Long lasting phosphorescence in oxygen-deficient zinc–boron-germanosilicate glass–ceramics

Long lasting phosphorescence has been observed in oxygen-deficient zinc–boron-germanosilicate glass–ceramics after 254 nm ultraviolet lights irradiation at room temperature. Electron spin resonance (ESR) spectrum confirms the presence of two paramagnetic centers. And the ESR signal shows a synchronized decay process with afterglow intensity after removing the excitation light, suggesting the afterglow is associated with the paramagnetic centers which are generated during the irradiation. Based on the approximate t−1 decay law of the phosphorescence intensity, the long lasting phosphorescence is attributed to thermal assisted tunneling recombination between pairs of distant electrons and Ge-related oxygen-deficient centers.