Effects of Ga substitution in Ce:Tb3GaxAl5-xO12 single crystals for scintillator applications

Bulk single crystals of Ce-doped Tb3GaxAl5-xO12 (x = 0-4) were successfully synthesized by the floating zone method. The samples exhibit photoluminescence and scintillation with an intense broad emission due to the 5d-4f transitions of Ce3+ peaking around 550nm as well as a few sharp peaks due to the 4f-4f transitions of Tb3+. Pulse height spectrum measurements under Cs-137 gamma-ray irradiation demonstrated a clear photoabsorption peak, in which the scintillation light yields were estimated to be 57,000 (x = 0), 28,000 (x = 1), 19,000 (x = 2), and 10,000 (x = 3) photons/MeV. Afterglow level can be suppressed with an appropriate addition of Ga, in which the optimum concertation is x = 2 leading an afterglow level of 23 ppm. (C) 2018 The Japan Society of Applied Physics