Studies Of The G Factor For Cr4+ Ion In Bi4ge3o12 Crystal From Crystal-Field And Charge-Transfer Mechanisms

Abstract

The complete third-order perturbation formulas of the g factors g|| and g⊥ for 3d2 ions in tetragonal MX4 clusters have been obtained by a cluster approach. In these formulas, in addition to contributions to the g factors from the crystal-field mechanism in the crystal-field theory, the contributions from the charge-transfer mechanism are included. From these formulas, the g factors g|| and g⊥ for a Cr4+ ion in a Bi4Ge3O12 crystal are calculated. The results agree with the observed values. The calculated Δ gi(i = || or ⊥) value due to the charge-transfer is opposite in sign and about 20% greater than that due to the crystal-field mechanism. So, for the 3dn ions having a high valence in crystals, a reasonable explanation of the g factors should take both the crystal-field and charge-transfer mechanisms into account.