KCdF3:Cr3+晶体EPR零场分裂参量与电荷补偿效应的研究

按照叠加模型与EPR零场分裂参量的三阶微扰理论,建立了KCdF₃:Cr³⁺晶体EPR零场分裂参量与四角对称Cr³⁺-Cd²⁺缺陷中心局域结构之间的定量关系.证实Cd²⁺空位与晶格畸变的存在,我们获得:围绕Cr³⁺离子的六个F^-配体分别向中心Cr³⁺移动Δ₁=0.00294nm,Δ₂=0.0010nm,Δ₃=0.0028nm (参见图2).EPR零场分裂参量与实验一致表明:Cd²⁺空位与晶格畸变的假设是合理的.尽管四角晶场主要来自Cd²⁺空位,但晶格畸变的贡献不可忽略.

STUDIES OF THE EPR PARAMETER AND THE CHARGE COMPENSATION EFFECT FOR KCdF3:Cr3+ CRYSTAL

The quantitative relationship between the EPR zero-field splitting parameter D and the structure parameters of the tetragonal Cr3+ centre in KCdF3:Cr3+ crystals has been established according to the superposition model and third-order perturbation theory.The existence of Cd2+ vacancy and the lattice distortion have been verified.Meanwhile,we observed that the F- ion moves toward the central Cr3+ ion by Δ1=0.00294nm,Δ2=0.0010nm,Δ3=0.0028nm (see Fig.2).Good agreement between the theoretical values and the experimental results shows that the assumption of the Cd2+ vacancy and the lattice distortion is reasonable.Although the main source of the tetragonal crystal field comes from the Cd2+ vacancy caused by the charge compensation,the contribution of the lattice distortion can not be neglected.