A Study of Structures and Order Parameters in Antiferroelectric PbHfO₃ by Synchrotron Radiation

Abstract

We present structures of PbHfO₃ between 100 and 525 K analyzed by a Rietveld method using synchrotron radiation. Spontaneous strain of a perovskite sublattice could be excellently expressed by a conventional phenomenological theory in a room-temperature antiferroelectric phase. Pb shifts along the a-axis and the square root of the spontaneous strain showed similar dependence on temperature as expected from the theory below 200 K, while one of the shifts showed a slight deviation at high temperature. Disordered arrangement of Pb atoms in the cubic phase was found as in the cubic phase of PbZrO₃, though the direction of the disorder in PbHfO₃ was not so obvious as that in PbZrO₃.