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Persistent luminescence in ZnGa2O4:Cr3+ transparent glass-ceramics

Given the increasing demand for optical in vivo bioimaging materials, persistent luminescence in the red/near infrared range is receiving particular attention. Within this work, several elaboration ways of ZnGa2O4:Cr3+, respectively by solid state, by microwave assisted hydrothermal synthesis and by glass crystallization have been carried out. Structural analysis shows that all methods lead to pure spinel structure. Powder micrometric material is obtained by solid state reaction while nanoparticles are obtained by the two other methods. In the case of the glass-ceramics process, the nanocrystals obtained are trapped in a glassy matrix. This kind of elaboration leads to nanoparticles with lower amount of defects, no surface contact with air and an increase signal of the persistent luminescence compared to disperse nanoparticles. These good persistent luminescence properties are well correlated to thermoluminescence glow curves analysis. Moreover, such glass ceramics can be used as a good tool to study more deeply the persistent luminescence process of nanoparticles in a transparent environment and samples are easier to characterize.