Effects of lanthanum modification on the antiferroelectric-ferroelectric stability of high zirconium-content lead zirconate titanate

Abstract

Lanthanum-modified lead zirconate titanate specimens with between 0 and 9 at.% lanthanum and a Zr/Ti ratio of 95/5, Pb1−xLax(Zr0.95Ti0.05)1−x/4O3 (PLZT 100x/95/5), have been investigated using dielectric spectroscopy, Sawyer–Tower polarization, and dilatometric measurements. La modification was found to suppress the stability of the ferroelectric state, changing the phase stability and phase sequence observed on cooling. PLZT 0/95/5 was found to be ferroelectric from room temperature to the Curie point; however, an antiferroelectric state was found to be stabilized as the long-range ferroelectric state was disrupted by La substitution on the Pb sites. With increasing La content (≳3 at.%), a multicell cubic (MCC) state was found to be stable near the temperature of the dielectric maximum. This MCC phase region was characterized by a dielectric plateau in the Curie temperature range and by the lack of any macroscopic symmetry changes. It is suggested that competition between long-range ferroelectric and short-range antiferroelectric couplings is responsible for the MCC state, changes in the relative phase stability, and subsequent changes in the macroscopic properties with increasing La content.