Structure and persistent luminescence of novel Pr-doped Mg3Lu2Ge3O12 garnet

Garnet-based materials are widely investigated for applications in optics. In this research, we report the structure and spectroscopic properties of novel Mg3Lu2Ge3O12: Pr3+ garnet that exhibits orange persistent luminescence. The atomic positions of Mg3Lu2Ge3O12 were calculated using Rietveld refinement. The local structure analysis using extended X-ray absorption fine structure (EXAFS) and site-selective spectroscopy revealed that activator ions predominantly incorporate in the Lu3+ position. The persistent luminescence processes in Mg3Lu2Ge3O12: Pr3+ were analysed using photoluminescence (PL), thermostimulated luminescence (TSL), and electron paramagnetic resonance (EPR) spectroscopy methods. The comparison of PL and persistent luminescence spectra imply that electron and hole traps are filled due to the photoionization of Pr3+ ions. Two paramagnetic defects related to O- sites were detected after the excitation. TSL analysis indicates a quasi-continuous charge trap distribution ranging from 0.57 to 1.51 eV in the investigated host, enabling efficient persistent luminescence. The persistent luminescence mechanism of Mg3Lu2Ge3O12: Pr3+ is proposed.