An investigation was made of the frequency, temperature, tetragonality and quenching temperature dependence of hysteresis loops in Pb[(Zr0.52Ti0.48)0.95(Mn1/3Nb2/3)0.05]O3 ceramics. It was demonstrated that the polarization-field hysteresis curves exhibited so-called pinched shapes when tested at room temperature, higher frequencies or when using a high-tetragonality specimen, whereas normal square-like loops were observed at 200C and 0.01Hz or when using low-tetragonality samples. Close relationships between the P–E loops and the applied frequency, temperature or tetragonality revealed that there existed a typical relaxation time which corresponded to reorientation of the defect dipoles. It could also be seen, from the quenching-temperature dependences of the loops, that reorientation of the defect dipoles could influence the pinching. Compared to the intrinsic de-pinning process induced by changes in the distribution of defect dipoles, new evidence was provided for extrinsic de-pinning of the defect dipoles in the ferro-electric ceramics.

Reorientation of Defect Dipoles in Ferroelectric Ceramics. B.S.Li, G.R.Li, S.C.Zhao, Z.G.Zhu, A.L.Ding: Chinese Physics Letters, 2005, 22, 1236-8