Photo-and radio-luminescence characterizations in rare-earth-doped sral₂O₄ crystals

SrAl₂O₄ bulk crystals doped with all rare-earth (RE) ions except for Sc, Y, La, Pm and Lu were synthesized by the optical floating zone method to systematically investigate the photoluminescence (PL) and radioluminescence (RL) properties for radiation detector applications. The crystal samples show PL and RL signals due to the 5d-4f or 4f-4f transitions of doped RE ions, and each decay curve consists of a sum of exponential functions with the typical decay time constants. Under VUV photon excitation, the Ce-, Pr-, Eu-, Tb-, Dy-and Ho-doped samples exhibit PL predominantly with two broad emission bands around 320 and 600 nm, which are possibly due to self-trapped excitons (STEs) perturbed by RE ions.