The synthesis and luminescence of Tb³⁺ and Dy³⁺ doped Li₆LuGd(BO₃)₃ borate phosphors

We report the synthesis and luminescence properties of Li₆LuGd(BO₃)₃: Tb³⁺, Dy³⁺ (Lithium lutetium gadolinium borate) phosphors. The well-known solid state reaction method was used to synthesize these phosphors, which were optimized for Tb³⁺ and Dy³⁺ concentrations i.e., 1 mol% for Tb³⁺ and 3 mol% for Dy³⁺. The phase analysis, crystallinity and overall morphology of the synthesized phosphors were investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The X-ray and ultraviolet-visible induced luminescence were measured for these phosphors. The emission spectrum of Li₆LuGd(BO₃)₃: Tb³⁺ phosphor comprised of five major emission bands corresponding to ⁵D_j →⁷F_j transitions, whereas, Li₆LuGd(BO₃)₃: Dy³⁺ phosphor comprised of four emission bands that correspond to ⁴F_9/2 →⁶H_j/2 transitions. The X-ray induced integrated light yield was measured to be 87% for Li₆LuGd(BO₃)₃: Tb³⁺ and 31% for Li₆LuGd(BO₃)₃: Dy³⁺ of that of commercially available X-ray imaging material Gd₂O₂S: Tb³⁺ (Gadox). The integrated light yield of both Li₆LuGd(BO₃)₃: Tb³⁺, Dy³⁺ phosphors were also compared with that of commercial grade PDP material (Y, Gd)₂O₃: Eu³⁺) i.e., 113% and 47%. The 1931 Commission Internationale de l'Eclairage (CIE) chromaticity coordinates were measured for the synthesized phosphors.