金红石TiO_2晶体中F型色心电子结构及其吸收光谱研究

THE ELECTRONIC STRUCTURE AND ABSORPTION SPECTRUM OF RUTIL TiO_2 CRYSTAL WITH F TYPE COLOR CENTER

运用F型色心的类氢离子波函数结合电荷自洽离散变分方法 ,对TiO2 晶体中F型色心的电子结构进行了计算 ,并利用能量最小原理优化了色心格点周围的Ti,O离子结构 ,得到了TiO2 晶体中F ,F+ 和F2 + 心的能带、态密度 ,并讨论了色心的光学跃迁模式。计算结果表明 ,F ,F+心在TiO2 晶体的禁带中引入了施主能级 ,F2 + 心在禁带中引入了浅受主能级 ,F和F+ 心的光学跃迁能分别是 0 85eV ,1 6 7eV .经还原后的TiO2 晶体 ,在光吸收实验中测到的 1 7μm(0 75eV) ,76 0nm(1 6 1eV)两个峰分别是由于还原过程中形成的F和F+ 心的吸收峰 ,并存在着F→F+ 的转型过程。

The electronic structure of rutile TiO\-2 crystal with F\|type color center is studied by using the H\|like wave function and Discrite Variation method with the relaxation of ions around color center,and their energy band,density of states are obtained.The results show that F and F\++ center have donor energy level in forbidden band,and F 2+ center has acceptor energy level in forbidden band.The optical transition energy are 0 85 eV and 1 67 eV for F and F\++ center,respectively.The optical absorption peaks 1\^7μm(0\^75 eV),760 nm(1\^61 eV) in the reduced sample of TiO\-2 are due to the F and F\++ center,and a transferring of F\++→F existed. [