title: Research on the optical spectra, g factors and defect structures for two tetragonal Y²+ centers in the irradiated CaF₂: Y crystal.
abstract: Based on the defect models that the tetragonal Y(2+) (1) center in the irradiated CaF(2): Y crystal is due to Y(2+) at Ca(2+) site associated with a nearest interstitial F(-) ion along C(4) axis and the tetragonal Y(2+) (2) center is Y(2+) at Ca(2+) site where the tetragonal distortion is caused by the static Jahn-Teller effect, the two optical spectral bands and anisotropic g factors for both tetragonal Y(2+) centers are calculated. The calculations are made by using two methods based on the cluster approach, one is the complete diagonalization (of energy matrix) method (CDM) and another is the perturbation theory method (PTM). The calculated results for each Y(2+) center from CDM and PTM coincide and show reasonable agreement with the experimental values. The calculated isotropic g factor for Y(2+) (2) center at higher temperature owing to the dynamical Jahn-Teller effect is also consistent with the observed value. The defect structures (i.e., tetragonal distortion) of the two Y(2+) centers are obtained from the calculation. It appears that both theoretical methods can be applied to explain the optical and EPR data, to study the defect model and to determine the defect structures for d(1) ions in crystals.
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: Yang
authors.initials: Y
authors.lastname: Mei
authors.forename: Yu-Guang
authors.initials: YG
authors.lastname: Yang
authors.forename: Hong-Gang
authors.initials: HG
authors.lastname: Liu
mesh_terms: D002124:Calcium Fluoride / Q000737:chemistry*; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D007477:Ions; D055620:Optical Phenomena
chemical_list: D007477:Ions; D002124:Calcium Fluoride