Ln3+ (Ln=Ce, Tb, Dy) and Hf doping of LuI3 powders - A material and spectroscopic study

The moisture sensitivity of LuI3:Ce,Hf and luminescent properties of undoped LuI3 and LuI3:M (M=Ce3+, Tb3+, Dy3+) powders were investigated. The possibility of improving the air and moisture stability of LuI3:Ce by Hf doping was tested. It was proven that the Hf contribution to the LuI3:Ce stability is very limited and is insignificant to render LuI3:Ce scintillator powders suitable for applications. Photoluminescence results of LuI3 without dopants added on purpose showed luminescence due to a plurality of rare-earth elements׳ impurities. Two types of self-trapped luminescence were found. Energy transfer between host lattice, self-trapped excitons and rare-earth ions was investigated.