STUDY ON THE ORDER OF THE FR(LT)-FR(HT) PHASE-TRANSITION OF PZT CERAMICS

By the experiments studying the F(R(LT)-F(R)(HT)) phase transition of PZT ceramics, it is reasonable to point out that the F(R(HT)) phase transition is of first order. The convincing experimental results show that during F(R(LT))-F(R(HT)) transition, an anomalous behaviour of specific heat, abrupt volume change in thermal expansion, shift of phase transition temperature under dc bias, thermal hysteresis of pyroelectric current, and structural change from one space group to another take place.