Synthesis and luminescence properties of SrMoO4:RE3+ (RE = Eu or Tb) phosphors

SrMoO4:RE3+ (RE = Eu or Tb) phosphors were synthesized with different concentrations of activator ions by using the conventional solid-state reaction method. The effects of the concentration of activator ions on the structural, morphological, and optical properties of strontium molybdate phosphors were investigated by using X-ray diffraction, scanning electron microscopy, and fluorescence spectrophotometry, respectively. XRD patterns revealed that all synthesized phosphors showed the tetragonal SrMoO4 structure, irrespective of the type and the concentration of activator ions. The crystallite size showed an overall increasing tendency with increasing concentration of activator ions. The emission spectra of Eu3+-doped SrMoO4 phosphors under excitation at 295 nm exhibited one intense red band at 619 nm and five weak bands centered at 541, 561, 596, 657, and 704 nm, respectively. For the Tb3+-doped SrMoO4 phosphors, a strong emission peak at 550 nm and two weak lines, 494 and 591 nm, were observed. The intensities of all the emission bands reached maxima when 0.05 mol of Tb3+ ions was used. The results suggest that the optimum concentrations for synthesizing highly-luminescent red and green phosphors are 0.01 mol and 0.05 mol, respectively.