DC BIASED DIELECTRIC PROPERTY OF MPB PZT CERAMICS WITH MONOCLINIC DISTORTION AT LOW TEMPERATURES

摘要

Complex dielectric properties of PbZr_(1-X)Ti_xO_3 ceramics with compositions in the vicinity of the morphotropic phase boundary (x=0.46, 0.48, and 0.51), as a function of dc bias fields, were measured under small ac signal conditions. In monoclinic phase, dielectric permittivity shows hysteresis behavior and decreases with increasing bias field when E_(bias)>BC. For compositions of tetragonal phase and near the on-set of the monoclinic phase transitions, dielectric permittivity increases with increasing bias electric field, indicating a continued polarization switching process. Such anomalous behavior is attributed to the B-field induced monoclinic phase, which allows polarization rotation without domain reversal. Temperature dependence of the dc biased dielectric property between 12K and 300K is also reported. Dielectric dispersion is mostly clamped out for both PZT 54:46 and PZT 52:48 as temperatures approaching 12K; however, remains significant in PZT 49:51.