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Electron paramagnetic resonance (EPR); impurities and defects; Pt³⁺; 𝛼-Al₂O₃.

The anisotropic 𝑔 factors and local structure for the trigonal Pt³⁺ centre in 𝛼-Al₂O₃ are theoretically investigated from the perturbation formulas of the 𝑔 factors for a $5d^7$ ion in trigonal symmetry. The Pt³⁺ impurity is found to experience an outward displacement by about 0.18 Å away from the centre of the oxygen octahedron along the $C_3$-axis. The calculated g factors based on the above axial displacement show good agreement with the observed values. Importantly, the pending problem of $+3$ valence state of the doped Pt in 𝛼-Al₂O₃ is theoretically clarified, and the possibility of Pt⁺ ($5d^9$) is thus excluded in this work.

Z H Zhang¹ S Y Wu^{1 2} S X Zhang¹ L L Li¹

1. Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China
2. International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China

Published

March 2012

Manuscript received

26 August 2010

Accepted

8 November 2011