Preparation And Characterization Of Vanadium Trioxide Nanostructured Powders Produced By Liquid Phase Reduction

Vanadium sesquioxide（V₂O₃）,as a member of low valent vanadium oxide,is a typical metal-to-insulator transition（MIT）.The optical,electrical and magnetic properties of V₂O₃ are widely used in metallurgy,new PTC materials,non-ferrous glass,sensors and other fields.Now the research of V₂O₃ mainly focuses on the preparation of thin films with many limitations.It is of great significance to explore an excellent process for preparing high-performance V₂O₃powders.In this thesis,V₂O₅ was used to obtain Vanadium xerogel by liquid phase reduction method.The precursor was calcined to obtain V₂O₃ powder.And the products were analyzed,characterized and electrochemical tests.The specific research contents were as follows:（1）Under the conditions of n（oxalic acid）/n（V₂O₅）=4 or 5（the concentration of vanadium source is 0.11 mol/L）,the effects of different calcination conditions on the morphology of the powders were studied.It was found that under the condition of n（oxalic acid）/n（V₂O₅）=4,the powders with single phase and good crystallinity were obtained at 500℃and 600℃,and had good redox characteristics.（2）Under the condition of n（oxalic acid）/n（V₂O₅）=4,the effects of the ratio of ethanol and deionized water on the reduction products were studied.It was found that the addition of ethanol was beneficial to the nanostructure of the materials.The condition of V（C₂H₅OH）/V（H₂O）=4 was used as the reaction solvent,it could not only accelerate the redox reaction,but also the powders obtained after calcination were small cubes with good morphology and nanoporous structure,showing good redox characteristics.（3）Under the conditions of n（oxalic acid）/n（V₂O₅）=4 and V（C₂H₅OH）/V（H₂O）=4,the effects of the addition of surface modifier NH₄Cl(mass concentration 1×10^-34×10^-3 g/mL)in precursor solution on the phase and powder morphology of the product were studied.It was found that the addition of NH₄Cl did not affect the synthesis of product V₂O₃,and when the mass concentration of NH₄Cl was 3×10^-3 g/mL,nano-wafer powders with regular morphology and the best dispersion were obtained.And the powders with better dispersibility can be obtained by preheating the precursors with addition of NH₄Cl.