Y_2Ti_2O_7:Cr^(3+)晶体中Cr^(3+)杂质中心EPR参量及缺陷结构研究  

Studies of the EPR parameters and defect structure for the Cr^(3+) impurity center in Y_2Ti_2O_7:Cr^(3+) crystal

作　　者：方旺[1] 陈恒杰[1] 杨文艳[1] 刘丰奎[1] 唐海燕[1] 

机构地区：[1]重庆科技学院数理学院物理系,重庆401331

出　　处：《四川大学学报（自然科学版）》2012年第6期1307-1312,共6页Journal of Sichuan University(Natural Science Edition)

基　　金：重庆市教委科学技术研究项目(KJ121419);重庆科技学院科研基金(CK2010B05)

摘　　要：本文利用强场图像中的高阶微扰公式计算了Y_2Ti_2O_7:Cr^(3+)晶体的电子顺磁共振谱(EPR)参量(g因子g_(//,g⊥)和零场分裂D),计算中采用双旋-轨耦合参量模型,同时考虑了中心离子和配体的旋-轨耦合对EPR参量的贡献,计算结果与实验值很好地吻合.结果表明Cr^(3+)掺入Y_2Ti_2O_7晶体会引起O^(2-)偏向[111]方向(C_3轴)2.55°,同时,杂质中心O^(2-)-Cr^(3+)键长相对于基质晶体的O^(2-)-Ti^(4+)键长增加0.005 A.The EPR Parameters （g factors g//, g and zero-field splitting D）, of Y2 Ti2O7 ： Cr3＋ crystal are calculated from the high-order perturbation formulas based on the strong field scheme. In the calcu- lations, two spin-orbit coupling parameters model is used, and both the contributions from the spin-or- bital coupling of central transition metal and the ligands are taken into account. The calculation results are in reasonable agreement with the experimental data. The results show that angle of O2. with C3 axis decreases 2.57° and O2- --Cr3＋ bond length increases 0. 055 A in defect center, with respect to the corre- sponding angle of O2- with C3 axis and 02_- Ti4＋ distance in host crystal, respectively,when doped-- Cr3＋ ions replace Ti4＋ ions in Y2Ti2O7 crystal.

关 键 词：顺磁共振理论(EPR) 晶体场理论 缺陷结构 Y_2Ti_2O_7:Cr^3+ 

分 类 号：O737[理学—晶体学] O482