VO2(B)热转化为VO2(R)和V2O3的高温XRD原位表征

In situ characterization on thermal transitions of VO2(B): toward VO2(R) and V2O3

摘要:

以草酸和V2O5为原料，采用水热法制备VO2(B)。通过高温原位X射线衍射技术研究VO2(B)在氮气保护下升高温度过程中的相变特性，采用X射线衍射仪(XRD)和场发射扫描电子显微镜(FE-SEM)分析所制备样品及其在不同温度热相变产物的微观形貌和物相组成。结果表明：以草酸和V2O5为原料，用水热法可制得单斜晶系VO2(B)，颗粒呈纳米片状；升温至430~700℃，VO2(B)不可逆转化为四方晶系VO2(R)，形貌由纳米片状变为亚微米及微米近球形；升温至1000℃左右，VO2(R)开始分解形成Magn閘i相系列化合物（VnO2n?1）；升温至大约1200℃完全转变为具有刚玉结构的V2O3烧结块。

Abstract:

VO2(B) was synthesized via a facile hydrothermal process using V2O5 and oxalic acid. The crystal structure and phase transition of VO2(B) during elevated temperatures in N2 were investigated by in situ X-ray diffraction (XRD). Meanwhile, the morphology and crystal structure of the samples obtained by annealing at different temperatures were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and XRD, respectively. The results show the as-synthesized nano platelet-like monoclinic VO2(B) irreversibly transforms into submicron and micron subsphaeroidal tetragonal VO2(R) between 430 and 700 oC. The as-obtained VO2(R) starts to decompose and form Magn閘i phases VnO2n?1 series compounds at 1000 oC, and totally transfers into a corundum V2O3 sintered block at ca. 1200 oC.