Photo- and radio-excited luminescence properties of Eu-doped La ₂O₃-Al₂O₃ based eutectics

Eutectic crystal of 0.5% Eu-doped 30LaAlO₃-70Al ₂O₃ (vol %) was prepared by micro-pulling down (μ-PD) technique under nitrogen atmosphere. Being excited at a wavelength of 320 nm, the crystal exhibited intense emission band with a maximum at 450 nm which is corresponding to 4f⁶5d-4f⁷(⁸S_7/2) transitions of Eu²⁺. The decay time and fluorescence quantum efficiency (QE) were determined to be about 475 ns and 60%, respectively. When alpha-ray excited the crystal, both Eu²⁺ 4f⁶5d-4f ⁷(⁸S_7/2) and Eu³⁺ 4f ⁶-4f⁶ (⁵D₀-⁷F _1,2) emission peaks were observed at 435 nm and 600 nm. By the pulse height spectra, the relative scintillation light yield of the crystal was about 4% compared with that of BGO commercial scintillator.