PERTURBED-ANGULAR-CORRELATION STUDIES OF ELECTRIC-FIELD GRADIENTS AT CD-111 IN THE PEROVSKITES PBZRO3 AND BATIO3

Phase transitions in perovskite PbZrO3 and BaTiO3 powder samples have been studied via Perturbed Angular Correlation spectroscopy, using imp lanted In-111 probe ions. In each phase one or two electric field grad ients have been identified. Arguments are presented that the In-111 pr obe atoms reach Zr or Ti cation sites surrounded by oxygen octahedra. Pronounced similarities with the results of previous PAC experiments e mploying Hf-181 probes were found in PbZrO3 which indicate a scaling o f the EFG. In the orthorhombic phase of this compound, the two identif ied EFG's differ by their symmetry, but not in their strength, and ind icate the presence of two kinds of oxygen octahedra of different symme try.