A study of the impurity structure for 3d ~3 (Cr ~(3+) and Mn ~(4+)) ions doped into rutile TiO _2 crystal

摘要

The local environment around 3d ~3 (Cr ~(3+) and Mn ~(4+)) ions doped into rutile TiO _2 crystals has been investigated using superposition model (SPM) analysis. The zero-field splitting (ZFS) parameters (ZFSPs) D and E are modeled for the Cr ~(3+) and Mn ~(4+) ions at both the substitutional Ti sites with local symmetry orthorhombic D _(2h) and the interstitial sites (ISs) with the same symmetry. Several model parameter sets are adopted so as to acquire the best agreement between the calculated ZFSPs and those measured by electron magnetic resonance (EMR). The feasible values of the structural distortions (ΔR _Y, ΔR _(XZ) and Δθ) resulting from dopant Cr ~(3+) and Mn ~(4+) ions are determined. As a result, it is confirmed that Mn ~(4+) ions substitute for Ti ~(4+) sites in rutile TiO _2 crystal; however, it is suggested that Cr ~(3+) ions may replace at not only Ti ~(4+) site but also IS.