Preparation and Properties of Variable Emissivity Thermochromic VO_2 Thin Films

The VO2 thin film was prepared by inorganic sol-gel process and vacuum post-annealing treatment.The film was characterized by X-ray diffraction and X-ray photoelectron spectroscopy,and results show that the pure VO2 thin film without other valences has been prepared.The film is polycrystalline with grain size about 30 nm.The thermal images of the VO2 thin film at different temperatures were derived using thermal imager and the emissivity was calculated.It was found that 7.5～14 μm emissivity of the VO2 thin film could change abruptly by about 0.6 during the phase transition,which shows that the VO2 thin film exhibits excellent thermochromic properties and is meaningful in the adaptive infrared camouflage.