Specific heat of gadolinium molybdate at the ferroelectric transition

Abstract

Measurements of the temperature dependence of the specific heat of gadolinium molybdate were carried out from room temperature to 240\ifmmode^\circ\else\textdegree\fi{}C, using an ac calorimetric method. The specific heat peaks sharply at the 159\ifmmode^\circ\else\textdegree\fi{}C ferroelectric transition. The data were reproducible on heating and cooling with no thermal hysteresis. The temperature dependence is logarithmic on the low-temperature side of the peak. Above the peak, a weak linear increase with temperature was found; possible logarithmic behavior just above the transition could not be verified. The latent heat and transition entropy calculated from these data were found to be 108 cal/mole and 0.25 cal/mole \ifmmode^\circ\else\textdegree\fi{}K, respectively.