Growth of LiF/LiBaF3 eutectic scintillator crystals and their optical properties

Li-containing materials can be applied as neutron scintillators, and LiBaF3 can discriminate neutron and gamma rays. Moreover, LIF/LiBaF3 can have higher cross section of thermal-neutron capture compared with LiBaF3. In this study, LiF (82.5 mol%) and (Ba1−x REx)F2 (17.5 mol%, RE = Ce and Eu, x = 0.002) eutectic crystals, LiF/RE:LiBaF3, were grown by the micropulling down method with different pulling rates (growth rate) in order to observe the eutectic structure. Lamellar microstructure was formed for each pulling rate. LiF/Ce:LiBaF3 excited by 5.5-MeV alpha rays had a broad peak at ~350 nm corresponding to 5d–4f transition of Ce3+. On the other hand, LiF/Eu:LiBaF3 had two scintillation processes; a sharp emission was originated from 6P7/2 → 8S7/2 transitions in the 4f electronic configuration of Eu2+ at 360 nm, and a broad one was attributed to Eu2+ trapped exciton recombination at 400–450 nm. Since scintillation light was observed for these materials, these scintillators are sensitive to neutrons.