Inverted reversible thermochromic and thermal insulation performances of K2O·nSiO2-based fire-resistant glass

Abstract

K₂O·nSiO₂-based laminated fire-resistant glass with inverted reversible thermochromic (IRTC) performance was prepared by in-situ reaction method using a high solid content (55 wt% ± 1 wt%) SiO₂ sol and introducing NH₄⁺ by doping with NH₄HCO₃. The structure, morphology, thermochromic and optical performances of these materials were studied in detail and characterized. The microporous structure formed by the addition of NH₄HCO₃ was clearly observed using scanning electron microscopy (SEM), This structure increased the number of micropores and enhanced thermal insulation by extending heat transfer pathways. By analyzing the differences in light transmission intensity (T), the thermochromic mechanism of the material was elucidated. The combination of Derivative thermogravimetry (DTG) and Raman spectroscopy revealed that the addition of NH₄HCO₃ resulted in the difference of the distribution percentage of silica bridged oxygen atoms in the samples, indicating that the NH₄HCO₃ was the key factor enabling the inverted reversible thermochromic (IRTC) performance of the K₂O·nSiO₂-based material. This work provides a novel strategy and preparation method for t for developing the thermochromic smart fire-resistant windows.