Effects of Air Annealing on Luminescent Properties of Cerium-Doped Lutetium Oxyorthosilicate Scintillation Ceramics

Cerium-doped lutetium oxyorthosilicate ( Lu
₂
SiO
₅
: 0.5 mol%Ce, LSO:Ce) scintillation ceramics was fabricated by pre-sintering at 1650° C for 4 h in air followed by a post hot isostatic pressing (HIP) at 1600° C under 150 MPa for 1 h in Ar atmosphere. Luminescent and scintillation properties of the as-HIPed LSO:Ce ceramics was seriously affected by these oxygen vacancies. They were effectively filled through a post-annealing at 1300° C for 4 h in air. Ce LIII edge X-ray absorption near edge structure (XANES) spectra of LSO:Ce ceramics manifest that most of Ce ions in LSO ceramics still remain Ce(III) valence state after annealing in air. Photoluminescence (PL) and PL excitation (PLE) spectra show that emission intensity of the as-HIPed LSO:Ce ceramics was about 3 times lower than that of post-annealed sample. Light yield of the post-annealed LSO:Ce ceramics reaches 2.7 times of that of the as-HIPed sample, which exceeds 3 times of the light yield of BGO crystal.