Enhancement of sodium ions on the luminescent properties of the KNa₄B₂P₃O₁₃: Sm phosphor

Rare-earth ions Sm³⁺ were doped into borophosphate KNa₄B₂P₃O₁₃ by a high-temperature solid-state reaction so that orange-red emission was displayed. The influence of sodium ions (Na⁺) as charge compensators on the luminescent properties was studied. Powder X-ray diffraction, Fourier infrared, UV-Vis diffuse reflection, fluorescence spectra, lifetime, and quantum efficiency were performed to characterize the phase, morphology and luminescence properties of the material. The research showed that the fluorescence emission of the phosphor originated from the ⁴G_5/2→⁶H_5/2 (562 nm), ⁴G_5/2→⁶H_7/2 (598 nm) and ⁴G_5/2→⁶H_9/2 (645 nm) transitions of Sm³⁺ ion, the introduction of Na⁺ ion enhanced the luminescent intensity without any change of the shapes and positions for the typical transitions of Sm³⁺ ion. When the doping concentration of Na⁺ ions was 1%, the integrated luminescent intensity could be increased by 48%. In addition, the doped Na⁺ ions had little effect on the fluorescence lifetime and color coordinates of the phosphor, and the color coordinates of the phosphor were located in the orange-red area.