High temperature limitation due to onset of depoling in BiScO3–PbTiO3

Abstract

Thermal depoling is investigated with impedance spectroscopy as a function of temperature and frequency for unmodified and ZnSc′ modified compositions around the morphotropic phase boundary (MPB) in the high temperature material (1−x)BiScO3–xPbTiO3 (BSPT). By tracking the shape and width of the fundamental resonance peaks and phase angle during impedance analysis, it was shown that the depoling temperature (Td), usually considered a single temperature, can actually be characterized as occurring over a range with an onset temperature (Tdonset) and a final temperature (Tdfinal). When this technique is applied to the rhombohedral compositions near the MPB of BSPT, it is seen that the peak narrowing in phase angle closely correlates to the rhombohedral-tetragonal phase transition decreasing from 350 °C to 300 °C when increasing from 58% to 62% PT. The Tdonset and the subsequent correlation to the phase transition are investigated further through aliovalent substitution of 1%, 2%, and 5% ZnSc in BS-PT. The Tdonset for the rhombohedral compositions displays enhancement over the unmodified compositions at ∼12 °C/1% ZnSc.