Luminescence of Ce3+ in different lattice sites of La2CaB10O19

A series of samples with nominal chemical formulas La2-xCexCaB10O19 and La2Ca1-2xCexNaxB10O19 were prepared by a solid state reaction route at high temperature. Their luminescence properties were investigated by the steady state excitation and emission spectra in the VUV-vis range, the luminescence decays, and the time-resolved emission spectra (TRES). The results demonstrate that Ce3+ ions occupy two lattice sites in all samples. The lowest 5d absorption bands for two sites are at about 272 (La3+ site) and 312 nm (Ca2+ site), respectively. The emission for Ce3+ in the La3+ site shows a shorter decay time of 12 ns, and the doublet emission bands have maxima at about 291 and 310 nm. The emission for the Ce3+ in Ca2+ site has a longer lifetime of 26 ns with band maxima at about 329 and 355 nm. Efficient energy transfer between both sites occurs in the samples.