Near infrared shielding properties of quaternary tungsten bronze Nanoparticle Na_0.11Cs_0.22WO₃

Reduced tungsten bronze nanoparticles of ternary and quaternary compounds were prepared by adding sodium and cesium to crystal structures of tungsten trioxides (Na_xCs_0.33-xWO₃, x = 0, 0.11) while maintaining the overall alkali metal fraction at 0.33, in an attempt to control near infrared (NIR) shielding property in the particular wavelength range of 780 to 1200 nm. The structure and composition analysis of the quaternary compound, Na_0.11Cs_0.22WO₃, revealed that 93.1% of the hexagonal phase was formed, suggesting that both alkali metals were mainly inserted in hexagonal channel. The NIR shielding property for Na _0.11Cs_0.22WO₃ was remarkable, as this material demonstrated efficient transmittance of visible light up to 780 nm and enhancement in NIR shielding because of the blue-shifted absorption maximum in comparison to Cs_0.33WO₃.