Bridging Phases at the Morphotropic Boundaries of Lead-Oxide Solid Solutions

TL;DR

This review summarizes recent advances in understanding the phase behavior and piezoelectric properties of lead-oxide solid solutions near morphotropic boundaries, highlighting new phases and their impact on piezoelectric responses.

Contribution

It compiles recent experimental and theoretical findings on phase transitions and piezoelectric enhancements in lead-based solid solutions near morphotropic boundaries.

Findings

Identification of monoclinic phases near x=0.50 in PZT

Enhanced piezoelectric coefficients in related lead-based crystals

Recent progress in understanding phase boundaries and their effects

Abstract

Ceramic solid solutions of PbZr(1-x)TixO3 (PZT) with compositions of about x= 0.50 are well-known for their extraordinarily large piezoelectric responses. The latter are highly anisotropic, and it was recently shown that, for the rhombohedral compositions (x< 0.5), the piezoelectric coefficients were largest away from the polar direction, contrary to common belief. Shortly afterwards a low-symmetry monoclinic phase was observed by synchrotron x-ray diffraction at around x=0.50. Similar behavior and features are also present in a number of related lead-based strongly-piezoelectric single crystals, such as PMN-PT, PZN-PT, and PSN-PT, with piezoelectric coeficients of about 2500 pm/V, the highest values recorded to date. Recent experimental and theoretical work has greatly improved our understanding of these technologically-important systems, but there are still some open questions. In this review we try to summarize the most recent progress in the field.