Nanomechanical actuation from phase transitions in individual VO2 micro-beams

The mechanical response due to structural phase transitions in individual VO2 nanowires was quantitatively investigated in situ in a transmission electron microscope. The electron beam was employed to locally heat the nanowire, and stress-strain was measured in situ using a microfabricated push-to-pull device. Tensile loading was found to increase the metal-insulator transition temperature and decrease the insulator-insulator transition temperature, consistent with the phase diagram of VO2. These phase transitions resulted in an axial mechanical response of the VO2 nanowires, an effect that can potentially be used to actuate nanostructures or gauge the local temperature change induced by electron beam irradiation.