Luminescence and site symmetry studies of new red phosphors (Ca, Ba) ₃(VO₄)₂:Eu³⁺ under blue excitation

In this paper, the (Ca, Ba)₃(VO₄)₂:Eu ³⁺ red phosphors were prepared by the solid-state reaction method for the first time, and the preferable sintered condition was obtained at 1050°C for 6 h. To improve the luminescence intensity of Ca _2.82(VO₄)₂:0.12Eu³⁺, an attempt was made to replace Ca²⁺ by Ba²⁺. It was found that the substitution of 6.7%-9.9% Ba²⁺ ions instead of the Ca²⁺ ions enhanced the emission intensity under 465 nm excitation. According to the changes of the lattice constants, this enhancement can originate from the lower site symmetry of the Eu³⁺ ion in the center with noninversion symmetry. And we observed the optimum value of the Ba²⁺ content (y) was at 9.9 mol% in (Ca_1-yBa_y)_2.82(VO ₄)₂:0.12Eu³⁺. Compared with commercial oxysulfide and sulfide red phosphors suitable for blue excitation, our synthesized phosphor (Ca, Ba)₃(VO₄)₂:Eu ³⁺ has the advantages of no chemical instability or sulfur pollution. In addition, the emission peak at 614 nm and the CIE (International Commission on Illumination) chromaticity points of (0.644, 0.355) for the (Ca _0.901Ba_0.099)_2.82(VO₄) ₂:0.12Eu³⁺ phosphor indicate this phosphor can be used as a potential candidate for the phosphor-converted white light emitting diode with a blue chip (450-470 nm).