Research on the g factors of Cr3+ ion in elpasolite crystals Cs2NaYX6 (XÂ =Â Cl, Br)

The g factors of Cr3+ ions at the cubic octahedral Y3+ sites of elpasolite crystals Cs2NaYX6(X = Cl, Br) are computed from the high-order perturbation formula founded on the two-mechanism model. In the model, both the contribution from the crystal-field (CF) mechanism in the vastly-applied CF theory and that from the frequently-omitted charge-transfer (CT) mechanism are taken into account. The parameters used in the calculations are acquired from the first-principles calculations and experiment. The calculated results are in rational accordance with the observed values. The negative g-shift Δg (=g − ge, where ge ≈ 2.0023, the g value of free electron) for Cs2NaYCl6:Cr3+ and the positive g-shift Δg for Cs2NaYBr6:Cr3+ are therefore explained. The reasonableness of the above calculated formula and the parameters used are confirmed.