Role of Joule Heating in the Electro-Induced Metal-Insular Transition of a Composite Film Filled with VO2

Vanadium dioxide is a typical representative of a strong electronic correlation system. Triggered by stimuli such as heat and electric fields, VO2 can undergo a reversible transition from insulating to metallic phase and has therefore attracted attention of many researchers. In this work, a hydrothermal method was used to prepare nano-VO2 particles with phase transition. According to the phenomenology, finite element simulation and theoretical calculation models of the electro-induced phase transition (E-MIT) in the VO2-filled Polyethylene glycol were established. Electrode-gap effect on the phase-transition voltage of E-MIT was discussed. Furthermore, the phase transition and heat distribution processes were analyzed. The results revealed that high-temperature conductive channels are formed in the VO2 structure during the electro-induced phase transition. Moreover, position of these channels is determined by the high-voltage edge effect of the electrode and the heat dissipation effect of the material. The ideal adiabatic E-MIT process was also evaluated. The phase change voltage curve of the theoretical model was well matched with the simulation model. The results reveal that the temperature in the channel is significantly lower than the typical phase change temperature when a phase transition occurs. In addition, owing to an applied voltage, the resistance of the VO2 composite material can drop suddenly even if the temperature rise is small. The analysis results verified that Joule heating is an important factor in the electro-induced phase transition of VO2-filled polymers. The experimental results are helpful in understanding the E-MIT mechanism of VO2 composite materials and the subsequent application of these materials.