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Investigations of the axial displacements of Co2+and Ni3+ in Al2O3

Journal Defect and Diffusion Forum (Volumes 261 - 262)
Volume Defects and Diffusion in Semiconductors - An Annual Retrospective IX
Edited by David J. Fisher
Pages 93-102
DOI 10.4028/www.scientific.net/DDF.261-262.93
Citation Shao Yi Wu et al., 2007, Defect and Diffusion Forum, 261-262, 93
Online since January, 2007
Authors Shao Yi Wu, Qiang Fu, Guang Duo Lu, Jin Song Yao
Keywords Al2O3, Co2+, Crystal Field Theory, Defect Structures, Electron Paramagnetic Resonance (EPR), Ligand Field Theory, Ni3+
Abstract

The axial displacements for Co2+ and Ni3+ in Al2O3 are theoretically investigated starting from the perturbation formulas of the EPR parameters for a 3d7 ion with high spin (S=3/2) and low spin (S=1/2) in trigonal symmetry, respectively. Based upon these studies, the Co2+ is found to shift towards the center of the oxygen octahedron by an amount ZCo (≈ 0.03 Å) along the C3 axis, while the Ni3+ may suffer another axial displacement ZNi (≈ −0.38 Å) away from the center of the octahedron. The calculated EPR parameters based upon the above axial displacements show good agreement with the observed values. The differences in the EPR parameters and the axial displacements for the two 3d7 ions are discussed.

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