Thermal and Dielectric Properties of a New Ferroelectric LaBGeO₅

Abstract

Thermal and dielectric properties of LaBGeO 5 , a new ferroelectric with a stillwellite-type structure are investigated. The specific heat, C p , shows one clear anomaly (Δ S =0.114 R) at 802.5 K. The basic thermodynamic parameters are determined on the basis of the Landau theory. However, an additional hump in C p was found in a different sample just above T c . This dependence on samples is confirmed by the measurements of dielectric constants. The appearance of the new intermediate phase may be caused by some impurities or defects. The Rhodes-Wohlfarth plot suggests that the nature of the phase transitions is of the displacive-type.