The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

TLDR

Ultrahigh piezoelectricity in relaxor‑ferroelectric single crystals is a breakthrough, yet the role of polar nanoregions—nanoscale inhomogeneities coexisting with ferroelectric domains—remains unclear. The study quantitatively assesses how polar nanoregions influence dielectric and piezoelectric responses of relaxor‑ferroelectric crystals through cryogenic experiments and phase‑field simulations. A mesoscale mechanism proposes that polar nanoregions aligned within a ferroelectric matrix enable polarization rotation, accounting for the high piezoelectricity. Polar nanoregions contribute 50–80% to room‑temperature dielectric and piezoelectric properties, underscoring the critical influence of local structure on macroscopic ferroelectric behavior.

Abstract

Abstract The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50–80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.