Growth and luminous properties of Pure, Ce-and Eu-doped LiSr 2 I 5 single crystals

Abstract

We have grown pure LiSr₂I₅, Ce 3+ doped LiSr₂I₅, and Eu 2+ doped LiSr₂I₅ crystals, and investigated the effects of ionic doping on their luminescent properties. Single crystals with diameters of 10 and 15 mm were grown using the vertical Bridgman method. The optical band gap of LiSr2I5 is 4.84 eV, which is higher than the theoretically calculated band gap. The luminescence spectrum reveals an emission peak at 420 nm characteristic of STE luminescence, consistent with the radiative emission spectrum. Time-resolved fluorescence decay spectroscopy under 375 nm excitation of pure LiSr2I5 crystal exhibits both a short-lived component of 72 ns and a long-lived component of 200 ns. The exciton lifetimes for the Ce 3+ -doped and Eu 2+ -doped crystals are 244 ns and 366 ns, respectively. Temperature-dependent spectroscopy reveals that doping with Eu increases the exciton binding energy and enhances exciton stability in STE luminescence. Overall, LiSr2I5 provides nontoxicity and high-radioluminescence intensity, thus laying good foundations for potential application in low-dose radiography.