Nano Preparation And Morphology Of Vanadium Dioxide Impact On Performance

This dissertation used V₂O₅ as raw material by using hydrothermal synthesis and by using three types of reducing agent,including oxalic acid,absolute alcohol and formaldehyde to obtain nano-VO₂ of different morphologies,and we tokened the producers by using SEM and TEM.We explored the impact of reaction temperature,reaction pressure,reaction time, pH value,etc on the morphology of nano-VO₂,and tested their resistance changes with temperature.The main research results were as follows:(1)When used oxalic acid as reducing agent,we could obtained sheet nano-VO₂, optimized its preparation conditions:V₂O₅:oxalic acid=1:2(molar ratio),the reaction temperature was 200℃,the reaction time was 48h,preserved in vacuum desiccator.(2)When used absolute alcohol as reducing agent,we could obtain rod-like nano-VO₂, optimized its preparation conditions:V₂O₅0.01mol,absolute alcohol 60mL,distilled water: 20mL,the reaction temperature was 180℃,the reaction time was 24 h,preserved in vacuum desiccator.(3)When used formaldehyde as reducing agent,we could obtain wirelike nano-VO₂, optimized its preparation conditions:V₂O₅0.4g,formaldehyde:20 mL,distilled water:60mL, the reaction temperature was 180℃,the reaction time was 24 h,preserved in vacuum desiccator.(4)The primary and secondary sequence of the factors that effected the morphology of nano-VO₂:the species of reducing agent,the reaction pressure,the reaction temperature,the reaction time.(5) Nano-VO₂'resistance changes with temperature was different if their morphology was different,the width of wirelike nano-VO₂ by used formaldehyde as reducing agent was minimum,the sminimum resistance and the most metal.