Nanomechanical actuation from phase transitions in individual VO ₂ 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.