蓝宝石(α-Al_2O_3:Fe~(3+))体系基态分裂与局域晶格畸变的研究

2002年Scholz和Buzaré对蓝宝石晶体中Fe3+离子的基态分裂重新进行了EPR实验测量和研究,他们的初步分析表明在蓝宝石晶体中Fe3+离子的6A1基态分裂有可能同时与两个方向的畸变角(θ和φ)有关.本文采用对角化d5组态在C3点群对称下的252×252完全能量矩阵的方法,对蓝宝石晶体中Fe3+离子的光谱和EPR谱进行了系统的研究.计算结果表明蓝宝石体系中Fe3+离子的6A1基态分裂确实将明显依赖于两个方向的畸变角θ和φ,这一理论结果与Scholz和Buzaré等的实验相符合.同时,通过拟合Fe3+离子在蓝宝石体系中的实验光谱和EPR参量,确定了蓝宝石晶体中(FeO6)9团簇局域晶格畸变角θi的范围.

Study on the ground-state splitting and the local lattice distortion of α-Al2O3：Fe3+ system

Electron paramagnetic resonance (EPR) spectra for Fe³⁺ in sapphire were measured and studied by Scholz and Buzaré in 2002. Their analysis shows that the ground-state splitting for Fe³⁺ in sapphire may be associated with two distortion angles Δθ and Δφ. By diagonalizing 252×252 complete energy matrix for the d⁵ configuration ion in C₃ symmetry ligand-field, in this paper a systematic investigation about the ground-state splitting for Fe³⁺ in sapphire is given. Our results indicate that the ⁶A₁ ground-state splitting are sensitively dependent on the local lattice distortion along the two directions, respectively, which supports the Scholz and Buzaré’s opinion. Meanwhile, by simulating the optical spectra and the EPR spectra for Fe³⁺ in sapphire, the local lattice distortion parameter Δθ_i can be obtained.