A facile method for the preparation of W-doped VO2 films with lowered phase transition temperature, narrowed hysteresis loops and excellent cycle stability

We present a facile method to prepare W - doped VO2 films with lowered phase transition temperature (T-t), narrowed hysteresis loops width (Delta T-t) and excellent cycle stability. The W - doped VO2 films have been obtained by inorganic sol - gel method. And W dopant is introduced by pouring melt V2O5 into ammonium tungstate solution. The properties of the samples are measured by XRD, XPS, SEM and transmittance spectra. The T-t is reduced from 73 degrees C to 20 degrees C along with the Delta T-t narrowed from 10 degrees C to 4 degrees C as W dopant increasing from 0 to 3.2 at%. Besides, no obvious attenuation is observed on crystal structure, variation of transmittance (Delta T-2000mn), T-t and Delta T-t for W - doped VO2 films after 550 alternate heating and cooling cycles, while the pure VO2 films show obvious degradation. Since the surface morphology has no obvious changes after 550 cycles, it suggests that the W - dopant induced distorted crystal structure strengthen the cycle stability of W - doped VO2 films. These encouraging results show great potential and understanding of VO2 films for practical applications.