Luminescence and Scintillation Properties of Scintillators Based on Orthorhombic and Monoclinic BaLu$_{2}$F$_{8}$ Single Crystals

The rare-earth-doped orthorhombic BaLu
₂
F
₈
vacuum-ultra-violet scintillator crystals have been studied. The fast emission around 185 nm with a decay time of several nanoseconds was due to the allowed 5d-4f transition of the Nd
³⁺
ion. The high temperature phase BaLu
₂
F
₈
orthorhombic crystals have been prepared by micro-pulling-down method. Unfortunately, no 5d-4f emission (neither from Nd
³⁺
nor from Tm
³⁺
) was observed in the crystals under excitation by ionizing radiation at all. This was explained by preferential energy transfer from the host to the lattice defect states. Further improvement of the scintillation efficiency by facilitating the energy transfer from the host matrix to the Nd
³⁺
luminescence center by Tm
³⁺
-codoping was attempted. The energy transfer from the Tm
³⁺
ions to the Nd
³⁺
ones has been proved, however, no improvement of the overall scintillation efficiency was observed.