ac calorimetric study of single crystals of antiferroelectric PbZrO3 and PbZr1-xTixO3 (x=0.01)

Heat capacity of single crystals of antiferroelectric PbZrO3 and PbZr1-xTixO3 (x=0.01) was measured in a wide temperature region from r.t. to 650K by a.c. calorimetry. In PbZr1-xTixO3, two clear anomalies were observed which correspond to a series of phase transitions. However only one sharp anomaly could be detected at about 504 K in the case of pure PbZrO3 single crystal both on heating and cooling run. The absence of an intermediate phase in PbZrO3 was confirmed also by Neutron diffraction. The transition entropies Delta S are 0.396 cal/K . mol for PbZrO3 and 0.262 cal/K . mol and 0.001 cal/K . mol for PbZr1-xTixO3.