微波水解法制备纳米ZnO及其气敏特性研究

以Zn(CH₃COO)₂-2H₂O为原料,采用微波水解法和恒温水解法制备了纳米ZnO粉体,用X射线衍射仪、透射电镜对产物的相组成和微观结构进行了表征和分析,并且测试了其气敏特性.为了改善纳米ZnO的气敏性能,利用微波水解法,通过掺杂Pt、Pd贵金属制备出其相应的纳米复合氧化物.与恒温水解法相比,微波水解法所需反应时间显著缩短、反应物浓度提高;两种方法制备的纳米ZnO粉体皆对酒精和汽油具有较高灵敏度;掺杂Pt或Pd可提高纳米ZnO对酒精和汽油的选择性.     

Fe掺杂NiO纳米花状微球的制备及其气敏性能研究

采用水热法成功制备了Fe掺杂NiO纳米花状微球,研究了Fe掺杂量对微球结构、形貌和气敏性能的影响。气敏实验结果表明:Fe掺杂NiO纳米微球基气敏元件对丙酮的气敏性能较纯相NiO显著提高;当Fe掺杂量为0.03g时,气敏器件在工作温度为280℃,丙酮质量浓度为3.7×10~(-4) mg/L条件下,气体灵敏度为41.8,是相同条件下未掺杂NiO基气敏元件的12倍,该气敏元件在检测低浓度丙酮气体时也表现出优异的性能。     

铝共掺杂调制ZnO∶Mn纳米棒阵列的磁学和电学特性

采用磁控溅射方法制备了锰掺杂氧化锌和铝、锰共掺杂氧化锌纳米棒阵列并详细研究了它们的电学和磁学特性。微结构测试的结果表明,掺杂后的氧化锌纳米棒阵列保持了纤锌矿晶体结构,掺杂锰离子和铝离子占据了晶体中锌离子的位置实现了替位式掺杂。磁学性质测试结果表明铝、锰共掺杂氧化锌纳米棒在室温下具有明显的铁磁性,饱和磁矩为0.33μB/Mn atom,是居里温度高于室温的一维稀磁半导体材料。电学性质测试结果表明铝的共掺杂可以使得锰掺杂氧化锌纳米棒的电阻率降低4个数量级,使得铝、锰共掺杂氧化锌纳米棒有可能在未来自旋电子器件中作为高效自旋注入元器件得到广泛应用。     

溶剂热法制备铝掺杂纳米ZnO及其气敏性能

采用溶剂热法合成了铝掺杂的纳米ZnO气敏材料,运用XRD和BET等手段对产物进行了表征并进行了相应的气敏性能测试.结果表明,掺杂1.5%Al后的ZnO比表面最大,粒径最小;材料对乙醛、90#汽油、90#乙醇汽油、硫化氢、二氧化氮响应较高.掺杂量为1.5%Al的元件对90#汽油在浓度为50ppm时灵敏度接近120.     

ZnO纳米棒的制备与气敏性能的研究

以Zn(NO3)2·6H2O和NaOH为原料,CTAB为表面活性剂,通过微波辅助液相反应过程在低温下成功地制备了ZnO纳米棒.X射线衍射谱和扫描电镜结果表明,产物是六方纤锌矿结构ZnO纳米棒,长度为5～30μm,直径为0.1～1μm.气敏性能测试表明,所制备的ZnO纳米棒对H2S气体具有较好的选择性,但灵敏度不高.对ZnO纳米棒进行In掺杂后,对H2S气体的灵敏度和选择性大幅提高,在工作温度为332℃时,对体积分数为50X10-5的H2S灵敏度为29.217,说明In掺杂的ZnO纳米棒是有潜力的探测H2S气体的气敏传感器材料.     

掺杂Fe2 O3对ZnO多孔纳米固体厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Fe2O3,纳米粉(平均粒径90 nm)为原料,利用传统的厚膜气敏传感器制备工艺,制备了纯ZnO多孔纳米固体厚膜气敏传感器和掺杂Fe2O3(掺杂量为1wt%,2wt%和5wt%)的ZnO厚膜气敏传感器.分别测试了这四种厚膜气敏传感器的本征电阻(传感器在空气中的电阻值)及其对乙醇,汽油,丙酮,对二甲苯,氢气,甲烷和CO敏感特性.结果表明:当工作温度在较低时,Fe2O13,的掺杂可明显降低ZnO多孔纳米固体厚膜气敏传感器的本征电阻,并提高其工作稳定性,而适量Fe2O3的掺杂可以提高ZnO多孔纳米固体厚膜气敏传感器对乙醇蒸气和汽油的灵敏度.结合对传感器厚膜的显微结构分析结果,我们对出现上述差异的原因进行了初步讨论.     

Nb2O5半导体纳米材料形貌调控与气体敏感性能研究

以NH_4HF_2、氧化铌和氨水为原料,采用水热制备法,通过精确调控Nb前驱体溶液的pH,实现了Nb_2O_5纳米材料的形貌调控,制备得到了六方相Nb_2O_5纳米球及纳米棒材料。采用X射线衍射仪、扫描电子显微镜、比表面积和孔径分布分析仪对Nb_2O_5纳米材料的物相、形貌及比表面积进行了表征分析;采用静态配气法对其进行气敏性能测试,讨论了形貌对Nb_2O_5纳米材料气敏性能的影响。结果表明:Nb_2O_5纳米球与纳米棒均对丙酮表现出良好的选择性。与Nb_2O_5纳米球相比,Nb_2O_5纳米棒表现出更高的气敏响应及更短的响应时间和恢复时间:对50×10~(-6)(体积分数,下同)丙酮气体,Nb_2O_5纳米棒的气敏响应可达3.15,响应时间为7s,恢复时间为10s;Nb_2O_5纳米棒对丙酮表现出更好的气敏性能应归因于其具有更大的比表面积。     

ZnO纳米棒的微波合成及Pt掺杂对其气敏性能的改善

以Zn(NO3)2·6H2O和NaOH为原料,CTAB为表面活性剂,微波加热到90℃,反应30min,成功制备了ZnO纳米棒.X射线衍射仪(XRD)和扫描电镜(SEM)结果表明,产物是六方纤锌矿结构ZnO纳米棒,长度为1～5μm,直径为50～100nm左右.对ZnO纳米棒进行了Pt掺杂,并对掺杂前后的气敏性能进行了对比...     

不同衬底生长氧化锌纳米棒阵列及其场发射性能的研究

采用低温水热法在五种不同基底上制备得到了氧化锌纳米棒阵列，通过SEM、TEM、XRD、EDS和XPS表征研究了所得产物的微观形貌和元素组成，并对不同基底生长的氧化锌纳米棒阵列进行了场发射性能和附着力测试。结果表明：硅片、导电玻璃、镍片、不锈钢和镍钛合金上生长的氧化锌纳米棒样品的开启电场依次升高；由于氧化锌纳米棒与硅基底之间具有更好的附着性能，硅片基底制备的氧化锌纳米棒场发射性能最好，并显示出最好的发射稳定性，在电流密度0.5mA/cm²下持续工作15h时，其电流波动小于10%。     

氧化锌气敏传感器性能的改善及在民航系统的应用

氧化锌是多功能N型半导体材料,具有优良的气敏性能,在气体传感器方面具有广泛的用途。氧化锌气敏材料及测试方法进一步优化后,传感器具有更高的灵敏度和更广泛的适用性。对纳米氧化锌传感器的气敏机理、改善气敏性能的主要方法以及传感器在民用航空方面的应用做了详细的综述。     

纳米氧化锌粉体制备技术及应用的研究

纳米氧化锌(ZnO)作为一种功能材料,有着许多优异的性能和广泛的应用价值。通过对纳米ZnO的各种制备方法及其特点进行对比,指出了各制备方法的特点、存在的问题及未来的研究方向,探索纳米ZnO材料降低成本、产业化制备最有潜力的方法,并以纳米ZnO的性能为主线,介绍了纳米ZnO在各个领域的实际应用,提出了应用研究中出现的一些问题,同时对未来的应用研究提出了一些看法。     

Effect of zinc oxide type on ageing properties of Styrene Butadiene Rubber compounds

The presence of zinc oxide in rubber compounds is tried to be minimized due to environmental concerns. In this study; the effect of different zinc oxide types on ageing properties of SBR compounds was investigated. Active zinc oxide and zinc oxide coat on CaCO₃ core were used in SBR compounds and their ageing characteristics were compared. The changes in tensile properties, hardness and rebound resilience were followed and evaluated.     

液相法合成纳米氧化锌的研究进展

综述了近年来合成纳米氧化锌的液相方法,包括沉淀法、水热法、溶剂热法、溶胶-凝胶法、微乳液法等.分析了这几种方法的优缺点和最新的研究进展.同时指出,微波、超声等新技术也引入到液相法纳米氧化锌的制备工艺中,纳米氧化锌合成的未来发展方向是合成技术综合化.     

Hazardous phytotoxic nature of cobalt and zinc oxide nanoparticles assessed using Allium cepa

The increasing use of nanotechnology requires the clarification of the behavior and the effects of nanoparticles (NPs) as they are released into the environment. This study was to investigate the phytotoxicity of cobalt and zinc oxide NPs using the roots of Allium cepa (onion bulbs) as an indicator organism. The effects of cobalt and zinc oxide NPs on the root elongation, root morphology, and cell morphology of a plant, as well as their adsorption potential, were determined through the hydroponic culturing of A. cepa. A. cepa roots were treated with dispersions of the cobalt and zinc oxide NPs having three different concentrations (5, 10, and 20 μg ml(-1)). With increasing concentrations of the NPs, the elongation of the roots was severely inhibited by both the cobalt and the zinc oxide NPs as compared to that in the control plant (untreated A. cepa roots). Massive adsorption of cobalt oxide NPs into the root system was responsible for the phytotoxicity. Zinc oxide NPs caused damage because of their severe accumulation in both the cellular and the chromosomal modules, thus signifying their highly hazardous phytotoxic nature.     

Influence of oxides on the stability of zinc foam

The influence of oxides on the stabilisation of zinc foam made by foaming-compacted powder mixtures has been investigated by varying the oxide content in the zinc powder used by oxidation and reduction. Optical, scanning electron and transmission electron microscopy as well as energy dispersive X-ray mapping were used to determine the oxide distribution, morphology and structure in the foams. The study revealed that with increase in the oxide content of the foam, the maximum expansion and expansion rate increased. Small amount of nano-sized oxide particles and their cluster, which are randomly distributed, were observed within the bulk of foam. But the major fraction of oxides is observed on the surface of pores in the form of clusters. These clusters are distributed uniformly all over the surface. Effect of these oxides on the stability of foam is discussed. The formation of satellite pores, which is characteristic signature of zinc foams, and their stability, is investigated.     

A reflection electron diffraction study on some metal oxide solar collector coatings: Part I

The capability of reflection electron diffraction (RED) in the structural analysis of thin films is shown with studies made on copper oxide, zinc oxide, black chrome and cobalt oxide solar-selective coatings. The growth of copper oxide layers could be observed as changing from an initial epitaxial growth to random orientation followed by growth of oxide needles. The resulting copper oxide coating was found to consist of a needle structure of cupric oxide formed on a smooth cuprous oxide layer. In the zinc oxide overgrowths, epitaxial growth could not be observed, and the coating consisted of relatively small zinc oxide crystallites throughout the film. No crystalline zinc inclusions could be found in this layer.Black chrome deposited onto nickel showed an increase in chromium oxide with distance from the substrate, although no change in the orientation of the microcrystalline chrome could be observed. The formation of black cobalt was also investigated using scanning electron microscopy (SEM) and reflection diffraction analysis. The plated cobalt overgrowths were found to change from an initially smooth nodular coating to a plate-like oxide layer with heat treatment time. This latter layer could be indexed to cobalt(II, III) oxide.The study conclusively shows that RED, combined with SEM and ion milling procedures, can indeed lead to structural characterization of thin films without the need for their removal from their substrates and the concominant introduction of artifacts.     

Preparation of zinc oxide-montmorillonite hybrids

The new hybrid materials of zinc oxide with montmorillonite were synthesized by a reaction between the aqueous solutions of the reactants of zinc oxide (zinc chloride and sodium hydroxide solutions) and montmorillonite or hexadecyltrimetylammonium-montmorillonite. The hybrids were characterized by powder X-ray diffraction, Fourier transform-infrared, UV-visible and photoluminescence spectroscopies. The diffuse reflectance absorption spectra of the hybrids exhibited the absorption onsets at 375 nm for zinc oxide-montmorillonite and at 378 nm for zinc oxide-hexadecyltrimetylammonium-montmorillonite, respectively, confirming the formation of zinc oxide in the hybrid materials. The photoluminescence bands of both hybrids, which can be attributed to singly ionized oxygen vacancy in zinc oxide, were observed at 548 nm. The enhancement in emission intensity of the zinc oxide hybrids may be probably due to increase in oxygen vacancies defect arose by the surrounding environment of montmorillonite.     

Zinc oxide molecules and clusters formed in a quasiclosed volume of reactive gas-discharge plasma

Plasma-deposited zinc oxide films were studied and it was established that oxide molecules may form and their clusters nucleate within a recombination burning zone in the volume of plasma, provided that the ion range does not exceed the size of a discharge chamber. The nucleation zone is rather narrow and its position depends on the gas pressure in the chamber. The zinc oxide films grown in this zone possess a texture with small misorientation angle and are characterized by small thickness of the nucleation texture and high piezoelectric activity.     

Preparation of extrapure zinc oxide and zinc acetate from diethylzinc

We have developed a process for the preparation of extrapure zinc oxide and zinc acetate from diethylzinc, which includes ultrapurification of this compound through low-pressure fractional distillation, oxygen oxidation of the purified diethylzinc in combustion mode, and heat treatment of the resultant zinc oxide. Zinc acetate was obtained by dissolving the zinc oxide in acetic acid. The content of regulated metallic impurities (iron, copper, aluminum, silicon, cadmium, nickel, cobalt, tin, lead, chromium, molybdenum, and magnesium) in the zinc oxide and zinc acetate was 10^?5 to 10^?6 wt %, and their net content was <5 × 10^?4 wt %.     

基于欧珀模板磁控溅射生长氧化锌薄膜及其光学特性

采用常温射频磁控溅射方法在聚苯乙烯欧珀模板上生长氧化锌薄膜, 通过煅烧去除模板得到了类似纳米碗结构的氧化锌. 用SEM分析了模板和氧化锌的形貌. 实验结果表明: 模板为FCC结构的聚苯乙烯密堆小球, 氧化锌呈六角排列的纳米碗结构. XRD分析结果表明, 实验中制备的ZnO为沿(001)方向择优生长的六方晶型结构薄膜. 样品FTIR、UV-Vis和PL谱等的分析表明, 欧珀模板-氧化锌复合结构光致发光强度比除去模板后的氧化锌薄膜高4～5倍. 这可能是由于样品的微结构造成的, 其机理值得进一步研究.