纳米晶ZnO可见发射机制的研究

Study on the Visible Emission Mechanism of Nanocrystalline ZnO powder

利用化学沉淀法制备了纳米ZnO粉体 ,室温下测量了样品的光致发光谱 (PL)、X射线衍射谱 (XRD) ,给出了样品的透射电子显微照片 (TEM ) X射线衍射 (XRD)的结果表明 :纳米晶ZnO具有六角纤锌矿晶体结构 ,颗粒呈球形或椭球形 观察到二个荧光发射带 ,中心波长分别位于 398nm的紫带和 5 10nm的绿光带 发现随退火温度升高 ,粒径增大 ,紫带的峰值减弱、绿带的峰值增强

Nanocrystalline ZnO powder are prepared by chemical precipitation method. Photoluminescence spectra of nanocrystalline ZnO with excitation wavelength 365nm are measured at room temperature. Two emission bands are observed, one being an violet band its central wavelength is 398nm and the other being green visible band its central wavelength is 510nm.Relationship between photoluminescence intensity of nanocrystalline ZnO and annealing temperature were given.Crystal structure of samples are examined by X ray diffraction pattern (XRD) and tunnel electron microscope picture (TEM). the mean grain size of nanocrystalline ZnO are calculated by with Debye Scherrer formula. The results indicate that well crystallized nano ZnO is obtained with annealing temperature at 350℃. grain of nanocrystalline ZnO are global or oval. The other purpose of the present paper is to study the luminescence properties of the obtained sample. In particular the mechanism behind the visible luminescence has also been discussed in this paper. it should be said that the mechanism behind the visible luminescence is still a question of debate. In this paper the visible emission processes of nanocrystalline ZnO attributed oxygen vacancies to the recombination centers.