Structure Refinement and Two-Center Luminescence of Ca3La3(BO3)5:Ce3+ under VUV–UV Excitation

A series of Ca3La3(1–x)Ce3x(BO3)5 phosphors were prepared by a high-temperature solid-state reaction technique. Rietveld refinement was performed using the powder X-ray diffraction (XRD) data, which shows occupation of Ce3+ on both Ca2+ and La3+ sites with a preferred location on the La3+ site over the Ca2+ site. The prepared samples contain minor second phase LaBO3 with contents of ∼0.64–3.27 wt % from the Rietveld analysis. LaBO3:1%Ce3+ was prepared as a single phase material and its excitation and emission bands were determined for identifying the influence of impurity LaBO3:Ce3+ luminescence on the spectra of the Ca3La3(1–x)Ce3x(BO3)5 samples. The luminescence properties of Ca3La3(1–x)Ce3x(BO3)5 samples under vacuum ultraviolet (VUV) and UV excitation were investigated, which exhibited two-center luminescence of Ce3+, assigned to the Ce(1)3+ center in the La3+ site and Ce(2)3+ center in the Ca2+ site, taking into account the spectroscopic properties and the Rietveld refinement results. The influences of the doping concentration and the excitation wavelength on the luminescence of Ce3+ in Ca3La3(1–x)Ce3x(BO3)5 are discussed together with the decay characteristics.