Al2O3:V3+晶体局域结构及其自旋哈密顿参量研究

提出了解释掺杂离子局域结构畸变的配体平面移动模型，建立了此模型下晶体微观结构与自旋哈密顿参量之间的定量关系.在考虑自旋与自旋、自旋与另一电子轨道和轨道与轨道作用等微小磁相互作用的基础上，采用全组态完全对角化方法，对Al₂O₃晶体中V³⁺的局域结构和自旋哈密顿参量进行了系统的研究.结果表明，V³⁺掺入Al₂O₃晶体后，上下配体氧平面间距离增大了0.0060 nm.从而成功地解释了Al₂O₃:V³⁺晶体的自旋哈密顿参量.在此基础上，研究了三角晶场下3d²离子自旋哈密顿参量的微观起源.研究发现，自旋三重态对自旋哈密顿参量的贡献是主要的，微小磁相互作用对自旋哈密顿参量的贡献只与自旋三重态有关.

Investigations of lattice distortion and spin-Hamiltonian parameters for V3+ in Al2O3 crystal

In order to study the local structure distortion and spin-Hamiltonian parameters of Al₂O₃:V³⁺ crystal, a new model has been proposed. On the basis of it, the relationship between the crystal structure parameters and spin-Hamiltonian (SH) parameters is established using Newman crystal-field superposition model. the lattice distortion and SH parameters of Al₂O₃:V³⁺ crystal, taking into account the slight magnetic interactions, including spin-spin, spin-other-orbit and orbit-orbit interactions, have been studied using the complete diagonalization method. The calculated results are in good agreement with experimental ones. It is found that the distance between upper and lower ligand oxygen plane increases by 0.0060 nm when V³⁺ is doped into Al₂O₃ crystal. Based on the local structure distortion model, at the same time, the microscopic origins of the SH parameters have been investigated for 3d² ions in trigonal-symmetry crystal field. The results show that the SH parameters are mainly depend on spin triplets, and the contributions to SH parameters from slight magnetic interactions are related to spin triplets only.