Near-infrared long-lasting phosphorescence in transparent glass ceramics embedding Cr3+-doped LiGa5O8 nanocrystals

Cr3+ doped transparent glass ceramics of SiO2–Ga2O3–Li2O were fabricated by melt-quenching and subsequent crystallization. X-ray diffraction and transmission electron microscopy analyses evidenced that cubic LiGa5O8 nanocrystals were homogeneously precipitated among the silicate glass matrix. The incorporation of Cr3+ ions into LiGa5O8 nanocrystals was evidenced by absorption, emission and time-resolved luminescence spectra. Impressively, the present Cr3+ doped glass ceramics were demonstrated to be a new near-infrared (∼720 nm) long-lasting bulk phosphor whose luminescence can last for more than 2 h after stoppage of UV (250–350 nm) irradiation. The occurring of Cr3+ long-lasting phosphorescence in the glass ceramics was confirmed to be mainly due to the precipitation of Cr3+:LiGa5O8 nanocrystals from glass matrix. The filling/releasing of electrons into/from the intrinsic traps of LiGa5O8 nanocrystals through the conduction band of host were proposed to be responsible for the realization of the long-lasting phosphorescence of the investigated Cr3+ doped glass ceramics.