The Preparation And Electrochromism Property Of Vanadium Pentoxide

Electrochromism was conceptualized in1961and is generally accepted as aphenomenon caused by electric field—the color of particular electrochromic materialmay be varied when small ions （H⁺, Li⁺） insert and extract.V₂O₅crystallizes in a layered structure and has been widely used in a variety ofscientific and technological applications. It can be used as a catalyst, as a cathode forsolid-state batteries, as a window for solar cells and for electrochromic devices as wellas for electronic and optical switches. Various properties of V₂O₅including structural,electronic, optical and electric properties have been investigated. The study of theoptical properties in the visible and infrared region gets much attention.We used magnetron sputtering, including Radio Frequency （RF） sputtering andDirect Current （DC） sputtering, to prepare the V₂O₅film. The characterizationmethods such as the transmission spectra, X-ray diffusion （XRD）, atomic forcemicroscope （AFM）, cyclicvoltaic （CV）, Raman spectra were used to characterize thesamples.The RF sputtering was used to prepared V₂O₅film by employing the metal Vtarget. The transmission of the samples of different deposition pressures, differentAr/O2flow ratios, different sputtering time were investigates to determine thefundamental preparation condition for the further analysis. The fundamental condition:the deposition pressure0.6Pa, Ar/O2flow ratio9:1, deposition time2h. The securityvolt range of samples was determined by electrochemical test. The chosen sampleswere annealed in Ar or air to compare the CV curves and transmission spectra. It isconcluded that the annealed films have a good electrochromic properties in theshort-wavelength range and have no clear phenomena in the long-wavelength. Theannealing makes the films have a good reversibility but lowers the electrochromicproperty. The metal V films were prepared by DC sputtering. The thickness of mental Vfilms was adjusted by changing time. The mental V films were annealed in air at400℃for1h to oxidize to V₂O₅, and the security volt range of samples was determinedby electrochemical test. The transmission spectra before and after electrochromismwere compared. It is concluded that the films prepared in30min have a goodelectrochromic property both in the range of short-wavelength and long-wavelength,and long-time deposition results in the increase of the film and oxidizing insufficiently.So the transmission rate of the films is too small to have a good electrochromicphenomenon.