钛铁矿型六方相ZnTiO3的电子结构和光学性质

分别采用基于密度泛函理论(DFT)的局域密度近似(LDA)和广义梯度近似(GGA)方法对钛铁矿型六方相ZnTiO₃的电子结构进行了第一性原理计算, 并在局域密度近似下计算了六方相ZnTiO₃的光学性质, 并将计算结果与实验数据进行了对比. 结果表明, 在局域密度近似下计算得到的结构参数更接近实验数据. 理论预测六方相ZnTiO₃属于直接带隙半导体材料, 其禁带宽度(布里渊区Z 点)为3.11 eV. 电子态密度和Mulliken 电荷布居分析表明Zn―O键是典型的离子键而Ti―O键是类似于钙钛矿型ATiO₃ (A=Sr, Pb, Ba)的Ti―O共价键. 在50 eV的能量范围内研究了ZnTiO₃的介电函数、吸收光谱和折射率等光学性质, 并基于电子能带结构和态密度对光学性质进行了解释.

Electronic Structures and Optical Properties of Ilmenite-type Hexagonal ZnTiO3

The electronic structures of ilmenite(IL)-type hexagonal ZnTiO2 were investigated using the generalized gradient approximation(GGA)and local density approximation(LDA)based on density functional theory(DFT).The optical properties of ZnTiO3 were also calculated by the LDA method.The calculated results were compared with experimental data.Results show that the structural parameters obtained by the LDA calculation are rather close to the experimental values.IL-type hexagonal ZnTiO3 is a kind of direct bandgap(Eg=3.11 eV)semiconductor material at the Z point in the Brillouin zone.An analysis of the density of states(DOS)and the Mulliken charge population clearly reveal that the Zn-O bond is a typical ionic bond whereas the Ti-O bond,which is similar to the Ti-O bond in perovskitas ATiO3(A=Sr,Pb,Ba),is covalent in character.Furthermore,the dielectric function,absorption spectrum,and refractive index were obtained and analyzed on the basis of electronic band structures and the DOS for radiation up to 50 eV.