Extraordinary Dynamic Mechanical Response of Vanadium Dioxide Nanowires around the Insulator to Metal Phase Transition

Abstract

Nanomechanical resonators provide a compelling platform to investigate and exploit phase transitions coupled to mechanical degrees of freedom because resonator frequencies and quality factors are exquisitely sensitive to changes in state, particularly for discontinuous changes accompanying a first-order phase transition. Correlated scanning fiber-optic interferometry and dual-beam Raman spectroscopy were used to investigate mechanical fluctuations of vanadium dioxide (VO2) nanowires across the first order insulator to metal transition. Unusually large and controllable changes in resonator frequency were observed due to the influences of domain wall motion and anomalous phonon softening on the effective modulus. In addition, extraordinary static and dynamic displacements were generated by local strain gradients, suggesting new classes of sensors and nanoelectromechanical devices with programmable discrete outputs as a function of continuous inputs.

Switchable molecule-based materials for micro- and nanoscale actuating applications: Achievements and prospects

“…Indeed, their properties and potential applications show many similarities with different materials exhibiting structural or electronic phase transitions. In particular the emerging metal-insulator transition (MIT) actuators, such as VO 2 [14,62,63], can be an interesting source of inspiration for their molecular analogs. Another field of inspiration is that of stimuli-responsive polymers [30,64].…”

Vanadium Dioxide: The Multistimuli Responsive Material and Its Applications

“…For example, the thermo‐optical devices such as smart windows and camouflage are based on the significant changing of refractive index ( n ) and extinction coefficient ( k ) during the MIT ( Figure a), and which leads to the optical responses such as the changing of transmittance and reflectance (Figure b) at different wavelength. Meanwhile, the thermomechanical devices like resonator and actuator are based on the crystal contraction along the c ‐axis (≈1%) and expansion on the a ‐axis direction (≈0.6%) when MIT happens . Moreover, as the conductivity of VO 2 changes up to five magnitudes upon the MIT due to the overlapping and separation of energy band in the crystal, the fabrication of temperature sensor and other thermal activated electrical device becomes possible.…”

“…VO 2 based resonator meets the requirements of nanomechanical system due to its capability to dynamically control the eigenfrequency by thermal stimuli. A simple design of VO 2 based resonator is to attach VO 2 nanowire to a ceramic heater for supporting and heating ( Figure a) . The single crystal VO 2 nanowire has an orientation along the [001] direction of rutile (R) phase (Figure b,c).…”

Tuned hydrothermal synthesis of vanadium dioxide nanotubes

“…They have also demonstrated potential for applications in nanodevices [2,3]. Specifically, 1D vanadium dioxide (VO 2 ) nanostructures have attracted considerable attention due to their special optical and electrochemical properties [4]. To date, nanoscale 1D VO 2 has been widely applied in chemical sensing, lithium ion batteries, optical switching devices, modulator, energy efficiency windows and optical data storage media, etc.…”

“…[5][6][7][8][9]. In principle, VO 2 undergoes a phase transition from monoclinic crystal to tetragonal crystal (R type) when heated above 68 1C; this results in transitions from insulator to conductor and from infrared light transmission to reflection [4,10]. From the point of view of synthesis, VO 2 nanowires have been prepared by reducing V 2 O 5 nanowires in a flowing atmosphere of H 2 /Ar gases.…”