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Applied Surface Science (v.258, #10)

Spectroscopic and capacitance–voltage characterization of thin aminopropylmethoxysilane films doped with copper phthalocyanine, tris(dimethylvinylsilyloxy)–POSS and fullerene cages by Jolanta Klocek; Karsten Henkel; Krzysztof Kolanek; Ehrenfried Zschech; Dieter Schmeißer (pp. 4213-4221).

► The combination of the XPS and CV techniques. ► The incorporation of POSS within the APTMS based material increases the surface resistance against the ambient influence. ► The application of POSS and CuPc dopants allowed to decrease the composite dielectric constant to 1.8. ► CuPc molecules decrease the hysteresis inside the CV measurements of the composite film.We report on studies about novel 3-aminopropyltrimethoxysilane (APTMS) based hybrid composites doped by copper phthalocyanine (CuPc), [6,6]-phenyl-C₆₁-butyric acid methyl ester and tris(dimethylvinylsilyloxy)–POSS (POSS). APTMS was used as siloxane matrix in order to produce thin layers of composite materials spin-coated onto silicon. The surface chemistry and the dielectric properties were investigated by the combination of X-ray photoelectron spectroscopy and capacitance voltage technique. We observed strong correlations between the dopant concentration and the chemical composition, homogeneity and electrical properties (permittivity, hysteresis) of the produced layers. Hence, an increase of the surfaces chemical resistance against the ambient conditions due to the POSS incorporation into the siloxane matrix was found. Furthermore, this work demonstrates that a properly chosen concentration of CuPc and POSS dopants within the siloxane matrix leads to homogenous films with an extremely low dielectric constant in the range of 1.8.

Keywords: X-ray photoelectron spectroscopy; Capacitance–voltage characterization; 3-Aminopropyltrimethoxysilane; Low-; k; materials

Selective adsorption of protein on micropatterned flexible poly(ethylene terephthalate) surfaces modified by vacuum ultraviolet lithography by Shaoying Li; Zhongkui Wu; Hongxiao Tang; Jun Yang (pp. 4222-4227).

► Modification methods introduced here can be extended to other polymers and will be useful in protein patterns are desired. ► Selective protein adsorption was realized on the flexible PET substrates modified by VUV lithography. ► Chemical composition and topographies changes of the modified PET surfaces were characterized. ► Clear fluorescence micropatterns that are faithful reproductions of the copper mesh were obtained on the patterned PET–PEG surface.Protein micropattern was fabricated on the flexible poly(ethylene terephthalate) (PET) surfaces modified by vacuum ultraviolet lithography (VUV). Chemical composition and topographies changes of the modified PET surfaces were characterized and analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and static water contact angle. As demonstrated in fluorescence microscope, the protein patterns were surrounded by a protein-repellant layer of poly(ethylene glycol) (PEG) that were faithful reproductions of the copper mesh. These results suggested that this technique can be extended to other polymeric materials and will be useful in fields where arrays of protein patterns are desired.

Keywords: Self-assembled monolayer; Micropatterning; Selective protein adsorption; VUV; PET

Mg-doped nano ferrihydrite—A new adsorbent for fluoride removal from aqueous solutions by M. Mohapatra; D. Hariprasad; L. Mohapatra; S. Anand; B.K. Mishra (pp. 4228-4236).

(a) TEM images Mg-doped ferrihydrite, (b) TEM image fluoride loaded Mg-doped ferrihydrite (c) EDAX pattern of fluoride loaded Mg-doped ferrihydrite showing presence of fluoride.Display Omitted► High surface area nano powder of Mg-doped ferrihydrite was synthesized. ► Batch adsorption data for fluoride adsorption has been generated. ► Kinetic and isotherm models were applied to adsorption data. ► Thermodynamic parameters were evaluated. ► Regeneration studies were carried out and fluoride adsorption capacity of 64mg/g was achieved.The present study evaluates synthesized Mg-doped nano ferrihydrite powder as an adsorbent for F⁻ removal from aqueous solutions. High surface area Mg-doped ferrihydrite was prepared by co-precipitation method under controlled conditions. Samples were prepared by varying Mg content in the range of 0.39–1.12%. Preliminary test work revealed that under similar conditions, with the increase in Mg content from 0.39 to 0.98% in doped ferrihydrite, % F⁻ adsorption increased from 66 to 91%. Hence this sample was characterized by XRD, TEM, SAED and TG–DTA. Batch adsorption experiments were carried out by varying contact time (30–480min), initial pH (1.0–10), initial fluoride concentration (10–150mg/L), adsorbent dose (0.5–4g/L), temperature (20–45°C) and Cl⁻ or SO₄²⁻ concentrations (nil to 50mg/L). The results showed 0.98% Mg-doped ferrihydrite to be an excellent fluoride adsorbent giving maximum adsorption capacity of 64mg/g. The time data fitted well to pseudo second order kinetic model. The isothermal data followed Langmuir model. Thermodynamic parameters confirmed the adsorption process to be spontaneous and endothermic. 89% of fluoride could be desorbed from loaded sample using 1M NaOH.

Keywords: Fluoride; Adsorption; Nano iron oxides; Kinetics; TEM

Post-deposition heat-treated Ni_xZn1−_xFe₂O₄ films exhibiting higher resonance frequency by Dangwei Guo; Changjun Jiang; Xiaolong Fan; Huigang Shi; Desheng Xue (pp. 4237-4239).

► All the ferrite films were well crystallized and single-phase with a spinel structure. ► There was no significant change occurred in the XRD patterns and SEM images by the heat treatment. ► M_s increased and H_c decreased for the ferrite films after post-annealed treatment. ► f_r of the annealed ferrite films shifted to a higher frequency range, especially for x=0.28 which increased from 1.8GHz to 2.2GHz.The effect of thermal annealing with applying magnetic field on structural and magnetic properties has been investigated for Ni_xZn1−_xFe₂O₄ ( x=0.28 and 0.45) films deposited on Si(111) substrates by radio frequency magnetron sputtering. The post-deposition heat-treated ferrite films exhibited better soft magnetic properties that a slight increase in the saturation magnetization and decrease in the coercivity. The complex permeability μ= μ′− iμ″ values of the ferrite films as-deposited and post-deposition heat-treated were measured at frequency up to 5GHz. The results showed that the resonance frequency of the post-annealed ferrite films shifted to a higher frequency range, especially for x=0.28 which increased from 1.8GHz to 2.2GHz.

Keywords: Ferrite films; Post-deposition heat-treatment; Resonance frequency; Soft magnetic property

Separation mechanism of photogenerated charges for p-type α-Bi₂O₃ nanoparticles with surface states by Xiangyang Liu; Jin Liu; Haiwu Zheng; Xiansheng Liu; Guoqiang Li; Weifeng Zhang (pp. 4240-4245).

► α-Bi₂O₃ nanoparticles exhibit an obvious photovoltaic response from 325 to 500nm with two ranges. ► The electric-field induced surface photovoltage spectroscopy presents different results under positive and negative bias. ► We analysed the micro-process of the separation of photogenerated charges for α-Bi₂O₃ and put forward the quantitative analysis. ► The build-in electric field due to Schottky barrier and surface states mainly contribute to the photovoltaic response.α-Bi₂O₃ nanoparticles were prepared via a sol–gel method. A strong absorption from the onset at 450nm is observed, and α-Bi₂O₃ also exhibits an obvious and broad photovoltaic response from 325 to 500nm with two ranges. The electric-field induced surface photovoltage spectroscopy increases evidently under positive bias, but it increases initially under weak negative bias and reaches saturation with the bias intensity stronger than −2V. For this peculiar phenomenon about p-type characteristic of α-Bi₂O₃, we explained emphatically the micro-process and physical mechanism of the separation of photogenerated charges in the sandwich structure. Based on the results and our analysis, we think that both the build-in electric field due to Schottky barrier and surface states mainly contribute to the photovoltaic response for nanomaterial of α-Bi₂O₃.

Keywords: α-Bi; ₂; O; ₃; nanoparticles; Surface photovoltage spectroscopy (SPS); Schottky barrier; Surface states

Effect of UV/ozone irradiation on the surface properties of electrospun webs and films prepared from polydimethylsiloxane–urea copolymers by Emel Yilgor; Orkun Kaymakci; Mehmet Isik; Sevilay Bilgin; Iskender Yilgor (pp. 4246-4253).

Display Omitted► Highly hydrophobic surfaces of silicone–urea copolymers were transformed into hydrophilic ones upon UV/ozone treatment. ► The extent of surface modification was strongly dependent on the sample preparation method, surface topography and the exposure time. ► The physical and chemical changes at the copolymer surfaces were analyzed by spectroscopic (XPS, ATR-FTIR), microscopic (SEM) techniques and static water contact angle measurements. ► UV/ozone process is a very simple and facile method to transform hydrophobic silicone-rich surfaces into fairly hydrophilic ones under mild conditions.Highly hydrophobic surfaces of silicone–urea copolymers were transformed into hydrophilic ones upon UV/ozone treatment. The extent of surface modification was strongly dependent on the sample preparation method and the exposure time. The physical and chemical changes at the copolymer surfaces were analyzed by spectroscopic (XPS, ATR-FTIR), microscopic (SEM) techniques and static water contact angle measurements. ATR-FTIR spectra clearly showed the dramatic change in the strongly hydrogen bonded urea hard segments and the degradation of dimethylsiloxane units in silicone–urea copolymers. XPS results revealed the formation of SiO_x on the surface, which gradually increased with exposure time. After 3h of UV/ozone exposure, Si(2p) binding energy shifted from 101.9 to 102.85eV, which is a clear indication of an increase in the oxidation state of silicon. The deterioration of microroughness of the electrospun webs upon UV/ozone exposure, which was revealed by SEM, resulted in a dramatic decrease in the static water contact angle values from 129 to 62°. These results clearly show that UV/ozone process is a very simple and facile method to transform hydrophobic silicone–urea copolymer surfaces into fairly hydrophilic ones.

Keywords: UV/ozone; Polydimethylsiloxane; Hydrophilic/hydrophobic surfaces

Large scale, highly dense nanoholes on metal surfaces by underwater laser assisted hydrogen etching near nanocrystalline boundary by Dong Lin; Martin Yi Zhang; Chang Ye; Zhikun Liu; C. Richard Liu; Gary J. Cheng (pp. 4254-4259).

Display Omitted► We presented a new method to generate large scale and highly dense nanoholes. ► LSP with recrystallization is critical to form larger angle nano-grain boundary (nGB) for nanohole generation. ► Hydrogen etching near nGBs is to form large scale and highly dense nanoholes.A new method to generate large scale and highly dense nanoholes is presented in this paper. By the pulsed laser irradiation under water, the hydrogen etching is introduced to form high density nanoholes on the surfaces of AISI 4140 steel and Ti. In order to achieve higher nanohole density, laser shock peening (LSP) followed by recrystallization is used for grain refinement. It is found that the nanohole density does not increase until recrystallization of the substructures after laser shock peening. The mechanism of nanohole generation is studied in detail. This method can be also applied to generate nanoholes on other materials with hydrogen etching effect.

Keywords: Nanoporous surfaces; Underwater laser assisted hydrogen etching; Nanocrystalline surface; Laser shock peening

Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition by H. Gül; F. Kılıç; M. Uysal; S. Aslan; A. Alp; H. Akbulut (pp. 4260-4267).

► We have aimed to incorporate large amount of the SiC particles into Ni layer. ► A nickel sulfate bath was used as the plating electrolyte containing SiC particles. ► The effect of particle concentration on wear resistance of coatings has been studied. ► We have systematically increased the amount of the SiC particles codeposition. ► The wear mechanisms of submicron SiC reinforced MMC coatings were investigated.In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000nm was used as the plating electrolyte. The aim of this work is to obtain Ni–SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280–571HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55–65%). The results showed that the wear resistance of the nanocomposites was approximately 2–2.2 times more than those of unreinforced Ni.

Keywords: Electrocodeposition; Nano-SiC; Dispersion strengthening; Microstructure; Friction; Wear resistance

Contrastive study of anodic oxidation on carbon fibers and graphite fibers by Xin Liu; Changling Yang; Yonggen Lu (pp. 4268-4275).

► A homogenous thickness reduction model was established for the anodic oxidation. ► The kinetics constant for the graphite fibers was 1/6 of that for the carbon fibers. ► The wettability of fiber bunch provides a practical guidance to fabricate composites. ► Raman spectrum was used to derive the shear strength of the fibers to matrix.Anodic oxidation of polyacrylonitrile (PAN) graphite fibers was investigated in comparison with that of carbon fibers. The mechanical and interfacial properties of the treated fibers along with their surface structures were studied with X-ray photoelectron spectroscopy, atomic force microscope, contact angle analyzer, tensile strength instrument and Raman spectrometer. The results show that the graphite fibers were inactive during anodic oxidation for the higher graphitic carbon, while the carbon fibers were active and the surface oxygen content got saturated soon. The dynamics of anodic oxidation for the fibers can be described by a homogenous thickness reduction model, which indicated that the kinetic constant of anodic oxidation for the graphite fibers was only one sixth of that for the carbon fibers. Surface roughness contributed to the improvement on fiber/matrix adhesion as well as the surface oxygen content. The achievement of the surface treatment was proved by Raman spectroscopy mapping the stress of the fiber inside an epoxy resin droplet. The increase of interfacial shear strength from the untreated graphite fibers to the anodized graphite fibers was 160% (from 65 to 170MPa), much higher than 70% that from untreated carbon fibers to the anodized ones (from 135 to 230MPa).

Keywords: Carbon fiber; Graphite fiber; Surface treatment; Interfacial strength; Anodization dynamics

Facile fabrication of superhydrophobic flower-like polyaniline architectures by using valine as a dopant in polymerization by Jun Sun; Hong Bi (pp. 4276-4282).

The flower-like PANI architectures with superhydrophobic surface which can be tuned by varying polymerization time as well as valine doping quantity.Display Omitted► Large-scale, superhydrophobic flower-like PANI architectures were fabricated by using valine as a dopant in polymerization. ► The hydrophobic PANI architectures can be tuned easily by varying the polymerization time and the valine doping quantity. ► Valine plays a key role in both growth of the hierarchical structure and formation of the superhydrophobic surface. ► Similar flower-like PANI architectures were prepared by using other amino acids such as threonine, proline and arginine.A facile method was developed to fabricate superhydrophobic, flower-like polyanline (PANI) architectures with hierarchical nanostructures by adding valine in polymerization as a dopant. The water contact angle of the prepared PANI film was measured to be 155.3°, and the hydrophobic surface of the PANI architectures can be tuned easily by varying the polymerization time as well as valine doping quantity. It is believed that valine plays an important role in not only growth of the hierarchical PANI structures but also formation of the superhydrophobic surface, for it provides functional groups such asCOOH,NH₂ and a hydrophobic terminal group which may further increase intra-/inter-molecular interactions including hydrogen bonding, π–π stacking and hydrophobic properties. Similar flower-like PANI architectures have been prepared successfully by employing other amino acids such as threonine, proline and arginine. This method makes it possible for widespread applications of superhydrophobic PANI film due to its simplicity and practicability.

Keywords: Superhydrophobic; Flower-like architectures; Polyaniline; Amino acid

Growth of rutile TiO₂ nanorods on TiO₂ seed layer deposited by electron beam evaporation by V. Tamilselvan; D. Yuvaraj; R. Rakesh Kumar; K. Narasimha Rao (pp. 4283-4287).

Display Omitted► Hydrothermal growth of rutile TiO₂ nanorods on anatase TiO₂ seed layer. ► Anatase seed layer was deposited by using electron beam evaporation method. ► Crystalline nature of rutile TiO₂ nanorods has been observed. ► As prepared rutile TiO₂ nanorods show hydrophobicity.Dense rutile TiO₂ nanorods were grown on anatase TiO₂ seed layer coated glass substrate by solution technique. The crystalline nature of nanorods has confirmed by transmission electron microscopy. The band gap of the TiO₂ seed layer and nanorods were calculated using the UV–vis absorption spectrum and the band gap value of the anatase seed layer and rutile nanorods were 3.39eV and 3.09eV respectively. Water contact angle measurements were also made and showed that the contact angle of rutile nanorods was (134°) larger than the seed layer contact angle (93°). The RMS surface roughness of the TiO₂ seed layer (0.384nm) and nanorods film (18.5nm) were measured by an atomic force microscope and correlated with their contact angle values.

Keywords: Titanium dioxide; Hydrothermal crystal growth; UV absorption; Hydrophobic property

Microstructures and photocatalytic properties of porous ZnO films synthesized by chemical bath deposition method by Huihu Wang; Shijie Dong; Ying Chang; Xiaoping Zhou; Xinbin Hu (pp. 4288-4293).

► Different porous ZnO films were prepared using chemical bath deposition method. ► Both zinc acetate concentration and sintering temperature affect film structures. ► Porous structures and crystallinity determines photocatalytic property of ZnO film. ► Successive nest like ZnO porous film demonstrates the highest photoactivity.Different porous ZnO film structures on the surface of alumina substrates were prepared through a simple chemical bath deposition method in the methanolic zinc acetate solution. The surface morphology and phase structure of porous ZnO film were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Both initial zinc acetate concentration and sintering temperature have great impact on the final film structures. With the increase of initial zinc acetate concentration, the porous structures can be finely tuned from circular nest like assemblies composed film into successive nest like film, and finally to globular aggregates composed film. By increasing the sintering temperature, the porous structure of successive nest like film can be further controlled. Furthermore, the crystallinity of photocatalysts also can be greatly improved. The photodegradation results of Methyl Orange revealed that porous ZnO film with successive nest like structure sintered at 500°C exhibited the highest photocatalytic activity under UV illumination.

Keywords: ZnO film; Chemical bath deposition; Photocatalysis; Methyl Orange

A molecular dynamics simulation of self-diffusion on Fe surfaces by Changqing Wang; Zhen Qin; Yongsheng Zhang; Qiang Sun; Yu Jia (pp. 4294-4300).

Arrhenius diagram for the vacancy diffusion on three Fe surfaces. For the Fe (110), Fe (100) and Fe (111) surface, simple jumping, diagonal exchange and zigzag exchange mechanism have been given, respectively. The corresponding migration energy has been deduced and given, as well.Display Omitted► An adatom and vacancy diffusion processes on three Fe low index surfaces have been simulated by molecular dynamics method. ► Adatom adsorption and diffusion migration energies have similar monotonic trend: adsorption energy,Ea(110)aR₍₁₁₀₎< R₍₁₀₀₎< R₍₁₁₁₎, adsorption energy,Ea(110)a

Keywords: EAM potential; Molecular dynamics; Diffusion; Nudged elastic band (NEB) method; Iron; Adsorption; Vacancy

Preparation and characterization of aminated graphite oxide for CO₂ capture by Yunxia Zhao; Huiling Ding; Qin Zhong (pp. 4301-4307).

► Polyamines are covalently attached to the layers of graphite oxide (GO). ► We use aminated graphite oxide as CO₂ adsorbent. ► Aminated graphite oxide shows higher adsorption capacity for CO₂ than bare GO. ► GO modified by EDA shows better adsorption performance than that modified by DETA or TETA. ► GO with 50wt% EDA has larger adsorption capacity than that with 10wt% or 100wt% EDA.Adsorption with solid sorbents is one of the most promising options for postcombustion carbon dioxide (CO₂) capture. In this study, aminated graphite oxide used for CO₂ adsorption was synthesized, based on the intercalation reaction of graphite oxide (GO) with amines, including ethylenediamine (EDA), diethylenetriamine (DETA) and triethylene tetramine (TETA). The structural information, surface chemistry and thermal behavior of the adsorbent samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), transmission electron microscope (TEM), elemental analysis, particle size analysis, nitrogen adsorption as well as differential thermal and thermogravimetric analysis (DSC–TGA). CO₂ capture was investigated by dynamic adsorption experiments with N₂CO₂ mixed gases at 30°C. The three kinds of graphite oxide samples modified by excess EDA, DETA and TETA showed similar adsorption behaviors seen from their breakthrough curves. Among them, the sample aminated by EDA exhibited the highest adsorption capacity with the longest breakthrough time of CO₂. Before saturation, its adsorption capacity was up to 53.62mgCO₂/g sample. In addition, graphite oxide samples modified by different amount of EDA (EDA/GO raw ratio 10wt%, 50wt% and 100wt%) were prepared in the ethanol. Their CO₂ adsorption performance was investigated. The experimental results demonstrated that graphite oxide with 50wt% EDA had the largest adsorption capacity 46.55mgCO₂/g sample.

Keywords: Graphite oxide; Amine modification; Carbon dioxide adsorption; Breakthrough curve

Nanomechanical properties of NbN films prepared by pulsed laser deposition using nanoindendation by M.A. Mamun; A.H. Farha; A.O. Er; Y. Ufuktepe; D. Gu; H.E. Elsayed-Ali; A.A. Elmustafa (pp. 4308-4313).

► NbN thin films were successfully deposited on Si(100) by pulsed laser deposition (PLD) in nitrogen background. ► Structural and mechanical properties of NbN thin films were investigated using X-ray diffraction, atomic force microscopy, and nanoindentation. ► NbN films reveal simple cubic δ-NbN structure with the corresponding reflections of (111), (200), and (220) planes. ► The average modulus of the film is 420±60GPa. ► The hardness of the film increases monotonically from an average of 12GPa for deep indents (Si substrate) to an average of 25GPa.Structural and mechanical properties of niobium nitride thin films deposited by pulsed laser deposition were investigated using X-ray diffraction, atomic force microscopy, and nanoindentation. Niobium nitride was deposited on Si(100) by pulsed laser deposition (PLD) of Nb in nitrogen background. A Nanoindenter XP equipped with a dynamic contact module (DCM II) head was used in conjunction with the continuous stiffness method (CSM) in depth and load control modes to measure the hardness and modulus of the NbN thin films. NbN film reveals simple cubic δ-NbN structure with the corresponding reflections of (111), (200), and (220) planes. Highly textured NbN film shows a strong (111) preferred orientation. The NbN thin films depict polycrystalline structure, with a wide range of grain sizes that range from 15 to 40nm with an average surface roughness of 6nm. The average modulus of the film is 420±60GPa, whereas for the substrate the average modulus is 180GPa, which is considered higher than the average modulus for Si reported in the literature due to pile-up. The hardness of the film increases monotonically from an average of 12GPa for deep indents (Si substrate) measured using XP CSM and load control (LC) modes to an average of 25GPa measured using the DCM II head in CSM and LC modules. The average hardness of the Si substrate is 12GPa.

Keywords: NbN; PLD; Nanoindentation; Hardness; Modulus; Nanomechanical properties; TEM; XRD; AFM

Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material by Hui Li; Yuzhuo Li; Zhiping Li; Xiyang Peng; Yanan Li; Gui Li; Xianzhou Tan; Gongxi Chen (pp. 4314-4321).

► Used surface imprinting technique with silica gel as sacrificed support material. ► Characterization of polymer using FTIR and SEM technique. ► Improved adsorption capability of MIP compared with the reference method. ► Investigated thermodynamic and kinetic adsorption of MIP.Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2μmolg⁻¹ and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

Keywords: Molecular imprinted polymer; Surface imprinting technique; Berberine hydrochloride; Silica gel

Proliferation and differentiation of osteoblastic cells on titanium modified by ammonia plasma immersion ion implantation by Fei Liu; Bin Li; Junying Sun; Hongwei Li; Bing Wang; Shailin Zhang (pp. 4322-4327).

► A New approach for surface treatment of titanium using NH₃ plasma immersion ion implantation (PIII) technique was provided. ► Nitrogen-rich and more hydrophilic surface of titanium has been achieved using NH₃ PIII treatment without changing its surface morphology. ► Proliferation and differentiation of MC3T3-E1 pre-osteoblasts were markedly promoted on NH₃ PIII-treated titanium.We report here a new method of titanium surface modification through ammonia (NH₃) plasma immersion ion implantation (PIII) technique and its effect on the cellular behaviors of MC3T3-E1 osteoblastic cells. The NH₃ PIII-treated titanium substrates (NH₃–Ti) were characterized by X-ray photoelectron (XPS), which showed that NH₃–Ti had a nitrogen-rich surface. However, there was no significant difference between the surface morphology of NH₃–Ti and unmodified Ti. When MC3T3-E1 cells were cultured on NH₃–Ti substrates, it was found that cell proliferation was accelerated at 4 and 7 days of culture. Meanwhile, cell differentiation was evaluated using type I collagen (COL I), osteocalcin (OC) and bone sialoprotein (BSP) as differentiation markers. It was found that expression of COL I and OC genes was up-regulated on NH₃–Ti substrates. However, no significant difference was found in BSP gene expression between NH₃–Ti and unmodified Ti substrates. Therefore, findings from this study indicate that surface modification of titanium through NH₃ PIII favors osteoblastic proliferation and differentiation and as a result, it may be used to improve the biocompatibility of Ti implants in vivo.

Keywords: Titanium; Ammonia; Plasma immersion ion implantation; MC3T3-E1 cells

Synthesis and characterization of natural zeolite supported Cr-doped TiO₂ photocatalysts by Cheng Wang; Huisheng Shi; Yan Li (pp. 4328-4333).

► Natural zeolite supported Cr-doped TiO₂ photocatalysts were synthesized. ► Cr dopant was presented as Cr³⁺ and Cr⁶⁺ species in the samples. ► The band gap energy of the sample significantly reduced after Cr-doping. ► Photocatalytic activity of the samples could be enhanced as Cr ions were doped. ► The 10%Cr/TiO₂/zeolite calcined at 400°C exhibited higher photocatalytic activity.Natural zeolite supported Cr-doped TiO₂ photocatalysts were synthesized for the sake of improving the recovery and photocatalytic efficiency of TiO₂. The materials were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface areas, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (UV–vis DRS) and photoluminescence (PL). The photocatalytic activity was evaluated by the degradation of methyl orange in aqueous solution. The results show that the Cr concentration and the calcination temperature play important role on the microstructure and photocatalytic activity of the samples. The 10mol% Cr-doped TiO₂/zeolite calcined at 400°C exhibits higher photocatalytic activity than that of the other samples.

Keywords: Zeolite; Cr; TiO; ₂; Photocatalyst

Preparation of superhydrophilic mesoporous SiO₂ thin films by Peiyi Chen; Yun Hu; Chaohai Wei (pp. 4334-4338).

► Mesoporous SiO₂ thin films are prepared with a simple method. ► Films are colorless and transparent. ► Films perform the superhydrophilicity without UV light irradiation. ► Increasing thickness of films will improve the superhydrophilicity. ► Films can keep superhydrophilic after exposed to air for 3 months.Using a simple sol–gel/spin-coating method, mesoporous SiO₂ thin films were prepared on glass slides. All of the prepared thin films were colorless and transparent as original glass substrates. XRD and TEM measurements revealed that the prepared SiO₂ thin films coated 3–12 times possess hexagonal mesoporous structure. The mesoporous SiO₂ thin films performed the superhydrophilicity and antifogging property in the absence of UV light irradiation. The results suggested that the appropriate film thickness and mesoporous structures can improve the surface superhydrophilic behavior of SiO₂ thin films.

Keywords: Mesoporous SiO; ₂; thin films; Transparent; Superhydrophilicity; Antifogging

The influence of surfactants on the crystalline structure, electrical and photocatalytic properties of hybrid multi-structured (SnO₂, TiO₂ and WO₃) thin films by Alexandru Enesca; Luminita Andronic; Anca Duta (pp. 4339-4346).

► Inorganic particles are partially stabilized by surface-adsorbed SDS surfactant. ► Indicates how different structures prevent the recombination of the carrier charge. ► Steric hindrance imposed by the HTAB branch chain surfactant. ► Highest surface energy corresponds to the samples where HTAB surfactant was used. ► Photocatalytic activity with efficiency values that varies from 40% to 80%.The paper presents the influence of surfactants additives (anionic and cationic) on the crystalline structure (XRD), morphology (AFM), surface energy (contact angle), optical (absorbance and reflectance) and electrical properties of mono and multi-structured thin films containing SnO₂, TiO₂ and WO₃ layers. The anionic surfactant supports the structure densification with regular grains distribution. Contrary, the films obtained using cationic surfactants have defects in the layer morphology and the samples are non-homogeneous and non-uniform. The samples have photocatalytic activity with an efficiency of 80% for the Ti sample and up to 65% for bi (Sn_Ti, Sn_W) and tri-component (Sn_W_Ti) samples.

Keywords: Spray pyrolysis deposition; Hybrid layers; Morphology; Electrical properties; Photocatalysis

Effect of UV irradiation on wear protection of TiO₂ and Ni-doped TiO₂ coatings by Yong Wan; Baojian Sun; Zhen Xu; Wenliu Chao (pp. 4347-4350).

► TiO₂ and Ni-doped TiO₂ films with good wear protection are prepared by sol–gel technology. ► UV illumination resumes the hydrophobicility of both TiO₂ and Ni-doped TiO₂ films. ► UV illumination greatly damage wear protection properties of both TiO₂ and Ni-doped TiO₂ films.The relationship between UV photoinduced hydrophilicity and tribological performance of the thin films of pure and Ni-doped TiO₂ was investigated in this paper. The films were prepared on a glass substrate by sol–gel and spin coating process from specially formulated ethanol sols. The chemical structure and morphologies of the films surface were observed with X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD) and atomic force microscope (AFM). The tribological properties of obtained thin films, when sliding against steel ball, were evaluated on a one-way reciprocating friction tester. It is clearly observed that UV irradiation resume the hydrophobicility of the films of pure and Ni-doped TiO₂, however greatly worsen their wear protection properties.

Keywords: Thin film; Sol–gel; TiO; ₂; Friction; Surface energy

The initial release of zinc and aluminum from non-treated Galvalume and the formation of corrosion products in chloride containing media by Xian Zhang; Thanh-Nam Vu; P. Volovitch; C. Leygraf; K. Ogle; I. Odnevall Wallinder (pp. 4351-4359).

► Emphasis on short- and long-term corrosion and release processes for Galvalume. ► Close relation between corrosion product formation and release patterns. ► Selective release of zinc over aluminum in chloride-rich environments. ► Zinc and aluminum rich corrosion products predominantly formed in interdendritic areas.This study explores the initial release of zinc and aluminum from non-treated Galvalume and the parallel formation of corrosion products when exposed to synthetic seawater and rainwater of different chloride content. Comparisons were made with long-term field exposures at non-sheltered marine conditions. Observed release rates from short-term conditions agree qualitatively with the long-term findings with a selective release of zinc over aluminum. The release and corrosion processes were intertwined through the formation of corrosion products with properties that influence the long-term release process. Prior to exposure, Al₂O₃ dominated the entire surface, and was subject to local destruction upon interaction with chloride ions. As a consequence Al₂O₃ was gradually replaced and covered by zinc-rich corrosion products primarily in interdendritic areas during the first year of marine exposure. This was followed by the gradual formation and integration of aluminum-rich corrosion products, reflected by an increased zinc release rate during the first year, followed by a gradually decreased rate during subsequent years. The importance of Al₂O₃ was also evident in deaerated synthetic rainwater or seawater, where the formation of Al₂O₃ was presumably hindered. In synthetic rain water this resulted in a higher ratio between released aluminum and zinc compared with non-deaerated conditions.

Keywords: Galvalume; Metal release; Corrosion products; Chlorides

Preparation and characterization of graphite-dispersed styrene-acrylic emulsion composite coating on magnesium alloy by Renhui Zhang; Jun Liang; Qing Wang (pp. 4360-4364).

Display Omitted► Electrically conductive composite coating is formed on Mg alloy by anodic deposition. ► The composite coating consists mainly of graphite-dispersed styrene-acrylic emulsion. ► The deposition process of the composite coating on Mg alloy is proposed. ► The composite coating provides superior corrosion resistance to Mg alloy.In this work, an electrically conductive, corrosion resistant graphite-dispersed styrene-acrylic emulsion composite coating on AZ91D magnesium alloy was successfully produced by the method of anodic deposition. The microstructure, composition and conductivity of the composite coating were characterized using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and four electrode volume resistivity instrument, respectively. The corrosion resistance of the coating was evaluated using potentiodynamic polarization measurements and salt spray tests. It is found that the graphite-dispersed styrene-acrylic emulsion composite coating was layered structure and displayed good electrical conductivity. The potentiodynamic polarization tests and salt spray tests reveal that the composite coating was successful in providing superior corrosion resistance to AZ91D magnesium alloy.

Keywords: Composite coating; Magnesium alloy; Anodic deposition; Conductivity; Corrosion resistance

Novel horseshoe-shaped ZnO nanorods and their optical properties by Junlin Li; Huizhao Zhuang (pp. 4365-4369).

► Large areas of well-aligned ZnO horseshoe-shaped nanorods have been fabricated vertically. ► The pre-coated MgO layers to grow novel horseshoe shape of ZnO nanorods arrays are seldom in the past articles. ► The PL spectrum exhibits at 500.8nm, 387.7nm and 648.6 nm indicates that the ZnO arrays have excellent optical quality. ► The two-step process is a simple and cost-effective approach for growing nanorods on a large scale.Large areas of ZnO horseshoe-shaped nanorods have been fabricated vertically on MgO-coated Si (111) substrates by chemical vapor deposition method. The well-aligned nanorod arrays were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and photoluminescence spectroscopy (PL). The results show that the nanorods are perfect single crystals with hexagonal wurzite structure along the [0001] growth direction. The nanorods have regular horseshoe shape, and the diameter of the rods rang 70–99nm while the length is about 600nm. The PL spectrum exhibits a strong peak at 500.8nm and two relatively weak emission bands centered at 387.7nm and 648.6nm, which indicates that the ZnO arrays are of excellent optical quality.

Keywords: ZnO; Nanorods; Crystal growth; Optical properties

Photocatalytic activity of CdS nanoparticles synthesized by a facile composite molten salt method by Xiaoyan Li; Chenguo Hu; Xue Wang; Yi Xi (pp. 4370-4376).

► CdS nanoparticles with clean surface have been obtained for the first time by the CMS approach. ► The influence of temperature, time and amount of salts on the size was systematically investigated. ► High photocatalystic activity of the CdS nanoparticles for degradation of RhB and MB was found.Single-crystalline CdS nanoparticles were synthesized for the first time by the composite-molten-salt (CMS) method, with advantages of one-step, ambient pressure, low temperature, template-free and low cost. The influence of temperature, growth time and amount of salts on the morphology of CdS nanoparticles was systematically investigated. It shows that a smaller size of CdS nanoparticles can be obtained under lower temperature, less growth time and more composite salts. UV–vis reflection spectrum of the nanoparticles reveals that the nanoparticles have a bandgap of 2.34eV. Photoluminescence spectrum was also carried out to explore its optical property. Photocatalytic degradation of rhodamine B (RhB) and methylene blue (MB) in presence of the CdS nanoparticles was compared with that in presence of the commercial TiO₂ nanoparticles under the simulated sunlight.

Keywords: CdS; Nanoparticles; Composite-molten-salt; Photodegradation

Surface characterization of alkali- and heat-treated Ti with or without prior acid etching by Sang-Hyun An; Takuya Matsumoto; Hiroyuki Miyajima; Jun-Ichi Sasaki; Ramaswamy Narayanan; Kyo-Han Kim (pp. 4377-4382).

► Acid etching was done prior to the further alkali- and heat-treatments of Ti. ► On pre-acidetched Ti surface, bonelike apatite formed early in simulated body fluid. ► The pre-etched surface also showed better osteoblastic cell activity. ► Roughness and wettability of the pre-etched surface was higher than other surface.Titanium and its alloys are used as implant materials in dental and orthopaedic applications. The material affinities to host bone tissue greatly concern with the recovery period and good prognosis. To obtain a material surface having excellent affinity to bone, acid etching prior to alkali- and heat-treatment of Ti was conducted. The surface characteristics of the prepared sample indicated that the roughness as well as the wettability increased by pre-etching. Bone-like apatite was formed on pre-etched, alkali- and heat-treated Ti surface in simulated body fluid (SBF) within 3 days, while it takes 5 days on the solely alkali- and heat-treated surface. Osteoblastic cells showed better compatibility on the per-etched surface compared to the pure Ti surface or alkali- and heat-treated surface. Moreover, the pre-etched surface showed better pull-off tensile adhesion strength against the deposited apatite. Thus, acid etching prior to alkali- and heat-treatment would be a promising method for enhancing the affinity of Ti to host bone tissue.

Keywords: Titanium; Alkali treatment; Acid etching; Simulated body fluid (SBF); Adhesion strength

Solid surface dependent layering of self-arranged structures with fibril-like assemblies of alpha-synuclein by V. Bukauskas; A. Šetkus; I. Šimkienė; S. Tumėnas; I. Kašalynas; A. Rėza; J. Babonas; V. Časaitė; S. Povilonienė; R. Meškys (pp. 4383-4390).

► Self-arranged layers of alpha-synuclein based fibrils on the solid surfaces. ► Re-arrangement of β-sheet amyloid fibrils depending on the surface origin. ► Specific transformation of the proteins and the fibrils on the CaF₂ and KBr surfaces. ► The surface–protein electrostatic interaction defines the transformation mechanism.In present work the formation of hybrid constructions composed of alpha-synuclein-based colloidal solutions on various solid surfaces (silica coated Si, mica, CaF₂ and KBr) is investigated by scanning probe microscopy, spectrocopic ellipsometry, Fourier transformed infrared spectroscopy and vibrational circular dichroism. Prior to the modification of the solids, the proteins were intentionally fibrilled under special conditions. It is proved that the multi-component coatings are self-arranged on the solid substrates. Depending on the substrate material, the interface films consisting of individual biomolecules can be detected on the solid surfaces. The coatings with fibril-like alpha-synuclein objects can be obtained on solid surfaces with negligible or comparatively thick interface films. The results are interpreted in terms of the charged surface-controlled electrostatic interaction between the substrate and the biomolecules. Solubility of solids is considered in this interpretation.

Keywords: Biomolecular structures; Scanning probe microscopy; Optical properties

Surface analysis and anti-graffiti behavior of a weathered polyurethane-based coating embedded with hydrophobic nano silica by A. Mohammad Rabea; M. Mohseni; S.M. Mirabedini; M. Hashemi Tabatabaei (pp. 4391-4396).

Display Omitted► Incorporation of silicon additive and nano silica in polyurethane coatings. ► Studying surface properties and mechanical analysis by different analytical techniques. ► Weathering silica loaded films at different UV conditions. ► Studying the surface free energy of UV exposed films.In this study, a permanent anti-graffiti polyurethane coating was prepared using concomitant loading of an OH-functional silicone modified polyacrylate additive ranging from 2 to 15mol% and hydrophobic silica nanoparticles from 1 to 5wt%. UV–visible spectroscopy, contact angle measurement and dynamic mechanical thermal analysis (DMTA) analysis were conducted on selected samples to study the weathering performance of samples containing various amounts of silica nanoparticles before and after accelerated weathering conditions. The results showed that higher amounts of additive had inferior effects on the anti-graffiti performance of the coating samples after exposure. However, silica nanoparticles could positively affect the anti-graffiti performance against ageing cycles. This improvement was attributed to lower degradation of samples containing silica nanoparticles and barrier property of nanoparticles against graffiti penetration. The presence of silica nanoparticles did not have any significant effect on the surface free energy of the samples prior and after ageing.

Keywords: Anti-Graffiti; Polyurethane; Silicone additive; Surface free energy; Silica nanoparticles; Weathering

A detailed approach to study the antibacterial mechanisms of nanostructure by Fang Fang; Xuan Fang; Jinhua Li; Zhipeng Wei; Xin Wang; Xiaohua Wang (pp. 4397-4401).

► We study the antibacterial process of nanostructure at single cell level. ► A facile image assessment is combined with CLSM to help the study. ► It is quantified by relative time-dependent mean fluorescence intensity dynamics. ► Three different nanostructures are examined with this system. ► Such incorporation technique provides more detailed information.To overcome the limitations of the conventional inhibition method for mechanism study, here we developed a combined CLSM technique as an alternative approach to evaluate and explain the antibacterial process of nanostructure at single cell level. Three different nanostructures (dumbbell-shaped ZnO, rod-shaped ZnO and ZnO/Ag composites) were examined here as a model system. Their antibacterial processes against Escherichia coli ( E. coli) were quantitatively studied in detail. According to the obtained time-dependent mean fluorescence intensity (MFI) decay dynamics, an interesting two-step cellular disruption process was observed and discussed for the first time. The combined CLSM technique described here is superior to standard growth method for they can provide a more detailed and reliable description of cell–nanostructure interactions.

Keywords: ZnO; Nanomaterial; Antibacterial; CLSM

Removal of fluoride from aqueous solution by adsorption on Apatitic tricalcium phosphate using Box–Behnken design and desirability function by M. Mourabet; A. El Rhilassi; H. El Boujaady; M. Bennani-Ziatni; R. El Hamri; A. Taitai (pp. 4402-4410).

► Response surface methodology was employed for the removal of fluoride. ► Experiments were carried out as per Box–Behnken surface statistical design. ► pH, adsorbent dose, temperature and F⁻ concentration have significant effect. ► Optimization of responses is performed by desirability function method. ► Optimum pH, adsorbent dose, temperature and initial concentration are 4, 0.29g, 40°C, and 60mgL⁻¹, respectively.The adsorption method was used for fluoride removal from aqueous solution by Apatitic tricalcium phosphate. In this study, response surface methodology was employed for the removal of fluoride. Experiments were carried out as per Box–Behnken surface statistical design with four input parameters namely adsorbent dose (0.1–0.3g), initial concentration (30–60mgL⁻¹), temperature (20–40°C) and pH (4–11). Contact time (90min) was taken as a fixed input parameter. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination ( R²) value of 0.966 and Fisher F-value of 10.28. Applying the method of the desirability function, optimization of adsorbent dose (29g), initial concentration (60mgL⁻¹), T (40°C) and pH (4) gave a maximum of 82.34% fluoride removal white desirability of 0.916 by Apatitic tricalcium phosphate. Dynamic adsorption data were applied to pseudo-first-order and pseudo-second-order rate equations. Pseudo-second-order kinetic model well expressed fluoride adsorption onto Apatitic tricalcium phosphate. According to the correlation coefficients, the adsorption of fluoride on the Apatitic tricalcium phosphate was correlated well with the Langmuir and Freundlich models.

Keywords: Fluoride; Box–Behnken design; Optimization; Response surface methodology; Desirability function; Apatitic tricalcium phosphate

Influence of absorbed moisture on surface hydrophobization of ethanol pretreated and plasma treated ramie fibers by Zhou Zhou; Jilong Wang; Xiao Huang; Liwen Zhang; Senelisile Moyo; Shiyuan Sun; Yiping Qiu (pp. 4411-4416).

► Ramie fibers are plasma treated with ethanol pretreatment at different moisture regains. ► Surface hydrophobicity was improved after the plasma treatments. ► Moisture regain of the ramie fibers had negative influence on hydrophobization of the fiber surface.The existence of moisture in the substrate material may influence the effect of atmospheric pressure plasma treatment. Our previous study has found that the employment of ethanol pretreatment and plasma treatment can effectively induce hydrophobic surface modification of cellulose fiber to enhance the compatibility to polypropylene (PP) matrix, and this study aims to investigate the influence of fiber moisture regain on the treatment effect of this technique. Ramie fibers with three different moisture regains (MR) (2.5, 6.1 and 23.5%) are pretreated with ethanol followed by atmospheric pressure plasma treatment. Scanning electron microscope (SEM) shows that the 2.5% MR group has the most significant plasma etching effect. X-ray photoelectron spectroscopy (XPS) analysis indicates an increase of CC and a decrease of CO bond in the plasma treated groups, and the largest raise of CC bond for the 2.5% MR group. The water contact angles of the 2.5 and 6.1% MR groups increase, whereas no significant change is showed in the 23.5% MR group. The interfacial shear strengths (IFSS) measured by microbond pull-out test are raised by 44 and 25% when moisture regains are 2.5 and 6.1%, while presented no apparent improvement at high moisture regain of 23.5%. Therefore, it can be concluded that moisture regain has negative influence on the surface hydrophobization of ramie fibers in the improvement of adhesion property to PP matrix.

Keywords: Atmospheric pressure plasma; Ramie fiber; Ethanol; Moisture regain; Interfacial shear strength

Influence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) on zinc electrodeposition by I.L. Lehr; S.B. Saidman (pp. 4417-4423).

► Zinc electrodeposits were produced on SAE 4140 steel in solutions containing AOT. ► The presence of the surfactant alters the nucleation and growth stages. ► Adherent and porous zinc films are obtained.This work is a study of the electrodeposition of zinc onto SAE 4140 steel electrodes using solutions containing zinc sulfate and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). The influence of different parameters such as electrolyte concentration, electrodeposition time and temperature on the morphology of the electrodeposits was analyzed. The deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction. The variation of open circuit potential over time in chloride solutions was also evaluated. The nucleation-growth process and consequently the morphology of the electrodeposits are modified in the presence of AOT. The surfactant induces the formation of a porous deposit.

Keywords: Zinc; Electrodeposition; Stainless steel; AOT

Generation of the periodic surface structures on the dental Co–Cr–Mo alloy by Nd:YAG laser in an inert atmosphere by M.A. Vasylyev; V.A. Tinkov; V.S. Filatova; S.M. Voloshko; P.A. Gurin (pp. 4424-4427).

► Influence of the impulse laser irradiation on the surface morphology of the dental Co–Cr–Mo alloy surface. ► Laser-induced periodic surface structure. ► Periodic ring relief appears at the modes of the treatment with melting and evaporation of the material.The influence of the impulse laser irradiation (Nd:YAG laser λ=1.06μm) in an inert atmosphere (Ar) with different power density on the surface morphology of the dental Co–Cr–Mo alloy surface was studied. It is set that periodic ring relief appears at the modes of the treatment with melting and evaporation of the material. The analysis of the periodic structure main characteristics was performed.

Keywords: Co–Cr–Mo alloy; Nd:YAG laser; Surface periodic structure; Scanning electron microscopy

Nitric oxide adsorption on Nb(110) surface by Hua Ning; Jian-Qiu Cai; Xiang-Ming Tao; Ming-Qiu Tan (pp. 4428-4435).

► In the p(1×1) structure, the theoretical calculation is in good agreement with the available data from HREELS experiments. ► On the Nb(110) surface, NO prefers to adsorb in top sites uprightly. With decreasing the coverage NO gradually tilts in hollow sites. ► At lower coverage NO is adsorbed in part dissociatively on hollow sites and in part molecularly on top sites.We have studied nitric oxide (NO) adsorption and dissociation on the Nb(110) surface by means of density-functional theory and total-energy calculations. The top adsorption sites on the Nb(110) surface are found to be energetically the most favorable at the p(1×1) surface periodicity, which is in line with experiments investigated by high-resolution electron energy-loss spectroscopy (HREELS). On the Nb(110) surface, NO prefers to adsorb in top sites uprightly. With decreasing the coverage NO gradually tilts in hollow sites. At lower coverage (∼0.25ML), the tilted hollow site has been determined to be the preferred adsorption site from total-energy comparison. We have found that NO is easy to dissociate on the Nb(110) surface. Four typical dissociation pathways with oxygen atoms of NO dissociated to bridge and top sites are discussed. The further analysis based on electronic states reveal that at 0.25ML the essential interaction between a NO monomer and metal substrate is the hybridization of NO 5σ, 2π*-orbital and the d-bands of surface niobium atoms for p(2×2) surface.

Keywords: Nitric oxide; Nb(1; 1; 0) surface; Adsorption energy; Dissociation

Improvement of hydrophilic property of rubber dipping former surface with Ni/B/TiO₂ nano-composite film by L. Sikong; M. Masae; K. Kooptarnond; W. Taweepreda; F. Saito (pp. 4436-4443).

► Ni/B/TiO₂ photocatalytic film coated on glass former via sol–gel. ► Film for improvement of rubber former hydrophilic property. ► Rubber films prepared by using this former have smooth surface and high tensile strength.The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO₂ composite films were prepared by sol–gel method. Glass formers were coated with the Ni/B/TiO₂ nano-composite film by dipping method and annealed at 400°C for 1h. Phase formation of TiO₂ was characterized by XRD. Morphology of the TiO₂ films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV–vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO₂ composite films with and without UV irradiation. It was found from the experimental study that the Ni/B/TiO₂ nano-composite film can improve wet-ability of the coated former surfaces, leading to enhancement of tensile strengths of the vulcanized natural rubber (NR) latex films.

Keywords: Sol–gel; Photocatalytic reaction; Hydrophilicity; Ni/B/TiO; ₂; nano-composite film; Natural rubber (NR) latex

Study on the inorganic–organic surface modification of potassium titanate whisker by Shan Yun; QianQian Song; DongMei Zhao; GuiMin Qian; XinNing Li; Wu Li (pp. 4444-4448).

► The surface of potassium titanate whisker (PTW) coated with ZnO successfully. ► ZnO coated PTW shows better UV absorption. ► ZnO coated PTW is easier to react with coupling agent. ► The surface of modified ZnO coated PTW shows more hydrophobic and lipophilic.ZnO coated potassium titanate whisker (PTW) was prepared via a facile chemical method, and coupling agent KH550 was used to modify the surface of ZnO coated PTW. Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectrophotometer and surface contact angle measurement were used to characterize the effect of surface modification. The results showed that the surface of PTW was uniformly coated by ZnO nanoparticles, and exhibited better ultraviolet absorption when the coating amount of ZnO was 5%. After modified by KH550, the modified ZnO/PTW showed better dispersion in ethanol solvent and the surface of modified ZnO/PTW became more hydrophobic–lipophilic than that of modified uncoated PTW. The method of inorganic–organic surface modification of PTW might be an effective way to greatly improve the compatibility of the whisker and the polymer matrix.

Keywords: Potassium titanate whisker; Zinc oxide; Modification; Hydrophobic–lipophilic

Sorption/desorption differences among three ferrihydrites prepared by different synthesis methods by Shan Meng; Hui Liu; Caihong Yang; Yu Wei; Denglu Hou (pp. 4449-4454).

Ferrihydrites prepared under different conditions exhibit different adsorption capacity and binding ability for Pb(II) ions.Display Omitted► Fh was prepared under three different conditions. ► Three Fhs exhibit different adsorption capacity for Pb(II) ions. ► The degree of reversible adsorption of Pb(II) ions on the three Fhs was evaluated. ► Effect of aging of Fh on its ability to bind Pb(II) ions was studied. ► The adsorption property of Pb(II) on dense and gel samples was compared.Ferrihydrites named Fh-1, Fh-2, and Fh-3 were prepared under different environmental conditions. The sorption/desorption of Pb(II) onto/from the three ferrihydrites was studied. The effects of the most relevant operating conditions (e.g., pH, concentration of metal ions and temperature, etc.) were investigated. Adsorption/desorption isotherms were employed to evaluate the degree of reversible adsorption of Pb(II) onto the three ferrihydrites. Fh-3 exhibited the largest adsorption capacity and highest irreversible degree for Pb(II). Moreover, Fh-3 can lock metal ions very well. This phenomenon indicated that the formative conditions of ferrihydrite were critical in predicting the toxicity, transport, and fate of trace metals in a subsurface environment.

Keywords: Ferrihydrite; Formation environment; Adsorption–desorption; Pb(II)

Oxygen interstitials enhanced room temperature ferromagnetism in undoped zinc oxide by H. You; J. Yang; J.Y. Zhu; W.F. Xu; X.D. Tang (pp. 4455-4459).

► Pure zinc oxide (ZnO) particles were fabricated by a simple aqueous solution route. ► Hydrogen peroxide (H₂O₂) treatment was used to reduce the negative influences of oxygen vacancies and promote the proportion of oxygen interstitials. ► There is an enhancement in the ferromagnetism of ZnO after H₂O₂ treatment. ► Oxygen interstitials may have some close connections with the ferromagnetism of ZnO.Pure zinc oxide (ZnO) particles fabricated by a simple aqueous solution route were treated with hydrogen peroxide (H₂O₂) solution. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed the homogeneous growth of particles throughout the substrate with the wurtzite phase. Magnetic properties were measured and a correlation between immersion time and ferromagnetism (FM) was observed. X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) were then performed to investigate the influence of hydrogen peroxide (H₂O₂) treatment on oxygen-related defects. It is revealed that oxygen interstitials (I_O) may be considered to be playing an important role in tailoring the magnetic properties of ZnO.

Keywords: PACS; 75.50 Pp; 78.67 Bf; 81.65 Mq; 81.70 FyZnO; H; ₂; O; ₂; Magnetic properties; Oxygen interstitials

Fabrication of nanostructured clay–carbon nanotube hybrid nanofiller by chemical vapour deposition by Dhanagopal Manikandan; Ramalinga Viswanathan Mangalaraja; Rajendran Siddheswaran; Ricardo E. Avila; Solaiappan Ananthakumar (pp. 4460-4466).

Display Omitted► Carbon nanotubes with very high selectivity ( I_D/ I_G=0.53) were grown over montmorillonite. ► Novel carbon nanotubes-montmorillonite (CNT/MM) hybrid materials were produced. ► CNT/MM hybrid material is a promising candidate for Nafion based nanocomposite membranes.Growth of multiwalled carbon nanotube (CNT) assemblies by chemical vapour decomposition (CVD) technique was achieved through decomposition of acetylene using iron impregnated montmorillonite (MM) catalysts. Various amounts of iron loaded montmorillonite catalysts were prepared by wet impregnation method and calcined at 450°C. The catalysts were subjected to X-ray diffraction (XRD) and surface area analyses. Acetylene decomposition at a feed ratio of N₂:H₂:C₂H₂=1:1:0.18 was conducted in the presence of iron impregnated montmorillonite catalysts in the CVD reactor for the growth of CNT structures. The role of Fe-activated clay catalyst on the formation of CNT structures has been systematically examined at various temperatures and correlated with the morphological features of CNTs. Catalyst assisted acetylene decomposition results the formation of different carbon nanostructures such as nanotubes, nanofibres and nanoflakes. These clay–CNT products were characterised for their morphological, thermal, qualitative and quantitative analyses. The morphological variations of CNT assemblies reveal Fe-montmorillonite catalysts have high selectivity at given reaction conditions. Thermogravimetric and Raman spectral analyses prove that the CNTs contain a good crystallanity and less structural defects.

Keywords: Carbon nanotubes; Montmorillonite; Nanofiller; Catalysts; Chemical vapour deposition (CVD)

Microwave assisted chemical bath deposition of vertically aligned ZnO nanorods on a variety of substrates seeded by PVA–Zn(OH)₂ nanocomposites by J.J. Hassan; M.A. Mahdi; C.W. Chin; Z. Hassan; H. Abu-Hassan (pp. 4467-4472).

► In this study we have grown high quality vertically aligned ZnO nanorods on GaN, sapphire, ITO glass and quartz substrates. ► We used PVA–ZnO nanocomposites as seed layer for the growth of ZnO nanorods. ► We characterized the produced nanorods by XRD, FESEM, PL, and Raman techniques. ► We found that ZnO nanorods grown on GaN substrates have high quality, well vertical alignment and have high texture coefficient compared to other substrates.Vertically aligned zinc oxide (ZnO) nanorods were synthesized successfully on p-type GaN, c-lattice Al₂O₃, ITO glass, and quartz single crystal substrates using the microwave-assisted chemical bath deposition method. All substrates were seeded with a PVA–Zn(OH)₂ nanocomposites layer prior to nanorods growth. The effect of substrate type on the vertically alignment and morphology of the zinc oxide nanorods was studied. The diameter of the grown ZnO nanorods ranged from 30 to 170nm. Their structural quality and morphology were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which revealed hexagonal wurtzite structures perpendicular to the substrate along the z-axis in the direction of (002) plane. Photoluminescence (PL) measurements of the grown ZnO nanorods on all substrates exhibited high UV peak intensity compared to broad visible peak. Raman scattering studies were conducted to estimate the lattice vibration modes.

Keywords: ZnO nanorods; PVA–Zn(OH); ₂; nanocomposites; MA–CBD; Photoluminescence; XRD; FESEM

Molecular dynamics simulations of the temperature effect in the hardness on Cr and CrN films by S. Amaya- Roncancio; D.F. Arias-Mateus; M.M. Gómez-Hermida; J.C. Riaño-Rojas; E. Restrepo-Parra (pp. 4473-4477).

► Molecular dynamics with different models reproduces experimental hardness measures. ► Increasing the system temperature produces a decrease in the hardness. ► As the system temperature increases, voids and slips appear in the film.Three-dimensional molecular dynamics (MD) simulations of nanoindentation technique was carried out for Cr and CrN thin films that present BCC and FCC crystalline structures respectively. Structures were oriented in the plane (100) and placed on silicon substrates. A pair wise potential was employed for simulating the interaction between atoms of each layer and a repulsive radial potential was used for representing a spherical tip indenting the sample. Mechanical properties of these two materials were obtained varying the temperature from 300K to 1000K with steps of 100K. The hardness and elastic parameters were found for each temperature, showing a better mechanical response for films at low temperature. Structural changes evolution was observed presenting vacancies and slips as the temperature was increased. A temperature smoothing occurred because of the long range of slips and vacancies propagation. Then, the interatomic force decreases as the kinetic energy of the particles involved in nanoindentation process increases.

Keywords: Molecular dynamics; Nanoindentation; Cr; CrN; Thin films; Morse potential

Theoretical study of the adsorption of rhodium on a TiO₂(110)-1×1 surface by P. Mutombo; N. Balázs; Z. Majzik; A. Berkó; V. Cháb (pp. 4478-4482).

► We performed DFT calculations of Rh adsorption on TiO₂(110) surface. ► Rh prefers the hollow site between a bridging oxygen atom, a threefold oxygen atom and a fivefold coordinated Ti atom. ► 1D growth of Rh particles along the [001] direction is due to attractive Rh–Rh interaction. ► Simulations of theoretical STM images of dimer and trimer clusters on the TiO₂(110) surface.Density functional theory (DFT) calculations were used to study the adsorption of rhodium on a TiO₂(110)-1×1 surface as a function of coverage. It was found that Rh atom prefers the hollow site between a bridging oxygen atom, a threefold oxygen atom and a fivefold coordinated Ti atom, regardless of the coverage used. DFT calculations also suggest that Rh–Rh interaction is attractive along the [001] direction, implying that the Rh 1D nanostructure should grow preferentially along this direction. Simulated Rh dimer clusters resemble strongly Pd dimers resolved in STM experiments suggesting that both metals occupy the same adsorption site at the TiO₂(110) surface.

Keywords: Density functional theory; Rhodium; Oxide surface; Scanning tunneling spectroscopy

Surface modification of 5083 Al alloy by electrical discharge alloying processing with a 75mass% Si–Fe alloy electrode by Kuralay Stambekova; Hung-Mao Lin; Jun-Yen Uan (pp. 4483-4488).

► The electrical discharge alloying process employed Si–Fe alloy as an electrode. ► The matrix of the alloyed layer has an amorphous-like structure. ► There are fine needle-like Si particles, block-like Si particles and nano-size Al_4.5FeSi and Al₁₃Fe₄ particles in the alloyed layer. ► The alloyed layer exhibited good corrosion resistance in NaCl aqueous solution.This study experimentally investigates the surface modification of 5083 Al alloy by the electrical discharge alloying (EDA) process with a Si–Fe alloy as an electrode. Samples were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), micro-hardness and corrosion resistance tests. The micro-hardness of EDA alloyed layer was evidently higher than that of the base metal (5083 Al alloy). The TEM results show that the matrix of the alloyed layer has an amorphous-like structure; the matrix contains fine needle-like Si particles, block-like Si particles and nano-size Al_4.5FeSi and Al₁₃Fe₄ particles. The TEM results support experimental results for the high hardness of the alloyed layer. Moreover, the EDA alloyed layer with composite microstructures has good corrosion resistance in NaCl aqueous solution.

Keywords: Electrical discharge alloying process; Alloying layer; Amorphous; Corrosion

Preparation of artificial canine femoral stem with HA–Ti ladder-type coating on plasma-sprayed pure Ti substrate and its performance evaluation by Xianlin Zeng; Jingfeng Li; Shuhua Yang; Qixin Zheng; Zhenwei Zou (pp. 4489-4496).

► In this study, the composite HA–Ti ladder-type coating group of pure Ti substrate sprayed onto titanium alloy under a vacuum had a successive laminate structure, and the intergranular bond in the HA surface layer on the gradient coating was compact with high crystallinity. ► Under a vacuum, plasma-sprayed layer is characterized by higher tightness, moderate porosity, higher bonding strength to HA, and higher HA crystallinity. ► The proposed coating will provide new cementless artificial femoral stem with improved bone-prosthesis bonding capacity and enhanced stability.An ideal, biological-type, artificial femoral stem prosthesis has good stability and improved bone-prosthesis bonding capacity. In the current study, pure hydroxyapatite (HA)-coated, cementless, artificial femoral stems were prepared by adopting different plasma spray powers and distances and were tested in terms of shear strength. The pure titanium (Ti) substrates, HA coatings, and composite Ti–HA ladder-type coatings prepared under vacuum and atmospheric conditions were examined to compare the shear strengths, microscopic constitutions, and structures of the coatings. The coating was fabricated and the bond strength was improved by adopting 35kW of spray power and an 80mm spray distance. The comparisons show that the shear strength of the Ti coating prepared under vacuum conditions was higher than that of the coating prepared under atmospheric conditions ( P<0.05). Moreover, the pressure–shear strength of the Ti+HAG+Ti+V group coating was statistically significantly different from those of the HA+Ti+V and HA+Ti+A groups ( P<0.05). The coatings were compared using scanning electron microscopy, X-ray diffraction, and infrared spectrum analysis. The composite HA–Ti ladder-type coating group, where pure Ti substrate was sprayed onto the Ti alloy under vacuum conditions, had a successive laminate structure. In addition, the intergranular bond in the HA surface layer on the gradient coating was compact and highly crystallized. Under vacuum conditions, the plasma-sprayed layer was characterized by higher tightness, moderate porosity, higher bonding strength to HA, and higher HA crystallinity. The proposed coating can be used in new, cementless, artificial femoral stems with improved bone–prosthesis bonding capacity and stability.

Keywords: Hydroxyapatite (HA); Titanium (Ti); Ladder-type coating; Biomechanics; Hip prosthesis

A micro-spectroscopy study on the influence of chemical residues from nanofabrication on the nitridation chemistry of Al nanopatterns by B. Qi; S. Ólafsson; A.A. Zakharov; B. Agnarsson; H.P. Gislason; M. Göthelid (pp. 4497-4506).

► The Al nanopatterned surface was studied by a micro-spectroscopy combined photoemission electron microscopy. ► Fluorocarbons, e-beam exposed- and unexposed-polymethylmethacrylate (PMMA) residues from the nanofabrication were identified on the nanopatterns. ► The fluorocarbons influenced the chemical composition of the nanopatterns by forming AlF compounds before nitridation. ► In the PMMA residue-free area, the AlF compounds on the sidewalls were decomposed and transformed to AlN by nitridation. ► The PMMA residues between the individual nanopatterns were partially decomposed by nitridation.We applied spatially resolved photoelectron spectroscopy implemented with an X-ray photoemission electron microscopy (XPEEM) using soft X-ray synchrotron radiation to identify the compositional and morphological inhomogeneities of a SiO₂/Si substrate surface nanopatterned with Al before and after nitridation. The nanofabrication was conducted by a polymethylmethacrylate (PMMA)-based e-beam lithography and a fluorine-based reactive ion etching (RIE), followed by Al metalization and acetone lift-off. Three types of chemical residues were identified before nitridation: (1) fluorocarbons produced and accumulated mainly during RIE process on the sidewalls of the nanopatterns; (2) a thick Al-bearing PMMA layer and/or (3) a thin PMMA residue layer owing to unsuccessful or partial lift-off of the e-beam unexposed PMMA between the nanopatterns. The fluorocarbons actively influenced the surface chemical composition of the nanopatterns by forming AlF compounds. After nitridation, in the PMMA residue-free area, the AlF compounds on the sidewalls were decomposed and transformed to AlN. The PMMA residues between the nanopatterns had no obvious influence on the surface chemical composition and nitridation properties of the Al nanopatterns. They were only partially decomposed by the nitridation. The regional surface morphology of the nanopatterns revealed by the secondary electron XPEEM was consistent with the scanning electron microscopy results.

Keywords: X-ray photoemission electron microscopy; e-Beam lithography; Micro-spectroscopy; Nanopatterns; Nitridation

Interfacial layers in Ta₂O₅ based stacks and constituent depth profiles by spectroscopic ellipsometry by Y. Karmakov; A. Paskaleva; E. Atanassova (pp. 4507-4512).

► A novel approach to spectroscopic ellipsometry data interpretation with a proper algorithm was applied for characterization of the interfacial layers of Ta₂O₅/Si stacks. ► Simultaneous determination of the high- k oxide and interfacial layer thicknesses, as well as the interfacial optical dielectric function depth profiles was achieved. ► The main constituents into the inhomogeneous interfacial layers were recognized. ► The influence of the Hf oxide doping on the interfacial inhomogeneity and thickness was detected.The paper presents results on an optical interface characterization of Ta₂O₅ stacks by spectroscopic ellipsometry. Inhomogeneous in depth interfacial layers were identified by a novel approach and proper algorithm for ellipsometric data interpretation. Simultaneous determination of a high- k oxide thickness, an optical dielectric function profile and the thickness of the interfacial layer was achieved. The interfacial constituents and their depth profiles were recognized. The profiles were used as an additional tool for exact determination of thicknesses. The identical interfacial layers were detected for samples produced by similar Si surface treatment, independent of the Ta₂O₅ thickness (<20nm) and methods of Ta₂O₅ fabrication. High inhomogeneous amount of Si constituent phase in interfacial depth was detected in all investigated samples. The thickness reduction and homogenization of the interfacial layers was established after Hf-doping of Ta₂O₅.

Keywords: PACS; 68; 68.47.Fg; 68.55.Nq; 68.55.jd; 77.55.+f; 78.67.−n; 78.68.+mSpectroscopic ellipsometry; Algorithm; Depth; Profile; Ta; ₂; O; ₅; based stack; Interfacial layer; Constituents

A study of estimating cutting depth for multi-pass nanoscale cutting by using atomic force microscopy by Zone-Ching Lin; Ying-Chih Hsu (pp. 4513-4522).

This paper studies two models for estimating cutting depth of multi-pass nanoscale cutting by using an atomic force microscopy (AFM) probe. One estimates cutting depth for multi-pass nanoscale cutting by using regression equations of nanoscale contact pressure factor (NCP factor) while the other uses equation of specific down force energy (SDFE). This paper proposes taking a diamond-coated probe of AFM as the cutting tool to carry out multi-pass nanoscale cutting experiments on the surface of sapphire substrate. In the process of experimentation, different down forces are set, and the probe shape of AFM is known, then using each down force to multi-pass cutting the sapphire substrate. From the measured experimental data of a central cutting depth of the machining groove by AFM, this paper calculates the specific down force energy of each down force. The experiment results reveal that the specific down force energy of each case of multi-pass nanoscale cutting for different down forces under a probe of AFM is close to a constant value. This paper also compares the nanoscale cutting results from estimating cutting depths for each pass of multi-pass among the experimental results and the calculating results obtained by the two theories models. It is found that the model of specific down force energy can calculate cutting depths for each nanoscale cutting pass by one equation. It is easier to use than the multi-regression equations of the nanoscale contact pressure factor. Besides, the estimations of cutting depth results obtained by the model of specific down force energy are closer to that of the experiment results. It shows that the proposed specific down force energy model in this paper is an acceptable model.

Keywords: Specific down force energy (SDFE); Atomic force microscopy (AFM); Nanoscale multi-pass; Cutting; Contact pressure factor

Influence of different buffer gases on synthesis of few-layered graphene by arc discharge method by Baoshou Shen; Jijun Ding; Xingbin Yan; Wangjun Feng; Jun Li; Qunji Xue (pp. 4523-4531).

Few-layered graphene sheets were synthesized by arc discharge in H₂–He buffer gases. Their ethanol dispersions were stable after two months in comparison to chemically reduced graphene.Display Omitted► Influence of different buffer gases on the microstructures of samples is studied. ► Graphene sheets have been prepared using three containing H₂ buffer gases. ► As-obtained graphene sheets can be easily dispersed into organic solvents. ► The sprayed graphene films shows good hydrophobility.Few-layered graphene sheets were synthesized by direct current arc discharge using different buffer gases. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and four-probe method. Moreover, the hydrophobility and the field emission properties of the sprayed-coating graphene films prepared by a direct solution process were studied. As a result, the generation of graphene sheets shows strong dependence on the composition of buffer gases and containing H₂ buffer gases are necessary to prepare few-layered graphene sheets. The graphene sheets produced in H₂–He buffer gases have better crystallinity and higher specific surface area compared with those produced in others containing H₂ buffer gases. The as-obtained graphene sheets are mainly no more than 5 layers and their lateral dimensions are about 40–200nm. The graphene sheets show excellent thermal stability and there is only less than 3wt.% weight loss up to 800°C in N₂ atmosphere. The graphene sheets can be easily dispersed into ethanol and the as-obtained suspension can be stable for more than two months. The sprayed graphene films show good hydrophobility and a typical cold cathode field emission behavior.

Keywords: Graphene; Arc discharge; Buffer gas; Hydrophobility; Field emission

The influence of metal interlayers on the structural and optical properties of nano-crystalline TiO₂ films by Y. Yang; Q. Zhang; B. Zhang; W.B. Mi; L. Chen; L. Li; C. Zhao; E.M. Diallo; X.X. Zhang (pp. 4532-4537).

► TiO₂–M–TiO₂ (M=W and Co) multilayer films with pure anatase phase have been deposited on glass substrates. ► Compared with pure TiO₂ film, the crystallization temperature for TiO₂–M–TiO₂ films decreased significantly to 500°C. ► The optical band gap of TiO₂–M–TiO₂ films became narrower than that of pure TiO₂ film. ► The crystallization of TiO₂–M–TiO₂ films was attributed to the structural deformation due to the oxidation of metal layers.TiO₂–M–TiO₂ (M=W, Co and Ag) multilayer films have been deposited on glass substrates using reactive magnetron sputtering, then annealed in air for 2h at 500°C. The structure, surface morphology and optical properties of the films have been studied using X-ray diffraction, Raman spectroscopy, atomic force microscopy and UV–vis spectroscopy. The TiO₂–W–TiO₂ and TiO₂–Co–TiO₂ films showed crystalline phases, whereas the TiO₂–Ag–TiO₂ films remained in the amorphous state. The crystallization temperature for the TiO₂–M–TiO₂ films decreased significantly compared with pure TiO₂ film deposited on quartz. Detailed analysis of the Raman spectra suggested that the crystallization of TiO₂–M–TiO₂ films was associated with the large structural deformation imposed by the oxidation of intermediate metal layers. Moreover, the optical band gap of the films narrowed due to the appearance of impurity levels as the metal ions migrated into the TiO₂ matrix. These results indicate that the insertion of intermediate metal layers provides a feasible access to improve the structural and optical properties of anatase TiO₂ films, leading to promising applications in the field of photocatalysis.

Keywords: TiO; ₂; film; Multilayer; Nanocrystalline; Raman spectroscopy; X-ray diffraction; Atomic force microscopy; UV–vis spectroscopy; Anatase; Annealing

Effects of surface mechanical attrition treatment (SMAT) on a rough surface of AISI 316L stainless steel by B. Arifvianto; Suyitno; M. Mahardika (pp. 4538-4543).

► A roughness decreasing phenomenon during the SMAT is observed. ► Stages in surface smoothening by the SMAT: (1) rapid reduction, (2) saturation roughness. ► Indentation and material removal by the impact of milling balls are the two principal mechanisms. ► A smoother surface and larger mass reduction are yielded by the SMAT with bigger milling balls. ► The initial surface roughness does not influence the work hardening by the SMAT.Surface mechanical attrition treatment (SMAT) improves mechanical properties of metallic materials through the formation of nanocrystallites at their surface layer. It also modifies the morphology and roughness of the work surface. Surface roughening by the SMAT has been reported previously in a smooth specimen, however in this study the starting point was a rough surface and a smoothening phenomenon is observed. In this paper, the mechanisms involved in the surface smoothening of AISI 316L stainless steel during the SMAT are elucidated. The SMAT was conducted on a specimen with a roughness of R_a=3.98μm for 0–20min. The size of milling balls used in the SMAT was varied from 3.18mm to 6.35mm. The modification of subsurface microhardness, surface morphology, roughness and mass reduction of the specimen due to the SMAT were studied. The result shows the increasing microhardness of the surface and subsurface of the steel due to the SMAT. The impacts of milling balls deform the surface and produce a flat-like structure at this layer. Surface roughness decreases until its saturation is achieved in the SMAT. The mass reduction of the specimens is also detected and may indicate material removal or surface erosion by the SMAT. The size of milling ball is found to be the important feature determining the pattern of roughness evolution and material removal during the SMAT. From this study, two principal mechanisms in the evolution of surface morphology and roughness during the SMAT are proposed, i.e. indentation and surface erosion by the multiple impacts of milling balls. A comparative study with the results of the previous experiment indicates that the initial surface roughness has no influence in the work hardening by the SMAT but it does slightly on the saturated roughness value obtained by this treatment.

Keywords: Surface; Roughness; Morphology; AISI 316L; SMAT

Effect of chemical etching on the morphology of anodic aluminum oxides in the two-step anodization process by Pembe Erdogan; Behiye Yuksel; Yucel Birol (pp. 4544-4550).

► Etching treatment impacts the morphological features of the AAO templates. ► Etching treatment time must at least one half that of the anodization treatment. ► H₃PO₄-based etching solutions fail to remove the aluminum oxides from the first anodization step. ► Addition of 2% CrO₃ offers a marked improvement in the AAO pore features. ► An etching solution temperature of 55°C produces the best pore features.Morphological features of the anodic aluminum oxide (AAO) templates fabricated by electrochemical oxidation under different chemical etching conditions were investigated. The chemical etching treatment had a paramount impact on the morphological features of the AAO templates produced with the two-step anodization process. Increasing the etching treatment time was found to be favourable, provided that the ratio of the etching treatment time to that of anodization must be at least one half. Etching solutions based merely on H₃PO₄ fail to remove the aluminum oxides from the first anodization step. The addition of as much as 2% CrO₃ offers a marked improvement in the AAO pore features. Increasing the H₃PO₄ concentration in H₃PO₄–CrO₃ mixtures improves the pore features while an increase in the CrO₃ concentration has no effect. The temperature of the etching solution also affects the morphology of AAO pores remarkably. An etching solution temperature of 55°C is the optimum.

Keywords: Anodic aluminum oxide; Chemical etching

Reduced graphene oxide–titanate hybrids: Morphologic evolution by alkali-solvothermal treatment and applications in water purification by Thuy-Duong Nguyen-Phan; Viet Hung Pham; Eui Jung Kim; Eun-Suok Oh; Seung Hyun Hur; Jin Suk Chung; Byunghwan Lee; Eun Woo Shin (pp. 4551-4557).

Display Omitted► Reduced graphene oxide–titanate hybrids are synthesized by solvothermal process. ► Reduced graphene oxide acts as a two dimensional platform for titanate growth. ► Titanate sheets transform into tubes or ribbons at high solvothermal temperatures. ► The hybrids possess large surface areas and high pore volumes. ► The hybrid materials exhibit excellent adsorptivity of dye contaminants.The reduced graphene oxide–titanate (RGO–Ti) hybrids were fabricated by incorporating spherical TiO₂ nanoparticles with graphene oxide (GO) layers in aqueous NaOH solution following by the solvothermal treatment. The morphologic evolution of RGO–Ti hybrid by varying alkali-solvothermal temperatures has been first investigated. The titanate nanosheets peeled off, folded and scrolled into tubular structure; and eventually, cracked and destroyed to be ribbon-like shape. The chemical interaction and attachment of low-dimensional titanate onto RGO layers and the reverse order were elucidated by X-ray photoelectron spectra. The hybrids in sheet and tubular titanate structures possessed larger surface areas (>350m²/g) and higher pore volumes (>1cm³/g) than the other. The presence of RGO sheets as a two-dimensional (2D) platform for the deposition of titanate significantly promoted much better adsorptivity of dye contaminants compared to pure materials.

Keywords: Titanate; Graphene; Hybrid; Solvothermal treatment; Morphology control; Adsorption

Frequency dependence of magnetoelectric effect in epitaxial La_0.7Sr_0.3MnO₃/BaTiO₃ bilayer film by Tingxian Li; Zhou Hu; Ming Zhang; Kuoshe Li; Dunbo Yu; Hui Yan (pp. 4558-4562).

► The bilayer showed inherent ferromagnetic and ferroelectric properties. ► There is a particular frequency dependence of ME behavior from 0.1kHz to 100kHz. ► The ME voltage coefficient was around 213mV/cmOe at 1kHz, which was at least one order of magnitude higher than the similar structures. ► The interface coupling coefficient k=0.88 at 1kHz. It revealed that there existed an excellent interface coupling between LSMO and BTO.The epitaxial La_0.7Sr_0.3MnO₃/BaTiO₃ bilayer film was deposited on (001) oriented SrTiO₃ single-crystal substrate by pulsed laser deposition. The bilayer film possessed inherent ferromagnetic, ferroelectric properties. The frequency dependence of magnetoelectric (ME) voltage coefficient revealed a strong ME coupling from 0.1kHz to 100kHz. The value of ME voltage coefficient ( α_E) was around 213mV/cmOe at 1kHz, which was at least one order of magnitude higher than other reports in the similar structure due to the rather low dielectric constant of BTO film. The measured value of α_E corresponded to the theoretical expectation when interface coupling coefficient was 0.88.

Keywords: Magnetoelectric effect; Composite film; Pulsed laser deposition; Interface coupling coefficient

Nitrogen-doping effects on the growth, structure and electrical performance of carbon nanotubes obtained by spray pyrolysis method by Mihnea Ioan Ionescu; Yong Zhang; Ruying Li; Hakima Abou-Rachid; Xueliang Sun (pp. 4563-4568).

► Bulk yield growth of nitrogen doped carbon nanotubes by spray pyrolysis CVD at low carrier gas flow rates. ► Nitrogen amounts tailored by changing the concentration ratio of precursors. ► Pyridinic nitrogen to graphitic nitrogen ratio increased with increasing nitrogen concentration. ► Increased electrical conductivity of bulk CNx as the nitrogen concentration increased.Vertically aligned nitrogen-doped carbon nanotubes (CNTs) with modulated nitrogen content have been synthesized in a large scale by using spray pyrolysis chemical vapor deposition technique. The effects of nitrogen doping on the growth, structure and electrical performance of carbon nanotubes have been systematically examined. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman techniques have been employed to characterize the morphology, composition, and vibrational properties of nanotubes. The results indicate that the nitrogen incorporation significantly influences the growth rate, morphology, size and structure of nanotubes. Electrical measurement investigation of the nanotubes indicates that the change in electrical resistance increases with temperature and pressure as the nitrogen concentration increases inside the tubes. This work presents a versatile, safe, and easy way to scale up route of growing carbon nanotubes with controlled nitrogen content and modulated structure, and may provide an insight in developing various nitrogen-doped carbon-based nanodevices.

Keywords: Carbon nanotubes; Chemical vapor deposition; Spray pyrolysis

Improved moisture resistance of SrSO₄:Sm³⁺ phosphors coated with SiO₂ by Jiayue Sun; Randi Sun; Haiyan Du (pp. 4569-4573).

► The SiO₂ coating is obtained by the ultrasonic sonochemical process. ► The method is facile and effective. ► The wt% of coated SiO₂ is little.SrSO₄:Sm³⁺ phosphors obtained by precipitation method are coated with SiO₂ and their photoluminescence (PL) degradation behavior is investigated. The SiO₂ coating is obtained by the ultrasonic sonochemical process using tetraethylorthosilicate (TEOS) as silicon coating reagent and the coating content is varied from 0.5 to 2wt%. Powder X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), fluorescence spectrometer, and Fourier transform infrared spectrometer are employed to characterize the coating. Moisture resistances of coated SrSO₄:Sm³⁺ phosphors have been enhanced to a great degree without more loss of their optical properties based on the existence of the SiO₂ thin layer. The PL intensity of the coated phosphors decreases to ∼83% of the original value after 38h soaking the phosphors in deionized water, while the uncoated phosphor decreases to ∼40%.

Keywords: Surfaces; Phosphors; SrSO; ₄; :Sm; ³⁺

Deposition, characterization and electrochemical evaluation of Ni–P–nano diamond composite coatings by Hamed Mazaheri; Saeed Reza Allahkaram (pp. 4574-4580).

► Diamond nanometer particles have been co-deposited to Ni–P matrix successfully by electroless process. ► The composite structure of the deposition was evaluated as nano size without using any surfactants. ► Incorporation of diamond nanometer particles significantly increase the hardness of depositions as compared to the Ni–P as deposited matrix. ► Corrosion behavior improves by embedding nano-diamond particles within Ni–P matrix due to decreasing porosity density by the accommodation of nano particles to them. ► It was revealed that 1g/L concentration of diamond nanometer particles provides the optimum deposition condition for Ni–P/nano-diamond coating.Simultaneous electroless deposition of particles between layers of Ni–P depositions can improve their properties, especially general corrosion and erosion–corrosion behavior by means of nano diamond as reinforcing particles. In this study Ni–P/nano-diamond composite deposition were coated on steel substrate. Structure of the coatings and corrosion resistance of them were investigated by scanning electron microscopy (SEM) and electrochemical evaluations in salty media. The nano-sized structure of the composite depositions was obtained without using any surfactants. The results demonstrated higher corrosion resistance and greater hardness as compared to the deposited Ni–P. The optimum concentration of diamond nano-particles was found by study of hardness measurement, linear polarization and electrochemical impedance spectroscopy (EIS).

Keywords: Electroless deposition; Composite coating: nano-diamond

First-principles study of boron, carbon and nitrogen adsorption on WC(100) surface by Kai Bi; Jun Liu; Qixun Dai (pp. 4581-4587).

► B, C and N atoms can form chemical adsorptions on WC(100) surface. ► The most stable adsorption occurs at hollow site. ► At the same adsorption site, the adsorption of N atom is the strongest. ► B, C and N adatoms on WC(100) surface mainly interact with the surface W atoms.The adsorption of boron (B), carbon (C) and nitrogen (N) atoms on WC(100) surface is studied using first-principles density-functional theory (DFT). The corresponding adsorption structure, adsorption energy, density of states (DOS) and Mulliken population are calculated. The results show that B, C and N atoms can form chemical adsorptions at four kinds of high symmetry adsorption sites on WC(100) surface, with the most stable adsorption occurring at hollow site (HC). The chemical adsorption is mainly a result of the hybridization between the B, C and N atoms’ 2p, 2s orbits and the surface W atoms’ 5d orbit. In the adsorption process, a portion of the outer electrons of the surface W atoms transfer to B, C and N adatoms and redistribute. At the same adsorption site on the WC(100) surface, the adsorption of N atom is the strongest, and that of B atom the weakest.

Keywords: First-principles; Adsorption energy; Density of states; Mulliken population

Effects of ZnO buffer layer on GZO RRAM devices by Jian-Wei Zhao; Jian Sun; Hai-Qin Huang; Feng-Juan Liu; Zuo-Fu Hu; Xi-Qing Zhang (pp. 4588-4591).

► We employed ZnO film as buffer layer to improve resistive switching characteristics. ► The operation voltages were very low. ► A high-voltage forming process in initial state was not required.Ag/GZO/ZnO/Pt structure resistive switching devices were fabricated by radio frequency (RF) magnetron sputtering, in which ZnO was used as a buffer layer. These devices have large ratio of high resistance state (HRS) to low resistance state (LRS), which is 2×10³. The storage time measurement indicates that these devices have an excellent data retention characteristic. Moreover, the operation voltages are very low, which is 0.4V (ON state) and −0.35/−0.55V (OFF state). The electroforming process in initial state was not needed, and multistep reset process was found.

Keywords: GZO; ReRAM devices

Visible light assisted photodecolorization of eosin-Y in aqueous solution using hesperidin modified TiO₂ nanoparticles by K. Vignesh; A. Suganthi; M. Rajarajan; R. Sakthivadivel (pp. 4592-4600).

(a) UV–vis absorption changes of eosin-Y in the presence of Hes-TiO₂, (b) photodecolorization curves of eosin-Y in the presence of Hes-TiO₂ and TiO₂.Display Omitted► The complete mineralization of organic pollutants into CO₂ and H₂O can be brought about by TiO₂ semiconductor photocatalysis. ► Hesperidin modified TiO₂ nanoparticles greatly improve the photodecolorization of eosin-Y. ► Hesperidin modification sharpens the band gap of TiO₂. ► COD experiments confirm the mineralization of eosin-Y during photocatalysis. ► A possible reaction mechanism for the decolorization of eosin-Y was proposed by GC–MS analysis.Hesperidin a flavanoid, modified TiO₂ nanoparticles (Hes-TiO₂) was synthesized to improve the visible light driven photocatalytic performance of TiO₂. The synthesized nanoparticles were characterized by UV–visible diffuse reflectance spectroscopy (UV–vis-DRS), FT-IR, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of Hes-TiO₂ was investigated based on the decolorization of eosin-Y under visible light irradiation. Hes-TiO₂ showed high efficiency for the decolorization of eosin-Y. The influences of various reaction parameters like effect of pH, catalyst dosage and initial dye concentration on the photocatalytic efficiency were investigated. The adsorption of eosin-Y on Hes-TiO₂ was found favorable by the Langmuir approach. The removal percentage of chemical oxygen demand (COD) was determined to evaluate the mineralization of eosin-Y during photodecolorization. Based on the intermediates obtained in the GC–MS spectroscopic technique, a probable degradation mechanism has been proposed.

Keywords: Photocatalysis; Hes-TiO; ₂; Eosin-Y; Visible light; Photodecolorization

Competition between quantum fluctuation and ferroelectric order in Eu1−_xBa_xTiO₃ by T. Wei; Q.J. Zhou; X. Yang; Q.G. Song; Z.P. Li; X.L. Qi; J.-M. Liu (pp. 4601-4606).

► The quantum ferroelectric (QFE) state for Eu1−_xBa_xTiO₃ has been revealed. ► The strong quantum fluctuation (QF) in EuTiO₃ has been identified. ► It has been suggested that Eu1−_xBa_xTiO₃ can be a substitute for the important perovskite oxide (Sr, Ba) TiO₃.A series of polycrystalline Eu1−_xBa_xTiO₃ (0.0≤ x≤1.0) samples were synthesized through solid-state reaction method, and their microstructural, ferroelectric, dielectric, and phase transition properties are researched. We investigated the structural properties of Eu1−_xBa_xTiO₃ system and revealed the structure transition from cubic perovskite to tetragonal perovskite with increasing x. More importantly, it is found that there exists strong quantum fluctuation (QF) in EuTiO₃ and the ferroelectric state is built only at relatively high level Ba doping. Furthermore, quantum ferroelectric state (QFE) with broad scope is revealed for Eu1−_xBa_xTiO₃ system through our ferroelectric and dielectric measurements.

Keywords: PACS; 77.22.−d; 77.80.Bh; 77.84.−sEuTiO; ₃; Incipient ferroelectric

Mathematical characterization of oxidized crystalline silicon nanowires grown by electroless process by Robert G. Mertens; Kalpathy B. Sundaram (pp. 4607-4613).

► Silicon nanowires (SiNWs) created via the electroless etching technique & oxidized. ► SEM of original and oxidized SiNWs. ► SiNWs cause “surface area amplification,” a formula for which is provided. ► Formula for polar plot provided illustrating shape of SiNWs after oxidation.Silicon nanowires were created via the electroless etching technique using silver nitrate (AgNO₃)/hydrofluoric acid (HF) solution. The prepared raw samples were oxidized for various intervals, so as to have an end result of various nanowire thicknesses. Scanning electron microscope (SEM) images were taken of the original nanowires, the oxidized nanowires and then the oxidized and etched (in HF solution) nanowires. When silicon nanowires are made, the area of exposed silicon undergoes “amplification,” a formula for which is provided herein. When silicon nanowires are oxidized, the growth rate of the oxide layer varies according to the crystalline alignment. A formula for a polar plot is provided for illustrating the shape of a silicon nanowire after oxidation for various intervals, based on the Deal–Grove and Massoud models of oxidation.

Keywords: Silicon; Nanowires; Oxidation; Orientation

Comparison study of PE epitaxy on carbon nanotubes and graphene oxide and PE/graphene oxide as amphiphilic molecular structure for solvent separation by Linghao He; Xiaoli Zheng; Qun Xu; Zhimin Chen; Jianwei Fu (pp. 4614-4623).

Display Omitted► We reported a comparison study of PE epitaxy on GO and CNTs. PE/CNTs formed nanohybrid “shish-kebab” structure. ► GO sheets were decorated with petal-like PE crystals. ► The distinct morphologies depend on the substrates and the interactions. ► PE/GO hybrids has markedly stratification phenomenon in the mixing solvent system.Carbon nanotubes (CNTs) and graphene nanosheets, as one-dimensional and two-dimensional carbon-based nanomaterials respectively, have different abilities to induce the polymer crystallization. In this study, hybrid materials, polyethylene (PE) decorating on CNTs and graphene oxide (GO), were prepared by a facile and efficient method using supercritical carbon dioxide (SC CO₂) as anti-solvent. And the morphology and crystallization behavior of PE on CNTs and GO were investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectra, wide angle X-ray diffraction, and differential scanning calorimetry. Although both CNTs and GO could act as nucleating agents to induce PE epitaxial growth, CNTs were decorated by PE lamellar crystals forming nanohybrid “shish-kebab” (NHSK) structure, whereas GO sheets were only decorated with petal-like PE crystals. The varying morphologies of the nanohybrids depend on the PE epitaxy and the interactions between polymer chains and substrates. High surface curvature and the perfect ordered crystal structure of CNTs make PE crystals periodically grow on CNTs. While PE crystals grow and form multiple orientation-lamellae on GO due to the lattice matching and complex interactions between PE chains and GO. In addition, our experimental results show an interesting and evident stratification phenomenon for the PE/GO hybrid material, implying that GO decorated by PE have a screening function for the solvents. We anticipate that this work can widen the area of functionalization of carbon-based nanomaterials with a controlled means by an environmentally benign method, which are important for the functional design in nanodevice applications.

Keywords: Carbon nanotube; Graphene oxide; Supercritical carbon dioxide; Morphology; Crystallization behavior

Multiscale simulations of nanoindentation and nanoscratch of single crystal copper by Pengzhe Zhu; Yuanzhong Hu; Fengzhou Fang; Hui Wang (pp. 4624-4631).

► A multiscale method is employed to study nanoindentation and nanoscratch processes of single crystal copper film. ► Load–depth curves obtained from both multiscale and full MD simulations match each other reasonably well. ► Indentation velocity has a great effect on the load–depth curve and hardness of single crystal copper film. ► The system size can be greatly expanded using the multiscale method without increasing computational cost.In this paper, a three-dimensional multiscale method coupling molecular dynamics (MD) and finite element (FE) analysis has been employed to study nanoindentation and nanoscratch processes of copper thin film. During the nanoindentation process, no discontinuities can be observed in the displacement gradient, which demonstrates a seamless coupling between MD and FE regions. The multiscale model of nanoindentation is further validated by the fact that the load–depth curves obtained from both multiscale and full MD simulations match each other reasonably well. The nanoindentation results using multiscale model are also compared with those using part MD model to elucidate the advantages of multiscale method. The multiscale simulation results of nanoindentation show that the indentation velocity has a great effect on the load–depth curve and hardness of copper. The continuity of displacement field during the nanoscratch also demonstrates a seamless information exchange between MD and FE regions. The deformation of substrate and forces in the nanoscratch process are also investigated using the multiscale method. The multiscale method can greatly expand the system size to be explored without significant increase in computational cost.

Keywords: Molecular dynamics simulation; Multiscale simulation; Finite element; Nanoindentation; Nanoscratch

Transparent high-surface-work-function Al-doped CdO electrodes obtained by rf magnetron sputtering with oxygen flow by Wei-Min Cho; Guan-Ru He; Ting-Hong Su; Yow-Jon Lin (pp. 4632-4635).

► AlCdO films were deposited by rf magnetron sputtering with and without oxygen flow. ► For AlCdO films deposited with oxygen flow, we measure the high work function. ► For AlCdO films deposited without oxygen flow, we measure the low work function. ► It is shown the peroxidic AlCdO surface with a high work function.The surface work function of transparent conducting oxides is a critical parameter influencing device efficiency by controlling charge transport across interfaces. In this study, Al-doped CdO films were deposited on glass substrates by rf magnetron sputtering with and without oxygen flow. For Al-doped CdO films deposited with (without) oxygen flow, we measure the high (low) surface work function close to 5.4 (4.6)eV. Our results suggest a method for fabricating Al-doped CdO electrodes with large, tunable work functions that could be relevant in designing electrodes for improving the performance of optoelectronic and electronic devices.

Keywords: Oxide; Thin films; Surfaces; Optical properties; Work function

Microwave plasma induced grafting of oleic acid on cotton fabric surfaces by Luis Cabrales; Noureddine Abidi (pp. 4636-4641).

► Microwave Plasma induced grafting of oleic acid on cotton fabric surface. ► Super hydrophobic properties were obtained. ► The concentration of the oleic acid in the solution has an effect on the hydrophobictiy of the cotton fabric.Cotton fabric surface was successfully functionalized with microwave plasma (2.45GHz, 500W) to impart water repellency. The hydrophobic agent used was oleic acid (CH₃(CH₂)₇CHCH(CH₂)₇COOH), a fatty acid derived from various plant seed oils. Non-polymerizing gas (Argon) was used to create the plasma. The exposure of the cellulose to Ar-plasma generated radicals, which were subsequently used to initiate co-polymerization reactions with oleic acid. The FTIR spectra showed the presence of additional vibrations located at 2918, 2849, and 1707cm⁻¹ in the functionalized samples. Dynamic contact angle measurements were performed to assess the hydrophobic properties of the functionalized cotton fabric. The grafted cotton fabric showed excellent water repellency. In addition, the use of plant-derived monomers and biopolymers provides a different approach to use renewable resources to create functionalized biopolymeric substrates.

Keywords: Plasma; Cotton fabric; Surface functionalization; Hydrophobic; Contact angle; FTIR; Fatty acids; Oleic acid

Characterization of Si(111)3×3-(Au,In) surface by optical second-harmonic generation by K.V. Ignatovich; A.V. Zotov; A.A. Saranin (pp. 4642-4644).

► SHG technique is used to characterize structural transformations occurring at (Au,In)/Si(111) surface. ► Removal of domain walls results in an extraordinary high increase in the SHG signal. ► Growth of random In islands leads to rapid decrease of SHG signal. ► SHG intensity is shown to be highly sensitive to surface homogeneity both in atomic and mesascopic scales.We investigated the change of optical second harmonic generation (SHG) intensity in the course of Si(111)3×3-(Au,In) surface formation and during subsequent In island growth on this surface. The Si(111)3×3-(Au,In) surface is essentially a modified Si(111)- α-3×3-Au surface in which the domain-wall network (characteristic of the original surface) is completely eliminated due to In adsorption. This surface shows up as the one having homogeneous highly ordered atomic structure. Its formation is accompanied by the extremely high (namely, tenfold) increase of the SHG signal. It was recognized that this increase is associated with an extraordinary high long-range atomic ordering of the Si(111)3×3-(Au,In) surface, while its other peculiar features, developing the 2D electron gas system and occurrence of the 2D gas of mobile adatoms on it, produce minor effects. Growth of random In islands on Si(111)3×3-(Au,In) at RT In deposition leads to the decrease of SHG signal indicating its sensitivity to the surface inhomogeneity not only in atomic scale but in the mesascopic scale also.

Keywords: PACS; 68.43.Hn; 68.37.Ef; 68.43.BcAtom–solid interactions; Silicon; Indium; Gold; Surface structure, morphology, roughness, and topography; Second harmonic generation (SHG)

Effects of carbon concentration on properties of nano-diamond films by Qingfeng Su; Weimin Shi; Dongmin Li; Jianming Lai; Liwen Jiang; Linjun Wang; Weizhong Ding; Yiben Xia (pp. 4645-4648).

► Nano-diamond film is a suitable material to fabricate high performance electronic devices. ► Deposition process affects the microstructure and properties of nano-diamond film. ► Grain size and roughness of nano-diamond film decrease with the increase of carbon concentration.Nano-diamond films synthesized by chemical vapor deposition (CVD) have attracted a great deal of interest for their smooth surface. The work focuses on the carbon concentration of nano-diamond films deposition and its effects on the microstructure of films. Nano-diamond films were deposited by hot filament chemical vapor deposition (HFCVD) method and effects of carbon concentration on the microstructure of nano-diamond films were characterized using scanning electron microscope, atomic force microscope, Raman spectroscopy and X-ray diffraction (XRD). The results indicate that the grain size decreases from 90nm to 30nm, the roughness decreases from 52.3nm to 30.6nm, the line width of peaks of Raman and XRD becomes broader and the intensity ratio of diamond decreases with the increase of carbon concentration from 2% to 3%. The sp³ carbon phase decreases while the sp² carbon phase increases in nano-diamond films with the decrease of grain size, when the carbon concentration ratio increases.

Keywords: Nano-crystalline; CVD diamond; Thin film; Roughness; Grain size

Rapid biomimetic deposition of octacalcium phosphate coatings on zirconia ceramics (Y-TZP) for dental implant applications by Martin Stefanic; Kristoffer Krnel; Irena Pribosic; Tomaz Kosmac (pp. 4649-4656).

► Octacalcium phosphate coatings were succesfully synthesized on zirconia ceramics. ► The two-step synthesis procedure is simple and reproducible. ► Rapid deposition of coatings.Octacalcium phosphate (OCP) coatings on zirconia oral implants have a great potential to improve the osseointegration of already existing ceramic implants, owing to high osteoconductive characteristics of OCP and its possibility of use as a drug delivery system. Such OCP coatings can be prepared with a simple two-step biomimetic procedure investigated in our study. In the first step, zirconia discs were immersed into the solution with a pH 7.4 and after 1h of soaking a thin nanostructured calcium phosphate (Ca-P) layer was precipitated on the ceramic substrate via three stages: (i) precipitation of an amorphous Ca-P; (ii) precipitation of the OCP; and (iii) the transformation of the OCP to apatite. This Ca-P layer later served as a template for the rapid deposition of a thicker OCP coating in the second step of the synthesis where the substrate was immersed into the solution with pH 7.0. The main benefits of the method are a relatively quick synthesis, simplicity and a good reproducibility. Moreover, the coatings show good tensile adhesion strength according to the tape tests (ASTM D-3359). In addition, mild physiological conditions of the synthesis may allow incorporation of biologically active molecules in the coating.

Keywords: Zirconia ceramics; Octacalcium phosphate; Apatite; Bioactive coating; Biomimetic

Atomic layer deposition of ZnO on thermal SiO₂ and Si surfaces using N₂-diluted diethylzinc and H₂O₂ precursors by Ke-Jia Qian; Sun Chen; Bao Zhu; Lin Chen; Shi-Jin Ding; Hong-Liang Lu; Qing-Qing Sun; David Wei Zhang; Zhenyi Chen (pp. 4657-4666).

► ZnO nanodots were grown first on SiO₂ and Si surfaces by ALD. ► Influence of deposition-temperature and reaction-cycles on ZnO was studied. ► The mechanisms related to different ZnO morphologies were addressed. ► The composition and crystallinity of ZnO was characterized by XPS and XRD.ZnO nanodots are attracting more and more attention in various photoelectrical applications due to multiple excition generation. In this article, atomic layer deposition (ALD) growth of ZnO nanodots has been realized for the first time on both thermal SiO₂ and Si surfaces using N₂-diluted gaseous DEZn and H₂O₂ precursors. The experimental results indicate that the ALD ZnO exhibits a nano-crystalline film with corrugated surfaces in the case of the deposition temperature of 200°C, likely due to concrescence among ZnO nanodots. When the deposition temperature is increased up to 300°C, ZnO is grown in the form of well-discrete nanodots. This is due to increased desorption of the reacting molecules and a reduction of nucleation sites on the growing surfaces at 300°C, thus leading to the reaction between DEZn andOH groups only on some favorable sites from thermodynamic and energy points of view. In terms of the thermal SiO₂ surface, ZnO nanodots with a density of around 5×10¹⁰cm⁻² are obtained for 100 cycles. As for the Si surface, ZnO nanodots with a density as high as ∼1×10¹¹cm⁻² are achieved for 50 cycles. Finally, the X-ray photoelectron spectroscopy and X-ray diffraction analyses reveal that the ALD ZnO at 300°C is dominated by ZnO bonds together with a small quantity of ZnOH bonds, and the deposition temperature of 300°C can result in preferential growth of ZnO (002) orientation and a bigger crystallite size.

Keywords: ZnO; Nanodots; Nano-crystalline film; Atomic layer deposition (ALD)

Nano-TiO₂@Ag/PVC film with enhanced antibacterial activities and photocatalytic properties by Fajia Liu; Hu Liu; Xiaoyun Li; Huanyu Zhao; Danping Zhu; Yingying Zheng; Chaorong Li (pp. 4667-4671).

TiO₂ nanowire was firstly prepared by a hydrothermal method. Then Ag nanoparticles were grafted on the surface of TiO₂ nanowire evenly in solution. When doped with TiO₂@Ag, the antibacterial and photocatalytic properties of PVC film were investigated systematically.Display Omitted► A facial route to prepare nano-TiO₂@Ag/PVC film is developed. ► Silver nanoparticles were grafted on the surface of TiO₂ nanowire evenly. ► The antibacterial property of nano-TiO₂@Ag/PVC film was improved. ► The photocatalytic property of nano-TiO₂@Ag/PVC film was improved.The antibacterial and photocatalytic PVC film was prepared by doping heteronanostructure of TiO₂ nanowire@Ag nanoparticles. TiO₂ nanowire with 50–60nm in diameter and 0.1mm in length was prepared by a hydrothermal method, and Ag nanopartical about 5–10nm in diameter was grafted on the surface of TiO₂ nanowire evenly in the solution. The antimicrobial ability and the photocatalytic properties of the nano-TiO₂@Ag/PVC film were systematically investigated by changing the influence factors such as the content of nano-TiO₂@Ag, pH value and the cultivation condition. It confirmed that the nano-TiO₂@Ag nanostructure could increase the antibacterial efficiency of the PVC film. Further, nano-TiO₂@Ag/PVC film also showed enhanced photocatalytic activity to decompose Rhodmine B (RhB).

Keywords: Nano-TiO; ₂; @Ag; PVC composite film; Bactericidal activities; Photocatalytic properties

Spatial variation of the number of graphene layers formed on the scratched 6H–SiC(0001) surface by J. Osaklung; C. Euaruksakul; W. Meevasana; P. Songsiriritthigul (pp. 4672-4677).

► We investigate the epitaxial graphene grown on SiC. ► Spatial variation of the number of graphene layers is measured by a low-energy electron microscope. ► The number of graphene layers is greater near scratched areas of SiC substrate. ► The thicker graphene areas can also extend significantly away from the edges of the scratch. ► This finding can be implemented as an additional technique for spatially modulating graphene thickness.The unique properties of graphene can vary greatly depending on the number of graphene layers; therefore, spatial control of graphene thickness is desired to fully exploit these properties in promising new devices. Using low energy electron microscopy (LEEM), we investigate how scratches on the surface of 6H–SiC(0001) affect the epitaxial growth of graphene. Oscillations in the LEEM-image intensity as a function of electron energy (I–V LEEM analysis) show that the number of graphene layers clearly differs between regions of scratched and smooth substrate. The extent of the thicker graphene layers formed above scratches is found to be significantly larger than the width of the scratch itself. This finding can be implemented as an additional technique for spatially modulating graphene thickness.

Keywords: Epitaxial graphene; SiC; Low-energy electron microscopy; Substrate scratch

Surface modification and characterization of impregnated paper by Shaoxia Wang; Riitta Mahlberg; Otto-Ville Kaukoniemi; Juha Nikkola; Juha Mannila; Saila Jämsä; Anne-Christine Ritschkoff; Jouko Peltonen (pp. 4678-4686).

► We developed two silane-based nano-hybrid coatings to improve the water repellence of PF (phenolic resin) impregnated paper. ► We characterized the surface structure and chemistry of the sol–gel coatings on impregnated paper. ► We found the wettability and surface energy of impregnated paper were clearly reduced by the applied coatings.Two organic–inorganic hybrid sol–gel coatings were developed in order to modify the surface energy and moisture behaviour of the commercial impregnated paper. The surface characteristics of the paper samples were studied by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS). It was found that the applied sol–gel coatings as well as the curing process changed the surface structural and chemical properties of the impregnated paper. The chemical bonding between the hydroxyl groups present on paper surface and silanol groups from sol–gel coatings was confirmed by the FTIR spectra. The measured surface energies divided into polar and dispersive components indicated that the coating B resulted in less polar surface than did the coating A which was more polar than the reference (the impregnated paper with water and heat treatment). Coating B brought about the lowest total surface energy. It was obtained that the water repellence of the impregnated paper was improved by both coatings and the curing process.

Keywords: Impregnated paper; Sol–gel coating; Surface morphology; Surface chemistry; Surface energy; Water repellence

Influence of the surface chemistry on the nanotribological behaviour of (AFM tip/graphite) couples by Khalil Jradi; Marjorie Schmitt; Sophie Bistac (pp. 4687-4697).

► Bare AFM tip/graphite: friction is not modified by variations of scanning velocity. ► Same couple: a rise of the friction is noticed when the contact load increases. ► Chemically treated AFM tips: friction is smaller with a hydrophobic tip.The development of the nanotechnology has made essential the knowledge of the tribological behaviour of carbonaceous materials, and more particularly of graphite. Atomic force microscopy (AFM) is thus used to study the friction properties at this nanoscopic scale. In this work, results concerning the friction of AFM tips against graphite pins are presented, with a particular emphasis on the effect of the chemical modification of these tips on the tribological behaviour of graphite.

Keywords: Surface chemistry; Nanofriction; Graphite

Effect of moderately high temperature heat treatment on surface morphology and structure of quartz fibers by Yu Zheng; Shubin Wang (pp. 4698-4701).

► Nanometer crystallites are detected on heated fiber surface. ► The structure translation causes further decrease of fiber tensile strength. ► Effect of heat-treatment at 600–900°C on quartz fibers strength is researched.In this study, quartz fibers were heated at 600°C, 700°C, 800°C and 900°C for 10h respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and fiber tensile test were employed to examine the surface morphology, structure and tensile strength of quartz fibers. The SEM images indicated that when fibers were heated up to 600°C, dot flaws appeared on fiber surface and when the temperature reached 700°C, new strip flaws appeared on the fiber surface. HR-TEM images showed that when fibers were heated up to 700°C, some ordered regions (nanometers) appeared on the fiber surface. Furthermore, the nanometer crystallites were found on fiber surface when fibers were heated at 900°C. The defects on fiber surface, according to fiber tensile test, had a significant effect on mechanical property of quartz fibers and caused drastic reduction in fiber tensile strength. It is considered that the mismatch between the ordered regions and amorphous regions induced new defects on fiber surface, which led to further decrease of fiber tensile strength.

Keywords: Quartz fibers; Surface crystallization; Heat treatment; Tensile strength

Effect of post-etch cleaning on Ru-capped extreme ultraviolet lithography photomask by Jisook Oh; Chanhyoung Park; Dongwan Seo; Juneui Jung; Sangwoo Lim (pp. 4702-4706).

► Formation of RuCl₃ on the Ru surface after Cl₂ etching. ► Increases in Ru surface roughness after Cl₂ etching. ► Removal of Cl and recovery of surface roughness after ozonated water cleaning.Ru-capped extreme ultraviolet lithography photomasks require cleaning after patterning of the absorber layer. In this study, it was confirmed that, during Cl₂ dry etching to remove the absorber layer, RuCl₃ was formed on the Ru capping layer surface, and the surface roughness thereby deteriorated. Therefore, the changes in RuCl₃ formation and surface roughness with various cleaning processes were investigated. Among the treatments used, i. e., sulfuric peroxide mixture, an ammonia peroxide mixture or ozonated water (DIO₃), DIO₃ exhibited the most effective Cl removal efficiency and surface roughness recovery. DIO₃ treatment successfully reduced the Cl-terminated Ru surface to its original state and decreased the surface roughness to the pre-Cl₂-etched Ru value.

Keywords: EUV; Photomask; Etching; Surface; Cleaning; Roughness

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane surface with stably anti-protein-fouling performance via a two-step surface polymerization by Qian Li; Qiu-Yan Bi; Bo Zhou; Xiao-Lin Wang (pp. 4707-4717).

Display Omitted► We modified the PVDF membrane with a zwitterionic polymer via a two-step polymerization. ► The cross-linking agent EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. ► The surface hydrophilicity of the PVDF membranes was signiﬁcantly enhanced. ► The extent of protein fouling was significantly reduced and most of the fouling was reversible. ► The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process.A zwitterionic polymer, poly(3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (poly(MPDSAH)) was successfully grafted in high density from the surface of poly(vinylidene fluoride) (PVDF) hollow fiber membrane via a two-step polymerization. Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) chains were firstly grafted from outside surface of PVDF membrane through atom transfer radical polymerization (ATRP) to provide the initiation sites for subsequent cerium (Ce (IV))-induced graft copolymerization of polyMPDSAH in the presence of N,N′-ethylene bisacrylamide (EBAA) as a cross-linking agent. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) confirmed that the EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. The dense poly(MPDSAH) layers on the PVDF membrane surface were revealed by the scanning electron microscope (SEM). The mechanical property of PVDF membrane was improved by the zwitterionic surface layers. The gravimetry results indicated the grafting amount increased to 520μg/cm² for a copolymerization time of more than 3h. Static and dynamic water contact angle measurements showed that the surface hydrophilicity of the PVDF membranes was significantly enhanced. As the grafting amount reached 513μgcm⁻², the value of contact angle dropped to 22.1° and the amount of protein adsorption decreased to zero. The cyclic experiments for BSA solution filtration demonstrated that the extent of protein fouling was significantly reduced and most of the fouling was reversible. The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process. The experimental results concluded a good prospect in obtaining the sulfobetaine-modified PVDF membranes with high mechanical strength, good anti-protein-fouling performance, and long-term stability via the two-step polymerization.

Keywords: Poly(vinylidene fluoride) membrane surface; Zwitterionic polymer; Two-step polymerization; Anti-protein-fouling performance; Mechanical property; Stability

Promoted cell and material interaction on atmospheric pressure plasma treated titanium by Inho Han; Barbora Vagaska; Hyok Jin Seo; Jae Kyeong Kang; Byeong-Ju Kwon; Mi Hee Lee; Jong-Chul Park (pp. 4718-4723).

Helium atmospheric pressure plasma treatment modified titanium surface which became super-hydrophilic. The cell adhesive protein, fibronectin, adsorption increased on the modified surface. Cytoskeleton development and proliferation of osteoblast cells were also enhanced.Display Omitted► Helium atmospheric pressure plasma treatment was performed on titanium specimens. ► Fibronectin adsorption increased. ► Attached cells were well spread and polygonal shaped with developed actin cytoskeleton. ► Proliferation of the cells was promoted. ► The plasma treatment enhanced biological responses on the treated titanium surface.Surface carbon contamination is a natural phenomenon. However, it interferes with cell–biomaterial interaction. In order to eliminate the interference, atmospheric pressure plasma treatment was employed. Dielectric barrier discharge treatment of titanium surface for less than 10min turned titanium super-hydrophilic. Adsorption of fibronectin which is the major cell adhesive protein increased after plasma treatment. Cell attachment parameters of osteoblast cells such as population, cell area, perimeter, Feret's diameter and cytoskeleton development were also enhanced. Cell proliferation increased on the plasma treated titanium. In conclusion, dielectric barrier discharge type atmospheric pressure plasma system is effective to modify titanium surface and the modified titanium promotes cell and material interactions.

Keywords: PACS; 52.80.Hc; 81.65.Cf; 81.17.Rt; 87.85.J−Dental implant; Plasma; Atmospheric pressure; Surface modification; Osteoblast

Corrosion behavior of superhydrophobic surfaces of Ti alloys in NaCl solutions by Junfei Ou; Mingzhi Liu; Wen Li; Fajun Wang; Mingshan Xue; Changquan Li (pp. 4724-4728).

► SHS possesses better corrosion resistance. ► A barrier layer of TiO₂ has been generated under the treatment of H₂O₂. ► SHS on HF/H₂O₂ possesses high corrosion durability.Superhydrophobic surfaces (SHS) are successfully prepared by 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane (coded as PFOTS) chemically and physically adsorbed onto the etched Ti alloy substrate. The film formation and its structures are characterized by the measurements of water contact angle (WCA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the SHS in the NaCl solutions is investigated using the potentiodynamic polarization. The results show that the corrosion resistance of the substrate is improved greatly due to the composite wetting states or interfaces with numerous air pockets between SHS and NaCl solutions. Moreover, it is found that the stability and corrosion resistance of SHS is influenced greatly by the interfacial bonding between PFOTS and the substrate. The strong chemical interfacial bonding (i.e., TiOSi) between PFOTS and the oxidized titanium substrate accounts for a higher stability and much lower corrosion current density as compared by SHS with physically adsorbed PFOTS outerlayer.

Keywords: Superhydrophobicity; Ti alloy; Corrosion

The study of multi-walled carbon nanotubes with different diameter as anodes for lithium-ion batteries by Yanping Zhang; Taiqiang Chen; Jinhe Wang; Guoquan Min; Likun Pan; Zhitang Song; Zhuo Sun; Weimin Zhou; Jing Zhang (pp. 4729-4732).

► The excellent electrochemical performance verifies the feasibility of MWCNTs as a promising candidate for the anode of LIBs. ► The variation of pore structure has a large impact on the electrochemical and energy storage characteristics. ► MWCNTs with a diameter of 40–60nm display the highest specific capacity and good cyclability.Multi-walled carbon nanotubes (MWCNTs) with different diameter range are employed as the anode materials in lithium-ion batteries (LIBs). The influence of diameter and pore structure on the electrochemical behavior of MWCNTs has been investigated by characterization of morphology and structure, nitrogen adsorption and desorption measurement, charge/discharge tests, and electrochemical impedance spectroscopy (EIS). The results show that MWCNTs with a diameter of 40–60nm display the highest specific capacity (187.4mAhg⁻¹ at the charge/discharge rate of 50mAg⁻¹) and good cyclability (101.9% Coulomb efficiency after 50 cycles). The excellent electrochemical performance verifies the feasibility of MWCNTs as a promising candidate for the anode of LIBs.

Keywords: Multi-walled carbon nanotubes; Lithium-ion batteries, Anode

Superior high-temperature oxidation resistance of a novel (Al₂O₃–Y₂O₃)/Pt laminated coating by Xiaoxu Ma; Yedong He; Deren Wang; Jin Zhang (pp. 4733-4740).

► A 7-layer (Al₂O₃–Y₂O₃)/Pt laminated coating was successfully prepared. ► The laminated coating provides excellent high-temperature oxidation resistance. ► The multi-sealed Pt layers effectively suppress the inward diffusion of oxygen. ► The laminated coatings exhibit excellent thermal shock resistance. ► The brittle/ductile laminated structure provides enhanced fracture toughness.A 7-layer (Al₂O₃–Y₂O₃)/Pt laminated coating was successfully prepared on a Ni-based superalloy by magnetron sputtering methods. It is observed that the as-prepared coating has dense and refined brittle/ductile laminated nanostructure. Cyclic oxidation tests were adopted to investigate the oxidation and spallation resistance of this novel laminated coating. The results revealed that the 7-layer (Al₂O₃–Y₂O₃)/Pt laminated coating can significantly improve the high-temperature oxidation resistance and spallation resistance of the Ni-based superalloy. In such laminated coating, the multi-sealed (Al₂O₃–Y₂O₃) and Pt layers can effectively suppress the inward diffusion of oxygen to an extremely low level, providing super oxidation resistance at 1200°C for 1000h. In addition, the excellent high-temperature mechanical properties of the (Al₂O₃–Y₂O₃)/Pt laminated coating are mainly induced by the increased thermal expansion coefficient and the brittle/ductile laminated composite structure by means of energy release mechanisms.

Keywords: Platinum; Ni-based superalloy; Magnetron sputtering; High-temperature oxidation; Thermal cycling

Modeling validity of femtosecond laser breakdown in wide bandgap dielectrics by Xufeng Jing; Ying Tian; Junchao Zhang; Shunli Chen; Yunxia Jin; Jianda Shao; Zhengxiu Fan (pp. 4741-4749).

► We report the modeling validity of optical field ionization and avalanche ionization on the femtosecond pulse breakdown in wide bandgap dielectrics. ► Also, a review of experimental and theoretical results published on this related topic is demonstrated.In order to accurately calculate the femtosecond laser breakdown threshold of wide band-gap dielectrics using the photoionization and avalanche ionization theories, the applied range of these classical methods is demonstrated quantitatively by the comparison of the calculated results with the available experimental data. It is found that these standard theories to estimate laser ablation threshold are valid when the laser pulse duration is less than about 600fs and the laser wavelength is more than around 400nm. Besides, we demonstrate that the multi-photon ionization of wide band-gap dielectrics is the dominant breakdown mechanism when the laser wavelength is at the region of 0.4μm<λ<1.3μm. But the tunneling ionization mechanism performs a significant role when the laser wavelength is at the range of λ<1.3μm. Based on our calculation, we found that a valence band (VB) electron can absorb simultaneously the greatest number photons of ten in the multiphoton ionization process. Furthermore, it is revealed that the photoionization in dielectrics ionization process can provide seed electrons even at the pulse duration down to sub-10fs.

Keywords: OCIS; 320.2250; 320.7110; 140.3440Keyword; Femtosecond laser breakdown

Hot-filament chemical vapor deposition of amorphous carbon film on diamond grits and induction brazing of the diamond grits by Bojiang Ma; Qingxian Yu (pp. 4750-4755).

► Hot-filament CVD for deposition amorphous carbon film on diamond grits. ► The deposited diamond grits were induction-brazed using NiCr alloy. ► The deposited diamond grits protruding from the filler alloy maintain good sharpness. ► The film enhances bonding strength between the filler alloy and diamond grits.The production of a high-quality brazed diamond tool has gradually drawn the attention of the tool industry. Hot-filament chemical vapor deposition (CVD) of amorphous carbon film on diamond grits was conducted. The deposited diamond grits were used to make brazed diamond tools by induction heating. Amorphous carbon film (1–2μm thick) was deposited onto the diamond surface. The diamond grits protruding from the filler alloy maintain their sharpness after induction brazing of the deposited diamond grits. Discontinuous irregular carbides are distributed evenly on the brazed diamond surface in the filler alloy. This considerably enhances the bonding strength between the filler alloy and diamond grits. Grinding tests of the brazed diamond wheels show a low percentage of pullouts from the matrix and whole grain fracture for the deposited diamond grits brazed by induction heating.

Keywords: Diamond; Hot-filament chemical vapor deposition; Induction brazing; Sharpness; Bonding strength; Chromium carbide

Preparation of mesoporous MnO₂/C catalyst for n-hexyl acetate synthesis by Zeheng Yang; Yanmei Pan; Zhousheng Mei; Weixin Zhang (pp. 4756-4763).

Display Omitted► A MnO₂/C composite with spherical morphology was prepared via a wet impregnation coupled with a redox process. ► The MnO₂/C composite has mesoporous structures with high specific surface area. ► The mesoporous MnO₂/C showed high catalytic activity to n-hexyl acetate synthesis.A mesoporous MnO₂/C composite was prepared by impregnating self-made porous carbon spheres with manganese nitrate aqueous solution and subsequently reacting with KMnO₄ aqueous solution. It was characterized with X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), the Brunauer–Emmett–Teller (BET) surface area and the Barrett–Joyner–Halenda (BJH) pore size distribution. The as-prepared mesoporous MnO₂/C composite was used as catalyst for the synthesis of n-hexyl acetate, and the effects of MnO₂ loading and esterification reaction parameters on the esterification rate were investigated. The results prove that MnO₂ loading has a significant effect on the catalytic activity and that the mesoporous MnO₂/C composite exhibits high catalytic activity with an esterification rate of 96.42% under the conditions below: MnO₂ loading (73.09wt%), catalyst dosage (0.1% in total weight), acetic acid/n-hexanol molar ratio (2:1), reaction temperature (130°C) and reaction time (5h).

Keywords: Mesoporous MnO; ₂; /C; Esterification; Catalyst; n-Hexyl acetate

Surface morphology, structure, magnetic and electrical transport properties of reactive sputtered polycrystalline Ti1−_xFe_xN films by X.C. Wang; W.B. Mi; G.F. Chen; X.M. Chen; B.H. Yang (pp. 4764-4769).

Display Omitted► The lattice orientation changes from (200) to (111) with the increasing x. ► All of the films are ferromagnetic with a Curie temperature of higher than 305K. ► Asymmetric M– H curves have been observed at low temperatures, and the shift of the M– H curves decreases with the increase of temperature. ► All of the samples show semiconducting-like behavior with a mechanism of variable-range hopping at low-temperature range.Polycrystalline Ti1−_xFe_xN films with different Fe atomic fractions ( x) were fabricated by reactive facing-target sputtering. The lattice orientation changes from (200) to (111) with the increase of x, which makes the surface morphology evolve from spherical, triangular-pyramid-like islands to random-leafs-like ones. The films are ferromagnetic with a Curie temperature of higher than 305K, and the saturation magnetization ( M_s) is very small. Obvious asymmetric M– H curves are observed at low temperatures, and the shift of M– H curves decreases with the increasing temperature because of the relaxation of the pinned moments at low temperatures. All of the samples show semiconducting-like behavior with a mechanism of variable-range hopping at low-temperature range. Magnetoresistance (MR) is very small. The small M_s and MR can be explained by the facts that the interaction between Fe³⁺–N³⁻–Fe³⁺ is antiferromagnetic superexchange coupling, and no double exchange exists in Fe³⁺–N³⁻–Ti³⁺, which is different from that in the Cr-doped TiN films.

Keywords: PACS; 75.47.−m; 75.50.Cc; 75.70.−i; 75.50.PpMetal nitride; Microstructure; Magnetic properties; Magnetoresistance

Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers by Ivan L. Stefanov; Georgi B. Hadjichristov (pp. 4770-4776).

Display Omitted► The non-local response of Si ion implanted PMMA is interferometrically characterized. ► The light-absorbing ion-implanted surface layer is examined in reflection geometry. ► Laser pump-probe technique reveals strong laser-induced thermooptic effect. ► The material in the near-surface region exhibits a large thermal non-linearity. ► A strongly expressed non-locality in the millimeter scale is found.Optical interferometric technique is applied to characterize the nonlocal response of optically transparent ion implanted polymers. The thermal nonlinearity of the ion-modified material in the near-surface region is induced by continuous wave (cw) laser irradiation at a relatively low intensity. The interferometry approach is demonstrated for a subsurface layer of a thickness of about 100nm formed in bulk polymethylmethacrylate (PMMA) by implantation with silicon ions at an energy of 50keV and fluence in the range 10¹⁴–10¹⁷cm⁻². The laser-induced thermooptic effect in this layer is finely probed by interferometric imaging. The interference phase distribution in the plane of the ion implanted layer is indicative for the thermal nonlinearity of the near-surface region of ion implanted optically transparent polymeric materials.

Keywords: Ion implanted polymers; Interferometry; Optical phase shift; Photo-thermooptic effect; Polymethylmethacrylate (PMMA); Materials science

Fractal characterization of impact fracture surface of steel by Wei Tang; Yong Wang (pp. 4777-4781).

► The impact fractures have fractal properties. ► Taking boundary to the feature parts of the binary image can increase the accuracy of the fractal dimension. ► Fractal dimension can be a parameter to reflect the roughness of the impact fracture and the fracture mechanism.The fracture surfaces have self-similar properties and are mostly expressed in the form of two-dimensional digital image. In this paper, a pixel-covering method is applied and an improvement is made to research the fractal characterization of the steel impact fracture surface. The results show that taking boundary to the feature parts of the gray image can increase the accuracy of the fractal dimension. The linearity of the fractal dimension curves of impact fractures is obvious, indicating the impact fractures have fractal properties and the pixel-covering method can describe it. Fractal dimension can be a parameter reflecting the roughness of the impact fracture surface. Rougher the surface is, the higher is the fractal dimension. There is a positive correlation between the fractal dimension of the impact fracture and the toughness of the material. It would be possible to establish a quantitative correlation between fractal dimension, surface roughness, impact toughness, and fracture mechanism, which presents a good potential to material and failure analysis of material.

Keywords: Fractal; Pixel-covering method; Morphology; Impact fracture

Palladium-free catalytic electroless copper deposition on bamboo fabric: Preparation, morphology and electromagnetic properties by Yinxiang Lu; Qian Liang; Longlong Xue (pp. 4782-4787).

► Palladium-free catalytic electroless copper deposition on bamboo fabric. ► Thiol group grafted on bamboo fabric via surface modification. ► High adhesion strength of copper coating on bamboo fabric. ► Good electrical conductivity and EMI shielding property of the composite.Bamboo fabric is subjected to solvent treatment with 3-mercaptopropyltrimethoxysilane (MPTS) before metal deposition. Raman and IR analyses indicate that MPTS is successfully grafted on the fabric. Copper is deposited on the pretreated fabric by a palladium-free catalytic electroless process, and then copper/bamboo fabric (Cu/BF) composite is obtained. SEM (scanning electron microscopy) observation reveals that copper is uniformly covered on the fabric. Chemical composition and crystal structure of the composite are detected by EDX (energy-dispersive X-ray analysis), XPS (X-ray photoelectron spectroscopy) and XRD (X-ray diffraction) measurements, peaks for Cu⁰ are found in these patterns. The water absorption ratio for the title composite is about 162% by immersion in water, or 8.9% by putting in an environmental condition (humidity of 65±2%). The Cu/BF composite is firm and can pass a Scotch^®-tape peel adhesion test. The electromagnetic interference (EMI) shielding effectiveness (SE) of the composite (copper on fabric: 39g/m²) is more than 48dB at frequency ranging from 0.2 to1000MHz.

Keywords: Copper/bamboo fabric composite; Electroless deposition; Palladium-free; Electromagnetic

Synthesis of a super-hydrophilic conducting polyaniline/titanium oxide hybrid with a narrow pore size distribution by Xingwei Li; Zhun Wang; Xiaohan Li; Gengchao Wang (pp. 4788-4793).

► A super-hydrophilic conducting polyaniline/titanium oxide hybrid was synthesized by a hydrolysis and condensation process of tetrabutyl titanate on the surface of polyaniline. ► This hybrid powder can be easily dispersed in the aqueous solution without any dispersants. ► The conductivity of polyaniline/titanium oxide hybrid is 0.25Scm⁻¹ at 25°C, and shows a good electrochemical performance in the electrolyte solution of pH 1.0–7.0 ► BET specific surface area of this hybrid is 171.7 m²g⁻¹, and 98% of contribution to specific surface area comes from the pores of 2–5nm.A super-hydrophilic conducting polyaniline/titanium oxide hybrid with a narrow pore size distribution, which has a conductivity of 0.25Scm⁻¹ at 25°C, has been prepared by a hydrolysis and condensation process of tetrabutyl titanate on the surface of polyaniline. This hybrid powder can be easily dispersed in the aqueous solution without any dispersants. The electrochemical investigation indicates that the electrochemical activity of polyaniline/titanium oxide hybrid is extended to a neutral electrolyte solution, and shows good electrochemical cycling stability even in the electrolyte solution of pH 5.0. Moreover, Brunauer–Emmett–Teller (BET) specific surface area of this hybrid is 171.7m²g⁻¹, and 98% of the contribution to specific surface area comes from the pores of 2–5nm. This work not only solves the problems of processing conducting polyaniline in aqueous media, but also explores a simple method to synthesize porous conducting polyaniline/inorganic hybrids with a narrow pore size distribution.

Keywords: Polyaniline; Titanium oxide; Hybrid; Super-hydrophilic; Pore size distribution

The deposition of a thick tetrahedral amorphous carbon film by argon ion bombardment by Han Liang; Liu Delian; Chen Xian; Yang Li; Zhao Yuqing (pp. 4794-4800).

► Ar ion is used to bombard tetrahedral amorphous carbon (ta-C) films. ► sp² bonds and sp² clustering of ta-C film are increased by the Ar ion bombardment. ► The soft top layer and the hard bulk are formed in the ta-C film bombarded by Ar ion. ► The multilayer thick ta-C film can be deposited.The argon (Ar) ion bombardment is used in the deposition of a thick multilayer tetrahedral amorphous carbon (ta-C) films. The bonding structure and surface morphology of the ta-C films are modified when the films are bombarded by Ar ion with different energy. Visible Raman spectroscopy and X-ray photoelectron spectroscopy is used to study the modification respectively. The results show that surface layer is etched, the bonding structure of the films is totally modified, and some sp³ bonds convert to sp² bonds in the surface layer of the films. The sp² cluster of the bulk increases with the increment of Ar ion energy. Hence, a soft top layer on the films is formed and the stress of the bulk is released. The RMS of roughness and etching pits on the surface of films were increased with the increment of the bombarding energy of Ar ion, which can increase the adhesion between layers. These are very important to deposit thick ta-C film. The surface morphology is tested by AFM. The RMS roughness of thick ta-C film is about 0.54nm. Using visible Raman spectroscopy, the sp³ fraction of as-deposited ta-C film with 1μm thickness is estimated to be about 70%.

Keywords: Tetrahedral amorphous carbon; Ar ion bombardment; Raman spectroscopy; X-ray photoelectron spectroscopy

Hydroxyapatite supported Ag₃PO₄ nanoparticles with higher visible light photocatalytic activity by Xiaoting Hong; Xiaohui Wu; Qiuyun Zhang; Mingfeng Xiao; Gelin Yang; Meirong Qiu; Guocheng Han (pp. 4801-4805).

Schematic drawing of photocatalytic degradation of dye on hydroxyapatite supported Ag₃PO₄.Display Omitted► Hydroxyapatite supported Ag₃PO₄ nanocomposites were synthesized by a wet impregnation process. ► UV–vis absorption spectra show a red shift of the absorption edge for the composites. ► The photocatalyst showed a pronounced photocatalytic activity. ► A synergic mechanism is proposed for the enhancement of photocatalytic performance.Hydroxyapatite supported Ag₃PO₄ nanocomposites have been synthesized by a wet impregnation process. UV–vis absorption spectra show a red shift of the absorption edges for the composite systems compared to pure hydroxyapatite support. The surface structure and morphology of the nanocomposites were characterized by Brunauer–Emmett–Teller (BET) apparatus, X-ray diffraction (XRD), transmission electron microscopy (TEM). The results suggest that Ag₃PO₄ nanoparticles (6–17nm in diameter) are well dispersed on the hydroxyapatite support and Ag₃PO₄ nanoparticles density is larger for the higher Ag⁺ loading sample. The as-prepared nanocomposite photocatalysts showed a pronounced photocatalytic activity upon decomposition of methylene blue dye in aqueous solution under both visible light (wavelength>400nm) and UV–vis light irradiation. A synergic mechanism of inherent photocatalytic capability of Ag₃PO₄ and the accelerated electron/hole separation resulting from the photoinduced electrons captured by the slow-released Ag⁺ at the interface of Ag₃PO₄ and hydroxyapatite is proposed for the nanocomposites on the enhancement of photocatalytic performance in comparison to that of pure Ag₃PO₄ nanoparticles. The support of hydroxyapatite may also act as an absorbent which favors the mass transfer in heterogeneous photocatalysis reaction.

Keywords: Hydroxyapatite supported Ag; ₃; PO; ₄; Photocatalysis; Synergic mechanism; Pronounced photocatalytic activity

Tuning electronic structure and photocatalytic properties by Ag incorporated on (001) surface of anatase TiO₂ by Yingtao Zhu; Wei Wei; Ying Dai; Baibiao Huang (pp. 4806-4812).

► The adsorbed Ag plays as an electron trapping center on TiO₂ (001) surface. ► The adsorptional Ag can be responsible for the visible light absorption peak. ► The substitutional Ag can suppress the recombination of photo-generated carriers. ► The interstitial Ag can also act as electron trapping center. ► Ag can improve the photocatalytic efficiency of TiO₂ (001) surface.The incorporation of Ag on (001) surface of anatase TiO₂ has been systematically investigated by means of density functional theory to understand the Ag effects on the electronic structure and photocatalytic properties in Ag/TiO₂ composites. Several possible adsorptional, substitutional and interstitial sites with two different Ag concentrations at surface and subsurface layers are examined. Our results about stability of various Ag-incorporated (001) surfaces indicate that the adsorption site is favorable neglect of the oxygen conditions and the substitution site becomes more stable under the oxygen-rich condition, but it becomes difficult to incorporate Ag onto the surface with high concentration, especially for substitution sites in the limited range of oxygen chemical potential. The adsorption of Ag introduces gap states near or below the conduction band minimum (CBM) and the Fermi level locates near or in the conduction band, which can act as photo-generated electron trap centers and inhibit the recombination of electron–hole pairs. The electron transitions from the impurity level to the level above the Fermi level may be responsible for the small visible light absorption peak in experiment. Substitution Ag introduces some localized gap states, while the Fermi level is pinned near the top of valence band, and the impurity states can trap the hole to suppress the recombination of photo-generated carriers. For the interstitial Ag in surface, the Fermi level locates at the bottom of conduction band, and the partial occupied states may also act as electron trap centers which can improve the photocatalytic efficiency.

Keywords: Anatase titania (0; 0; 1) surface; Density functional theory; Electronic structure; Photocatalytic properties

Application of the storing matter technique to the analysis of boron doped and implanted SiO₂/Si by C. Mansilla; T. Wirtz (pp. 4813-4818).

► Storing matter is a novel technique that avoids the matrix effect during SIMS analyses. ► Its efficacy is compared with traditional SIMS for a Boron-implanted silicon sample with native oxide at the surface. ► Improved intensity and concentration depth profiles are obtained.The storing matter technique is a new analytical technique which has been developed to avoid the matrix effect observed in secondary ion mass spectrometry. This new technique gives the possibility of decoupling the sputtering step from the subsequent analysis step by SIMS. During the sputtering the emitted matter is deposited on a well known collector. Since the matter sputtered from different samples or layers is deposited on the same virgin collector, it makes the quantification easier and more accurate.In order to study the efficacy of this technique, storing matter depth profiles are compared with traditional SIMS depth profiles for a boron implanted SiO₂/Si. A boron-doped sample was used as a reference. The traditional SIMS depth profile for the implanted sample shows two peaks caused by the matrix effect, an initial sharp peak due to native SiO₂ at the surface, and an additional broad peak due to the high concentration of¹¹B at 400nm below the surface. In contrast, the reconstructed depth profile by storing matter shows that those matrix effects can be eliminated, therefore avoiding problems of quantification.

Keywords: SIMS; Storing matter technique; Matrix effect; Quantification; Boron

Separation of methane–nitrogen mixtures using synthesis vertically aligned carbon nanotube membranes by Neda Gilani; Jafar Towfighi Daryan; Alimorad Rashidi; Mohammad Reza Omidkhah (pp. 4819-4825).

Display Omitted► Synthesis of vertically aligned carbon nanotube membranes with different CNT inner diameters via a simple CVD method. ► Separation of methane from binary mixtures of CH₄/N₂ using vertically aligned carbon nanotube membranes. ► Achievement of higher permeability for N₂ single gas compared to Knudsen permeability.In this paper, capabilities of carbon nanotube (CNT) membranes fabricated in cylindrical pores of anodic aluminum oxide (AAO) substrate to separate the binary mixtures of CH₄/N₂ are studied experimentally. For this purpose, the permeability and selectivity of three CNT/AAO membranes with different growth time as 6h, 12h and 18h are investigated. CNTs are grown vertically through holes of AAO with average pore diameter of 45nm by chemical vapor deposition (CVD) of acetylene gas. CNT/AAO membranes with the same CNTs’ outer diameters and different inner diameters are synthesized. The AAO are characterized by SEM analysis. In addition, SEM, TEM, BET N₂ adsorption analysis and Raman spectroscopy are employed to characterize aligned CNTs. Study on permeability and selectivity of membranes for three binary mixtures of CH₄/N₂ showed that when the CNT inner diameters are 34nm and 24nm, viscous flow is the governing mechanism and insignificant selectivities of 1.2–1.24 are achieved. However, the membrane with CNT inner diameter and wall thickness of 8nm and 16nm respectively is considerably selective for CH₄ over N₂. It was also found that CH₄ mole fraction in the feed and upstream feed pressure have major effect on permeability and selectivity. The membrane with 18h synthesis time showed the selectivity is in the range of 1.8–3.85. The enhancement factor for N₂ single gas diffusivity was also found to be about three times larger than that predicted by Knudsen diffusion model.

Keywords: Carbon nanotubes; Anodic aluminum oxide; Gas separation; CH; ₄; /N; ₂; mixture

Dissociation behavior and structural of ilmenite ore by microwave irradiation by Guo Chen; Jin Chen; Shenghui Guo; Jun Li; C. Srinivasakannan; Jinhui Peng (pp. 4826-4829).

In this study, the influences of microwave irradiation on the dissociation behavior and structural characterization of ilmenite ore were systematically investigated. The crystal structures, microstructure, and surface chemical functional groups of the samples were characterized before and after microwave irradiation using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR), respectively. Treatment variables, microwave power and exposure time, had statistically significant effects on the dissociation behavior and structural characterization of ilmenite ore. The XRD, SEM and FT-IR analysis results indicated that the crystal structures, microstructure, and surface chemical functional groups of microwave treated ilmenite ore are better than those of ilmenite ore.

Keywords: Microwave irradiation; Ilmenite ore; Crystalline compound; Surface chemical functional groups; Microstructure

Electrochemical behaviour of anodic zirconium oxide nanotubes in simulated body fluid by Lu-Ning Wang; Jing-Li Luo (pp. 4830-4833).

► Electrochemical behaviour of anodic zirconium dioxide nanotubes in simulated body fluid is firstly reported. ► Corrosion resistance was higher on annealed ZrO₂ nanotubes than as-formed ZrO₂ nanotubes and conventional Zr. ► EIS studies indicated that annealed nanotubes favored an effective passivation. ► A two layer equivalent circuit can be used as a model to interpret the surface layer properties of anodic ZrO₂ nanotubes. ► Annealing appears to stabilize ZrO₂ nanotubes for biomedical applications.Herein we report for the first time electrochemical behaviour of anodic zirconium dioxide nanotubes in simulated body fluid (SBF) using open circuit potentials, potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS). The data show that ZrO₂ nanotubes enhance the stability of Zr-containing metals. Potentiodynamic polarization studies showed that the corrosion resistance was higher for heat treated nanotubes than for as-formed nanotubes and conventional materials. EIS studies indicated that annealed nanotubes favoured an effective passivation. A two layer equivalent circuit can be used as a model to interpret the surface layer properties of Zr with ZrO₂ nanotubes. Annealing appears to stabilize ZrO₂ nanotubes for biomedical applications.

Keywords: Zirconium oxide; Nanotube; Anodization; Polarization; EIS; Simulated Body Fluid

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Applied Surface Science (v.258, #10)

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Applied Surface Science (v.258, #10)