Synthesis and photoluminescence of novel red-emitting ZnWO₄: Pr³⁺, Li⁺ phosphors.

Zn0.997WO4: Pr(3+)(0.003) and different concentrations (0.1 mol% to 0.9 mol%) of Pr, Li co-doped ZnWO4 red phosphors were prepared by means of solid-state reaction process. The crystalline, surface morphology and luminescent properties of Zn0.997WO4: Pr(3+)(0.003) and Zn(1-x-y)WO4: xPr(3+), yLi(+) phosphors were investigated by the X-ray diffraction patterns (XRD), scanning electron microscope (SEM) and fluorescent measurements. From powder XRD analysis, the formation of monoclinic structure with C(2/h) point-group symmetry and P(2/c) space group of the as-synthesized samples is confirmed. The SEM image showed that surface morphology of the phosphor powder is irregular cylindricality. The luminescent spectra are dominated by the red emission peaks at 607, 621 and 643 nm, respectively, radiated from the (1)D2→(3)H4, (3)P0→(3)H6 and (3)P0→(3)F2 transitions of Pr(3+) ions. The concentrations of the highest luminescent intensity is determined at 0.3 mol% Pr(3+) and 0.3 mol% Li co-doped ZnWO4 powder crystal, and the peak intensity is improved more than 3 times in comparison with that of 0.3 mol% Pr(3+) single-doped ZnWO4. The enhanced luminescence comes from the improved crystalline and from the charge compensation of Li(+) ions. The decay curve and CIE chromaticity coordinates of as-prepared samples are also studied in detail.