LiF:Ti3+ 和 LiF:Ti3+:Mg2+ 晶体中三种三角 Ti3+ 中心的缺陷模型
Defect models of the three trigonal Ti3+ centers in LiF:Ti3+ and LiF:Ti3+:Mg2+ crystals.
作者信息
Zheng Wen-Chen, Qing Zhou, Feng Wen-Lin, Yang Mei
机构信息
Department of Material Science, Sichuan University, Chengdu 610064, PR China.
出版信息
Spectrochim Acta A Mol Biomol Spectrosc. 2007 Apr;66(4-5):1312-6. doi: 10.1016/j.saa.2006.06.019. Epub 2006 Jun 27.
The EPR g factors of the trigonal Ti3+ center A in LiF:Ti3+ and two additional trigonal Ti3+ centers B and C in LiF:Ti3+:Mg2+ crystals are calculated from the third-order perturbation formulas based on the cluster approach. From the calculations and by considering the Ti3+ displacement along 111 axis obtained by ENDOR experiment, the defect models for the three Ti3+ centers are suggested. For center A, there are two possible models: (i) [Ti3+F3-O3(2-)] cluster and (ii) [Ti3+F6-] cluster with the Ti3+ off-center caused by a neighboring Li+ vacancy (VLi+) at <111> axis. The latter seems the more likely. The defect models of centers B and C are the [Ti3+F3-O(3)2-] clusters associated with a neighboring: Mg2+ ion at the Li+ site along 111 axis in the vicinity of three F- ions and three O2- ions, respectively. The reasonableness of these models is discussed.
基于团簇方法，从三阶微扰公式计算了LiF:Ti³⁺晶体中三角Ti³⁺中心A以及LiF:Ti³⁺:Mg²⁺晶体中另外两个三角Ti³⁺中心B和C的电子顺磁共振g因子。通过计算并考虑电子核双共振（ENDOR）实验得到的Ti³⁺沿〈111〉轴的位移，提出了这三个Ti³⁺中心的缺陷模型。对于中心A，有两种可能的模型：（i）[Ti³⁺F₃ - O₃(2 - )]团簇和（ii）[Ti³⁺F₆ - ]团簇，其中Ti³⁺由于〈111〉轴上相邻的Li⁺空位（VLi⁺）而偏离中心。后者似乎更有可能。中心B和C的缺陷模型是分别与三个F⁻离子和三个O²⁻离子附近〈111〉轴上Li⁺位置的相邻Mg²⁺离子相关的[Ti³⁺F₃ - O(3)2 - ]团簇。讨论了这些模型的合理性。
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