Long-lasting luminescent ZnGa2O4:Cr3+ transparent glass-ceramics†
Highly transparent ZnGa2O4 glass-ceramic materials are elaborated via a simple heat treatment of a 55SiO2–5Na2O–17ZnO–23Ga2O3 parent glass composition, which presents nanoscale spinodal phase separation. This optimized glass-ceramic exhibits 50 wt% of ZnGa2O4 nanocrystals showing a homogeneous and tuneable size. To describe the crystallization process, the glass and glass-ceramic nanostructures are studied by high resolution scanning transmission electron microscopy analysis coupled with in situ high temperature X-ray diffraction and optical measurements. From these results, an original mechanism is proposed to explain the crystallization process occurring in a spinodal phase separated glass. Remarkably, red long-lasting luminescence arising from the entire sample volume is observed in the Cr3+ doped transparent glass-ceramics, opening the route to a wider range of performing applications for this famous zinc gallate persistent phosphor.