Observation of the distribution of the transition temperature in PbIn1/2Nb1/2O3

PbIn1/2Nb1/2O3 (PIN) single crystal plates obtained by different thermal tr eatment were investigated by means of polarizing microscopic observations. It was found that, in an as,grown PIN (called partly disordered PIN), there is a coexistence state of the high and low temperature phases in a wide te mperature range from 30 to 130 degrees C. In the coexistence region, phase boundaries were observed to move according to temperature change, indicatin g that the phase transition temperature should distribute spatially in the sample plate. This distribution was also confirmed by the dielectric measur ement made at several different spots (about 0.04 mm(2)) in the sample. The distribution of the transition temperature in the partly disordered PIN sa mple was discussed.