Preparation And Properties Of Tungsten-doped Vanadium Dioxide Thin Films And SiO₂ @VO₂ Composite Films

Vanadium dioxide is a thermochromic material with a phase change temperature of 68?.When the vanadium dioxide phase changes,its transmittance,resistivity and magnetic susceptibility mutate at the same time.This paper mainly completed two systems:first,a super-hydrophilic self-cleaning,intelligent temperature control of tungsten doped VO₂ thin film's preparation and its performance research;second,a super-hydrophobic self-cleaning,intelligent temperature control preparation and properties research of SiO₂@VO₂ composite films.?1?a super-hydrophilic self-cleaning,intelligent temperature control of tungsten doped VO₂ film.In this paper,thermochromic tungsten doped vanadium dioxide thin films were prepared by sol-gel method.At the same time,a study was conducted on the tungsten doping amount of the vanadium dioxide film.Samples are characterized by XRD,SEM,XPS,CA and UV-3600.The results show that the vanadium dioxide thin film is composed of polycrystalline VO₂ lattice.In addition,the doping did not change the preferred orientation of the VO₂ thin film on the quartz glass substrate.It can be seen from the SEM image that the prepared vanadium dioxide film has a grain size of30-150 nm.Through the cross-sectional view we can see that the film thickness is basically between 200-400nm,and the distribution is relatively uniform.XPS analysis shows that the amount of tungsten actually observed in the vanadium dioxide doped with different tungsten doping amounts is basically the same as the amount of tungsten we cast.This also shows that tungsten ions have all been incorporated into the vanadium dioxide lattice.The results show that the prepared tungsten-doped vanadium dioxide film is hydrophilic,and when the tungsten doping amount is0.5mol%,the surface of the film exhibits excellent super-hydrophilicity,water contact angle WCA can reach 12°.UV results show that the VO₂ thin films prepared by this method can effectively change the optical transmittance before and after phase change and are consistent with the theoretical results.The results of thermally induced curves show that the tungsten doped VO₂ thin films used in this experiment can significantly reduce the phase transition temperature at 32?,which is widely used and closest to room temperature.?2?a super-hydrophobic self-cleaning,intelligent temperature control SiO₂@VO₂composite film.In the preparation of a super-hydrophobic self-cleaning and intelligent controlled temperature SiO₂@VO₂ composite thin film system,the super-hydrophobic SiO₂ film with high transparency is studied firstly,and then we compound super-hydrophobic film directly on the tungsten-doped vanadium dioxide film which is prepared in the system one.A super-hydrophobic SiO₂ film with high transparency was prepared by sol-gel method.Using the acid-base two-steps method,firstly,the methanol solution of methyltrimethoxysilane was hydrolyzed by acid catalysis,and then the alkali-catalyzed condensation polymerization was carried out to form the oxidized network gel.We have optimized the preparation process and studied the acid treatment time.The results show that when the acid treatment time is 3 h,the prepared silica film has a very good superhydrophobic effect,and the surface static water contact angle can reach 153°.At the same time,the transmittance of the prepared film can reach 90%or more.The effect of annealing temperature on the properties of superhydrophobic films was also studied.The results show that the transmittance of the film at an annealing temperature of 500?and 600?for 30 minute in an argon atmosphere can be as high as 95%or more.And this xerogel film can be coated in different substrates have a very good superhydrophobic properties.Therefore,we first prepared vanadium dioxide film with a low phase transition temperature,and then compound super-hydrophobic film on the surface,resulting in a super-hydrophobic self-cleaning,intelligent temperature control SiO₂@VO₂ composite film.