Nano-actuator concepts based on ferroelectric switching

TL;DR

This paper explores nano-actuators based on ferroelectric switching, demonstrating enhanced displacements through phase-field modeling of domain evolution and device design, including bending mechanisms.

Contribution

It introduces novel ferroelectric nano-actuator concepts with improved displacement capabilities using phase-field simulations and design optimization.

Findings

Ferroelectric switching produces strains several times greater than piezoelectric effect.

Bending of ferroelectric beams further increases displacement.

Phase-field modeling effectively tracks domain evolution during actuation.

Abstract

The concept of a nano-actuator that uses ferroelectric switching to generate enhanced displacements is explored using a phase-field model. The actuator has a ground state in the absence of applied electric field that consists of polarized domains oriented to form a flux closure. When electric field is applied, the polarization reorients through ferroelectric switching and produces strain. The device is mechanically biased by a substrate and returns to the ground state when electric field is removed, giving a repeatable actuation cycle. The mechanical strains which accompany ferroelectric switching are several times greater than the strains attained due to the piezoelectric effect alone. We also demonstrate a second design of actuator in which the displacements are further increased by the bending of a ferroelectric beam. Phase-field modelling is used to track the evolution of domain patterns in the devices during the actuation cycle, and to study the design parameters so as to enhance the achievable actuation strains.