Synthesis and thermochromic properties of vanadium dioxide colloidal particles

Abstract

A convenient route for the preparation of thermochromic VO₂ particles has been developed by combining solution-phase hydrolysis and a thermal reduction process. With this method, the particle size can be easily tuned from tens to hundreds of nanometres. The liquid dispersibility of these VO₂ particles facilitates convenient observation and effective measurement of the temperature-dependent optical properties in the visible region. We observe a blue shift of the resonance peak of metal-phase VO₂ particles with decreasing size. The size effect also exists in the phase transition behavior: smaller VO₂ particles exhibit a wider hysteresis curve during the semiconductor-to-metal transition. We also demonstrate that the VO₂ particles in the form of a colloidal dispersion can be easily incorporated into thin plastic thermochromic films that may be used as smart windows for energy management.