of gas detection.We report on the modification of ferroelectric hysteresis in Pb(Nb,Zr,Ti)O₃ thin films under the adsorption of CO₂ gas. The samples were exposed to the gas in ultra high vacuum while different voltages between the top (Ag) and bottom (Pt) electrodes were applied. After dosing, the samples were heated from room temperature at 1.8K/s, and a mass spectrometer was used to detect the desorbed molecules. The effective molecular sticking was demonstrated by the appearance of the carbon Auger peak in the surface of the sample and by the presence of CO₂ in the desorption curves. After +(−) 9.9V were applied to the bottom electrode during dosing, we found a shift of −0.52 (+0.58)μC/cm² in the remnant polarization. These evidences suggest the existence of a depolarizing field induced by molecular adsorption at the surface of the top electrode, and contribute to highlight the potential use of ferroelectric thin films as gas sensors.

Keywords: Ferroelectric thin films; Carbon dioxide adsorption; Pb(Nb,Zr,Ti)O3; Gas sensing

Modification of ferroelectric hysteresis in Pb(Nb,Zr,Ti)O₃ thin films induced by CO₂ adsorption by E. Ramos-Moore; D. Lederman; A.L. Cabrera (pp. 1181-1183).

Keywords: Ferroelectric thin films; Carbon dioxide adsorption; Pb(Nb,Zr,Ti)O3; Gas sensing

Preparation of UV curing crosslinked polyviologen film and its photochromic and electrochromic performances by Li-ping Gao; Guo-jing Ding; Yue-chuan Wang; Yu-lin Yang (pp. 1184-1191).

Polyether urethane diacrylate matrix (PEUDA) and acrylate-functional viologen (ACV²⁺) were successfully synthesized and characterized in detail by FTIR and¹H NMR spectra, respectively. Subsequently, they were used to prepare UV curing crosslinked polyviologen film in combination with 2-hydroxyethyl methacrylate (HEMA), trimethylolpropane ethoxylate triacrylate (TMPTA) and diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide (TPO). UV curing approach confined the polyviologen film on ITO electrode, which imparted the film excellent adhesion ability to ITO glass, good solvent resistance, excellent chemical stability, excellent optical and electrochemical properties. The crosslinked PACV²⁺ film exhibited excellent photochromic and electrochromic performances. After UV illumination for 60s, the crosslinked PACV²⁺ film can swiftly change its color from pale yellow to deep blue, while the optical transmission of crosslinked PACV²⁺ film at 610nm did not change significantly and still retained about 63.6% after 30 cycles. Simultaneously, the cyclic voltammetry experiment showed the PACV²⁺ film can undergo repeatable electrochemical redox reactions with good reversibility beyond the 10th scan. Furthermore, the electrochromic device composed of the PACV²⁺ film and gel electrolyte film can undergo reversible color change in response to the external voltages of −2.0V and 2.0V, respectively, while the contrast of EC device at 610nm did not change significantly and still retained about 39.5% after 10 cycles. This UV curing approach to preparing viologen-functional film offers a method to preparing large-scale photo- and electrochromic device, which is relatively simple, high productivity, energy saving, and environmental protection.

Keywords: UV curing crosslinked; Polyviologen; Photochromism; Electrochromism

Preparation of UV curing crosslinked polyviologen film and its photochromic and electrochromic performances by Li-ping Gao; Guo-jing Ding; Yue-chuan Wang; Yu-lin Yang (pp. 1184-1191).

Keywords: UV curing crosslinked; Polyviologen; Photochromism; Electrochromism

Theoretical studies of arsenite adsorption and its oxidation mechanism on a perfect TiO₂ anatase (101) surface by Zhigang Wei; Shaowen Zhang; Zhanchang Pan; Yue Liu (pp. 1192-1198).

There are many areas in the world where the ground water has been contaminated by arsenic. TiO₂ is one of the most promising materials that can remove arsenic from groundwater supplies by the adsorption-based processes. The TiO₂ surface is capable of photo-catalytic oxidation (PCO) changing the arsenite [As(III)] to arsenate [As(V)] which is more easily absorbed by the surface, increasing the efficiency of the process. In this paper, a density functional theory calculation has been performed to investigate the adsorption of As(III) on a perfect TiO₂ anatase (1 0 1) surface. All the As(III) solution species such as H₃AsO₃, H₂AsO₃⁻, HAsO₃²⁻ and AsO₃³⁻ are put onto the surface with many different possible attitudes to obtain the adsorption energy. Based on the adsorption energy and the concentration of H₃AsO₃, H₂AsO₃⁻, HAsO₃²⁻ and AsO₃³⁻ in an aqueous solution, the bidentate binuclear (BB) adsorption configurations of H₂AsO₃⁻ on the surface are more favorable at low As(III) concentrations, whereas BB form and monodentate mononuclear (MM) form may coexist at higher concentrations. By calculating H₂AsO₃⁻ co-adsorption with water and oxygen, we can confirm the deep acceptor character of an adsorbed O₂ molecule which implies that surface superoxide (or hydroperoxyl radical) plays an important role during the PCO process of As(III) on TiO₂ surface.

Keywords: Arsenite; TiO; ₂; Density functional theory; Adsorption; Absorption

Theoretical studies of arsenite adsorption and its oxidation mechanism on a perfect TiO₂ anatase (101) surface by Zhigang Wei; Shaowen Zhang; Zhanchang Pan; Yue Liu (pp. 1192-1198).

Keywords: Arsenite; TiO; ₂; Density functional theory; Adsorption; Absorption

TiO₂/polyaniline nanocomposite films prepared by magnetron sputtering combined with plasma polymerization process by Arup R Pal; Bimal K. Sarma; Nirab C. Adhikary; Joyanti Chutia; Heremba Bailung (pp. 1199-1205).

► We prepare TiO₂/polyaniline films by sputtering combined with plasma polymerization. ► Rutile-TiO₂/polyaniline composite film of crystallite size 3.6nm is reported. ► Colorless composite having small crystallite size is useful as antistatic coating. ► Nanocomposite shows improvement of conductivity compared to polyaniline and TiO₂.Radiofrequency plasma polymerization in combination with direct current reactive magnetron sputtering is utilized for the synthesis of TiO₂/plasma polymerized aniline nanocomposite thin films. In the composite film, X-ray diffraction measurements reveal formation of nanocrystalline rutile TiO₂ of crystallite size 3.6nm. Due to continuous bombardment of plasma species during simultaneous magnetron sputtering and plasma polymerization, the precursors of polymerization are broken and few functional groups are retained in the composite film. The plasma polymerized aniline has the direct optical band gap of 3.55eV and the nanocrystalline rutile TiO₂ is wide gap semiconductor with indirect gap of 3.20eV which suggests the existence of an energy barrier at the interface in the composite form. The ac conductivity of composite film shows significant improvement as compared to plasma polymerized aniline film and sputtered rutile TiO₂ film. The composite film may find potential application as antistatic coatings.

Keywords: TiO; ₂; /polyaniline nanocomposite; Plasma polymerization; Magnetron sputtering; Intermetallic dielectrics; Antistatic coating

Influence of high temperature annealing on the structure, hardness and tribological properties of diamond-like carbon and TiAlSiCN nanocomposite coatings by Z.W. Xie; L.P. Wang; X.F. Wang; L. Huang; Y. Lu; J.C. Yan (pp. 1206-1211).

► Annealing at 800°C does not change the chemical states of Ti, Si and Al. ► Graphitization of DLC evolves quickly as the annealing temperature exceeds 400°C. ► Graphitization of DLC reduces the hardness of the DLC–TiAlSiN nanocomposite coating.Diamond-like carbon (DLC) and TiAlSiCN nanocomposite coatings were synthesized and annealed at different temperatures in a vacuum environment. The microstructure, hardness and tribological properties of as-deposited and annealed DLC–TiAlSiCN nanocomposite coatings were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, nano-indentation and friction tests. The TEM results reveal that the as-deposited DLC–TiAlSiCN coating has a unique nanocomposite structure consisting of TiCN nanocrystals embedded in an amorphous matrix consisting of a-Si₃N₄, a-SiC, a-CN and DLC, and the structure changed little after annealing at 800°C. However, XPS and Raman results show that an obvious graphitization of the DLC phase occurred during the annealing process and it worsened with annealing temperature. Because of the graphitization, the hardness of the DLC–TiAlSiCN coating after annealing at 800°C decreased from 45 to 36GPa. In addition, the DLC–TiAlSiCN coating after annealing at 800°C has a similar friction coefficient to the as-deposited coating.

Keywords: Diamond-like carbon; TiAlSiCN; Nanocomposite; Annealing; Structure; Hardness

Pre-hydrolysed ethyl silicate as an alternative precursor for SiO₂-coated carbon nanofibers by M.I. Barrena; J.M. Gómez de Salazar; A. Soria; L. Matesanz (pp. 1212-1216).

► SiO2-coated CNFs were obtained using two sol-gel precursors. ► TEOS and pre-hydrolysed ethylsilicate can coat the CNF effectively. ► Pre-hydrolysed has faster gelation times and higher surface than TEOS. ► The use of pre-hydrolysed can be considered an alternative to TEOS.This work reported basically aims at understanding the extent of SiO₂-coated carbon nanofibers using two different sol–gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO₂ precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

Keywords: Carbon nanofibers; Sol–gel process; SiO; ₂; -coating; Pre-hydrolysed ethyl silicate

Pre-hydrolysed ethyl silicate as an alternative precursor for SiO₂-coated carbon nanofibers by M.I. Barrena; J.M. Gómez de Salazar; A. Soria; L. Matesanz (pp. 1212-1216).

Keywords: Carbon nanofibers; Sol–gel process; SiO; ₂; -coating; Pre-hydrolysed ethyl silicate

Preparation of monodisperse polystyrene/silica core–shell nano-composite abrasive with controllable size and its chemical mechanical polishing performance on copper by Lei Zhang; Haibo Wang; Zefang Zhang; Fei Qin; Weili Liu; Zhitang Song (pp. 1217-1224).

► A novel silica-coated polystyrene nano-composite abrasive for copper chemical mechanical polishing applications was prepared. ► The slurry containing polystyrene/SiO₂ composite abrasive exhibited better surface quality than that containing silica. ► The composite abrasive exhibited little higher material removal rate than traditional silica abrasive.Monodisperse silica-coated polystyrene (PS) nano-composite abrasives with controllable size were prepared via a two-step process. Monodisperse positively charged PS colloids were synthesized via polymerization of styrene by using a cationic initiator. In the subsequent coating process, silica formed shell on the surfaces of core PS particles via the ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane. Neither centrifugation/water wash/redispersion cycle process nor surface modification or addition surfactant was needed in the whole process. The morphology of the abrasives was characterized by scanning electron microscope. Transmission electron microscope and energy dispersive X-ray analysis results indicated that silica layer was successfully coated onto the surfaces of PS particles. Composite abrasive has a core–shell structure and smooth surface. The chemical mechanical polishing performances of the composite abrasive and conventional colloidal silica abrasive on blanket copper wafers were investigated. The root mean square roughness decreases from 4.27nm to 0.56nm using composite abrasive. The PS/SiO₂ core–shell composite abrasives exhibited little higher material removal rate than silica abrasives.

Keywords: PS/SiO; ₂; Core–shell; Nano-composite abrasive; Copper; Chemical mechanical polishing

An investigation on erosion behavior of HVOF sprayed WC–CoCr coatings by Lalit Thakur; N. Arora; R. Jayaganthan; R. Sood (pp. 1225-1234).

► HVOF sprayed WC–CoCr cermet coatings were deposited with different WC grain size. ► An in-flight particle temperature and velocity measurement system was used. ► Erosion testing was performed using pot-type slurry erosion tester. ► Microstructural analysis had shown the different wear mechanisms. ► Fine WC grain coating exhibits high hardness and better slurry erosion resistance.Present work is an investigation of slurry erosion behavior of WC–CoCr cermet coatings deposited with two different WC grain sizes. HVOF thermal spray process was employed due to its high velocity and low flame temperature characteristics resulting in quality coating. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control its heating. Slurry erosion testing was performed using a pot-type slurry erosion tester to evaluate slurry erosion resistance of the coatings. Two parameters were considered for testing viz. erodent particle size and slurry concentration. Surface morphology was examined using SEM images and phase identification was done by XRD. The erosion behavior and mechanism of material removal was studied and discussed based on microstructural examination. It was observed that WC–CoCr cermet coating deposited with fine grain WC exhibits higher slurry erosion resistance under all testing conditions as compared to conventional cermet coating.

Keywords: WC–CoCr; HVOF; Cermet; Slurry erosion; Nanostructured

An investigation on erosion behavior of HVOF sprayed WC–CoCr coatings by Lalit Thakur; N. Arora; R. Jayaganthan; R. Sood (pp. 1225-1234).

Keywords: WC–CoCr; HVOF; Cermet; Slurry erosion; Nanostructured

Initial oxidation of brass induced by humidified air by Ping Qiu; Christofer Leygraf (pp. 1235-1241).

► Microstructure of brass (Cu–20Zn) surface results in Volta potential variations. ► They cause a duplex oxide growth during exposure of brass to humidified air. ► Initial accelerated growth of Zn to ZnO and retarded growth of Cu to Cu₂O. ► Improved protective properties of the duplex oxide than of the oxides on Cu or Zn. ► A schematic model for the duplex oxide growth on brass is presented.Complementary surface and near-surface analytical techniques have been used to explore a brass (Cu–20Zn) surface before, during, and after exposure in air at 90% relative humidity. Volta potential variations along the unexposed surface are attributed to variations in surface composition and resulted in an accelerated localized growth of ZnO and a retarded more uniform growth of an amorphous Cu₂O-like oxide. After 3 days the duplex oxide has a total mass of 1.3μg/cm², with improved corrosion protective properties compared to the oxides grown on pure Cu or Zn. A schematic model for the duplex oxide growth on brass is presented.

Keywords: Atmospheric corrosion; Brass (Cu–20Zn); Humid air; Surface analysis; Cu; ₂; O; ZnO

Initial oxidation of brass induced by humidified air by Ping Qiu; Christofer Leygraf (pp. 1235-1241).

Keywords: Atmospheric corrosion; Brass (Cu–20Zn); Humid air; Surface analysis; Cu; ₂; O; ZnO

Effect of the duty ratio on the indium tin oxide (ITO) film deposited by in-line pulsed DC magnetron sputtering method for resistive touch panel by Min Hyung Ahn; Eou-Sik Cho; Sang Jik Kwon (pp. 1242-1248).

► The ITO film was deposited on PET using in-line pulsed DC magnetron sputtering system. ► The reverse time and the frequency of pulsed DC were used to change duty ratios. ► The optimal ITO/PET film was obtained when the duty ratio was about 80%.The indium tin oxide (ITO) film was deposited on PET (polyethylene terephthalate) film using in-line pulsed DC magnetron sputtering system with different duty ratios. The reverse time and the frequency of pulsed DC power were changed to obtain the different duty ratios. From the electrical and optical properties such as the sheet resistance, resistivity, thickness and transmittance, the pulsed DC sputtered ITO/PET films were also superior to the DC sputtered ITO/PET films. The reverse time had little effect on the properties of the ITO/PET film and the frequency of pulsed DC power had an immerse effect on the properties of the ITO/PET films. The optimal ITO/PET film was obtained when the frequency was 200kHz, the reverse time was 1μs, and the duty ratio was about 80%.

Keywords: Reverse time; Frequency; Pulsed DC sputtering; Indium tin oxide (ITO); Duty ratio

Preparation of visible light responsive N doped TiO₂ via a reduction–nitridation procedure by nonthermal plasma treatment by Shaozheng Hu; Fayun Li; Zhiping Fan (pp. 1249-1255).

TiO₂ samples (TOHN x) prepared by reduction–nitridation procedure showed much higher photocatalytic activities than that of samples (TON x) prepared by simple nitridation treatment under visible light.Display Omitted► N-doped TiO₂ was prepared via a reduction–nitridation procedure by nonthermal plasma treatment. ► Reduction–nitridation procedure led to the more favorable formation of the substitutional N-doping. ► The photocatalytic activities of TOHN x were much higher than that of TON x samples under visible light. ► The sample prepared by reduction–nitridation procedure exhibited better photocatalytic stability.A visible light responsive N-doped TiO₂ was prepared via a reduction–nitridation procedure by nonthermal plasma treatment. X-ray diffraction, N₂ adsorption, UV–vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared TiO₂ samples. The plasma treatment did not change the phase composition and particle sizes of TiO₂ samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of TiO₂ prepared by reduction–nitridation procedure were much higher than that of samples prepared by simple nitridation treatment. The enhanced activity was ascribed to the substitutional N-doping and appropriate concentration of oxygen vacancies. TOHN10 prepared by reduction–nitridation procedure exhibited excellent photocatalytic stability. A possible mechanism for the photocatalysis was proposed.

Keywords: Plasma; N-doping; TiO; ₂; Photocatalysis; Visible light

Preparation of visible light responsive N doped TiO₂ via a reduction–nitridation procedure by nonthermal plasma treatment by Shaozheng Hu; Fayun Li; Zhiping Fan (pp. 1249-1255).

Keywords: Plasma; N-doping; TiO; ₂; Photocatalysis; Visible light

Enhanced dielectric permittivity in poly (vinylidene) fluoride/multiwalled carbon nanotubes nanocomposite thin films fabricated by pulsed laser deposition by Chetan Chanmal; Meenal Deo; Jyoti Jog (pp. 1256-1260).

► Pulsed laser deposition of thin film PVDF/MWCNT nanocomposites. ► Remarkable increase in dielectric permittivity at lower dielectric losses. ► Films show higher percolation threshold with lower conductivity. ► Enhancement of ferroelectric phase in PVDF/MWCNT nanocomposites.The fabrication of high quality thin films of poly (vinylidene fluoride) embedded with multiwalled carbon nanotubes using pulsed laser deposition technique is reported. The prepared films were characterized for structural, morphology and dielectric properties. The morphology analysis revealed uniform dispersion of multiwalled carbon nanotubes throughout the polymer matrix. X-ray diffraction results suggested that the poly (vinylidene fluoride) film is in amorphous phase while addition of multiwalled carbon nanotubes showed presence of crystalline peaks in the nanocomposites films. It was interesting to note that the nanocomposite films exhibits significant enhancement of the ferroelectric β-phase as evidenced by the X-ray diffraction and Fourier transform infrared spectroscopy results. The dielectric analysis shows a remarkable enhancement in the dielectric permittivity of nanocomposites with lower loss and conductivity level. The results can be attributed to the formation of minicapacitor network and relatively higher percolation threshold in the nanocomposites.

Keywords: Percolation threshold; Dielectric permittivity; Ferroelectric polymer; Pulsed laser deposition; Thin films

Effects of post-annealing on the structural and nanomechanical properties of Ga-doped ZnO thin films deposited on glass substrate by rf-magnetron sputtering by Szu-Ko Wang; Ting-Chun Lin; Sheng-Rui Jian; Jenh-Yih Juang; Jason S.-C. Jang; Jiun-Yi Tseng (pp. 1261-1266).

► ZnO:Ga films are deposited on glass substrates by rf-magnetron sputtering. ► ZnO:Ga films are annealed at 300°C, 400°C and 500°C. ► XRD shows that the annealed ZnO:Ga films had a predominant (002) orientation. ► Hardness and Young's modulus of all ZnO:Ga films are measured by nanoindentation.In this study, the effects of post-annealing on the structure, surface morphology and nanomechanical properties of ZnO thin films doped with a nominal concentration of 3at.% Ga (ZnO:Ga) are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) and nanoindentation techniques. The ZnO:Ga thin films were deposited on the glass substrates at room temperature by radio frequency magnetron sputtering. Results revealed that the as-deposited ZnO:Ga thin films were polycrystalline albeit the low deposition temperature. Post-annealing carried out at 300, 400 and 500°C, respectively, has resulted in progressive increase in both the average grain size and the surface roughness of the ZnO:Ga thin film, in addition to the improved thin films crystallinity. Moreover, the hardness and Young's modulus of ZnO:Ga thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The hardness and Young's modulus of ZnO:Ga thin films increased as the annealing temperature increased from 300 to 500°C, with the best results being obtained at 500°C.

Keywords: ZnO:Ga thin films; XRD; AFM; Nanoindentation; Hardness

Structural and optical properties of GaN thin films grown on Al₂O₃ substrates by MOCVD at different reactor pressures by A. Guillén-Cervantes; Z. Rivera-Álvarez; M. López-López; A. Ponce-Pedraza; C. Guarneros; V.M. Sánchez-Reséndiz (pp. 1267-1271).

► Surface voids and spirals were imaged by field-emission SEM on GaN/Al₂O₃ films. ► Such defects strongly affect the PL response. ► An optimum MOCVD reactor pressure avoids surface defects and improves the GaN optical and structural properties.GaN thin films grown by MOCVD on (0001) Al₂O₃ substrates at different growth pressures were characterized by field-emission scanning electron microscopy, atomic force microscopy, micro-Raman, and photoluminescence at room temperature. It was found that there is an optimum pressure of 76Torr at which the structural and optical properties of the GaN samples are superior. On the other hand samples grown at higher pressure exhibited hexagonal surface pits and surface spirals. The results showed that the growth pressure strongly influences the morphology, and significantly affects the structural and optical properties of the GaN epilayers.

Keywords: MOCVD; Field-emission SEM; Hexagonal-shaped pits; Surface spirals; Photoluminescence

Surface adhesion and demolding force dependence on resist composition in ultraviolet nanoimprint lithography by Alborz Amirsadeghi; Jae Jong Lee; Sunggook Park (pp. 1272-1278).

► Two similar UV curable oligomers with only different chain lengths were used. ► Oligomers were mixed with various amounts of cross-linking agent. ► Decreasing the cross-linking agent content lowers the Young's modulus of the resist. ► A lower Young's modulus results in a lower surface adhesion force. ► Young's modulus and surface adhesion dependence on the cross-linking agent content is stronger when a longer chained oligomer was used.Demolding, the process to separate stamp from molded resist, is most critical to the success of ultraviolet nanoimprint lithography (UV-NIL). In the present study we investigated adhesion and demolding force in UV-NIL for different compositions of a model UV-curable resist system containing a base (either tripropyleneglycol diacrylate with shorter oligomer length or polypropyleneglycol diacrylate with longer oligomer length), a cross-linking agent (trimethylolpropane triacrylate) and a photoinitiator (Irgacure 651). The demolding force was measured using a tensile test machine with homemade fixtures after imprinting the UV resist on a silicon stamp. While decreasing the cross-linking agent content from 49 to 0wt% has little effect on the resist surface energy, it reduces the resist's elastic modulus drastically. The decrease in elastic modulus results in a decreased adhesion force at the resist/stamp interface thereby facilitating the demolding. The decrease in elastic modulus and, therefore, demolding force by lowering the cross-linking agent content was markedly less pronounced in tripropyleneglycol diacrylate-based resists due to its shorter oligomer length. These general findings will be useful in designing new resists for UV-NIL process.

Keywords: UV nanoimprint lithography; Demolding force; Adhesion force; Young's modulus; Surface energy

Surface adhesion and demolding force dependence on resist composition in ultraviolet nanoimprint lithography by Alborz Amirsadeghi; Jae Jong Lee; Sunggook Park (pp. 1272-1278).

Keywords: UV nanoimprint lithography; Demolding force; Adhesion force; Young's modulus; Surface energy

Effect of C60 ion sputtering on the compositional depth profiling in XPS for Li(Ni,Co,Mn)O₂ electrodes by Li-Shin Chang; Yi-Chun Lin; Ching-Yi Su; Hung-Chun Wu; Jing-Pin Pan (pp. 1279-1281).

The performance of a Li-ion cell strongly depends on the solid-electrolyte interface (SEI) on electrodes. The depth distribution of composition in SEI is normally determined by means of X-ray Photoelectron Spectroscopy (XPS) via Ar ion sputtering. Recently, a new kind of ion gun using C60 ions as sputtering source was introduced. In this report, a comparison between the effects of these two kinds of ion guns on the quantification of Li(Ni,Co,Mn)O₂ electrodes was made. It was found that the C60 ion gun is more suitable for analyzing the composition and chemical state of Li(Ni,Co,Mn)O₂ electrode since that it causes lower chemical damage in the superficial layer.

Keywords: XPS; Depth profile; Ion sputtering; C60; Li(Ni,Co,Mn)O; ₂

Effect of C60 ion sputtering on the compositional depth profiling in XPS for Li(Ni,Co,Mn)O₂ electrodes by Li-Shin Chang; Yi-Chun Lin; Ching-Yi Su; Hung-Chun Wu; Jing-Pin Pan (pp. 1279-1281).

Keywords: XPS; Depth profile; Ion sputtering; C60; Li(Ni,Co,Mn)O; ₂

Sections

Personal tools

Applied Surface Science (v.258, #3)

Sections

Personal tools

Local resources

Applied Surface Science (v.258, #3)