EPR g factors and defect structures for Co2+ ions at the substitutional and interstitial sites of SnO2 lattice

Abstract

The EPR g factors g i (i=x, y, z) for Co2+ ions at both the substitutional (i.e. Sn4+) and interstitial sites of SnO2 lattice are calculated from the second-order perturbation formulas based on the cluster approach for g factors of 3d7 ions in rhombic octahedral clusters. The calculated results for Co2+ at the substitutional site are in line with the experimental values. For Co2+ at the interstitial site, the calculated g y and g z are close to the observed values, but the calculated g x is in disagreement with the observed one. The causes resulting in the disagreement are discussed. The defect structures of both Co2+ centers in SnO2 are also estimated from the calculations.