Abstract View
Aerosol-assisted Production of Sodium Tungsten Bronze Particles for NIR Shielding
HAO TU, Wei-Ning Wang, Da-Ren Chen, Virginia Commonwealth University
Abstract Number: 9
Working Group: Nanoparticles and Materials Synthesis
Abstract
Because of close-to-50% energy in solar radiation is in the infrared (IR) range, it is very desired to have transparent medium, e.g., window glasses, with NIR (near Infrared) shielding function in order to save the energy and cost on air conditioning of a building. Different kinds of NIR shielding transparent medium have been developed and applied, for examples, as automobile windshields and building windows. They are primarily composite membranes made by multilayers of polymer film, or metal (Ag/Au) sputter-coated on ceramics (ITO/ATO) (Padiyath et al., 2007). However, the polymer aging, high price of raw materials, and the requirement of complex coating equipment make limits the wide application of NIR shielding transparent medium. Rare-earth hexaboride particles were also proposed for the same applications (Takeda et al, 2008). Due to the high transmittance in visible range (VLT) and excellent absorption in NIR range, tungsten bronze oxides (MxWO3) are viewed as one of potential candidates for NIR shielding material which could be applied to transparent media. Liquid phase reactions are typically in making particles of tungsten bronze oxides. The majority of published MxWO3 research focus on CsxWO3 because of its the great performance in VLT and NIR shielding. Unfortunately, caesium (Cs) is expensive for large scale production.
In this study, we introduce a new aerosol-assisted method to produce crystalline NaxWO3 particles from low-cost precursors. The production process, evolved from that reported in our previous work (Tu, et al, 2020) is in one step, continuous and without any aftertreatment. The sizes of as-produced NaxWO3 particles could be controlled by adjusting the dilution and quenching of reaction agents. By investigating the size effect on VLT, we confirm that the smaller size of NaxWO3 particles have the higher VLT, consistent with what reported by Adachi, K. (2010) on the investigation of LaB6 for the same applications. The above finding offers an alternative and cheap way to improve the performance of MxWO3 particles on the VLT and NIR shielding. The detail of our production method and the findings will be presented in this talk.
[1] Tu, H., Wang, W. and Chen, D.-R. (2020). Aerosol-assisted production of NIR shielding nanoparticles: Sodium tungsten bronze. Aerosol Air Qual Res 20: 690-701.
[2] Adachi, K., Miratsu, M. and Asahi, T. (2010). Absorption and scattering of near-infrared light by dispersed lanthanum hexaboride nanoparticles for solar control filters. J. Mater. Res. 25: 510-521.
[3] Padiyath, R., Haak, C. and Gilbert, L. In Proceedings of the Annual Technical Conference-Society of Vacuum Coaters, 2007, p. 669.
[4] Takeda, H., Kuno, H. and Adachi, K. (2008). Solar control dispersions and coatings with rare-earth hexaboride nanoparticles. J. Am. Ceram. Soc. 91: 2897-2902.