微波水热时间对 ZnWO4纳米晶形貌及光学性能的影响

Influence of Reaction Time on Morphology and Optical Property of ZnWO_4 Nanocrystallites Prepared by Microwave Hydrothermal Process

采用微波水热法,以Na2WO4 2H2O和Zn(COOCH3)2 2H2O为原料,在无模板剂的条件下,可控合成了黑钨矿钨酸锌纳米晶。利用X射线衍射仪、透射电子显微镜和紫外-可见吸收光谱分别对产物的物相、形貌和光学性能进行了表征。结果表明:在微波水热条件下,反应温度为180℃时,反应时间为10min即可制备出纯相的ZnWO4纳米晶。随着反应时间的延长,产物由短棒状纳米晶逐渐生长为长棒状纳米晶。光谱研究发现,所制备的ZnWO4纳米晶具有较强的紫外吸收特性,其禁带宽度可控制在3.77～3.89eV,随反应时间延长,其禁带宽度逐渐增加。

The wolframite zinc tungstate nanocrystallites were prepared by a microwave hydrothermal method in the absence of template with Na2WO4·2H2O and Zn（COOCH3）2·2H2O as start materials. The phase, morphology and optical properties of the as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy and UV-Vis absorption spectra, respectively. The results indicated that the wolframite ZnWOa nanocrystallites can be obtained by the microwave hydrothermal method at 180 ℃ for only 10 minutes. The morphology of ZnWO4 nanocrystallites changed from short to elongated rod-like with increasing microwave hydrothermal time. The as-prepared ZnWO4 nanocrystallites have a strong absorption in ultraviolet band. The corresponding band-gap of the ZnWO4 nanocrystallites increased with the increase of reaction time, which can be controlled in the range of 3.77-3.89 eV.