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
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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