A cost-effective process to prepare VO₂ (M) powder and films with superior thermochromic properties

VO₂ powder with superior phase transition performance was prepared by convenient thermolysis method. The results illustrated that VO ₂ powder show high purity and crystallinity. VO₂ particles are transformed from cluster to quasi-sphere with the increase of annealing temperature. The DSC analysis proves that VO₂ show superior phase transition performance around 68 C. The phase transition temperature can be reduced to 33.5 C by 1.8 at% tungsten doping. The maximum decreasing efficiency of phase transition temperature is about -30 K/at% with w = 0.4 at%. After mixing VO₂ powder with acrylic resin, the maximal visible transmission of the composite thin films on glass is 48% and the transmission modulation at 2000 nm is 37.3% with phase transition temperature of 66.2 C. Though the phase transition performance is weakened by tungsten doping, the film prepared by 1.3 at% tungsten doped VO₂ still show superior transmission modulation about 26.4% at 2000 nm, which means that it is a potential candidate as smart windows.