Photoluminescence in singly and co-doped K₃Gd(PO₄)₂:Sm³⁺, Eu³⁺ phosphate phosphors

Singly and co-doped K₃Gd(PO₄)₂:Sm³⁺, Eu³⁺ phosphate phosphors were prepared using the solid-state reaction (SSR) technique. X-ray diffraction (XRD) analysis confirms the centro-symmetric primitive monoclinic system with space group P2₁/m. The luminescence was studied by photoluminescence spectroscopy and to explore the energy transfer from Gd³⁺ to activator Sm³⁺ and Eu³⁺ ions, the fluorescence decay curve of the synthesized phosphors was verified. The strong photoluminescence emission (PL) in the visible region recorded at 615 nm was attributed to ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions and 600 nm attributed to ⁵G_5/2 → ⁴H_7/2 transition of Sm³⁺ ions. The energy transfer from Sm³⁺ to Eu³⁺ is discussed using an energy level diagram. The CIE coordinates and color-correlated temperature of K₃Gd(PO₄)₂ phosphor were estimated. This phosphor has potential applications in w-LEDs.