微波诱导燃烧法合成类花状ZnO纳米材料及其晶体结构、荧光性质研究

以硝酸锌Zn(NO3)2.6H2O]和尿素CO(NH2)2]作前驱体,通过微波诱导燃烧技术可控合成具有不同形貌的ZnO纳米晶体,并用热重分析和差热分析进行了研究。对各种生长条件:微波功率,辐射时间和尿素/Zn2+物质的量的比对ZnO纳米晶体形貌的影响作了分析。结果表明:尿素/Zn2+物质的量的比对ZnO纳米材料的形貌具有显著影响。X衍射图表明合成的ZnO纳米结构呈六角形。傅里叶变换红外光谱图中400~500 cm-1处明显的峰为Zn-O的振动峰。ZnO纳米结构的发光光谱在366 nm的带边发射,因缺陷又由许多可见光发射峰组成。用扫描电子显微镜、透射电子显微镜、选区电子衍射研究了花状ZnO纳米结构的增长机理。本方法仅需几分钟就获得的了ZnO纳米结构。

Microstructures and Photoluminescence Property of Flower-Like ZnO Nanopowders Synthesized by Microwave-Induced Combustion Technique

ZnO crystals with different morphologies were controllably synthesized by the microwave-induced combustion technique. A solution of zinc nitrate Zn(NO₃)₂·6H₂O] and urea CO(NH₂)₂] was used as the precursor. The precursor of ZnO nanocrystal powders was studied by TG-DTA analysis. The effect of growth conditions, such as microwave power, radiation time, and urea/Zn²⁺ molar ratio, on the morphology of the ZnO nanocrystals was investigated. The results show that the molar ratio of urea/Zn²⁺ is the key factor affecting the morphology of the ZnO nanostructures. X-ray diffraction study indicates that the synthesized ZnO nanostructure is hexagonal. A sharp Zn-O vibration peak at 400~500 cm^-1 confirms the presence of ZnO. The photoluminescence spectrum of ZnO nanostructure consists of a band-edge emission at 366 nm and visible light emission peaks due to defects. Based on the morphological information provided by scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction, a growth mechanism for the formation of flower-like ZnO nanostructures is suggested. It only takes a few minutes to obtain ZnO nanostructures by the present approach.