Designable Phase Transition Temperature of VO2 Co-Doped with Nb and W Elements for Smart Window Application

Monoclinic vanadium dioxide (VO2 (M)) particles co-doped with niobium and tungsten, with potential application in smart windows, were synthesized by hydrolysis and subsequent thermal decomposition of vanadyl sulfate. All the doped VO2 particles exhibited a monoclinic crystalline phase and the critical phase transition temperature (T-c) of VO2 (M) was adjusted by Nb and W co-doping. The T-c of Nb-doped VO2 (M) decreased at a rate of approximately 10 degrees C/at% Nb dopant, and the transition temperature could also be accurately controlled to room temperature (about 27 degrees C) by co-doping with Nb and W. A film prepared using co-doped VO2 (M) particles showed a solar modulation ability of similar to 18% and a luminous transmittance of 40%, indicating that the co-doped VO2 (M) particles represent suitable candidates for smart window applications.