Gram scale synthesis of monoclinic VO2 microcrystals by hydrothermal and it argon annealing treatment

We report gram scale synthesis of 100% phase fraction of VO2 (M) monoclinic in powder form with reversible phase transition by combining hydrothermal method and Ar annealing at high temperature. Optimization of single phase VO2 (M) growth and its phase transition characteristics have been analysed systematically by varying growth parameters such as time, synthesis temperature and post growth annealing conditions. Argon annealing of hydrothermally grown VO2 powders at 800 degrees C found to play key role in obtaining VO2 (M) phase in gram scale with characteristic phase transition temperature of 68 degrees C. In-situ TEM has been performed to investigate the microstructure and phase change across the annealing temperature. Detailed characterizations have been carried out to correlate the phases, microstructure and transition temperature of VO2 with respect to growth parameters.