Pressure-Induced Anomalous Phase Transitions and Colossal Enhancement of Piezoelectricity in PbTiO$_3$

TL;DR

This study reveals pressure-induced phase transitions in PbTiO3 that lead to colossal piezoelectric effects, challenging the notion that such properties require complex disordered systems.

Contribution

It demonstrates that giant piezoelectricity and morphotropic phase boundaries can occur in pure, ordered materials under pressure, without the need for compositional disorder.

Findings

Pressure induces a tetragonal-to-monoclinic-to-rhombohedral-to-cubic phase sequence.

Giant dielectric and piezoelectric responses occur at phase transition regions.

Pure PbTiO3 can exhibit properties similar to complex piezoelectric solid solutions.

Abstract

We find an unexpected tetragonal-to-monoclinic-to-rhombohedral-to-cubic phase transition sequence induced by pressure, and a morphotropic phase boundary in a pure compound using first-principles calculations. Huge dielectric and piezoelectric coupling constants occur in the transition regions, comparable to those observed in the new complex single-crystal solid-solution piezoelectrics such as Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$-PbTiO$_{3}$, which are expected to revolutionize electromechanical applications. Our results show that morphotropic phase boundaries and giant piezoelectric effects do not require intrinsic disorder, and open the possibility of studying this effect in simple systems.