Pre-Transitional Effect and an Intermediate Phase in the Antiferroelectric PbZr0.80Sn0.20O3 Single Crystal

The temperature dependences of electrostrictive strain and birefringence for a PbZr0.80Sn0.20O3 single crystal have been measured with a high accuracy close to the high temperature phase transitions into the paraelectric phase. Characteristic features are the existence of local maxima on M-11(T) dependence and irregular Delta n(T) dependences that indicate existence of an intermediate phase between the antiferroelectric and paraelectric phase. Above T-C a local Delta n(T) maximum appears on heating caused probably by interactions of polar regions embedded in the non-polar cubic matrix. The existence of these regions could be accounted for by a disorder of Sn ions in the lead zirconate lattice.