M- (Sm, Pr, Ga) 掺杂TiO2带隙及电子结构的第一原理研究
Band gap and electronic properties of M- (Sm, Pr, Ga) doped TiO2 from first principles

采用密度泛函理论对M-（Sm、Pr、Ga）掺杂锐钛矿型TiO2能带和电子性质进行了系统的理论研究. 计算结果表明，通过Sm和Pr的掺杂可以降低TiO2的带隙进而使其产生吸收边红移，通过Ga的掺杂能使带隙稍增加. 这主要是由于Sm和Pr的掺杂使Sm和Pr上的4f层电子与原子相邻O原子上的2p层电子相互作用，形成的杂质能级影响了Ti-O的能带结构，从而降低带隙，提高TiO2的可见光吸收性能.
The band gap and electronic properties of M- (Sm, Pr, Ga) doped anatase TiO2 been investigated systematically using density functional theory calculations. Our calculated results show that the Sm- and Pr- doped systems can induce the red shift of the absorption edge by reducing their band gap, whereas the band gap slightly increases by Ga-doped. These results can be attributed to different characters in the electronic properties of the doped metal element (M), and there are more electrons transfer from the 4f electrons of Sm and Pr atom to an adjacent O atom to affect the strength of the hybrid orbital of M-O, and the hybridized orbitals can form some impurity energy levels, which can reduce the band gap and improve the visible-light absorption performance of TiO2 gradually.