Fig. 13

(a) PL excitation spectra of synthesized Na₂Ca₄(PO₄)₃F: Dy³⁺/Tb³⁺/Eu³⁺ phosphor with different varying concentration located at emission 616 nm. Figure 13. (b-d) PL emission spectra of synthesized Na₂Ca₄(PO₄)₃F: Dy³⁺/Tb³⁺/Eu³⁺ phosphor with different varying concentration located at excitation (a) 365 nm, (b) 382 nm, (c) 395 nm.