Investigations of EPR parameters for Cr³⁺ and Mn⁴⁺ ions in anatase (TiO₂) crystals

Abstract

Abstract The electron paramagnetic resonance (EPR) parameters ( g factors g ‖ and g ⊥ and zero‐field splitting D ) of 3d 3 ions Cr 3+ and Mn 4+ at the tetragonal substitutional site of anatase (TiO 2 ) crystals are calculated from the complete high‐order perturbation formulas based on the cluster approach. These formulas involve not only the widely used crystal field (CF) mechanism, but also the charge transfer (CT) mechanism (which is neglected in the CF theory). The calculated results are in agreement with the observed values. It is found that the relative importance of the CT mechanism for EPR parameters increases with increasing valence state of the 3d 3 ion. So, in the case of 3d 3 ions having high valence state (e.g. Mn 4+ ion), a reasonable explanation of EPR parameters should take both CF and CT mechanisms into account. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)