热解氧钒碱式碳酸铵法M型二氧化钒粉体的制备

Preparation of M-vanadium dioxide powder by thermolysis of ammonium oxovanadium carbonate hydroxide

以五氧化二钒、浓盐酸、水合肼和碳酸氢铵为原料,合成氧矾碱式碳酸铵前驱体,并通过控制退火温度在氮气气氛下热处理前驱体制备M型二氧化钒粉体。采用X射线衍射、差热分析、扫描电子显微镜等方法对样品成分、相变温度和晶体形貌进行了分析。结果显示：当升温速率和保温时间一定时,不同的热处理温度和气氛对粉体的晶型和成分有重要影响;不同的热处理温度热解氧钒碱式碳酸铵,保温30min能得到不同价态的氧化钒粉体;当500℃温度热处理30min时,可以得到纯的M型二氧化钒粉体。有序结构的理论晶粒尺寸为20～40nm,实际颗粒尺寸在1μm左右,粉体相变温度为66℃;通过热处理氧钒碱式碳酸铵前驱体可以制备M型二氧化钒粉体,工艺简单、条件容易控制。

The precursor of ammonium oxovanadium carbonate hydroxide was synthesized using vanadium pentoxide,hydrochloric acid,hydrazine hydrate and ammonium bicarbonate,then it was annealed in the atmosphere of nitrogen to prepare vanadium dioxide（M）powder when the temperature was controlled.X-ray diffraction,differential thermal analysis and scanning electron microscope were employed to characterize the component,phase transition temperature and crystal morphology of the powder.The results show that the change of annealing temperature and atmosphere has a great influence on the crystal structure and component of the powder when the heating rate and holding time is constant;different oxidation state of vanadium can be obtained when the precursor is annealed for 30min at different temperatures in the atmosphere of nitrogen;the pure vanadium dioxide（M）powder is obtained after the precursor annealed for 30min at 500℃;the theoretical grain size of orderly structure is between 20nm and 40nm while actual particle size is about 1μm,phase transition temperature of the powder is 66℃;The process of preparing vanadium dioxide（M）powder by annealing ammonium oxovanadium carbonate hydroxide is simple and easily controlled.