EPR INVESTIGATION OF GD3+ AND EU2+ IN THE ALPHA-PHASE AND BETA-PHASE OF LEAD PHOSPHATE

The X‐band EPR spectra of Gd3+ and Eu2+ diluted in Pb3(PO4)2 crystals are studied. Lead phosphate exhibits a ferroelastic phase transition at 180°C and the EPR spectra obtained in each phase differ from each other. The spectra are very complex because the zero field splitting has the same order of magnitude as the Zeeman term. The spin Hamiltonian parameters and the energy levels are computed. “Forbidden” or “missing” transitions and line intensities can be explained. Very likely Gd3+ substitute a PbI ion. For Gd3+ in β‐phase g ≈ 2 and b 20 = 990 × × 10−4 cm−1 (200°C); for Gd3+ in α‐phase at 25°C g ≈ 2, b 20 = 930 × 10−4 cm−1 and b 22 = −77 × × 10−4 cm−1. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA