Storage luminescence and scintillation properties of Eu-doped SrAl₂O₄ crystals

Eu-doped SrAl₂O₄ (Eu:SrAl₂O₄) crystals are prepared by a floating zone (FZ) method. In photoluminescence (PL), an intense broad emission peak around 510 nm due to 5d-4f transition of Eu²⁺ appear under excitation at 250-450 nm. The PL decay time constants are about 800 ns due to the 5d-4f transitions of Eu²⁺. In the nondoped sample, emission peaks around 480 and 560 nm are observed upon excitation at 316 nm. The X-ray induced scintillation spectra also show an intense broad emission peak around 510 nm, and the decay time constants are approximately 500 ns. In the pulse height spectra of the 2.5% Eu:SrAl₂O₄ crystal, the absolute light yield is ∼46,000 ph/MeV. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 120 and 400°C. In optically stimulated luminescence (OSL) after X-ray irradiation, emission peaks are observed around 510 nm while exposing the samples to the stimulation light at 800 nm.