Al_2O_3中掺杂Cr^(3+)、Cr^(4+)离子EPR零场分裂的理论解释

Theoretical Investigations of the Zero-Field Splittings for Cr 3+ and Cr 4+ in Al 2O 3 Crystal

在晶体场理论基础上，研究了刚玉Ａｌ２Ｏ３中分别掺杂Ｃｒ３＋和Ｃｒ４＋的ｄ－ｄ电子光谱和ＥＰＲ零场分裂Ｄ，理论计算同实验值符合好。研究表明，掺杂晶体Ａｌ２Ｏ３：Ｃｒ４＋中络离子（ＣｒＯ６）８－局域结构应有压缩的三角畸变（Δθ≈３０）。

Based on the crystal-field theory,the optical absorption spectra and zero-field splittings(ZFS) D for Cr 3+ and Cr 4+ in the Al 2O 3 crystal have been studed.The theoretical results agree well with experimental findings.The investigations show that the local structure of the (CrO 6) 8- group in the Al 2O 3:Cr 4+ crystal is of the compressed trigonal distortion(θ k-θ ko ≈3°).That is why the ZFS D (≈7cm -1 )for the Al 2O 3:Cr 4+ is unusually large.