Enhanced orange-red emission in Eu3+/Li+ co-doped Na5Lu9F32 fluoride single crystal upon excitation of 394 nm

Abstract

In this study, a series of transparent 0.5 Eu3+/χ Li+ (χ = 0, 0.3, 0.6, 0.9, and 1.2): Na5Lu9F32 fluoride single crystals with high-quality were successfully grown by a modified Bridgman technique. The impacts of Li+ ion dopant on the luminous properties of Na5Lu9F32 doped Eu3+ single crystals were studied by fluorescence spectra, decay curves and absorption spectra. The doping of Li+ was beneficial for improvement of the orange-red emission, and the emission intensity of Eu3+ singly doped crystal could be doubled by co-doping 0.9 mol% Li+ ions. The variations of local environment around the Eu3+ ions after Li+ ions doping were probed by the emission spectra and the changes of ratios between red and orange emission intensities (R/O). Additionally, internal quantum efficiency of Eu3+/Li+: Na5Lu9F32 single crystal could be reached to ∼18.25%. Therefore, Eu3+/Li+: Na5Lu9F32 single crystal was considered as a potential material for orange-red laser and related optical devices.