【作者】 杨枣；

【导师】 刘全慧；

【作者基本信息】 湖南大学 ， 材料物理和化学， 2008， 博士

【摘要】 准一维纳米材料,包括纳米线/棒、纳米针、纳米带、纳米同轴电缆和纳米管等,近年来引起了极大的研究热潮。在这些材料中,氧化物半导体一维纳米材料又受到了特殊的关注,这不仅因为丰富多样的氧化物纳米结构不断被制备出来,更因为氧化物中阳离子价态可变、氧空位浓度可调,从而氧化物半导体的性质可以有效调控。本文主要对准一维纳米材料ZnO进行了研究。研究了ZnO纳米棒,纳米粒子的制备新方法,并讨论了影响ZnO纳米结构的生长因素和生长机理。对合成的ZnO纳米棒的光学特性进行了研究,并研究了不同的ZnO纳米结构形貌对光学性能的影响。对新方法进行改进合成无衬底,高质量的,单晶ZnO纳米棒密堆积阵列,并对它的生长机制进行研究。用ZnO密堆积阵列为气敏材料做成高性能酒精传感器。并对它的高灵敏度的酒敏机理进行研究。用相同的方法制得形状为n型ZnO纳米棒,并研究了它的生长机理和酒敏性。主要完成以下工作:1.我们用一种简单的新方法合成ZnO纳米棒,直径为25—100nm,长度为0.2—1um,长径比为10-40。测试结果表明ZnO纳米棒为单晶,属于六方晶系,晶形很好,很少或者没有结构缺陷,具有沿[0001]方向择优生长的特征。单晶ZnO纳米棒的制备成功为开发其潜在应用,制作各种纳米电子器件及光电子器件提供了一条简单廉价的途径,也为研究Graetzel型太阳能电池的电子传输机理、大幅度提高光电转换效率提供了一个可能的方法。同时为制备其它一维半导体纳米材料提供了一条崭新的途径。2.我们研究了影响ZnO结构的生长因素,在其它条件不变下,随着柠檬酸的浓度增加,纳米棒的长度减少,直径增大。在其它条件不变下,随着煅烧温度的升高,纳米ZnO的形态由棒状向颗粒状转变,并且粒子之间发生明显的团聚,当其它条件不变下,随着煅烧时间的增加,ZnO纳米棒的直径增加长度减少。3.我们用前面介绍的方法合成了ZnO纳米棒,通过IR,PL,UV-vis研究了ZnO纳米棒的光学特性,我们发现ZnO纳米棒有着很好的晶体质量和优秀的光学特性。同时我们研究了ZnO纳米棒和ZnO纳米粒子的光学特性,发现不同的形貌对ZnO的光学特性有一定的影响。4.对新方法进行改进制得无衬底,高质量的,单晶ZnO纳米棒密堆积阵列。ZnO密堆积阵列每一根棒都沿着[0001]方向,平均直径为50nm,平均长度为0.5μm,长径比为10。ZnO纳米棒密堆积阵列在紫外一可见光吸收谱在372nm有着一个强烈的激子吸收锋,相对于体材料(387nm)发生蓝移。研究了ZnO纳米棒密堆积阵列的生长机制。5.我们用ZnO密堆积阵列为气敏材料做成高性能酒精传感器。在1PPm酒精中,灵敏度为10,我们认为高灵敏度由密堆积耗尽和全面接触引起的。我们的结果表明ZnO密堆积阵列是合成气体传感器最适合的气敏材料。6.我们用前面介绍的方法制得形状为n型ZnO纳米棒。这些纳米棒以一个薄的片状物的基底来相互平行生长成形状为n型ZnO纳米棒,薄的片状物基底的宽度为50到130nm。直径长度为25到60nm,长度为0.2—0.6μm。用它作成的酒精传感器对酒精很敏感。在1PPm的乙醇中有灵敏度达到3.5,结果证明形状为n型的ZnO纳米棒是合成气体传感器最适合的气敏材料。更多还原

【Abstract】 Quasi-one-dimensional (1D) nanomaterials, including nanowires (rods), nanoneedles, nanobelts, nanotubes/nanocables, etc, are attracting considerable attention recently. Among these materials, functional oxide semiconductor nanostructures can be used as fundamental ingredients of intellgent systems, because their physical and chemical properties can be tuned through adjusting cation valence state and anion deficiency. In this dissertation, we focus on one dimensional ZnO nanomaterial. A new method of synthesizing ZnO nanorods and ZnO nanoparticles is researched. We discuss the growth factor, the growth mechanism of ZnO nanostructure and study optical property of ZnO nanorods. The optical property of different ZnO nanostructure is discussed. High-quality single-crystalline ZnO nanorod close-packed arrays are successfully fabricated in a substrate-free manner by improving new method. The growth mechanism of ZnO nanorod close-packed arrays is proposed. We report the fabrication and characterization of ethanol sensors with extremely high sensitivity using ZnO nanorod closed-packed arrays as the sensing materials. The ethanol sensing mechanism about it are studyed. N-shape ZnO nanorods are fabricated by the same method. We study growth mechanism and ethanol sensing of N-shape ZnO nanorods. The main contents and conclusions are summarized as:1. We synthesize ZnO nanorods of 25-100 nm in diameter and lengths from 0.2 to 1μm in length. The aspect ratio is 10-40. The results show ZnO nanorods possess a single crystal hexagonal structure. There is few or no structure defect. The growth direction of ZnO nanorods is [0001]. The fabrication of single crystal ZnO nanorod provides a simple inexpensive way for developing its latent application, manufacturing all kinds of nanoelectronic device and the photoelectronic device. It also provide a possibility method for studying the Graetzel solar cell’s electronic transmission mechanism and improving photoelectric transformation efficiency. This new route may be extended to the controllable formation of a wide variety of one-dimensional semiconductor nanomaterial.2. We study affected growth factor of ZnO structure. When other conditions are invariable, The length decreases but the diameter increases with addition of the mass of citric acid at the same temperature;With the rising of the calcining heat, the shape of ZnO changes from rod to granule for a given amount of citric acid and the granules have the obvious reunion. With extension of calcine time, the diameter of ZnO nanorod increases but the length decreases.3. We synthesize ZnO nanorods bythe frontal method. We study optical property of ZnO nanorod by IR,PL,UV-vis. We find that ZnO nanorods have very good crystal quality and the excellent optical property. We discover that the different appearance of ZnO have certain influence on ZnO optical property by studying optical property of ZnO nanorods and ZnO particles.4. ZnO nanorod close-packed arrays are successfully fabricated in a substrate-free manner by improving new method. Each nanorod of ZnO nanorod close-packed arrays grows along the [0001] direction and is single crystalline with an average diameter of 50 nm, and an average length of 0.5μm. The aspect ratio is 10.The ZnO nanorod close-packed arrays show a strong exciton absorption peak at 372 nm in UV–visible absorption spectra, exhibiting a blue-shift relative to the bulk exciton absorption (387 nm). Finally, a new growth mechanism is proposed for the substrate-free preparation of ZnO nanorod close-packed arrays.5. We report the fabrication and characterization of ethanol sensors with extremely high sensitivity using ZnO nanorod closed-packed arrays as the sensing materials. The sensitivity of the sensors is about 10 to 1 ppm ethanol.The high sensitivity is explained in terms of closed-packed surface-depletion and full face contact model. Our results demonstrate that ZnO nanorod closed-packed arrays are very promising materials for fabricating gas sensors.6. N-shaped ZnO nanorods were first synthesized by glacial acetic acid assisted annealing process. These nanorods grow from a thin platelet base and are parallel to each other to form n-shaped ZnO nanorods. The widthes of thin platelet bases range from 50 to 130nm. The diameters of the nanorods are 25～60nm and their lengths are 0.2～0.6um. Sensors realized from n-shaped ZnO nanorods were very sensitive to ethanol gases. The sensitivity was as high as 3.5 at 1 ppm ethanol exposure. These experimental results strongly suggested that n-shaped ZnO nanorods could be an excellent candidate for applications in gas sensors at the industry level.更多还原