Structure Refinement and Two-Center Luminescence of Ca<sub>3</sub>La<sub>3</sub>(BO<sub>3</sub>)<sub>5</sub>:Ce<sup>3+</sup> under VUV–UV Excitation

Abstract

A series of Ca<sub>3</sub>La<sub>3(1–<i>x</i>)</sub>Ce<sub>3<i>x</i></sub>(BO<sub>3</sub>)<sub>5</sub> 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 Ce<sup>3+</sup> on both Ca<sup>2+</sup> and La<sup>3+</sup> sites with a preferred location on the La<sup>3+</sup> site over the Ca<sup>2+</sup> site. The prepared samples contain minor second phase LaBO<sub>3</sub> with contents of ∼0.64–3.27 wt % from the Rietveld analysis. LaBO<sub>3</sub>:1%Ce<sup>3+</sup> was prepared as a single phase material and its excitation and emission bands were determined for identifying the influence of impurity LaBO<sub>3</sub>:Ce<sup>3+</sup> luminescence on the spectra of the Ca<sub>3</sub>La<sub>3(1–<i>x</i>)</sub>Ce<sub>3<i>x</i></sub>(BO<sub>3</sub>)<sub>5</sub> samples. The luminescence properties of Ca<sub>3</sub>La<sub>3(1–<i>x</i>)</sub>Ce<sub>3<i>x</i></sub>(BO<sub>3</sub>)<sub>5</sub> samples under vacuum ultraviolet (VUV) and UV excitation were investigated, which exhibited two-center luminescence of Ce<sup>3+</sup>, assigned to the Ce(1)<sup>3+</sup> center in the La<sup>3+</sup> site and Ce(2)<sup>3+</sup> center in the Ca<sup>2+</sup> 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 Ce<sup>3+</sup> in Ca<sub>3</sub>La<sub>3(1–<i>x</i>)</sub>Ce<sub>3<i>x</i></sub>(BO<sub>3</sub>)<sub>5</sub> are discussed together with the decay characteristics

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