Long-lasting luminescent ZnGa2O4:Cr3+ transparent glass-ceramics

Abstract

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.