基于第一性原理研究Y掺杂锐钛矿TiO2的磁光性质

Study on the magnetic and optical properties of Y dopedanatase TiO based on first principles

建立了未掺杂和三种Y掺杂量的锐钛矿TiO2模型,基于第一性原理方法,对各个模型的形成能、磁性、电子结构及吸收光谱进行了计算.结果表明:掺入锐钛矿晶格的不同Y原子之间没有团簇趋势;Y掺杂量越大,实现掺杂所需的能量越高;Y掺杂的锐钛矿体系具有铁磁性,因而晶格中的自旋能级分裂效应能降低锐钛矿的带隙宽度,但当Y掺杂量升高时,这种影响显著减弱;随着Y掺杂量增加,弱束缚的O-2p态电子浓度增加,导致价带顶的O-2p态跨越费米能级,使得带隙值减小,进而提高了改性锐钛矿TiO2对可见光的吸收系数.

The anatase TiO2 models with undoped and three Y doping amounts were established. Based on first principle,the formation energy,magnetism,electronic structure and absorption spectrum of all models were calculated. Results showed that there is no cluster trend between different Y atoms doped into the anatase lattice;the larger the Y doping amount,the higher the energy required to achieve doping;Y doped anatase is ferromagnetic,so that the spin-electron band splitting effect in the lattice can reduce the band gap of anatase;but when the Y doping amount increases,this effect is significantly weakened. As the Y doping amount increases,the weakly bound electron concentration of O-2 p states increases,causing the O-2 p state at the valence band maximum to cross the Fermi level,which reduces the band gap and further improves the absorption coefficient for visible light of anatase TiO2.