Investigations of the g-factors and local phase-transition behavior for Ni3+ ion in the tetragonal phase of RbCaF3 crystal

摘要

The EPR g factors g(parallel to) and g(perpendicular to) for Ni3+ ion (created by room-temperature X-irradiation of nickel-doped RbCaF3) in the tetragonal phase of RbCaF3 crystal are calculated from the second-order perturbation formulas based on a cluster approach for high-spin 3d(7) ions in tetragonal octahedral clusters. The calculated results are in reasonable agreement with the experimental values. The local phase-transition behavior of the Ni3+ impurity center in RbCaF3 is also estimated from the calculation. It is found that the local phase-transition behavior in the Ni3+ center is unlike the intrinsic one in the host crystal (in particular, the fluorine octahedra surrounding the cations change from tetragonal compression in the host crystal to tetragonal elongation in the Ni3+ impurity center). The results are discussed.