title: Defect models of the three trigonal Ti3+ centers in LiF:Ti3+ and LiF:Ti3+:Mg2+ crystals.
abstract: 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.
authors.affiliation: Department of Material Science, Sichuan University, Chengdu 610064, PR China. zhengwc1@163.com
authors.forename: Wen-Chen
authors.initials: WC
authors.lastname: Zheng
authors.forename: Zhou
authors.initials: Z
authors.lastname: Qing
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Feng
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
mesh_terms: D003460:Crystallization; D005459:Fluorides / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D008956:Models, Chemical; D014025:Titanium / Q000737:chemistry*
chemical_list: D018020:Lithium Compounds; C027651:lithium fluoride; D014025:Titanium; D008274:Magnesium; D005459:Fluorides