过渡离子Fe^3＋在KMgF3中局域晶体结构理论的研究

通过对角化能量矩阵研究了KMgF3：Fe^3＋系统的EPR谱．引入了双层配体模型，即6个F离子为第一层配体和8个K离子为第二层配体，来描述KMgF3：Fe^3＋系统．通过同时模拟第二和第四个EPR参量D和（a-F），在理论上发现了沿C3轴的一个K^＋离子向Fe^3＋离子的移动，并且这个移动导致了第一层的六个F配体的移动．用Fe^3＋-F^-键和C3轴的夹角θ1和θ2描述这个畸变．在室温下，得到两个畸变角△θ1=5．54～6．07°，△θ2=-4．60～5．00°．这个结果与重叠模型估计的角度具有可比性．

Theoretical study of electron paramagnetic resonance spectrum for Fe3+ ion in KMgF3:Fe3+ system

The electron paramagnetic resonance spectrum of the KMgF3：Fe^3＋ system is studied on the basis of the complete energy matrices of d^5 configuration ion with a trigonal symmetry. A two-layer-ligand model, which includes six Fions in the first layer and eight next nearest-neighbor K^＋ ions in the second layer, is proposed to describe the real ligand-field. By simulating the second-order and fourth-order EPR parameters D and （ a -F） simultaneously, a displacement ofa K^＋ion along C3 axis towards the Fe^3＋ ion is found theoretically, and this displacement will give rise to the distortion of the octahedron constructed by six F^- ligand ions in the first layer. Two angles θ1 and θ2 between the Fe^3＋-F band and C3 axis are taken to describe the local distortion along the 111] direction. The range of the local distortion parameters △θ1=5.54～6.07°,△θ2=-4.60～5.00°, are determined, and the EPR spectrum of the KMgF3：Fe^3＋ system is satisfactorily explained by the two-layer-ligand model.