Research On The Vanadium Oxide Thermochromic Functional Films Fabricated By Magnetron Sputtering Process

Thermochromic functional films is a layer of reversible heat discolorationmaterials which is coated on the glass substrate, the performance of phase-changematerial will be abrupt change when the environment temperature reached a tippingpoint. The phase transition temperature of VO2is68℃, it becomes the research hotspot because it is close to room temperature. VO2thin film has high transmittance atlow temperature and low transmittance at high temperature to near-infrared light, itcan be smart to regulate the temperature of the environment, reduce air conditioningload, save energy consumption when it is used to the coating material of buildingwindows and automobile glass.This article applies the method of coating vanadium oxide thin films in normalsodium calcium silicon glass substrate with magnetron sputtering plating system.Microscopic testing technology of X-ray diffraction,scanning electron microscopeand the analysis of film thickness,optical transmittance,phase transition temperatureand film composition are applied to reach the magnetron sputtering power,workingpressure,Ar/O2and the relationship between the system of heat treatment temperatureand film properties. Through the experiment the best system of heat treatmenttemperature was deterrmined, the vanadium oxide thermochromic functional filmswith good phase transition performance can be made.The main work of the paper and experimental results show that:(1) Under the reasonable scope of process parameters, the vanadium oxidethermochromic functional films with good phase transition performance are madethrough heat treatment after reaction sputtering at room temperature, the main processparameters are as follows：sputtering power180~220W, work pressure0.5~1.0Pa,Ar/O220:1~10:1, heat treatment temperature350~500℃, Sputtering time controlbetween10~30min, the temperature of film is60℃, the change of the near infraredtransmittance after phase transition reach50%.(2) The influence of process parameters on the film performance are discussed.The film deposition rate increases with the increase of sputtering power, decreaseafter increase of work pressure; Ar/O2determines the composition of the film andinfluence the rate of film deposition; the best heat treatment system is through heat treatment with2h under the condition of450℃.(3) VO2/TiO2film system is designed in connection with the effects of sodiumion diffusion, explore the effects of barrier layer on the film performance. Thevanadium oxide thermochromic functional films with good phase transitionperformance are made by adjusting the process parameters of the composite film andchoosing the best heat treatment system.(4) The structure of film、composition and microstructure are analyzed bymicroscopic testing technology of X-ray diffraction(XRD),scanning electronmicroscope(SEM), through the reach we can know the film composition: barrier layeris TiO2with anatase structure which preferred orientation on (101) crystal plane,functional layer is monoclinic VO2with distortion of rutile structure. In the process ofheating and cooling, the phase transition temperature is different,optical transmittancecurves do not overlap and thermal hysteresis is discovered.