Local phase-transition behaviour for Fe3+ and Gd3+ in RbCdF3 and RbCaF3 crystals

In this paper, the local release factor k, which is introduced to characterize the release or elongation effect of the impurity-ligand bond along the C-4-axis at the cubic-to-tetragonal phase transition, is studied for Fe3+ and Gd3+ in RbCdF3 and RbCaF3 crystals by analysing the EPR data. From the studies, it is found that, similar to the local rotational order parameter phi, the local release factor k is different from the corresponding intrinsic release factor ii,,, of the host crystal as well as from impurity to impurity. It appears that the impurity ion call influence the local phase-transition behaviour in the vicinity of the impurity ion in the doped crystals. (C) 1999 Elsevier Science B.V. All rights reserved.