钼酸钙晶体中钙空位的理论研究

The Theoretical Study of Ca Vacancy of CaMoO₄ Crystal

本文采用DFT + U方法计算了含有钙空位的钼酸钙的电子结构以及光谱。通过对电子结构进行分析可以发现空穴是均匀分布在钙空位最近邻的4个氧原子上。此外,我们还计算了含有钙空位的钼酸钙晶体的吸收谱和发射谱,计算结果表明负一价的钙空位的吸收峰为3.68 eV,负二价的钙空位的吸收峰为3.86 eV,负一价的钙空位的发射峰位于3.51 eV (353 nm),负二价的钙空位的发射峰在3.73 eV (332 nm),负一价和负二价的钙空位的发射峰的波长都属于紫外区,说明钙空位是CaMoO4晶体在紫外区发光的原因。

The electronic structures as well as the optical spectrums of CaMoO4 containing Ca vacancy are calculated by the DFT + U method. The analysis of electronic structure shows that the hole is shared by 4 nearest O atoms of Ca vacancy. The optical absorption and luminescence energy of Ca vacancy in −1 and −2 charge state are calculated, the absorption peak of Ca vacancy of −1 charge state is 3.68 eV, the absorption peak of Ca vacancy of −2 charge state is 3.86 eV, the emission peak of Ca vacancy of −1 charge state is located at 3.51 eV (353 nm), the emission peak of Ca vacancy of −2 charge state is located at 3.73 eV (332 nm), the wavelengths of the emission peaks of Ca vacancy of −1 charge state and −2 charge state both belong to the ultraviolet region, indicating that the Ca vacancy is responsible for the luminescence of the CaMoO4 crystals in the ultraviolet region.