Luminescence and color center distributions in K₃YB₆O₁₂:Ce³⁺ phosphor

Polycrystalline Ce³⁺-doped K₃YB₆O₁₂ (1–14 mol%) phosphors were prepared by facile chemical sol–gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4 f  –5 d transitions of Ce³⁺ ions. The absolute quantum efficiency (QE) of K₃YB₆O₁₂:Ce³⁺ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce³⁺ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce³⁺ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce³⁺ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole–dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host. (paper)