均匀自支撑的二氧化钒纳米线的水热合成及相变特性研究

Hydrothermal Synthesis and Phase Transition Properties of Uniform Free-standing Vanadium Dioxide Nanowires

摘要:

二氧化钒(VO₂)在接近室温时发生由半导体态向金属态的Mott相变，在智能窗和红外自适应伪装技术领域具有一定的应用前景。本文采用一种新颖的水热法制备均匀自支撑的VO₂纳米线。合成的纳米线的直径为150±30 nm，长度达到几十微米。通过X射线衍射、X射线光电子能谱、高分辨透射电镜和选取电子衍射等手段验证了高纯单斜相VO₂纳米线的成功制备。而且,VO₂纳米线的可逆相变性能采用差示量热扫描、变温XRD和变温Raman光谱进行了探究。结果表明：VO₂纳米线升温相变点为65.2 °C,磁滞回线宽度窄至6.5 °C,具有良好的可逆相变性。这些为VO₂纳米线的金属-半导体相变研究提供基础。

Abstract:

Vanadium dioxide (VO₂) undergoes a Mott metal-insulator transition (MIT) close to room temperature, and has been suggested as a candidate for use in smart window and adaptive infrared camouflage. Here we report the synthesis of uniform free-standing VO₂ nanowires using a novel hydrothermal method. The synthetic nanowires have typical diameters of 150±30 nm and lengths of tens of micrometer. These VO₂ nanowires exhibit high crystallinity and feature a pure monoclinic phase and composition characterized by X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and selected area electron diffraction. Moreover, reversible phase transition properties of VO₂ nanowires are monitored via differential scanning calorimetry, variable temperature X-ray diffraction and temperature-dependent Raman spectroscopy. The results show VO₂ nanowires obtained exhibit a reversible phase transition with an endothermic phase transition at 65.2 °C and a narrow hysteresis width of 6.5 °C. These VO₂ nanowires should provide promising materials for fundamental investigations of nanoscale metal-insulator transitions.