Transparent\nand Thermally Stable Rare-Earth-Doped\nLuminescent Gallate Glass toward Passive Daytime Radiative Cooling\nApplications

Currently,\nthe implementation of passive daytime radiative cooling\nbased on zero-energy cooling methodologies primarily focuses on polymers\nand composite materials, whereas the available literature on all-inorganic\nmaterials is relatively few. Here, we present a novel microcrystalline\nglass material CaGa<sub>0.5</sub>Al<sub>1.5</sub>O<sub>4</sub> (CGAO),\ndoped with rare-earth elements and prepared by the high-temperature\nmelting method. This material exhibits long-term stability at 200\n°C, coupled with an effective infrared radiation cooling function,\ndemonstrating a 4.9 °C temperature reduction at solar noon. The\nenergy transfer and luminescence mechanisms of Tb<sup>3+</sup> and\nSm<sup>3+</sup> doped CGAO glass have been thoroughly investigated,\nalong with thorough assessments of its thermal stability and hardness.\nThe glass exhibits ultrahigh light transmission in the ultraviolet\nto near-infrared range, with the transmittance reaching 98% in specific\nspectral bands. Furthermore, it demonstrates superior luminescent\nthermal stability, retaining 85.6% and 71.2% of its initial luminescence\nintensity at 423 and 523 K, respectively. The high-temperature resistance\nand stability and long-term cooling properties render CGAO glass as\nan optimal candidate for integration into future energy-efficient\nand sustainable building designs.