LiNbO3∶Fe3+晶体的光谱精细结构、零场分裂参量及Jahn-Teller效应

应用不可约张量方法和群的理论构造了三角对称晶场中3d⁵组态离子的252阶可完全对角化的微扰哈密顿矩阵，利用该矩阵计算了LiNbO₃∶Fe³⁺晶体的光谱精细结构、零场分裂、晶体结构、Jahn-Teller(J-T)效应，其理论计算值与实验值相符合，并研究了自旋四重态、自旋二重态分别对基态能级的影响，证明了自旋四重态对基态能级的贡献是主要的，自旋二重态对基态能级的贡献虽很小，但却是不可忽略的.在此基础上,进一步研究了自旋-轨道耦合作用、自旋-自旋耦合作用对LiNbO₃∶Fe³⁺晶体的光谱精细结构和零场分裂参量的影响，发现自旋-轨道耦合作用是最主要的，自旋-自旋耦合作用也是不可忽略的. 研究表明，该种物质的四重态光谱结构中含有J-T效应. 其产生原因是自旋-轨道耦合及三角畸变的共同作用的结果，两者缺一不可.

The spectral fine structure, zero-field splitting parameters and Jahn-Teller effect of LiNbO3∶Fe3+crystals

The 252 rank completely diagonalized Hamiltonian matrix of the 3d⁵ configuration with trigonal symmetry have been established by group theory, crystal field theory and irreducible tensor operator method. The spectral fine structure, zero-field splitting parameters, and Jahn-Teller effect, as well s the influence of spin doublet state and spin quartet state on the ground-state energy levels in LiNbO₃∶Fe³⁺ crystals were studied with this matrix. The results show that the contribution of spin quartet state on the ground- state energy levels is the most important, the contribution of spin doublet state is weak but can not be neglected. The calculated results are in good agreement with the experiments. On their basis, the influence of spin-orbit interaction and spin-spin interaction on the spectra fine structure and zero-field splitting parameters were further studied, and we found that the influence of spin-orbit interaction is dominant, but the influence of spin-spin interaction can not be neglected. The research shows this substance has J-T effect in the spectral structure of spin quartet state. The reason is the combined action of spin-orbit interaction and trigonal distortion.