Investigations of defect structures and g factors for octahedral (CrO6)7- and (VO6)8- clusters in rutile-type crystals

The electron paramagnetic resonance (EPR) g factor formulas for Cr5+ and V4+ ions in Al2O3, TiO2 and VO2 crystals are deduced from Jahn-Teller effect and contributions of the charge transfer (CT) levels. The tetragonal distortions. Delta R (R-parallel to - R-1) = -0.0184, -0.0045 and -0.0124 nm, and Delta theta = 0 degrees, -0.001 degrees and 0 degrees, for Al2O3:Cr5+, TiO2:V4+ and VO2, respectively. The calculations of the g factors agree well with the experimental values. The contributions of the CT levels to g factors increase with the increasing valence state. It must be taken into account in the precise calculations of g factors for the high valence state d(1) ions in crystals.