Synthesis and photoluminescent properties of LaPO4:RE3+ (RE = Tb, Ce) phosphors

LaPO4:RE3+(RE = Tb or Ce) phosphor powders were synthesized with different activator ion concentrations by using the solid-state reaction method. The effect of the activator ion concentration on the structural, morphological, and luminescent properties of lanthanide-phosphate phosphors was investigated. XRD patterns revealed that the synthesized phosphors with different activator ions showed a monoclinic structure with a main (120) diffraction peak for both activator ions. The crystallite size was estimated by using the Scherrer formula, and the maximum size was obtained at 0.01 mol of Ce3+ions and at 0 mol of Tb3+ions. The emission spectra of Tb3+-doped LaPO4 phosphors under excitation at 210 nm exhibited one intense green band at 548 nm and three weak lines peaking at 493, 590, and 640 nm, respectively. The intensities of all the emission bands reached their maxima at 0.10 mol of Tb3+ ions. As for the Ce3+-doped LaPO4 phosphors, two strong emission bands were observed, one each at 324 and 340 nm, and the energy difference between the two peaks was 0.18 eV. These results suggest that multicolor emission can be realized by controlling the concentrations of the activator ions incorporated into the host lattice.