金纳米颗粒等离激元对不同形貌氧化锌薄膜发光性能的调控

采用化学气相沉积法制备了纳米棒状的氧化锌纳米结构薄膜和没有纳米棒的氧化锌薄膜,通过直流溅射在所制备的有纳米棒和没有纳米棒的氧化锌薄膜上淀积约3 nm厚的金纳米颗粒薄膜,研究了金纳米颗粒对不同表面形貌氧化锌薄膜的发光特性的影响。实验发现金纳米颗粒的存在使具有纳米棒的氧化锌薄膜的紫外发射增强,但使来自缺陷的可见光发射受到很大的抑制。通过比较有纳米棒和没有纳米棒的氧化锌薄膜在镀金纳米颗粒前后的发光特性,发现金表面等离激元对氧化锌发光的调控取决于氧化锌的表面形貌,纳米棒的存在更有利于金纳米颗粒等离激元调控氧化锌的发光特性。     

聚乙烯亚胺对氧化锌纳米阵列形貌的影响

采用化学沉淀法,以硝酸锌和六次亚甲基四胺的水溶液为生长溶液,在涂覆氧化锌晶种层的玻璃衬底上制备了定向生长的氧化锌纳米棒阵列,并研究了添加剂聚乙烯亚胺的浓度对氧化锌纳米棒形貌和结构的影响。X射线衍射和场发射扫描电镜的结果表明,合成的氧化锌纳米棒阵列较为均匀致密,具有六方纤锌矿结构,且有沿(002)晶面择优生长的特性;随着聚乙烯亚胺浓度的增加,氧化锌纳米棒的直径减小,直径分布趋于均匀,且氧化锌纳米棒的形貌也从锥状转变为柱状结构;另外,聚乙烯亚胺的加入对氧化锌的生长速度具有抑制作用,当聚乙烯亚胺的浓度增加至0.012 mol·L-1时,无氧化锌阵列生长。对氧化锌纳米棒阵列进行了拉曼光谱表征,结果表明,随着溶液中聚乙烯亚胺浓度的增加,氧化锌纳米棒的氧空位缺陷减少。最后,对聚乙烯亚胺浓度对氧化锌纳米阵列影响的机理进行了探讨。     

晶种分布对氧化锌纳米棒生长的影响

采用水热法在氧化锌晶种修饰的衬底上生长氧化锌纳米棒,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)系统地分析了晶种分布状态对氧化锌纳米棒排列的影响.SEM结果表明随着晶种密度的增大,氧化锌纳米棒从排列无序向具有高度取向的紧密有序纳米棒阵列转变,反映纳米棒端面垂直生长优化;XRD表征显示,随着晶种密度的增大,(002)峰增强,(110)峰减弱,即端面衍射增强,侧面衍射减弱,与SEM结果相对应.同时在生长的氧化锌纳米棒中存在链状和花状的簇结构,分析表明这些簇结构与晶种在衬底上的特殊分布状态有关.     

热蒸发法制备的球棒状氧化锌晶体的形貌及生长过程

在不用催化剂的条件下,通过热蒸发锌粉的方法,一种新颖的球棒状的氧化锌纳米结构被沉积在硅基片上.每一根球棒状的氧化锌纳米棒("纳米球棒")由三部分构成,分别是六边形"球棒头"、"球棒把手"以及一个连接过渡的部分.高分辨率透射电镜和选区电子衍射结果表明,纳米棒呈单晶特性,沿着[0001]方向择优生长.根据对实验结果的分析,纳米球棒的生长过程可以利用气-固生长机制进行解释,合理地提出其生长模型.     

LED光激活氧化锌纳米棒的乙醇气敏特性

利用水热法制备了氧化锌纳米棒材料,分析表征了样品的形貌及晶体结构特征,并测试了氧化锌纳米棒的光致发光谱。在室温条件下,研究了ZnO 纳米棒在不同波长的发光二极管(LED)光激发下对乙醇气体的气敏特性。结果表明:波长小于405 nm的紫外光对氧化锌纳米棒的气敏特性有着显著的影响,光致载流子对氧化锌的气敏特性有重要作用。分析讨论了室温下光激活纳米氧化锌气敏的机理。     

氧化锌纳米棒的生长过程研究

利用高分子聚乙烯吡咯烷酮(PVP)和乙酸锌的配合物作为前驱体,在300 ℃温度下煅烧,并制备了氧化锌纳米棒。生成的产物用XRD,TEM,SAED等测试方法进行了表征。为了研究氧化锌纳米棒的生长过程,我们通过控制制备前驱体所需原料的比例不变,改变在300 ℃温度下煅烧的时间,分别为0.5, 3, 12和24 h,来观察生成产物的形貌特征。实验发现在110 ℃温度下干燥的前驱体中已经有氧化锌微晶生成;在300 ℃温度下煅烧0.5 h后就出现了明显的由几个纳米大小的微晶所组成的氧化锌纳米棒;煅烧3 h后的产物是结构非常完整的径直单晶ZnO纳米棒;12和24 h煅烧前驱体生成的ZnO纳米棒长度有所增加,ZnO的量基本保持不变。实验发现氧化锌的生长是沿着c轴方向,但是在横向也有生长方向。     

室温离子液体中超声辐照制备氧化锌纳米棒的研究

离子液体与超声技术结合在纳米材料的制备中具有广阔的前景,但目前以离子液体为溶剂超声制备纳米材料的报道还不多见,相关的反应机理研究也亟待开展。本文首次在室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐中超声制备了氧化锌纳米棒,该方法具有简便、快速和环境友好等特点。采用X射线衍射(XRD)、透射电子显微镜(TEM)对纳米氧化锌的结构和形貌进行表征。作为比较研究,采用传统的低蒸汽压有机溶剂二缩三乙二醇在同样的超声反应条件制备了纳米氧化锌材料。离子液体中超声合成样品为直径约20 nm,长度30~50 nm的纳米棒,而在二缩三乙二醇中超声制备的样品为直径6~8 nm的纳米颗粒。利用光声光谱(PAS)研究了纳米氧化锌样品的光学性能和量子尺寸效应。对离子液体中超声制备氧化锌纳米棒可能的反应机理进行了讨论并建立了的反应模型。结果表明在在超声辐照和离子液体溶剂的共同作用下氧化锌纳米棒得以生成。     

氧化锌叶片状纳米晶的结构和光谱特性

熔盐法对sol-gel法生成的前驱物处理合成新颖的叶片状的氧化锌纳米结构,TEM照片显示其长度300-500nm,宽度为50-80nm,两头尖端约呈25°夹角,形状基本沿中轴呈中心对称。其生长过程进行了研究:弯曲了的ZnO纳米棒闭合形成框架结构,框架内沿中轴方向并排生长的ZnO纳米线填满框架内的空隙形成叶片状的氧化锌纳米结构。Raman谱测量发现该结构是晶化的六角相氧化锌。对叶片状的氧化锌的声子限制效应进行了研究,并与纳米颗粒氧化锌予以比较。435cm-1的E2峰的Fano不对称具有正的Fano耦合系数。发现在585nm处出现光致发光峰,归于ZnO纳米结构中氧缺陷的作用。     

氧化锌纳米棒场发射性能研究

采用简单物理气相沉积法制备出取向和非取向的氧化锌纳米棒，他们的场致电子发射性能测量结果表明，ZnO纳米棒具有较好的场发射性能，但是高度取向的ZnO纳米棒阵列并不利于获得高的场致电子发射电流密度.这可能是由于高密度ZnO纳米棒之间具有较高的屏蔽效应，降低了ZnO纳米棒阵列的场放大因子，从而影响了其场发射性能.相反，非取向ZnO纳米棒由于相互之间的屏蔽效应比较弱，而且表面存在容易成为发射中心的微小突起，表现出较好的场发射效果.这些结果不仅有助于加深我们对准一维纳米材料场致电子发射性能的理解，也为未来场发射电子器件的实际应用提供了可靠的依据. 关键词： 氧化锌 场发射 非取向     

一维有序ZnO纳米棒阵列的制备与表征

通过改进传统水热法的密闭、高压的条件,在非密闭、常压环境下在氧化铟锡玻璃衬底上自组装生长了取向高度一致并且分散性好的ZnO纳米棒阵列.首先将乙酸锌溶胶旋涂到氧化铟锡玻璃衬底上,经热处理得到致密的ZnO纳米晶薄膜,然后将其垂直放入前驱体溶液中通过化学溶液沉积生长得到ZnO纳米棒阵列.室温条件下,对样品进行了SEM和XRD的测试.表明生成的氧化锌纳米棒阵列沿c轴取向,实现了定向生长,且纳米棒结晶较好,为六方纤锌矿结构,直径约为40 nm,长度达到微米量级.室温下的吸收光谱表明,由此方法得到的纳米棒纯度较高,有强的紫外吸收.室温下,观测到了该有序ZnO纳米棒阵列在387 nm处强的窄带紫外发射,半高宽小于30 nm,在468 nm处还有一强度较弱的蓝光发射峰.     

Highly ordered zinc oxide nanotubules synthesized within the anodic aluminum oxide template

Zinc oxide (ZnO) nanotubules were prepared by sol-gel synthesis within the pores of an anodic aluminum oxide (AAO) template. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and X-ray Diffraction (XRD) were used to investigate the morphology and crystalloid structures of the ZnO nanotubules. The results indicate that polycrystalline ZnO nanotubules are very uniformly assembled and parallel to each other in the membrane pores of the AAO template. Received: 15 January 2001 / Accepted: 1 February 2001 / Published online: 27 June 2001     

高压对纳米ZnO和ZnO/SnO2复合材料的结构和发光性能的影响

 利用溶胶-凝胶法制备出了纳米晶ZnO与含有3%摩尔分数SnO₂的ZnO/SnO₂复合材料,在六面顶压机上对制备出的两种样品进行了室温下、6GPa的高压处理。采用X射线衍射（XRD）、透射电子显微镜（TEM）和光致荧光谱（PL）等方法,对高压处理前后样品的结构和发光性质进行了表征。结果表明：高压处理后回收到的纳米晶ZnO和ZnO/SnO₂复合材料的平均粒径分别减小5.9%和26.3%;高压处理后ZnO和ZnO/SnO₂复合材料光致发光谱的发光带强度都有所降低,但ZnO/SnO₂复合材料发光带强度降低幅度比纯ZnO小,对产生这些现象的原因进行了讨论。     

Tunable negative refraction by electro-optical control in two-dimensional photonic crystal

This paper describes a simple hydrothermal procedure for high-yield synthesis of single-crystalline ZnO hexagonal nanoplates in a surfactant-free system at 70 °C. The structures and morphologies of the synthesized ZnO nanoplates are derived from characterisation by X-ray diffraction, and scanning and transmission electron microscopy. Their optical properties are recorded by Raman and photoluminescence spectroscopy. These ZnO hexagonal nanoplates exhibit the enhanced photocatalytic activity of phenol photodecomposition, suggesting that they could be served as an active system for the treatment of the waste water, in addition to their common applications. PACS 81.10.Dn; 61.10.Nz; 68.37.Hk; 78.55.Hx     

Synthesis of ZnO nanoparticles using nanosecond pulsed laser ablation in aqueous media and their self-assembly towards spindle-like ZnO aggregates

ZnO nanoparticles were fabricated by pulsed laser ablation (PLA) of a Zn metal in aqueous media, and aging effects on the morphology and photoluminescence properties of ZnO nanoparticles were investigated. The crystalline phase and particle morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that small, well-defined ZnO nanoparticles were obtained by PLA of a Zn plate in aqueous media, and subsequent aging of the obtained ZnO nanoparticle suspension produced in cetyltrimethylammonium bromide (CTAB) solution led to the formation of spindle-like ZnO aggregates. However, in deionized water not the spindle-like ZnO aggregates but fluffy round aggregates were obtained. High-resolution transmission electron microscopic (HRTEM) observation indicated that the spindle-like ZnO aggregates were composed of many well-defined nanoparticles. Spindle-like aggregates exhibited strong exciton emission, while green emission could be suppressed via an aging process in the presence of CTAB. Moreover, thin films prepared by electrophoretic deposition (EPD) of ZnO nanoparticles after PLA in the presence of CTAB also possessed highly elongated aggregate structures that were possibly formed by surrounding the ZnO nanoparticles with double layers of CTAB molecules.     

Synthesis of ZnO compound nanostructures via a chemical route for photovoltaic applications

A facile, low-temperature, and low-cost chemical route has been developed to prepare ZnO nanowire and nanosphere compound structures. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have systematically investigated the optical properties of the ZnO nanostructures by micro-Raman, photoluminescence, and transmission spectroscopy. The results demonstrate that the yielded ZnO nanostructures possess good optical quality with high light absorption. We have further successfully employed the obtained ZnO compound nanostructures in dye-sensitized solar cells. The light-to-electricity conversion results show that the compound nanostructure exhibits a significant enhancement of short-circuit current density due to the increased surface area and light scattering in the compound nanostructures. The present chemical route provides a simple way to synthesize various compound nanostructures with high surface area for nanodevice applications.     

Centimetre-Long Single Crystalline ZnO Fibres Prepared by Vapour Transportation

Centimetre-long ZnO fibres are synthesized by vapour transportation via thermal evaporation of ZnO powders. The growth process is carried out in a graphite crucible, in which ZnO powder is loaded as the source material, and a silicon wafer is positioned on the top of the crucible as the growth substrate. During the growth process, the source temperature is kept at 800℃ and the substrate temperature is kept at 600℃. Typical growth time to obtain centimetre-long ZnO fibres is 5-10 hours. Scanning electron microscopy （SEM）, x-ray diffraction （XRD）, transmission electron microscopy （TEM）, and selected area electron diffraction （SAED） measurement results show that ZnO fibres are single crystalline with high crystalline quality and very low defects concentration.     

Synthesis of ZnO hollow spherical structures with different surface-to-volume ratios

ZnO hollow spherical structures with different surface-to-volume ratios were prepared using solid Zn microspheres as template via a simple oxygen-controlled thermal evaporation approach. The results of scanning electron microscopy testify that ZnO hollow spherical structures with different morphologies can be realized by changing oxygen supply. The corresponding transmission electron microscopy images further reveal that the prepared spherical structures are hollow, and nanorods epitaxially grow from the surface of the sphere shell along the [0001] direction. A series of experiments indicates that the formation of hollow spherical structures involves the oxidization on the surface of Zn microspheres, sublimation of Zn, and growth of ZnO nanorods.     

Hierarchical ZnO/Bi2O3 nanostructures: synthesis, characterization, and electron-beam modification

Two types of ZnO/Bi₂O₃ nanonecklace heterostructures were fabricated using the vapor-phase transport (VPT) method for the first time. These hierarchical structures were well characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) attached. The growth mechanism of the novel structures were proposed based on these characterizations. Electron-beam irradiation was found to be a powerful and controllable tool in further tailoring such ZnO/Bi₂O₃ nanonecklace heterostructures. In addition, photoluminescence (PL) emission from the hierarchical nanostructures showed enhancement comparing to the pure Bi₂O₃ powder.     

两步法制备空间取向高度一致的ZnO纳米棒阵列

采用两步法,即先用磁控溅射在Si(100)表面生长一层ZnO籽晶层、再利用液相法制备空间取向高度一致的ZnO纳米棒阵列.用扫描电子显微镜、X射线衍射、高分辨透射电子显微镜和选区电子衍射对样品形貌和结构特征进行了表征.结果表明,ZnO纳米棒具有垂直于衬底沿c轴择优生长和空间取向高度一致的特性和比较大的长径比,X射线衍射的(XRD)(0002)峰半高宽只有0.06°,选区电子衍射也显示了优异的单晶特性.光致发光谱表明ZnO纳米棒具有非常强的紫外本征发光和非常弱的杂质或缺陷发光特性. 关键词： ZnO纳米棒阵列 ZnO籽晶层 两步法 液相生长     

ZnO Nanorods Produced by the Method of Arc Discharge

ZnO nanorods are fabricated by arc discharge with ZnO powder as source materials. The sample is characterized by x-ray diffraction, Raman scattering spectra, scanning electron microscopy and high-resolution transmission electron microscopy. The ZnO nanorods exhibit single crystals with the hexagonal wurtzite structure. Many of them are tetrapod-like. The diameters range from several nanometres to about lOOnm, and the main diameters of the nanorods is around 20nm. The length-to-diameter ratio is more than 5, and the grown directions are along the [001] axis. Photoluminescence spectra show a narrow ultraviolet emission at around 389nm and a broad green emission at around 520 nm. The growth process can be interpreted by the vapour-solid mechanism.