Preparations And Properties Of The Thermochromic Intelligent Glass VO₂Thin Film

As a sort of thermo-chromic material，vanadium dioxide can change its phasereversibly at68oC from monoclinic semiconductor to tetragonal metal status,andaccompanies with abrupt reversible changes in its electrical, optical and magneticproperties. It has a very broad application prospect in the fields of smart windows,photoelectric switches, laser protection, optical storage, uncooled infrared detectorsand so on. The preparation and properties are studied.The first chapter introduces the basic characteristics, crystal structure,phase transition mechanism and applications of VO₂, and outlines its researchbackground and significance.The second chapter describes the preparing methods, characterization methodsof VO₂thin film as well as instruments used in our experiments. It elaborates thecoating mechanism and experimental process of reactive magnetron sputtering.The third chapter studies the preparing processes of VO₂thin films bymagnetron sputtering and thermal reduction annealing. The effects of heattreatment process and sputtering pressure on the thin films are analyzed. Theexperimental results show with the oxygen and argon ratio of1.5:25, the sputteringtime of1hour, the power of100W and the gas pressure of1.5Pa, then annealingin hydrogen at500oC for2hours, the phase transition of the VO₂thin film is better.In addition, performances of VO₂thin films in quartz glass and silicon wafer areanalyzed.The forth chapter studies preparation of W-doped VO₂thin film by reactivemagnetron co-sputtering method, and the influences of different W sputteringpowers on the phase transformation and properties of W-doped VO₂thin film aregiven. The experimental results show that the phase transition temperature ofW-doped VO₂thin film is reduced to37oC, and the maximum value of TCR is-0.106/oC.In the fifth chapter, TiO₂/VO₂bilayer films were prepared by DC magnetronsputtering. The influences of TiO₂buffer layers on the phase transformation andproperties of VO₂thin films have been studied. Based on this, TiO₂/W-doped VO₂thin films were prepared further. The results show that the phase transitiontemperature of TiO₂/W-doped VO₂thin films reduces to36oC, and its visible light transmittance increases comparing to the VO₂thin film. Its infrared lighttransmittances are42.7%and5.1%before and after phase transition.