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利用零场分裂参量与晶体结构之间的定量关系 ,研究了双掺杂晶体KCdF3 ∶Cr3 + ,Li+ 的局域结构。指出 ,对于KCdF3 ∶Cr3 + ,Li+ 晶体 ,四角晶场的形成包含两个方面 :( 1 )由于电荷补偿而产生的等效电荷形成的四角对称晶场 ;( 2 )Cr3 + 的局域结构发生晶格畸变而产生的四角对称晶场。事实上 ,当Cr3 + 和Li+ 掺入KCdF3晶体时 ,Cr3 + 代替了Cd2 + 离子 ;由于Cr3 + 离子与Cd2 + 离子的半径不同、电荷不同、质量不同 ,导致Cr3 + 的局域结构发生晶格畸变 ,由此而产生四角对称晶场 ;由于电荷补偿 ,Li+ 离子取代了 [0 0 1 ]方向与Cr3 + 离子邻近的Cd2 + 离子 ,由此产生的等效电荷而形成的四角晶场。这样 ,Cr3 + 的局域结构由Oh 对称变为C4v点对称。文中建立了ZFS参量和晶体结构之间的定量关系。在考虑晶格畸变和等效电荷的基础上 ,研究了KCdF3 ∶Cr3 + ,Li+ 晶体的ZFS参量 ,理论结果和实验符合很好。得到了F-离子向中心离子分别移动为ΔR1=0 0 0 2 68nm ,ΔR2 =0 0 0 1nm ,ΔR3 =0 0 0 1 65nm。
Based on the quantitative relationship between zero-field splitting parameters and crystal structure, the local structures of double-doped crystals KCdF3: Cr3 + and Li + were studied. It is pointed out that the formation of tetragonal crystal field in KCdF3: Cr3 +, Li + crystal contains two aspects: (1) the tetragonal symmetry crystal field formed by the equivalent charge generated by charge compensation; (2) the local structure of Cr3 + Lattice distortion generated by the four symmetrical crystal field. In fact, when Cr3 + and Li + are doped into KCdF3 crystals, Cr3 + replaces Cd2 + ions. Due to the different charges and masses of Cr3 + ions and Cd2 + ions, the local structure of Cr3 + Resulting in a tetragonal symmetry crystal field. Due to the charge compensation, the Li + ions replace the Cd 2+ ions in the [0 0 1] direction adjacent to the Cr 3+ ions, resulting in the formation of a tetragonal crystal field with equivalent charges. In this way, the local structure of Cr3 + changes from Oh symmetry to C4v point symmetry. The quantitative relationship between ZFS parameters and crystal structure is established in this paper. Considering lattice distortion and equivalent charge, the ZFS parameters of KCdF3: Cr3 + and Li + crystals were studied. The theoretical results are in good agreement with the experiment. It was found that the movement of F- ions to the center ions was ΔR1 = 0 0 0 2 68nm, ΔR2 = 0 0 0 1nm, ΔR3 = 0 0 0 1 1 65nm, respectively.