超细VO_2粉末的制备及其可逆相变的原位表征  

Preparation of VO_2 Superfine Powders by a Redox Method and In Situ Characterization on the Reversible Phase Transition

作　　者：张少鸿[1] 付娟[1] 苏秋成[1] 付春红[1] 李新军[1] 

机构地区：[1]中国科学院广州能源研究所中国科学院可再生能源重点实验室,广东广州510640

出　　处：《稀有金属材料与工程》2015年第3期738-742,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51172233);广州地区分析测试基金(201212)

摘　　要：采用氧化还原法,在N2保护气氛中,通过程序控温,用草酸还原V2O5制备VO2超细粉末,重点考察原料配比对还原产物物相纯度的影响。采用X射线衍射仪（XRD）和扫描电子显微镜（SEM）及X射线能量色散谱仪（EDS）分析产物的相组成和微观形貌,通过同步热分析（STA）和原位XRD研究VO2粉体的热致可逆相变特性。结果表明：V2O5和草酸以1：1.2~1.4的摩尔比混合,可制得较纯的单斜晶系VO2超细粉末,颗粒呈近球形,平均晶粒度约为50 nm。低温为M相（单斜晶系,P21/c）,升温时可转化为R相（正方晶系,P42/mnm）,升温相变点为68.1℃,降温相变点为60.2℃,滞后7.9℃。具有良好的热致可逆循环相变稳定性,M/R相多次循环转换的DSC热滞回线呈现很好的重现性。Oxalic acid was chosen as the reductant to prepare superfine VO2 powders from V2O5 under high-purity N2 atmosphere. The effect of V2O5：H2C2O4 molar ratio on the VO2 purity was investigated. X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive X-ray spectroscopy（EDS） were applied to analyze the VO2 sample. The thermal induced reversible phase transition performance was characterized by simultaneous thermal analysis（STA） and in situ XRD. The results show that when the molar ratio of V2O5 to H2C2O4 is in the range from 1：1.2 to 1：1.4, relatively pure VO2 could be obtained. The as-prepared VO2 is superfine subspheroidal particles of uniform distribution. The mean crystallite size is about 50 nm. It has a reversible phase transition from a low temperature monoclinic phase（P21/c, M phase） to a high-temperature tetragonal phase（P42/mnm, rutile phase or R phase）. The DSC curve of the heating-cooling cycles is asymmetrical thermal hysteresis loop. The multicycle loops are coincident well. There is an endothermic phase transition at 68.1 °C, and an exothermic phase transition at 60.2 °C, with 7.9°C hysteresis.

关 键 词：二氧化钒 氧化还原 热致相变 X射线衍射 同步热分析 热滞回线 

分 类 号：TQ135.11[化学工程—无机化工]