Dual-Mode Mechanoluminescence Induced by Triboelectricity and Frictional Heat in Transparent Fluoride Glass Ceramic

Mechanoluminescence (ML) refers to the unique phenomenon that converts mechanical energy into optical energy. However, at present, there are many kinds of ML generation mechanism models, such as piezoelectric type, triboelectric type, trap-related type, etc., which seriously affect the understanding of the intrinsic mechanism models. Herein, a rare-earth-doped fluoride glass ceramic (Ba₂LaF₇:Yb³⁺ glass-ceramic, BYG) is developed capable of dual-mode near-infrared ML (NIR ML) via triboelectric and frictional heat pathways. The triboelectric-induced ML arises from interfacial charge transfer between the glass and organic polymer matrices, directly exciting Yb³⁺ emission centers. In contrast, frictional heat-induced ML involves the carriers released from oxygen vacancies generated by X-ray irradiation. Such dual-mode NIR ML demonstrates a robust linear correlation with applied stress, enabling the development of a visualized bright-field sensing platform for real-time monitoring of triboelectric potentials and frictional temperatures. Furthermore, this work not only advances the mechanistic understanding of ML but also provides a versatile strategy for indirect optical sensing in ambient environments.