Structure And Microstructure Ofpreparation Ofvanadium Dioxide By Microwave Hydrothermal Method

Nowadays,people need more intelligent materials so it is urgent to develop new materials and apply them.As a material with phase change properties,VO₂ has attracted extensive attention.As a thermal phase change material,the phase transition temperature of VO₂is around 68℃.When the temperature is lower than 68℃,VO₂ behaves as a monocline M phase.At this time,VO₂ behaves as a semiconductor with high infrared transmittance.When the temperature exceeds the phase transition temperature,VO₂ exhibits rutile R phase,which is in a metallic state and has a high refractive index for infrared.Before and after the phase transition,the optical and electromagnetic properties of VO₂ change dramatically.In addition,studies show that the phase transition temperature can be reduced by doping elements,which makes the application of VO₂ more widely.In this paper,vanadium acetyl acetonate oxide was used as raw material,and VO2 was prepared by ordinary hydrothermal method and characterized by XRD,DSC and SEM.It was concluded that the optimal molar concentration of vanadium acetyl acetonate oxide for the preparation of VO₂ was 0.3mol/L.VO₂ was prepared by microwave-assisted heating with 0.3mol/L vanadium acetyl acetonate.Then,we use XRD,DSC and SEM to analyze sample.The effects of H⁺concentration,microwave hydrothermal time,microwave hydrothermal power,annealing time and annealing temperature on the sample preparation were studied.Tungsten was also used as a doping element to prepare tungsten doped M phase VO₂.After analysis,when the doping amount was 3.5%,the phase transition temperature dropped to about 47.75℃In this paper,sample was prepared by microwave workstation using pollution-free vanadium acetonate as raw material and doped with tungsten element.While providing ideas for cleaner preparation of vanadium dioxide,the efficiency is further improved,and a new technological method for preparing tungsten doped samples is proposed to change the temperature of phase transformation.