Hexagonal cesium tungsten bronze nanoparticles produced by solvent-free spray pyrolysis and their near infrared absorption properties†
Abstract
Cesium tungsten bronze (Cs0.32WO3) nanoparticles (NPs) have attracted attention as a transparent near-infrared (NIR) absorbing material. In this study, a solvent-free aerosol method, namely solid-fed spray pyrolysis, was applied for the synthesis of Cs0.32WO3 NPs. Optimising the reaction temperature and H2 concentration in the carrier gas led to highly crystalline Cs0.32WO3 NPs with well controlled stoichiometry. The obtained Cs0.32WO3 NPs exhibited 13.7% NIR transmittance at 1425 nm with 80% visible light transmittance; these NIR absorption properties were superior to those of the Cs0.32WO3 NPs produced by a liquid-fed spray pyrolysis method. This improvement was examined in terms of the crystal structure and the mechanism of particle formation.