Local distortion effects on the spin Hamiltonian parameters of Gd3+substituted into the fluorites

The superposition model is used to analyse experimental spin-Hamiltonian parameters for Gd 3+ at cubic, tetragonal, trigonal and rhombic sites in the fluorites. New experimental results are presented which supplement and correct those already in the literature. Superposition model parameters are refined and constraints are determined on the local distortions at the various substituted sites. It is shown that the electronic structure of interstitial fluorines is very different to that of the fluorines on lattice sites.