Photostrictive Actuators Based on Freestanding Ferroelectric Membranes

Abstract

Complex oxides offer a wide range of functional properties, and recent advances in fabrication of freestanding membranes of these oxides are adding new mechanical degrees of freedom to this already rich functional ecosystem. Here, we demonstrate photoactuation in freestanding thin film resonators of ferroelectric Barium Titanate (BaTiO3) and paraelectric Strontium Titanate (SrTiO3). The free‐standing films, transferred onto perforated supports, act as nano‐drums, oscillating at their natural resonance frequency when illuminated by a frequency‐modulated laser. The light‐induced deflections in the ferroelectric BaTiO3 membranes are two orders of magnitude larger than in the paraelectric SrTiO3 ones. Time‐resolved X‐ray micro‐diffraction under illumination and temperature‐dependent and holographic interferometry provide combined evidence for the photostrictive strain in BaTiO3 originating from partial screening of ferroelectric polarization by photo‐excited carriers, which decreases the tetragonality of the unit cell. These findings showcase the potential of photostrictive freestanding ferroelectric films as wireless actuators operated by light.This article is protected by copyright. All rights reserved

Unfolding the Challenges To Prepare Single Crystalline Complex Oxide Membranes by Solution Processing

“…Among the family of complex oxides, BiFeO 3 (BFO) is a multiferroic material that can also show photoinduced effects, being thus an attractive candidate to be used in next-generation electronic devices for applications in information storage, spintronics, sensors, actuators, and optoelectronics. − Until recently, the preparation of epitaxial complex oxide films, such as BFO, was restricted to specific substrates that can stand high-temperature treatments, most of them on rigid surfaces or with a small bending strain. − Therefore, the use of these substrates dramatically narrowed the potential applications of the epitaxial complex oxide films grown on top. The development of fabrication approaches that allow detaching the complex oxide from the growth substrate and freely handling it has opened a new ground of research. , It provides an unparalleled opportunity to manipulate these structures by applying extreme deformations, unlocking the system’s elastic response upon applying an external stimuli, − creating artificial architectures with emerging phenomena at the new interfaces, and integrating them with the platform of choice. − …”

“…The development of fabrication approaches that allow detaching the complex oxide from the growth substrate and freely handling it has opened a new ground of research. 12 , 13 It provides an unparalleled opportunity to manipulate these structures by applying extreme deformations, 14 unlocking the system’s elastic response upon applying an external stimuli, 15 − 17 creating artificial architectures with emerging phenomena at the new interfaces, 18 and integrating them with the platform of choice. 19 − 23 …”