Non-Ergodic-Induced Negative Differential Piezoresponse in Relaxor Ferroelectrics

TL;DR

This paper reveals a novel negative piezoresponse in relaxor ferroelectrics caused by non-ergodic behavior, with potential applications in power generation and low-power transistors, supported by local and macroscale measurements.

Contribution

It demonstrates the occurrence of negative piezoresponse in relaxor ferroelectrics due to non-ergodic effects, a phenomenon not previously observed.

Findings

Negative piezoresponse observed over broad temperature range

Effect depends on pre-scan poling state

Supported by impedance and dielectric measurements

Abstract

Relaxor ferroelectrics exhibit a unique competition between long-range and short-range interactions that can be tuned electrically which prioritizes these materials in a broad range of electro-mechanical energy-conversion technologies, including biomedical imaging and electric-charge generators. Here, we demonstrate differential negative piezoresponse by utilizing the short-range interactions in relaxor ferroelectrics. The effect was observed over a broad temperature range with local piezoresponse spectroscopy in unpoled samples, while no negative piezoresponse was observed when the material was pre-scan poled. These measurements suggest that the effect, that is promising for power-generation applications, originates from non-ergodic behavior. Complementary macroscale impedance and dielectric constant measurements as a function of temperature and frequency supported the mesoscopic findings. Bearing in mind the direct relationship between piezoresponse and capacitance, relaxor ferroelectrics appear as an excellent platform for the emerging technology of low-power negative-capacitance transistors.