Hexagonal VO2 particles: synthesis, mechanism and thermochromic properties.
Hui Yan Xu1,2, Ke Wei Xu1,3, Fei Ma1,2
1State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University Xi'an 710049 Shaanxi China mafei@mail.xjtu.edu.cn.
RSC Advances
|May 11, 2022
Summary
Researchers synthesized hexagonal vanadium dioxide (VO2) with excellent thermochromic properties. Tungsten doping significantly reduced the phase transition temperature to 28°C, enhancing its potential for smart window applications.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Chemistry
Background:
- Vanadium dioxide (VO2) exhibits a thermochromic phase transition, making it suitable for smart windows.
- Controlling the morphology and phase evolution of VO2 is crucial for optimizing its thermochromic properties.
- Hydrothermal synthesis offers a versatile route for fabricating nanostructured materials.
Purpose of the Study:
- To synthesize monoclinic vanadium dioxide (VO2) with a hexagonal structure using a hydrothermal method.
- To investigate the phase evolution and the formation mechanism of the hexagonal morphology.
- To evaluate the thermochromic properties and the effect of W doping on the phase transition temperature.
Main Methods:
- Hydrothermal synthesis of VO2 nanoparticles.
- Characterization of crystal structure and morphology using X-ray diffraction and electron microscopy.
- Measurement of thermochromic properties and hysteresis.
- Tungsten (W) doping to tune the phase transition temperature.
Main Results:
- Successfully synthesized hexagonal VO2 (M) via hydrothermal method, with phase evolution confirmed.
- Hexagonal morphology attributed to low-energy coherent interfaces: (211̄)1//(21̄1̄)2 and (21̄1̄)1//(020)2.
- Particle size controlled by precursor concentration; hexagonal particles showed narrow hysteresis (5.9 °C) and high stability.
- Tungsten doping reduced the phase transition temperature to 28 °C.
Conclusions:
- The hydrothermal method enables controlled synthesis of hexagonal VO2 with excellent thermochromic properties.
- Low-energy coherent interfaces play a key role in the formation of the hexagonal morphology.
- W doping is an effective strategy to significantly lower the phase transition temperature of VO2, expanding its application potential.
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