Impurity and defect-related luminescence of Ce3+ doped LiLa9(SiO4)6O2 crystals upon UV-VUV, X-ray and cathode ray excitation

We report on the synthesis and comprehensive characterization of Ce3+ doped LiLa9(SiO4)6O2 (LLSO) crystals, grown using the slow cooling flux method. The luminescence and optical spectroscopic properties and luminescence decay kinetics were studied upon excitation with UV, VUV, X-ray photons and cathode rays. Two impurity Ce3+ centres substituting for La3+- ions in two nonequivalent crystal positions are observed in LLSO:Ce3+. They are well distinguished spectroscopically in the UV range both in emission and excitation spectra. Apart from emission associated with Ce3+ 5 d→4f interconfigurational transitions, a low-temperature defect-related emission has been observed upon UV-VUV and higher energy X-ray excitation. Processes lying behind the temperature quenching and host-to-impurity energy transfer are analyzed and discussed.