Luminescent properties of Na3Gd1−xEux(PO4)2 and energy transfer in these phosphors

A series of Eu³⁺ activated Na₃Gd_1−xEu_x(PO₄)₂ (0 ≤ x ≤ 1) phosphors were synthesized by solid-state reaction method. The structures and photo-luminescent properties of these phosphors were investigated at room temperature. The results of XRD patterns indicate that these phosphors are isotypic to the orthorhombic Na₃Gd(PO₄)₂. The excitation spectra indicate that these phosphors can be effectively excited by near UV (370-410 nm) light. The intensities of magnetic dipole transition ⁵D₀ → ⁷F₁ and forced electric dipole transition ⁵D₀ → ⁷F₂ are comparable, and the energy ratio (⁵D₀ → ⁷F₁/⁵D₀ → ⁷F₂) is 1.1. The emission spectra exhibit strong reddish orange performance (CIE chromaticity coordinates: x = 0.62, y = 0.38), which is due to the ⁵D₀ → ⁷F_J transitions of Eu³⁺ ions. The correlation between the structure and the photo-luminescent properties of the phosphors was studied. The energy transfer and concentration quenching of the phosphors were discussed. Na₃Gd_1−xEu_x(PO₄)₂ has a potential application for white light-emitting diodes.