Synthesis and characterization of Eu3+ activated hexagonal ABaGd(PO4)2 (A+=Li, Na, or K) phosphates

BaGd_0·5(PO₄)₂: Eu _0·5 ³⁺ and ABaGd_0·5(PO₄)₂: Eu _0·5 ³⁺ (where A⁺=Li, Na or K) double phosphates were synthesized by solid state diffusion method. These powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. XRD results showed many distinct lines in the XRD spectra. SEM measurement showed grains of different sizes in double phosphates. The Eu³⁺-ion emission lines for⁵ D ₀→⁷ F _j (j=1, 2, 3, and 4) transitions showed a splitting into 3, 2, 1, and 2 components, respectively. Strength of these lines was enhanced by the addition of alkali ion to BaGd_0·5(PO₄)₂: Eu _0·5 ³⁺ double phosphate. However, as the alkali ion varied from Li⁺ to K⁺, the intensity of⁵ D ₀→⁷ F ₂ line (617 nm) in the red region increased at the cost of⁵ D ₀→⁷ F ₁ line (599 nm) in the orange region. Suitable explanation has been proposed for this phenomena.