Optical and scintillation properties of Nd-doped SrAl2O4 crystals

Nd-doped SrAl2O4 (Nd: SrAl2O4) crystals were prepared by a floating zone (FZ) method with different dopant concentrations. The photoluminescence (PL) measurements under visible light excitations confirmed strong near infrared (NIR) emissions around 890 nm, which is due to the 4f-4f transitions of Nd3+, and the decay time constants were 300-400 mu s. Furthermore, VUV excitations revealed two broad emissions around 250-450 and 500-700 nm, which were attributed to self-trapped excitons (STEs) perturbed by Nd3+. Moreover, the X-ray induced scintillation spectra showed some small peaks at around 380 nm in addition to NIR emissions at 1064 nm similarly seen in PL. The former scintillation decay time constants were 30-40 mu s. In the undoped sample, these emissions mentioned above were not present but a weak broad emission around 450 nm appeared. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks were observed in the Nd-doped samples at around 100 and 250 degrees C.