Well‐Aligned ZnO Nanowire Arrays Fabricated on Silicon Substrates

Arrays of well‐aligned single‐crystal zinc oxide (ZnO) nanowires of uniform diameter and length have been synthesized on a (100) silicon substrate via a simple horizontal double‐tube system using chemical vapor transport and condensation method. X‐ray diffraction and transmission electron microscopy (TEM) characterizations showed that the as‐grown nanowires had the single‐crystal hexagonal wurtzite structure with detectable defects and a <0002> growth direction. Raman spectra revealed phonon confinement effect when compared with those of ZnO bulk powder, nanoribbons, and nanoparticles. Photoluminescence exhibited strong ultraviolet emission at 3.29 eV under 355 nm excitation and green emission at 2.21 eV under 514.5 nm excitation. No catalyst particles were found at the tip of the nanowires, suggesting that the growth mechanism followed a self‐catalyzed and saturated vapor–liquid–solid (VLS) model. Self‐alignment of nanowires was attributed to the local balance and steady state of vapor flow at the substrate. The growth technique would be of particular interest for direct integration in the current silicon‐technology‐based optoelectronic devices.     

Well‐Aligned ZnO Nanorods via Hydrogen Treatment of ZnO Films

The formation of well‐aligned ZnO nanorods has been achieved via H₂ treatment of as‐grown ZnO films. Structural analyses reveal that the ZnO nanorods on the ZnO films are preferentially oriented along the c‐axis direction and exhibit a single‐crystalline wurtzite structure. To investigate the mechanism of formation of ZnO nanorods on the film, further H₂ treatment of the as‐grown ZnO nanorods was performed. Thinner and longer ZnO nanorods were obtained after certain periods of H₂ treatment. It is proposed that both etching and re‐deposition processes are taking place during the process, resulting in the aspect‐ratio enhancement of the ZnO nanorods and the formation of ZnO nanorods on the ZnO films. It is suggested that an appropriate concentration of the etching products remaining from the initial rod‐forming H₂ treatment allows subsequent re‐deposition of the ZnO nanorods with enhanced differentiation of the growth rates on the 〈001〉 and 〈100〉 crystal facets.     

浅析10kV氧化锌避雷器常见故障及安装注意事项

鉴于氧化锌避雷器在整个10kV电力配网中的重要性,本文对10kV氧化锌避雷器常见故障及其成因进行了分析,并为了促进故障的优化和完善,就10kV氧化锌避雷器安装中的注意事项进行了探讨.以更好地促进其作用得到有效的发挥.     

Optimising conditions for the growth of nanocrystalline ZnS thin films from acidic chemical baths

The growth of nanocrystalline zinc sulfide thin films onto glass substrates by chemical bath deposition has been optimized at acidic pH. Powder X-ray diffraction (p-XRD) confirms the deposition of sphalerite, the cubic phase of ZnS. The crystallite size calculated by Scherrer equation was found to be 4.0 nm. Scanning Electron Microscopy (SEM) show clusters of spherical nanoparticles uniformly distributed over the surface of the glass substrates. Energy Dispersive X-ray (EDX) analysis of the deposited thin films show the zinc to sulfur ratio close to 1:1. The observed band gap (3.78 eV) of the deposited thin films is higher than that reported for cubic phase of bulk ZnS (3.54 eV) as expected due to nano-size crystallites. Binding energies calculated by X-ray Photoelectron Spectroscopy (XPS) confirm the material as ZnS and the photoluminescence measurements show the blue shift in emission maximum.     

Growth of Bulk ZnO Single Crystals via a Novel Hydrothermal Oxidative Pressure‐Relief Route

A novel hydrothermal oxidative pressure‐relief (HOPR) route has been successfully developed for the growth of high‐quality bulk ZnO single crystals, using metallic zinc and H₂O₂ as the raw materials, at 400 °C for 20 h in an alkali solvent. X‐ray powder diffraction reveals the ZnO crystals have a wurtzite structure. Two typical morphologies of perfect hexagonal pyramidal and hexagonal prismatic ZnO single crystals, and bidirectional adhesive crystals, are identified by scanning electron microscopy analysis. The average size of the single crystals is ～ 1.0 mm in length and ～ 0.2 mm in diameter. Short hexagonal prismatic, novel polygonal layer‐like, and nanowire ZnO crystals are also obtained by altering the reaction conditions, such as the reaction time and the speed of pressure release. The growth mechanism is a spontaneous nucleation and self‐growth process. This novel HOPR route gives an alternative choice for obtaining well‐crystallized ZnO bulk crystals from solution.     

Growth of Wurtzite ZnS Micrometer‐Sized Diskettes and Nanoribbon Arrays with Improved Luminescence

We report on the synthesis of wurtzite ZnS micrometer‐sized diskettes (including those lined up with ZnS nanowires) and ZnS nanoribbon arrays. Using ZnS powder as a source material, a vapor–solid growth based on a two‐stage temperature‐controllable thermal evaporation and condensation process is realized. Significant enhancement of luminescence compared to the ZnS source material is observed from these ZnS micro‐ and nanometer‐sized structures. The structures may serve as ideal model systems in the nano‐ to micrometer range for studying the optical and electronic properties of ZnS material. They can also be treated as prospective building blocks of two‐ and/or three‐dimensional arrays and are promising candidates for fabricating novel electronic and optoelectronic devices.     

锌精矿湿法制氧化锌的研究

用工业硫酸浸取焙烧脱硫后的锌精矿,经过一系列的除杂步骤,湿法制取氧化锌,所得产品氧化锌的纯度达99.71％,各项技术指标均符合产品标准,其中元素锌的总回收率达到87％以上。     

肉制品中食盐含量测定方法的改进

目的建立肉制品中食盐含量测定的新方法。方法用共沉淀剂沉淀肉制品中蛋白质等干扰物质,用硝酸银标准溶液滴定样品提取液中的氯化钠,根据硝酸银的消耗体积计算样品中食盐的含量。结果样品测定相对标准偏差为2.11%,平均回收率为99.3%。与国标方法对比差异无统计学意义。结论本法适于肉制品中食盐的含量测定。     

Factorial experimental design for biosorption of iron and zinc using Typha domingensis phytomass

Typha domingensis phytomass was used as a biosorbent for metal ions removal from wastewater. A full 2³ factorial design of experiments was used to obtain the best conditions of biosorption of Fe³⁺ and Zn²⁺ from water solutions. The three factors considered were temperature, pH, and biosorbent dosage. Two levels for each factor were used; pH (2.5 and 6.0), temperature (25 and 45 °C), and phytomass loading weight (0.5 and 1 g/50 ml). Batch experiments were carried out using 50 ml solutions containing 10 mg/l Fe³⁺ and 4 mg/l Zn²⁺ simulating the concentration of those metals in a real wastewater effluent. The removal percentages of iron and zinc after 120 min of contact time were then evaluated. The results were analyzed statistically using the Minitab 15 statistical software to determine the most important factors affecting the metals removal efficiency. The pH was found to be the most significant factor for the two studied metal ions.     

Unusual electrochemical response of ZnO nanowires-decorated multiwalled carbon nanotubes

A novel type of ZnO nanowires-modified multiwalled carbon nanotubes (MWCNTs) nanocomposite (ZnO-NWs/MWCNTs) has been prepared by a hydrothermal process. The ZnO-NWs/MWCNTs nanocomposite has a uniform surface distribution and large coverage of ZnO nanowires onto MWCNTs with 3D configuration, which was characterized by scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy methods were applied to investigate the electrochemical properties of ZnO-NWs/MWCNTs nanocomposite. Surprisingly, unlike the conventional n-type semiconducting ZnO nanowires grown on Ta substrate, the ZnO-NWs/MWCNTs nanocomposite exhibits excellent electron transfer capability and gives a pair of well-defined symmetric redox peaks towards ferricyanide probe. What's more, the ZnO-NWs/MWCNTs nanocomposite shows remarkable electrocatalytic activity (current response increased 4 folds at 0.3 V) towards H₂O₂ by comparing with bare MWCNTs. The ZnO-NWs/MWCNTs nanocomposite could find applications in novel biosensors and other electronic devices.