Use of silane coupling agent for surface modification of zinc oxide as inorganic filler and preparation of poly(amide-imide)/zinc oxide nanocomposite containing phenylalanine moieties

A series of novel poly(amide?Cimide)/ZnO nanocomposites with modified ZnO nanoparticles contents was prepared by ultrasonic irradiation. For this purpose, surface of ZnO nanoparticle was modified with $\boldsymbol\gamma$ -aminopropyltriethoxysilane as a coupling agent. Then the effect of surface modification on dispersion of nanoparticles, thermal stability and UV absorption property of the obtained nanocomposites were investigated. The resulting novel nanocomposites were characterized by several techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses of the nanocomposites were performed in order to study the dispersion of nanofillers in the polymer matrix. According to thermogravimetry analysis results, the addition of ZnO nanoparticles improved thermal stability of the obtained nanocomposites. Since the resulting nanocomposites contain phenylalanine amino acid and ZnO, they are expected to be biocompatible as well as biodegradable.     

表面改性方式对纳米氧化锌紫外吸收性能影响研究

纳米氧化锌是一种重要的无机紫外吸收剂,在应用时需要对其进行表面改性和分散,本文研究了不同的改性方式对纳米氧化锌紫外吸收性能的影响,分析研究了其不同的改性机理.结果表明原位改性是一种较好的改性方式,但对纳米氧化锌的外观形貌产生了影响,主要原因是聚乙二醇作为模板剂和表面活性剂影响了其前驱体氢氧化锌的形貌,而纳米氧化锌粉体表面改性是通过聚乙二醇的空间位阻作用使纳米氧化锌分散程度提高.使用同一种改性剂对纳米氧化锌原位改性和对纳米氧化锌粉体改性,对其紫外吸收性能没有大的影响.     

The use of silane silicon dioxide films to contour oxide edges

This paper demonstrates the use of silane silicon dioxide films to obtain controlled contours of oxide steps. In particular, the etch properties of composite oxide films are adjusted by controlling the amount of boron or phosphorous in chemically vapor deposited silane silicon dioxide films. The dependence of etch rate on impurity concentration is presented. Using the etch rate data, specific examples of composite oxide films are fabricated and the profiles after etching are examined by use of the scanning electron miscoscope.     

Electrical properties of polycrystalline silicon and zinc oxide semiconductors

Polycrystalline silicon and zinc oxide ceramic are important electronic materials. The electrical properties which determine the applications of polycrystalline silicon in integrated circuits and solar cells and that of ZnO ceramic in varistors are due primarily to grain boundary effects in them. A large amount of information in this area has already been gathered in literature but the quantitative understanding of grain boundary effects in these materials is not yet complete. In this review the important aspects of grain boundaries and their effects on transport and photoelectric properties of polycrystalline silicon and on the I–V characteristic of ZnO varistors are discussed. An erratum to this article is available at .     

Silicon nanocrystal production through non-thermal plasma synthesis: a comparative study between silicon tetrachloride and silane precursors

Silicon nanocrystals with sizes between 5 and 10?nm have been produced in a non-thermal plasma reactor using silicon tetrachloride as precursor. We demonstrate that high-quality material can be produced with this method and that production rates as high as 140?mg?h(-1) can be obtained, with a maximum precursor utilization rate of roughly 50%. Compared to the case in which particles are produced using silane as the main precursor, the gas composition needs to be modified and hydrogen needs to be added to the mixture to enable the nucleation and growth of the powder. The presence of chlorine in the system leads to the production of nanoparticles with a chlorine terminated surface which is significantly less robust against oxidation in air compared to the case of a hydrogen terminated surface. We also observe that significantly higher power input is needed to guarantee the formation of crystalline particles, which is a consequence not only of the different gas-phase composition, but also of the influence of chlorine on the stability of the crystalline structure.     

Fabrication of nano-porous silicon oxide layers by plasma polymerisation methods

We report on the synthesis of nano-porous silicon oxide (SiO₂) layers by gas phase polymerisation reactions of hexamethy disiloxane and oxygen. The SiO₂ layers are deposited onto one or more layers of poly(methylmethacrylate) (PMMA) particles spin coated onto the substrate surface. Subsequent annealing of the films to high temperature (500 °C) leads to the pyrolysis of the polymeric particles resulting in a 3D nanoporosity in the film. X-ray Photoelectron (XPS) and Fourier Transform Infra Red Spectroscopy (FTIR) show an SiO₂-like surface chemistry and virtually complete removal of the organic components. These materials offer a very high surface area-to-volume ratio suitable for sensing applications.     

Synthesis of zinc and zinc oxide nanoparticles from zinc electrode using plasma in liquid

Nanoparticles are synthesized efficiently from zinc electrode by microwave plasma in liquid. The nanoparticles synthesized from alcohol resulted in pure zinc particles in the shape of spheres or hexagonal cylinders with a production rate of 3.3 g/h, and energy consumption of 267 J/mg for 1 mg. Whereas the nanoparticles synthesized in pure water are composed of Zn and ZnO. The Zn reacts with water through heat or the passage of time to become ZnO, releasing hydrogen gas. An upper disk placed 1 mm away from the electrode along with the bubbles generated simultaneously with the plasma ignition plays a key role in the synthesis of nanoparticles.     

Surface modification of nano-TiN by using silane coupling agent

Titanium nitride (TiN) nano-particles were subjected to graft modification by silane coupling agent (KH-570) via a direct blending method. The hydroxyl groups on the surface of TiN nano-particles can interact with silanol groups [-Si-OCH₃] of KH-570 forming an organic coating layer. The covalent bonds (Ti-O-Si) formation was testified by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Through transmission electron micrograph (TEM) observations, it was found that KH-570 could improve the dispersibility of nano-TiN particles in ethyl acetate. Thermo gravimetric analysis (TGA) and contact angle measurements indicated that KH-570 molecules were adsorbed or anchored on the surface of nano-TiN particle and the net efficiency of it was 22.76 %, which facilitated to hinder the aggregation of nano-TiN particles.     

等离子体充电效应在薄氧化硅层产生陷阱密度的确定

通过比较经过和未经过等离子暴露的两种薄栅氧化硅层在恒电流条件下击穿时间 tbd的差 异,计算出在等离子体暴露过程中由充电效应导致的隧穿电流在天线比为 2000的 MOS电容栅氧 化硅层中产生的陷阱密度为 2.35× 1018cm-3,表明充电效应导致损伤的出现。     

Deposition of zinc oxide thin films by an atmospheric pressure plasma jet

The ZnO thin film deposition process by using an atmospheric pressure (AP) plasma jet is studied. In this process, nebulized ZnCl₂ solution is sprayed into the downstream of the nitrogen plasma jet to perform thin film deposition. X-ray diffraction analysis confirms that this AP jet has the capability to convert ZnCl₂ solution to well-crystallized ZnO thin films with a hexagonal wurtzite structure in a short time. This film exhibits a smooth and mirror-like appearance visually. Scanning electron microscopy and atomic force microscopy show that the deposited film is dense and continuous with a root mean square surface roughness of 8.6 nm. A 1.29 nm/s deposition rate is obtained using this process. Given the fast deposition rate, we believe that both the temperature and the reactivity of the plasma play important roles. A ZnO film on a larger substrate is fabricated, which suggests the process capability in large area and continuous processing applications.     

Relation between the plasma characteristics and physical properties of functional zinc oxide thin film prepared by radio frequency magnetron sputtering process

The ZnO thin film was deposited on a glass substrate by a RF reactive magnetron sputtering method. Results showed that plasma density, electron temperature, deposition rate and estimated ion bombardment energy increase with increasing applied RF power. Three distinct power regimes were observed, which are strongly correlated with plasma properties. In the low-power regime, the largest grain size was observed due to slow deposition rate. In the medium-power regime, the smallest grain size was found, which is attributed to insufficient time for the adatoms to migrate on substrate surface. In the high-power regime, relatively larger grain size was found due to very large ion bombardment energy which enhances the thermal migration of adatoms. Regardless of pure ZnO thin film or ZnO on glass, high transmittance (> 80%) in the visible region can be generally observed. However, the film thickness plays a more important role for controlling optical properties, especially in the UV region, than the applied RF power. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, is of good anti-UV characteristics, and is highly hydrophobic, which is highly suitable for applications in the glass industry.     

超细氢氧化镁的硅烷偶联剂表面改性

采用N-苯基-γ-氨丙基三甲氧基硅烷偶联剂对超细氢氧化镁进行了湿法表面改性,通过SEM、TGA-DSC和FT-IR分析改性机理,表明硅烷是以硅氧烷结构接枝到了氢氧化镁表面。并应用吸油率、沉降时间和氢氧化镁/液体石蜡悬浊液的粘度来表征改性效果,得出了硅烷湿法改性超细氢氧化镁的最佳用量为1.5%(质量分数)。改性氢氧化镁粉体的分散性和表面亲油性得到了明显的改善。     

Visible photoluminescence of zinc oxide films electrochemically deposited on silicon substrates

Continuous crystalline films of zinc oxide (ZnO) with thicknesses of 6–10 μm were obtained by electrochemical deposition from aqueous zinc nitrate solutions on silicon substrates with a buffer nickel layer. X-ray diffraction measurements showed that the polycrystalline films possess a hexagonal crystal lattice with predominant (0002) orientation. The obtained ZnO films exhibit strong photoluminescence in the visible spectral range at room temperature.     

Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet

Atmospheric-pressure plasma processing has attracted much interest for industrial applications due to its low cost, high processing speed and simple system. In this study, atmospheric-pressure plasma jet technique was developed to deposit indium-doped zinc oxide films. The inorganic metal salts of zinc nitrate and indium nitrate were used as precursors for Zn ions and In ions, respectively. The effect of different indium doping concentration on the morphological, structural, electrical and optical properties of the films was investigated. Grazing incidence X-ray diffraction results show that the deposited films with a preferred (002) orientation. The lowest resistivity of 1.8 × 10^− 3 Ω cm was achieved with the 8 at.% indium-doped solution at the substrate temperature of 200 °C in open air, and average transmittance in the visible region was more than 80%.     

The chemistry of cements formed between zinc oxide and aqueous zinc chloride

A series of cements has been prepared from zinc oxide powder and aqueous zinc chloride, using solutions corresponding to concentrations of 20%, 30%, 40%, 50% and 60% and a ratio of ZnO powder to zinc chloride solution of 1:1. As with cements of the zinc oxide/zinc nitrate system, these ZnO/ZnCl2 cements were found to be weak in compression (not exceeding 10 MPa) with strength rising with increasing concentration of ZnCl2. The pH change as the reaction proceeded was monitored and generally showed a rapid increase, followed by a slight decrease, and a subsequent slower increase. This is assumed to arise because the doubly charged aquo-zinc cation, Zn(H2O)2+n (n=4 or 6) behaves as a weak acid, due to so-called salt hydrolysis: Zn(H2O)2+n+H2OZnOH(H2O)+(n-1)+H3O+ and reacts to form a salt, thus setting up a classic weak acid/salt buffer system. Finally, cements were stored in water for 1 month, and were generally found to increase in mass during the first week, with the greatest increase occurring in the cement made from 20% ZnCl2 solution. All cements lost mass between 1 week and 1 month, showing them to be sparingly soluble at room temperature. © 1998 Chapman & Hall     

硅烷偶联剂及氧化石墨烯二次改性对芳纶纤维界面性能的影响EI北大核心CSCD

为改善芳纶纤维(PPTA)与丁腈橡胶(NBR)复合材料之间的界面强度,采用硅烷偶联剂A172和氧化石墨烯(GO)对芳纶纤维表面进行接枝改性处理,并对处理前后的芳纶纤维进行化学结构、表面形貌及H抽出力分析。利用SEM对抽出纤维表面和橡胶基芳纶纤维复合材料截面进行微观结构分析。结果表明:硅烷偶联剂和氧化石墨烯对芳纶纤维进行二次表面改性后,纤维表面含氧基团增加,化学活性提高,处理后表面存在明显的表层附着物,纤维结构未发生明显损伤且表面粗糙度得到明显改善。每个处理阶段后H抽出力均有提高,且氧化石墨烯二次改性后的芳纶纤维H抽出力提高效果最佳,从18.192 MPa提高到48.748 MPa,芳纶纤维与丁腈橡胶的界面结合力得到了显著提升,从而证实了硅烷偶联剂和氧化石墨烯二次改性芳纶纤维的有效性,为橡胶基芳纶纤维复合材料性能的研究提供了参考。     

Photovoltaic junctions between indium tin oxide and silicon

Photovoltaic junctions solar cells were made between indium tin oxide (ITO) and polycrystalline p-Si (poly-Si), or between ITO and single-crystal p-Si. A model based on the assumption that the grain boundaries in poly-Si introduce ionized energy states equivalent to an effective doping density is considered. The cell performance was calculated from current-voltage characteristics and capacitance-voltage measurements at various frequencies. From transient photovoltage decay measurements, an effective lifetime τ_eff of (300–400) × 10⁻⁹ s was found in the poly-Si/ITO junction, whereas in the single-crystal-Si/ITO junction τ_eff was 5 μs. The shorter lifetime of the injected carriers is one of the reasons for the lower conversion efficiency of these cells.Prior to ITO deposition, iodine ions were introduced to neutralize the trap states at the surface of the single-crystal silicon and to neutralize the traps at both the surface and grain boundaries of the poly-Si. An increase in the open-circuit voltage factor was observed.     

脉冲激光沉积方法生长硅基ZnO薄膜的特性

用脉冲激光沉积法(PLD)在n型硅(111)平面上生长ZnO薄膜.X射线衍射(XRD)在2θ=34°处出现了唯一的衍射峰,半高宽为0.75°;傅里叶红外吸收(FTIR)在414.92cm-1附近出现了对应Zn-O键的红外光谱的特征吸收峰;光致发光(PL)测量发现了位于370和460nm处的室温光致发光峰;扫描电子显微镜(SEM)和选区电子衍射(SAED)显示了薄膜的表面形貌以及晶格结构.利用PLD法制备了具有c轴取向高度一致的六方纤锌矿结构ZnO薄膜.