The experimental results show that the temperature of the substrate during coating is different, and the crystal state of the film is different. For the vanadium oxide film produced on the glass substrate and the substrate temperature is zero, there is no diffraction peak in the spectrum before the heat treatment, which indicates that there is no crystallized phase in the film and it is amorphous, and only after the heat treatment, different phase crystals appear. This shows that in the evaporation preparation of vanadium oxide films, increasing the temperature of the substrate can make the film crystallize better. In the vacuum heat treatment, the bonding weaker bond in the vanadium oxide film will break, and some oxygen atoms will precipitate, so that the proportion in the film will increase to achieve the purpose of reduction.

After the annealing, a series of diffraction peaks including several other low-valence vanadium oxides appear on the glass substrate and when the substrate temperature is respectively and when the vanadium oxide film is obtained. The strongest peak. Obviously, the vanadium oxide film whose substrate temperature is changed from the amorphous state to the polycrystalline state by the heat treatment, and different reduction reactions occur during the vacuum heat treatment process to generate various low-valence vanadium oxides. However, further studies have shown that the diffraction peak intensity of each crystalline phase obtained after the vacuum heat treatment is significantly lower and there is no phase, and the degree of reduction is relatively low. This is due to the higher substrate temperature used in the evaporation preparation of vanadium oxide films. Oxygen vacancies in the film make more bond bonding weaker, so many bonds will break during heat treatment, creating more low-valence vanadium oxides. When the film preparation conditions and the vacuum heat treatment conditions are the same but the substrates are different, the vanadium oxide film obtained has different phase composition. Before the vacuum heat treatment, a polycrystalline film was prepared on both the glass substrate and the silicon wafer. The orientation of the polycrystalline film was basically the same.