Non-negligible photostriction that accompanies the photoinduced phase transition process in VO₂

Abstract

<p>VO₂ experiences a transition from an insulating monoclinic phase to a metallic rutile phase near room temperature, which can be triggered by photoexcitation. This unique phenomenon highlights the significant potential of VO₂ in optoelectronic applications. However, the photoinduced shape deformation, also known as photostriction, which occurs during this phase transition has been largely overlooked. Here, we present findings on the photostriction of VO₂ ceramics and investigate the impact of photoinduced phase transition on its photostriction behavior. Large photostriction exceeding 0.1% is achievable in VO₂ ceramics when illuminated by both 405 and 655 nm monochromatic laser. In contrast to the majority of inorganic photostrictive materials, VO₂ demonstrates a nonlinear increase in photostriction as light intensity increases. Upon surpassing the threshold light intensity, the photo-triggered M-to-R phase transition leads to an anomalous increase, approximately 40%, in photostriction. Furthermore, the photoexcited structural evolution and the variation in photostrictive response to different light wavelengths are also depicted by ab initio molecular dynamics simulations. This study not only demonstrates VO₂ as an excellent inorganic material for photo-actuating applications, but also validates the effectiveness of utilizing photoinduced phase transition to explore high-performance inorganic photostrictive materials.</p>