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

BaGd0.5(PO4)2:Eu0.53+ and ABaGd0.5(PO4)2:Eu0.53+ (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 for 5D0-> 7Fj (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 BaGd0.5(PO4)2:Eu0.53+ double phosphate. However, as the alkali ion varied from Li+ to K+, the intensity of 5Do -> 7F2 line (617 nm) in the red region increased at the cost of 5Do -> 7F2 line (599 nm) in the orange region. Suitable explanation has been proposed for this phenomena. (author)