Phase transformation of "chem-prep" PZT 95/5-2Nb HF1035 ceramic under quasi-static loading conditions.

Abstract

Specimens of poled and unpoled "chem-prep" PNZT ceramic from batch HF1035 were tested under hydrostatic, uniaxial, and constant stress difference loading conditions at -55, 25, and 75°C. The objective of this experimental study was to characterize the mechanical properties and conditions for the ferroelectric (FE) to antiferroelectric (AFE) phase transformations of this "chem-prep" PNZT ceramic to aid grain-scale modeling efforts in developing and testing realistic response models for use in simulation codes. As seen from a previously characterized material (batch HF803), poled ceramic from HF1035 was seen to undergo anisotropic deformation during the transition from a FE to an AFE phase. Also, the phase transformation was found to be permanent for the two low temperature conditions, whereas the transformation can be completely reversed at the highest temperature. The rates of increase in the phase transformation pressures with temperature were practically identical for both unpoled and poled PNZT HF1035 specimens. We observed that temperature spread the phase transformation over mean stress analogous to the observed spread over mean stress due to shear stress. Additionally, for poled ceramic samples, the FE to AFE phase transformation was seen to occur when the normal compressive stress, acting perpendicular to a crystallographic plane about the polar axis, equals the hydrostatic pressure at which the transformation otherwise takes place.3