【作者】 王琳；

【导师】 欧阳世翕；

【作者基本信息】 武汉理工大学 ， 材料科学与工程， 2006， 博士

【摘要】 本文论述了ZnO的晶体结构和特性，低维ZnO材料制备方法及发展现状。采用平均粒径分别为200nm和20nm的ZnO粉末为原料，在不采用任何催化剂条件下通过控制合成温度和时间等工艺参数，分别采用915MHz和2450MHz微波加热法固相合成了一维棒状、多针状、一维六方柱状、六方微米管状ZnO材料，并研究了其合成工艺，通过XRD，SEM表征显示：线状、棒状、管状ZnO晶须都有较好的结晶度，线状和棒状ZnO晶须直径均匀，形貌规则。根据微波场加热的特点与ZnO晶体的极性生长特性，初步研究了不同形貌的ZnO晶须的生长过程，研究表明，晶须的生长机理为固-气生长：高温区的ZnO粉末蒸发成为ZnO气体，在低温区Zn蒸气和O₂重新结合发生化学反应形成固相ZnO沉积在气—固界面形核长大，在不同的工艺条件下合成形貌不同的晶须（棒状、针状、柱状）；当温度足够高时，氧空位集中点变成“蒸发源”，形成微米管。室温光致发光谱测试表明晶须具有一定的紫外发光性能，同时晶须中出现氧空位等缺陷。采用波导法，用Agilent N5230A型矢量网络分析仪对ZnO纳米粉、微米粉、棒状晶须的微波电磁性能进行了分析。结果显示：同ZnO纳米粉、微米粉相比，棒状ZnO晶须在11GHz左右具有更强的微波吸收特性。以Si（111）为基片，采用PLD方法以陶瓷ZnO靶在有氧的气氛下，通过正交实验法控制激光能量、基片温度、氧气分压、脉冲频率、沉积时间等工艺参数来研究ZnO薄膜生长的优化工艺，在150mJ脉冲能量、500℃基片温度、0.1Pa氧气压强、7Hz脉冲频率、60min沉积时间的PLD沉积工艺下获得的ZnO薄膜在379nm处出现了强的紫外带边发射峰，此时其XRD的（002）峰的半峰宽为0.275，具有高的薄膜质量。上述研究表明微波固相、PLD等外场制备方法能有效控制材料显微结构，其生产周期短、设备简单且能源消耗少、无污染，是一种适合当前社会发展需要的“绿色环保”的制备方法。更多还原

【Abstract】 In this paper, it was been summarized to the crystal structure and properties of ZnO and the fabrication methods and research present situation of low-dimensional ZnO materials, Using 200nm and 20nm in average particle size ZnO powder as raw materials and no using any catalyst and by controlling synthesis temperature and time parameters, different morphologies of low-dimensional ZnO had been synthesized in 915MHz and 2450 MHz microwave solid-phrase heating method respectively, such as one-dimensional rods, multi-needles, one-dimensional hexagonal prisms and hexagonal microtubes. The techniques of different ZnO morphologies whiskers have been researched through plenty of experiments and scientific analyses. The microstructure and morphologies of ZnO crystal whiskers are characterized with XRD, SEM. The results show that line, bar, tube of ZnO whiskers have better crystallization degree, there are uniform diameter and regular morphologies especially for line and bar of ZnO crystal whiskers.Base on the characteristics of microwave heating and the growing properties of ZnO polar crystal, it was researched on the growing process of ZnO whiskers with different morphologies. It indicates that growth mechanism of ZnO whiskers is V-S growth, the ZnO powder vaporized in the region of high temperature that was filled with ZnO （g）, Zn （g） and O₂ （g）. In the region of low temperature, the Zn （g） and O₂ generated chemical reaction and decomposed at the vapor-solid interface, the different morphologies hand been synthesized under different conditions, such as rods, needles and prisms. When the temperature is high enough, the centralized location of oxygen vacancies was as the source of evaporation, and then the microtubes had been formed.The PL spectra shows that there are UV property for the whiskers and some oxygen vacancies exist inside. Using wave guide method as well as Model Agilent N5230A vector-net analyzer, the microwave electromagnetic performances of nano-scale ZnO powder, micrometer scale ZnO powder, bar of ZnO crystal whiskers are analyzed, respectively. The results show that bar of ZnO crystal whiskers have stronger absorption at about 11GHz comparing with nano-scale ZnO and micrometer scale ZnO powder.Si（111） as substrate, ZnO ceramic as target, oxygen as environmental gas, base on the orthogonal test design rules, selecting laser energy, substrate temperature, oxygen concentration, pulse frequency, deposition time as parameters, using PLD methods optimize the deposition parameters for ZnO films growth. The ZnO films appears strong UV peak at 379nm in the PL spectra, FWHM of ZNO（002） peak in XRD is 0.275 at the deposition condition 150mJ laser energy, 500℃substrate temperature, 0.1Pa oxygen concentration, 7Hz pulse frequency, 60 min deposition time, it shows the ZnO films with high quality.The above-mentioned research proves that the microwave heating method is suitable to control the material morphology, short period of production, the convenient equipments, low cost, no pollution, saving energy, and is a green and environment friendship method with important significance and development.更多还原