A compositional ordering-driven morphotropic phase boundary in ferroelectric solid solutions

TL;DR

This paper introduces a new type of morphotropic phase boundary in ferroelectric solid solutions driven by compositional ordering, which enhances piezoelectricity and offers a novel design approach for high-performance materials.

Contribution

It proposes a compositional ordering-driven MPB in ferroelectric solutions, supported by machine-learning molecular dynamics simulations, revealing a new mechanism for high piezoelectricity.

Findings

Phase transition from rhombohedral to tetragonal with decreasing compositional ordering.

Enhanced piezoelectricity comparable to composition-driven MPB.

Polarization rotation mechanism under external field explains high piezoelectricity.

Abstract

Ferroelectric solid solutions usually exhibit giant dielectric response and high piezoelectricity in the vicinity of the morphotropic phase boundary (MPB), where the structural phase transitions between the rhombohedral and the tetragonal phases as a result of the composition or strain variation. Here, we propose a compositional ordering-driven MPB in the specified compositional solid solutions. By preforming machine-learning potential based molecular dynamics simulations on lead zirconate titanate, we find a phase transition from the rhombohedral to tetragonal phase with the decrease of compositional ordering, leading to the MPB on temperature-ordering phase diagram. The compositional ordering-driven MPB can enhances the piezoelectricity with a magnitude comparable to that at the composition-driven MPB. Finally, we demonstrate that the mechanism of high piezoelectricity is polarization rotation driven by external field. This work provides an additional degree of freedom, compositional ordering, to design the high-performance piezoelectric materials.