Ultrasound-Stimulated Luminescence from Mn2+-Activated Crystal-Free Germanate Glasses Charged by Sunlight

Inorganic materials which emit light when excited by ultrasound have garnered growing attention. While the phenomenon holds considerable potential for advanced sensing, damage detection, and remote illumination, it has so far been known only for crystalline and often opaque materials. Herein, persistent and ultrasound-induced luminescence of a Mn²⁺-containing germanate glass free of crystals is demonstrated, as confirmed by combined X-ray diffraction and transmission electron microscopy. The light emission intensity scales with the extent of ultrasonic heating, which is in turn governed by input power and duty ratio, and can be charged by exposure to sunlight. Such all-inorganic materials offer the advantageous processability and preserved transparency of glasses over ceramic and organic materials, combined with highly tunable luminescence properties enabled by the exceptional compositional adaptability of glass formulations. With this set of properties, they present attractive opportunities for numerous applications, from smart lighting and display technologies to bioimaging.