Thermal Oxidation of V2O3 Nanocrystals: A Template Method for the Fabrication of Monoclinic Phase VO2 Nanocrystals

We report the fabrication of VO2(M) nanocrystals by direct thermal oxidation V2O3 nanocrystals. The controlling of the thermal oxidation temperature and vacuum is essential for obtaining pure VO2(M) nanocrystals. The VO2(M) nanocrystals have nearly a spherical morphology with sizes ranging from 50 to 80 nm and well dispersed. The phase transition temperature is about 65 degrees C with relatively narrow endothermic and exothermal peaks in DSC curve. Variable temperature resistance and infrared transmission measurements demonstrate a reversible phase transition of the VO2(M) nanocrystals. Our method is facile, economical and can be easily scaled-up for mass production.