Solid Phase Synthesis And Characterization Of Doped VO₂ Nanopowders For Smart Window Glass

Vanadium dioxide(VO2)undergoes a reversible phase change at 68? and has promising thermochromic properties,which has aroused widespread attention in the application of smart window glass coatings.Due to the numerous stable oxides of vanadium,it is a great challenge to prepare single-phase VO2 nanopowders.The most important thing is the lack of industrial preparation methods,which greatly limits the large scale application of VO2 in smart window glass.The paper will start from the solid phase method to seek a way of industrial production.Firstly,VO2 nanopowders were prepared by solid phase mechanochemical methods,and the micromorphology was granular.For that,two technical routes were designed:NH4VO3+H2C2O4·2H2O and V2O5+H2C2O4·2H2O.First,the precursor was obtained by ball milling NH4VO3+H2C2O4·2H2O as a raw material,and then heat-treated to obtain VO2 nanopowders.W0.02V0.98O2 nanopowders were formed by doping ammonium metatungstate(AMT),and the phase transition temperature dropped to 59.1?.Secondly,the precursor was obtained by ball milling V2O5+H2C2O4·2H2O as a raw material,and then heat-treated to obtain VO2 nanopowders powders.W0.02V0.98O2 nanopowders were formed by doping ammonium metatungstate(AMT),and the phase transition temperature dropped to 50.7?.During the experiment,the effects of heat treatment temperature,heat treatment time,nitrogen flow rate and other factors on the phase composition and microstructure of the product.were studied.Secondly,Submicron VO2 powders were prepared by solid-phase thermal reduction.W0.02V0.98O2 and Cs0.02V0.98O2 powders were obtained by doping H2WO4 and CsCO3.During the experiment,the effects of raw material V2O5 morphology,thermal reduction temperature,thermal reduction time,nitrogen flow and other factors on the phase composition and microstructure of the product.were studied.Finally,VO2 nanopowders were prepared by solid-phase reaction method,and the micromorphology was granular.During the experiment,the effects of heat treatment temperature,heat treatment time,nitrogen flow and other factors on the phase composition and microstructure of the product were studied.In summary,the research in this thesis provides multiple solid-phase methods for the synthesis of VO2 powders.The preparation process is simple,the cost is low,there is no pollution,and it has a good industrial production prospect.