Effects of PbO content on the sintering behavior, microstructure, and properties of La-doped PZST antiferroelectric ceramics

Abstract

Effects of PbO content, from 4 mol % deficiency to 4 mol % excess, in the original lanthanum-doped lead zirconate titanate stannate powder compositions (PLZST) on the sintering behavior, microstructure, and properties of the antiferroelectric ceramics were investigated. PbO-deficient samples undergo solid-state sintering at temperatures above 1000 °C, which results in smaller pores but higher porosity in the materials, while PbO excess introduces an additional liquid-phase sintering mechanism and a fast densification at rather low temperatures, down to 700 °C, but leads to larger pores and exaggerated grain growth within the ceramics. It is indicated by the dilatometry data that the maximum solid-state sintering rate and corresponding temperature decrease with rising PbO content. The main fracture mode of the material changes from transgranular to intergranular with PbO content going from deficiency to excess. PbO content also influences the final density, the lattice parameters of the perovskite structure, and Young's modulus of the specimens. Altogether, the electric field for the transition from the antiferroelectric to the ferroelectric state decreases slightly with PbO content, while the back transition field exhibits the opposite trend. Thus, the hysteresis of the field-induced strain loop is found to decrease with an increase in the PbO content; the linear strain at the antiferroelectric to ferroelectric transition field, however, remains at about 0.2%, independent of the PbO content.