Synthesis of flake-like VO2 (M) by annealing a novel (NH4)0.6V2O5 phase and its thermochromic characterization

Flake-like VO 2 (M) has been successfully synthesized by annealing plate-like (NH 4 ) 0.6 V 2 O 5 in vacuum and its thermochromicity was investigated. Preparation conditions such as temperature and vacuum degree have been varied to obtain the pure phase. The formation mechanism from ammonium vanadium bronze to VO 2 (M) has been explored. The flake-like VO 2 (M) shows an excellent thermochromicity; the infrared modulation at 2500   nm was up to 56.6% with a 30% visible transmittance which will be beneficial for smart windows, smart curtains or other applications.