A promising route for developing green phosphor with mechanoluminescence and long persistent luminescence in Sr2Ga2GeO7: Tb3+

Mechanoluminescence (ML) materials featuring photon emission under mechanical stimulation have attracted the attention of scientists doing researches on structure monitoring, stress sensing, anti-counterfeiting and imaging. In this study, a novel series of ML green phosphors Sr2-xGa2GeO7: xTb3+ (0 ≤ x ≤ 0.05) have been synthesized by a high-temperature solid-state method for the first time. Their crystal structure, optical properties and attenuation profiles have been investigated. X-ray diffraction (XRD) analysis reveals that the sample is tetragonal with a space group of P 4¯ 21m, and Tb3+ partially replaces the lattice position of Sr2+ in the Sr2Ga2GeO7 crystals. The green ML emission mechanism is attributable to the typical 5D4 → 7F5 transition of Tb3+ ions, similar to persistent luminescence (LPL) and the photoluminescence (PL). To better understand the mechanism of potential LPL and ML in this system, the trap regulation is comprehensively investigated by a series of thermoluminescence (TL) measurements.