The Effect Of Ion Doping On The Microstructure And Properties Of VO 2 Films

Vanadium dioxide?VO₂?is considered to be a kind of smart materials since it was found to exhibit phase transition from metal-to?insulator transition?MIT?temperature around 68 ?,which is accompanied with a sharp change in electrical resistance spanning 5 orders of magnitude,and a change in infrared?IR?transmittance over the MIT temperature.Due to its great technological potential and intriguing physical properties,VO₂ film has a wide variety of potential applications.In this paper.V₂O₅ was chosen as a raw material to prepared vanadium oxide thin films by sol-gel method.The effects of annealing process on the structure and properties of vanadium oxide thin films were investigated.In addition.VO?acac?2 was chosen as precursor to prepared the Zr4+ doped VO₂ thin films using the sol-cgel and spin coating method.The effect of Zr4+ doping on VO₂ thin film's structural and thermochromic properties were investigated.They were characterized by XRD.SEM,TG,XPS,DSC and UV-vis-NIR spectrophotometer.The main research contents and results of this paper are as follows:?1?According to the TG,the"n" in V₂O₅·nH2O was calculated?n=1.67?.The XRD shows that the film almost have not crystallization when the annealing temperature is 390 ?,soaking time is 120 min.When the annealing temperature is 390 ?,soaking time is 240 min,the pure VO₂ film can be prepared.The SEM shows that the surface of vanadium oxide film is dense and a clear grain boundary with the increase of annealing temperature.The soaking time is also effect films to crystallization.The XPS showed that the Binding Energy?BE?span between the O1s and V2p3/2 core level for vanadium oxidation states of V5++2p3/2,V4+2p3/2,V3+2p3/2were set at 12.75 eV.14.0 eV and 14.7eV,respectively.The XPS also shows that the V₂O₅ thin film reduced to pure VO₂?M?when annealing temperature is 390?,soaking time is 240 min.UV-vis-NIR shows that the maximum transmittance mutation of the pure VO₂?M?thin film is 39%at the wavelength of 2500 nm,the phase transition temperature of this film is 64.3? and the temperature hysteresis width of this film is 12.1?.?2?In this paper,the zirconium doped VO₂ thin films were successfully prepared by the organic sol-gel method.The XRD showed that that there are only two main diffraction peaks in all samples,and these two diffraction shift slightly towards the small angle and crystallite size become larger with the Zr4+ atomic ratio increased.When 7 at.%Zr⁴⁺ doped in the VO₂ film,the deviation angle is 0.16° and the crystallite size is about 98 nm.The SEM shows that lots of grain have been found in the pure VO₂ films surface.The films surface become present a kind of layered structure when Zr4+doped in the VO₂.The effect of Zr4+ doping to decrease Tc is about 1 ? per 1 at.%averagely,and the Tc of 5 at.%film's phase transition temperature is 61.4 ?,Zr4+ ion can be decreased the transmittance of VO₂ films but 1 at.%Zr⁴⁺ doping can be increase the luminous efficiency??Tlum?and solar regulation efficiency??Tsol?,the ?Tlum of the pure VO₂ film and 1 at.%Zr4+ doped VO₂ films are 10.9%,11.2%and the ?Tsol are 14.4%,15.2%.respectively.