花状ZnO微/纳米结构的水热法制备及其发光性质

以Zn(Ac)2、NaOH为初始原料,采用水热法在较低温度下合成了由纳米棒紧聚而成的花状ZnO微/纳米结构。通过X射线衍射(XRD)、扫描电镜(SEM)、光致发光谱(PL)对样品进行了表征和分析,讨论了反应温度、反应时间对样品物相和形貌的影响,分析了其生长机制。XRD和SEM测试结果表明,ZnO纳米晶为六方纤锌矿结构,反应温度和时间对产物晶相及形貌有重要影响。室温下PL谱显示,样品在346nm和384nm处有较强的紫外发射,在450nm和468nm处有较弱的蓝光发射,在475～650nm出现强而宽的可见光发射带。该研究为探讨ZnO微/纳米材料的制备技术及在发光方面的应用提供了可行的方法。     

高压PLD法生长ZnO和Zn1-xMgxO纳米棒及其荧光性能

利用自主设计、组装的高压脉冲激光沉积(PLD)系统,研究了温度、靶材、催化剂厚度等生长参数对ZnO和Zn1-xMgxO纳米棒生长的影响,并对ZnO纳米棒的生长机理和Zn1-xMgxO纳米棒的光致发光性能进行了探讨.实验发现,当金膜催化剂厚度为2 nm、温度为925℃时,在单晶Si衬底上生长了直径均匀的ZnO纳米棒阵列,且具有明显的(002)择优生长取向.实验发现温度与催化剂厚度是影响ZnO纳米棒的直径和生长密度的重要因素.据此提出了ZnO纳米棒阵列的高压PLD生长过程应为气–液–固和气–固相结合的生长机制.通过在ZnO靶材中掺入氧化镁,获得了Zn1-xMgxO纳米线和纳米带结构,但生长无明显的择优取向.光致发光谱测量表明,镁掺杂明显增大了ZnO的带隙,但也在其禁带中引入了缺陷能级,导致可见发光明显增强.     

氧化锡纳米带的制备和光致发光性能研究

采用常压热蒸发锡粉的方法制备出尺寸均匀、表面光滑致密的SnO2纳米带。通过高温退火处理,氧化锡纳米带从Sn304和SnO2的混合相转变为SnO2金红石相。深入研究了SnO2纳米结构的光致发光性能,结果显示,退火前SnO2纳米带在600nm附近有一较强的发光峰,在375nm有一弱发光峰;退火处理后,375nm处的PL峰消失,此现象可能是由于退火后纳米带中晶格缺陷减少而导致。     

Zn/纳米棒阵列ZnO/聚噻吩复合电极的制备及光电化学性质

使用简单的水热法在锌片上生长ZnO纳米棒阵列,并用电化学共聚制备了ZnO纳米棒阵列与聚噻吩(Zn/ZnO/PTH)复合膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)等手段对ZnO的结构和形貌进行表征,XRD结果表明产物为六方纤锌矿型ZnO。SEM结果表明,在垂直锌片方向生长了包括纳米棒、纳米片、纳米线的表面光滑的ZnO纳米阵列,其中以纳米棒为主,其直径为30～100nm,长度1μm。用光电流作用谱、光电流-电势图研究了Zn/ZnO/PTH电极的光电转换性质。结果表明,PTH修饰ZnO/Zn电极可使光电流产生波长发生明显红移,使其光电转换效率提高了4倍,填充因子FF=33%,光电转换效率η=1.25%。     

Sn掺杂ZnO纳米带的制备及其光致发光性能研究

采用热蒸发法制备了单晶Sn掺杂ZnO纳米带,其中Sn的掺杂含量约为5%(原子分数).X射线衍射(XRD)结果表明Sn掺杂ZnO纳米带为单相纤锌矿结构.X射线光电子能谱(XPS)表明样品中Sn的价态为4+.样品的室温光致发光谱(PL)在445.8nm处存在较强的蓝光发射峰,对其发光机制进行了分析.     

ZnO/BaTiO3纳米复合材料的制备及其发光性质

采用溶胶-凝胶技术制备了ZnO/BaTiO₃纳米复合材料,用X射线衍射仪(XRD)、透射电子显微镜(TEM)测定了不同温度处理后样品的组成、结构、形貌和尺寸.对复合材料室温下的光致发光谱分析发现,复合材料的发光强度比纯的纳米ZnO发光显著增强;纳米ZnO中氧空位引起的510nm发光带的峰位随着热处理温度的不同而分别出现蓝移和红移现象.其中蓝移主要是量子尺寸效应引起的,而红移则可能与致密化的BaTiO₃所提供的高介电场有关.     

ZnO/BaTiO3纳米复合材料的制备及其发光性质

采用溶胶-凝胶技术制备了ZnO/BaTiO3纳复合材料，用X射线衍射仪（XRD）、透射电子显微镜（TEM）测定了不同温度处理后样品的组成、结构、形貌和尺寸。对复合材料室温下的光致发光谱分析发现，复合材料的发光强度比纯的纳米ZnO发光显著增强；纳米ZnO中氧空位引起的510nm发光带的峰位随着热处理温度的不同而分别出现蓝移和红移现象。其中蓝移主要是量子尺寸效应引起的，而红移则可能与致密化的BaTiO3所提供的高介电场有关。     

Co/Co_9S_8/ZnO核壳结构纳米微球的制备与表征

在无水无氧条件下通过热分解还原制备Co纳米微粒,利用Co9S8和ZnO晶格的相匹配性,通过层层自组装对Co表面进行修饰,得到Co/Co9S8/ZnO核壳结构纳米微球.采用XRD、TEM、SQUID、光致发光光谱(PL)等对产物进行了表征.通过调节反应参数制备出核壳结构的Co/Co9S8/ZnO复合纳米微球,平均粒径58.8nm,壳层厚度均匀,常温下显示铁磁性,矫顽力为18.7kA/m.PL表明,产物在380~390nm处的带边跃迁不明显,光致发光最强峰在468nm处,属氧缺陷发射峰,研究了影响产物形貌的主要因素.结果表明,以油酸(OLA)及三正辛基氧化磷(TOPO)为溶剂和表面活性剂,Zn(acac)2温度为70℃、用量为1mmol,控制Co的硫化反应时间为5min,有利于核壳结构产物的形成.初步分析了Co/Co9S8/ZnO核壳结构纳米微球的形成机理.     

静电纺丝技术制备NiOZnTiO3TiO2同轴三层纳米电缆及其形成机制

采用静电纺丝技术, 通过改进实验装置, 在最佳的纺丝条件下制备了 [Ni(CH₃COO)₂+PVP]-[Zn(CH₃COO)₂+PVP]-[Ti(OC₄H₉)₄+CH₃COOH+PVP] 前驱体复合电缆, 在600℃下将其进行热处理, 制备出了NiO-ZnTiO₃-TiO₂同轴三层纳米电缆。采用热重-差热 (TG-DTA)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析技术对样品进行了表征。对NiO-ZnTiO₃-TiO₂ 同轴三层纳米电缆的形成机制进行了讨论。结果表明, 所得产物为NiO-ZnTiO₃-TiO₂同轴三层纳米电缆。芯层为NiO, 直径大约为(42.024±4.405) nm; 中间层为ZnTiO₃, 厚度大约为(55.385±7.681) nm; 壳层为TiO₂, 厚度大约为(70.747±7.373) nm。      

SnO2/石墨烯锂离子电池负极材料的制备及其电化学行为研究

以氧化石墨和氯化亚锡为原料,采用原位合成法制得SnO2/石墨烯纳米复合材料。该方法不需外加还原剂,也避免了SnO2纳米粒子和石墨烯在机械混合过程中的团聚问题。XRD和TEM等的分析结果表明,纳米SnO2颗粒都均匀地分散在石墨烯表面,其中纳米SnO2的粒径和石墨烯的厚度分别为3~6 nm和1.5~2.0 nm。电化学测试结果表明:在200 mA/g电流密度下循环100次后,SnO2/石墨烯负极材料的嵌锂容量可稳定在552 mAh/g,容量保持率比单纯纳米SnO2提高了4.4倍;在40、400、800 mA/g的电流密度下,SnO2/石墨烯负极材料的放电容量可分别保持在724.5、426.0、241.3 mAh/g,表现出较好的倍率性能,该结果归因于石墨烯良好的导电性及其二维纳米结构。     

ZnO nanocone arrays on self-assembled Zn2SnO4 base: synthesis, structure, growth mechanism and optical property

ZnO nanocone arrays on self-assembled Zn2SnO4 base were successfully synthesized via a thermal evaporation method of two-step temperature-rising. The as-prepared ZnO nanocone products had a well crystalline wurzite structure with symmetry about the growth direction along [0001]. Based on the calculation of the lattice misfit between different families of crystal planes of ZnO and Zn2SnO4, Stranski-Krastanow growth mode of ZnO nanocones was proposed in which the ZnO relaxing layer plays an important role. The orientation relationship of nanocone and base was also investigated. For the optical property of this nanocones-base system, a strong green fluorescence-emission at 523 nm was detected while the Zn2SnO4 base provides a defect peak at 486 nm which broadens the green emission band.     

Exploring the interparticle electron transfer process in the photocatalytic oxidation of 4-chlorophenol

This work aimed to investigate the interparticle electron transfer (IPET) process within the coupled-photocatalyst systems on the basis of the degradation of 4-chlorophenol (4-CP). TiO(2), ZnO and SnO(2) are used as the model photocatalysts owing to their increasing energy levels which correspond to the IPET concept. In the single-photocatalyst tests, ZnO tests are associated with the highest degradation rate constants (0.347+/-0.083 h(-1) at pH 7 and 0.453+/-0.011 h(-1) at pH 11) and a better DOC reduction than in other single catalyst tests under given conditions. ZnO/SnO(2) coupled tests have constants of 0.612+/-0.068 and 0.948+/-0.069 h(-1) at pH 7 and 11, respectively. Additionally, the 4-CP prefers the breakdown of chloride group in TiO(2) system while proceeding hydroxylation reaction in ZnO systems. Meanwhile, a phenomenonlogical model coupled with the IPET effect was developed to explore the separation of photo-electrons and photo-holes within catalysts. Based on the model parameters, the recombination rate of photo-electrons and photo-holes in TiO(2)/SnO(2) and ZnO/SnO(2) systems is 20-45% lower than that obtained by a respective single catalyst. Thus, coupled-photocatalyst tests, TiO(2)/SnO(2) and ZnO/SnO(2) efficiently suppress the recombination, particularly for ZnO/SnO(2) tests at pH 11.     

Optical properties of zigzag twinned geometry of Zn2SnO4 nanowires

High-density single-crystalline Zn2SnO4 nanowires have been successfully synthesized by using a simple thermal evaporation method by heating a mixture of ZnO and SnO2 nano powders. The products in general contain various geometries of wires, with an average diameter of 80-100 nm. These nanowires are ultra-long, up to 100 microns. The transmission electron microscopy study showed that these nanowires exhibited zigzag twinned geometry, and grow along the (111) direction. Low-temperature photoluminescence properties of the nanowires were measured, showing a strong green emission band at about 515 nm and a weak peak corresponding to UV emission at about 378 nm, which have not been reported before.     

纳米SnO2、ZnO及ZnO／SnO2复合材料的气敏性能研究

以ZnO、S如纳米颗粒及ZnO／SnO2复合纳米材料分别作为气敏基料制成旁热式气敏元件,运用扫描电镜观察产物的形貌,用静态配气法对浓度为100ppm的甲烷气体进行气敏性能的测试。结果表明,这几类元件的最佳工作温度及灵敏度差异较大,当工作温度为350℃时SnO2纳米颗粒的气敏性能最佳。此温度下,SnO2响应时间和恢复时间也比纯ZnO纳米颗粒分别缩短了2S和3S。     

Metal organic chemical vapour deposition of vertically aligned ZnO nanowires using oxygen donor adducts

Vertically aligned zinc oxide (ZnO) nanowires (NWs) have been grown by liquid injection Metal Organic Chemical Vapour Deposition, using oxygen donor adducts of Me2Zn. The growth and characterisation of the nanowires grown using [Me2Zn(L)] where L = monodentate ethers, tetrahydrofuran (C4H8O) (1), tetrahydropyran (C5H10O) (2), furan (C4H4O) (3) and the bidentate ethers, 1,2-dimethoxyethane (C4H12O2,) (4) 1,4-dioxane (C4H8O2) (5) and 1,4-thioxane (C4H8SO) (6) is discussed. Single crystal X-ray structures of (4), (5), (6) have been established and are included here. The ZnO NWs were deposited in the absence of a seed catalyst on Si(111) and F-doped SnO2/glass substrates over the temperature range 350-600 degrees C. X-ray diffraction (XRD) data shows that the nanowires grown from all adduct precursors were deposited in the wurtzitic phase.     

ZnO-Sn:ZnO core-shell nanowires and ZnO-Zn2SnO4 comb-like nanocomposites

Novel single-crystalline ZnO-Sn:ZnO (SZO) core-shell nanowires and ZnO-Zn2SnO4 (ZTO) comb-like nanocomposites were synthesized by thermal chemical vapor deposition at a low temperature of 650 degrees C. Scanning electron microscopy and transmission electron microscopy show the diameters and lengths of the core-shell nanowires are in ranges of 25-60 nm and 300-500 nm, respectively. The atomic ratios of Sn to (Zn + Sn) in the central and shell parts of the nanowire are 0.4 at.% and 6.1 at.%, respectively. The ZnO-ZTO comb-like nanocomposites possess ZnO nanocombs with ZTO nano-layers deposited on both sides of them. The ZnO branches and ZTO layers are single-crystalline wurtzite and spinel structures growing along the [0002] and [111] directions, respectively. Room-temperature cathodoluminescence measurements show the nanocomposites exhibit strong ultraviolet (UV) emissions at 300, 384 nm, and a broad green emission. The novel luminescence shows promising singularity for opto-electronic applications.     

Zn-Sn-O系统透明导电薄膜的制备及其性能

本文采用溶胶-凝胶(Sol-Gel)过程和旋涂技术,通过高温烧结,得到了Zn-Sn-O系统的薄膜。结合干凝胶的差示扫描热分析(TG-DSC)和薄膜的X射线衍射分析(XRD),研究了干凝胶在烧结过程中发生的反应。通过控制溶胶的组成和薄膜烧结温度,得到了较纯净的Zn2SnO4晶相薄膜和ZnSnO3晶相薄膜。ZnSnO3晶体薄膜的电阻率显著低于Zn2SnO4晶体薄膜;N2气氛热处理后,ZnSnO3薄膜的电阻率升高而Zn2SnO4薄膜的电阻率大幅降低;当[Zn]/[Zn+Sn]=50.3at%时,薄膜的晶相仍为ZnSnO3,其电阻率较[Zn]/[Zn+Sn]=50.0at%的薄膜降低,约为8.0×102Ω.cm-1。通过上述两种晶相薄膜的X射线光电子能谱分析(XPS),探讨了这两种晶体不同的导电机理:Zn2SnO4晶体通过其中的氧空位导电,而ZnSnO3晶体则以间隙阳离子导电。紫外-可见光透过率(UV-Vis)分析表明:Zn2SnO4和ZnSnO3晶体薄膜在400~900nm的可见光波段的透过率可达80%以上。     

Synthesis of Zn2SnO4 nanowires and their photoluminescence properties

Single-crystalline Zn2SnO4 nanowires were successfully synthesized on a photoresist-coated Si substrate using a facile chemical vapor deposition method. The growth of the nanowires followed a self-catalytic vapor-liquid-solid process. During annealing, the photoresist was carbonized into a complex glassy and graphite carbon structure. The immiscibility between the carbon layer and the in-situ formed Zn2SnO4 was a prime factor in the formation of the one-dimensional Zn2SnO4 nanowires. A broad blue-red emission band centered at 490.4 nm was observed in the photoluminescence spectrum of these nanowires, and it was related to the oxygen vacancies in these nanowires.     

ZnO/SnO_2,SnO_2/ZnO UPF复合膜的制备及气敏特性研究

用直流气体放电活化反应蒸发沉积技术在普通玻璃基片上制备了ZnO／SnO2及SnO2／ZnO超微粒子（UPF）双层复合薄膜。样品经扫描电子显微镜（SEM）和X射线衍射仪分析，结论为超微粒子的复合薄膜。同时提出了最佳制备工艺。气敏测试结果表明：ZnO／SnO2及SnO2／ZnOUPF复合膜较单层ZnO及SnO2UPF表现出优良的选择性，其灵敏度和最佳工作温度也得到相应的改善。     

Preparation of zinc tin oxide films by reactive magnetron sputtering of Zn on liquid Sn

Zn is sputter-deposited on melted Sn films by radio-frequency magnetron sputtering in oxidizing plasma. The samples present an absorption cut-off wavelength close to the one of ZnO, and an optical transparency higher than 50% in the visible range. Ex-situ thermal annealing improves visible transparency and produces a slight blue-shift in the optical bandgap. X-ray diffraction patterns show typical spectra due to polycrystalline ZnO with evidence of the presence of crystalline SnO, before annealing, and Zn₂SnO₄, after annealing. Rutherford Backscattering studies reveal the existence of a ZnO layer on top of an O-rich (Zn, Sn)O thin film. After optimal thermal treatment, electrical characterization exhibits carrier concentrations of 10¹⁶-10¹⁷ cm⁻³ and mobilities of 20-80 cm² V⁻¹ s⁻¹ for the resulting (Zn, Sn)O n-type films.