Multimodal Optical Sensing Based on Sm3+-Activated Sr3Sn2O7 Phosphor: Stress Visualization and Temperature Monitoring

Abstract

Conventional mechanoluminescent (ML) materials are limited to stress sensing, restricting their application in integrated optical sensing. In this study, we develop a multimode-emitting phosphor, Sr2.996(Sn1.75Ge0.25)O7.002:0.004Sm3+, which exhibits simultaneously excellent ML properties through defect engineering of the host matrix, and non-contact temperature sensing capability based on the fluorescence intensity ratio (FIR). The incorporation of Li+ boosts the ML intensity by approximately 4-fold, resulting in an ML signal 30 times stronger than its persistent luminescence (PersL). The enhancement drastically suppresses the PersL interference during the stress sensing. Furthermore, the phosphor exhibits a high relative temperature sensitivity of 1.48%K−1 at 303 K. Experimental characterization and first-principles calculations elucidate the mechanism behind the ML enhancement. The multifunctional phosphors, capable of simultaneous non-contact stress and temperature sensing, offer significant potential for advanced optical sensing systems, particularly in high-temperature, high-pressure machinery monitoring, and is expected to find practical applications in industrial monitoring, biomedical devices, aerospace and deep-water exploration.