Optical and scintillation properties of Dy³⁺: Y₃Al₅O₁₂ and undoped Y₃Al₅O₁₂ crystals grown in reduction atmosphere

Optical and scintillation properties of a 1.0-mol% Dy-doped yttrium aluminium garnet (YAG) grown under N₂ atmosphere and undoped YAG crystals were investigated. Both crystals were grown by the Czochralski process. The one of the undoped YAG crystal was grown in an Ar + H₂ (97:3) reducing atmosphere. Absorption peaks at 352 nm and 366 nm observed in 1.0-mol% Dy-doped YAG originated from 4f-4f transition of Dy³⁺. In addition, the crystal showed sharp emission lines at near 482 nm and 584 nm under 352 nm UV and alpha-ray excitation. The light output of Dy-doped YAG was estimated to be approximately 20,000 photons/(5.5-MeV alpha ray, ²⁴¹Am). The scintillation decay time constants for Dy-doped YAG crystal was around 400 ns and 40 ns. Undoped YAG crystals grown under Ar + H₂(97:3) atmosphere showed absorption and excitation peak at 370 nm. A 400-nm emission peak was observed under 370-nm excitation. The light output of the crystal was also estimated to be 50,000 photons/(5.5-MeV alpha ray). The scintillation decay time constants of the crystal were around 370 ns and 50 ns.