| With the improvement of people's living quality and the enhancement of the aesthetic aspects, the uses of glass doors-windows or curtain wall in the modern buildings increase gradually. On the other hand, due to its serious heat loss, energy consumption,the heavy use of glass doors-windows caused a very bad influence for building energy conservation, ecological protection. VO2-based thin film with thermochromic properties is a potential material to make the building "warm in winter and cool in summer" smart window and attracted many attentions from scientists and technicians. However, it is not applied due to the phase transformation temperature much higher than room temperature, low transmission in visible region and high emissivity. This thesis aims to lower the phase transformation temperture, enhance transmission in visible range and lower emissivity of VO2 thin film, and studied the preparation and thermochromic properties by using magnetron sputtering method. The main conclusions are summarized below.1. Utilized the direct current and radio frequency reactive magnetron sputtering technology and vanadium metal target, VO2 films with phase transition property were prepared sucsessfully on a variety of substrates(glass, SiO2, SnO2, AZO). The near infrared switching efficiencies reached 17%~30%, the highest visible light transmittances reached 32%~32%, the phase transition temperatures were 49?~57?, lower than bulk state(68?). The diffusion of Na ions in glass can be partially provented by the pre-coated SiO2 layer which has property of promoting the growth of VO2 acicular crystals, the pre-coated tetragonal SnO2 thin film is also active in inducing the generation of M phase VO2 crystals.2. Using the magnetron sputtering technology-post oxidation process of metallic V or V-W film, VO2 thin films and W doped VO2 thin films with outstanding performance and better repeatability were prepared on quartz glass and the phase transition temperature can be low as 25?~35?. The results show that the oxidation processing such as oxidation pressure, temperature, heating rate and holding time, can affect the purity, grain size, grain boundary, crystal defect, surface morphology, interfacial energy, oxygen vacancy and other microscopic features of the thin films and hence the thermochromic properties of the thin films. The visible transmission of the films can improved by coating antireflective films or reducing the VO2 film thickness, and we realized 18% and 16% improvement respectively for 0.5%W:VO2 thin film.3. Adopting the process to float glass substrate, the oxidation of metalic film should be performed under lower oxygen pressure. Due to the serious Na+ ion diffusion, lots of NaV2O5 rod-shaped crystals formed in the film and resulted in the reduction of VO2 content which makes the VO2 thin film smaller near infrared switching efficiency. When preparing VO2 thin films on 100 nm SiO2 dielectric layer pre-coated on glass substrate, the near infrared switching efficiency is still small due to the interlayer cannot provent the Na+ ion diffusion completely. By W doping, W:VO2 thin films and W:VO2/SiO2 thin films were prepared sucessfuly with low phase change temperature were prepared(Tc: 27 ~ 39 ? ?), near infrared switching efficiencies upto 25%, and narrow thermal hysteresis loops, visible transmittance is upto 60%, reached the daylighting demand of the buildings.4. The VO2/Low-E composite thin films were prepared sucessfully on Low-E glass substrates(including FTO, AZO, ITO). We found that VO2/FTO thin films own the lowest emissivity(0.29 ~ 0.31), VO2/AZO thin films own the largest solar control ability(4.0%~7.6%), and the ITO/VO2 thin films own the largest near infrared control ability(14.5% ~ 15.8%). By W-doping, VO2/Low-E thin films with low emissivity and low phase transition temperature(?: 0.28~0.46, the Tc: 26?~38?) were fabricated. Meanwhile, the solar control ability and the visible transmittance value kept in a high level(?Tsol: 4.3%~8%; Tlum: 46% ~ 59%). |
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