Sb doping facilitates particle refinement and improves transparent NIR insulation of Cs_xWO₃ for energy-saving coating

Cesium tungsten bronze (Cs_xWO₃) is of significant interest due to its unique spectral selectivity, which is utilized in transparent thermal insulation coatings. However, the low-cost batch preparation of Cs_xWO₃ nanopowders remains a challenge. In this study, we performed an Sb doping modification of Cs_xWO₃. It was observed that Sb doping makes Cs_xWO₃ more prone to breakage, facilitating the preparation of nanoparticle Cs_xWO₃ through a simple solid-state reaction followed by mechanical milling. A 7 % Sb doping results in a small average particle size of 108 nm using moderate ball milling. Meanwhile, appropriate Sb doping enhances the transparent thermal insulation properties of Cs_xWO₃. A 3 % Sb doping raises the integrated visible light transmittance ( T _lum, 380–780 nm) of Cs_xWO₃ from 61.7 % to 65.40 %, and improves the near-infrared shielding efficiency ( Ψ _NIR, 780–2500 nm) from 61.20 % to 65.92 %, increasing by approximately 4 % and 5 %, respectively. The reasons for these property improvements are discussed based on experiments concerning bandgap ( E _g) and oxygen vacancy concentrations induced by Sb doping. This study indicates that Sb doping of 1–3 at% can produce Cs_xWO₃ nanopowders with better performance in a low-cost method, which is of great significance for advancing the production and practical application of nano-sized tungsten bronze powder in energy-saving coatings.