Energy transfer features in Eu2+Eu2+ and Ce3+Ce3+ doped LiCaAlF6LiCaAlF6 crystals

Energy transfer in Eu2+Eu2+ or Ce3+Ce3+ doped LiCaAlF6LiCaAlF6 crystals was investigated. Both ions occupy Ca2+Ca2+ sites in a colquiriite lattice. Eu2+Eu2+ ion does not require any compensation while the surplus charge of Ce3+Ce3+ ion is compensated by point defects. The different RE centre structure and environment modify properties of doped crystals. It is shown that the energy transfer in doped LiCaAlF6LiCaAlF6 is determined by the RE charge, volume and/or local disposition of charge compensative defects and redox reaction typical for RE3+RE3+. The light yield deterioration in Ce-containing crystals under radiation is caused by the decrease in the emission centre concentration due to the redox conversions of Ce3+Ce3+ ions. The luminescence re-absorption by the colour centres is an extra channel of scintillation efficiency losses. The energy storage in LiCaAlF6:CeLiCaAlF6:Ce depends on the Ce3+Ce3+ ion and compensative defects dislocated in the crystal volume.