Vanadium dioxide (VO2) has emerged as a promising micro-actuator material for its large amplitude and high work density across the transition between the insulating (M1 and M2) and metallic (R) phase. Even though M2–R transition offers about 70% higher transformation stress than M1–R structural phase transition, the application of the M2 phase in the micro-actuators is hindered by the fact that previously, M2 phase can only stay stable under tensile stress. In this work, we propose and verify that by synthesizing the VO2 nanowires under optimized oxygen-rich conditions, stoichiometry change can be introduced into the nanowires (NWs) which in turn yield a large number free-standing single-crystalline M2-phase NWs stable at room temperature. In addition, we demonstrate that the output stress of the M2-phase NWs is about 65% higher than that of the M1-phase NWs during their transition to R phase, quite close to the theoretical prediction. Our findings open new avenues towards enhancing the performance of VO2-based actuators by using M2–R transition. [Figure not available: see fulltext.].
Bibliographical noteKAUST Repository Item: Exported on 2021-03-30
Acknowledgements: This work was supported by the National Natural Science Foundation of China (Nos. 52031011, 91860109, 51927801, and 51621063), the National Key Research and Development Program of China (Nos. 2017YFB0702001 and 2016YFB0700404), 111 Project 2.0 of China (No. BP2018008), and funding from the Science and Technology Departments of Shaanxi and Xi’an, China (Nos. 2016KTZDGY-04-03, 2016KTZDGY-04-04, and 201805064ZD15CG48). The authors appreciate the helpful discussions and suggestions from Prof. Evan Ma from John Hopkins University (JHU). Y. Q. Z. acknowledges King Abdullah University of Science & Technology (KAUST) to support his six-months research and study at KAUST as an exchange student. We also appreciate the support from the International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies, and the Collaborative Innovation Center of High-End Manufacturing Equipment at Xi’an Jiaotong University, China. J. L. acknowledges support by National Science Foundation (No. CMMI-1922206). Authors declare no competing interests.
ASJC Scopus subject areas
- Materials Science(all)
- Electrical and Electronic Engineering