Broadband near-infrared persistent luminescence in Ni2+-doped transparent glass-ceramic ZnGa2O4†
Abstract
Transparent glass-ceramics are a highly attractive class of materials for photonic applications. Transition metal ions are promising candidates for luminescence centers thanks to the sensitivity of the ligand ions to d–d electron transition. Here, broadband second near-infrared (NIR-II) photoluminescence was achieved via precipitation of ZnGa2O4:Ni2+ nanocrystals within a zinc gallium–silicate glass matrix by a crystallization process. Excited by 260 nm UV photons, ZnGa2O4:Ni2+ GC displays NIR-II emission peaking at 1240 nm and has a full width at half maximum wider than 288 nm, attributed to 3T2g(3F) → 3A2g(3F) electronic transition of octahedrally coordinated Ni2+ ions. Moreover, broad persistent luminescence of Ni2+ ions can be effectively obtained after irradiation in UV light. Based on the electron paramagnetic resonance spectra and a thermoluminescence method, a physical model was constructed to demonstrate the mechanism of persistent luminescence. This developed afterglow luminescent glass-ceramic exhibits potential applications in biological imaging.