Y-Nb共掺杂金红石型Ti02电子结构和光学性质的第一性原理研究

目的计算分析Y-Nb共掺杂对金红石型TiO2的微观结构、电子结构和光学性质的影响，为实验研究和实际应用提供理论依据。方法采用基于密度泛函理论的第一性原理平面波超软赝势计算方法。结果Y掺杂后禁带宽度减小，出现受主能级并跨越了费米能级，低能区出现介电峰，价带主要由O2p态、Ti3d和Y3p4d态共同构成；Nb掺杂后禁带宽度有所减小，价带和导带整体负移，但是对介电峰没有明显的影响；Y-Nb共掺杂的形成能最低，杂质原子引起了晶格结构的畸变，使得以Ti为中心和分别以Y、Nb为中心的氧八面体正负电荷中心分离，从而产生内偶极矩，有利于光生电子空穴对的分离。结论Y-Nb共掺杂极大地减小了禁带的宽度，提高了金红石型TiO2对可见光吸收性，从而减少电子从价带跃迁到导带所需的能量。

The first-principles study of electronic structure and optical properties of Y-Nb co-doped rutile TiO2

Objective-To calculate and analyze the effects of Y-Nb codope on the microstructure, electronic structure and optical properties of rutile-type TiO2, and to provide a theoretical basis for ex perimental research and practical applications. Methods-Based on density functional theory, the first principles calculation method of plane wave ultra-soft pseudo potentials is adopted to investigate the a bove-mentioned objective. Results-The band gap of Y-doped TiO2 decreases, an acceptor impurity level appears and spans the Fermi level, a dielectric peak appears in low energy region as well, and the O 2p, Ti 3d and Y 3p4d states constitute the valence band; in Nb-doped TiO2, the valence and con duction bands entirely make negative shift, but the dielectric peaks are not significantly affected; the formation energy of Y-Nb co-doped rutile TiO2 is minimum, it is impurity atoms that caused the dis- tortion of lattice structure, making the centers of positive and negative charges in oxygen octahedronwith Ti as well as respective Y and Nb as a center separate, thereby producing the inner dipole mo ment, which is beneficial to the separation of photogenerated electron-hole pairs. Conclusion-Y-Nb co-doping doesn＇t only greatly reduce the width of the forbidden band but also improve the visible light absorption of rutile Ti02, thereby reducing the energy required by electrons jumping from the valence band to the conduction band.