Origin of Negative Longitudinal Piezoelectric Effect

TL;DR

This study reveals that negative longitudinal piezoelectric effects are more common than previously thought, driven by ionic bonding and rigid energy surfaces, with implications for designing advanced electromechanical devices.

Contribution

It demonstrates through first-principles calculations that several hexagonal ABC ferroelectrics exhibit negative longitudinal piezoelectric coefficients, revealing a general phenomenon.

Findings

Negative longitudinal piezoelectric effect is common in certain ferroelectrics.

The effect is due to strong ionic bonds and rigid potential energy surfaces.

Ferroelectrics with this effect show pressure-enhanced ferroelectricity.

Abstract

Piezoelectrics with negative longitudinal piezoelectric coefficients will contract in the direction of an applied electric field. Such piezoelectrics are thought to be rare but there is no fundamental physics preventing the realization of negative longitudinal piezoelectric effect in a single-phase material. Using first-principles calculations, we demonstrate that several hexagonal $ABC$ ferroelectrics possess significant negative longitudinal piezoelectric effect. The data mining of a first-principles-based database of piezoelectrics reveals that this effect is a general phenomenon. The origin of this unusual piezoelectric response relies on the strong ionic bonds associated with small effective charges and rigid potential energy surfaces. Moreover, ferroelectrics with negative longitudinal piezoelectric coefficients show anomalous pressure-enhanced ferroelectricity. Our results offer design principles to aid the search of new piezoelectrics for novel electromechanical device applications.