Hyperfine interactions in the perovskites SrHfO3 and BaHfO3 observed with In-111/Cd-111 perturbed angular correlations

The electric field gradients in perovskite SrHfO3 and BaHfO3 powder samples were investigated by means of Perturbed Angular Correlation spectroscopy, using implanted In-111 hyperfine probes. The measurements cover the tempera ture ranges from 22 to 893 K for SrHfO3 and from 293 to 875 K for BaHfO3, r espectively. In both compounds, three quadrupole interactions were establis hed. The largest fraction showing a pronounced dynamic interaction is assig ned to In-111/Cd-111 probe atoms on substitutional Hf sites in both compoun ds. For SrHfO3, the temperature dependence of the dynamic interaction was a ssociated to the Pnma <-> Imma phase transition for SrHfO3 at about 700 K. We discuss the results in relation to those obtained for In-111/Cd-111-prob es in PbZrO3 and BaTiO3, and for Hf-181/Ta-181-probes in AHfO(3) (A = Ca, S r, Ba). (C) 1999 Elsevier Science Ltd. All rights reserved.