Studies of the EPR parameters for two Gd3+ centers in cubic and tetragonal phases of CsSrCl3 crystals

The zero-field splittings b(2)(m) for the cubic and tetragonal Gd3+ centers in cubic and tetragonal phases of CsSrCl3 crystals are studied from the superposition model. Based on the studies, the superposition model parameters t(2) and (b) over bar(2) for (GdCl6)(3-) groups, the displacement Delta R of the intervening Cl- ion towards the Gd3+ ion in the tetragonal Gd3+ center in cubic phase, the rotational order parameters phi(a) ( = phi, phi is the order parameter in cubic center) and phi(b) ( = 0.67 phi) in tetragonal centers for the rotational axis parallel with and perpendicular to the compensation axis at the cubic to tetragonal phase transition are obtained. The values of these parameters are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.