含铅空位的PbWO_4晶体光学性质及其偏振特性的研究

Optical polarized properties for the PbWO_4 crystal containing lead vacancy

利用完全势缀加平面波局域密度泛函近似,计算了含铅空位的PbWO4(PWO)晶体的电子结构,模拟计算了复数折射率、介电函数及吸收光谱的偏振特性.比较含铅空位的PWO晶体与完整的PWO晶体的吸收光谱及其偏振特性,得到与铅空位相关的吸收光谱及其偏振特性,计算结果与实验结果基本相符.计算得到的含铅空位的PWO晶体的光学偏振特性反映了PWO晶体的结构对称性.计算结果表明PWO晶体中350,420,550和680nm的吸收带的出现与PWO晶体中铅空位的存在直接相关.

The electronic structure, dielectric functions, complex refractive indices and absorption spectra for the polarized light from the perfect PbWO4(PWO) crystal and the PWO crystal containing V-Pb(2-) have been calculated using LAPW + LDA method with lattice structure optimized. The peaks of the absorption spectra corresponding to the electronic transitions have been studied. The optical properties of PWO crystal containing V-Pb(2-) are anisotropic. It may be caused by the anisotropy of lattice structure of the PWO crystal. Our calculated results indicate that the perfect PWO crystal does not have absorption band in the visible and near-ultraviolet region, but the PWO. crystal containing V-Pb(2-) has absorption bands in visible and near-ultraviolet region. The absorption bands can be well decomposed into four Gaussian-shape bands peaking at about 350, 405, 550 and 670 nm. It predicates that these absorption bands are related to the existence of the V-Pb(2-) in the PWO crystal.