Cool white light emitting Ba₅Zn₄Y₈O₂₁:Dy³⁺ nanophosphors for single-phased WLEDs

A series of cool white light emitting, trivalent dysprosium activated, Ba₅Zn₄Y₈O₂₁ nanocrystals was prepared via a urea aided solution-combustion method. Powder X-ray diffraction analysis, coupled with Rietveld refinement technique, was used to confirm the phase purity and to obtain other structural parameters. The outcomes conclude that all the synthesized powders have a single-phased tetragonal matrix with I4/m (87) space group symmetry. The semi-spherical crystallites were found to exhibit the size domain ranging from 45 to 55 nm. The photoluminescence emission of the synthesized nanophosphors exhibits two characteristics peaks i.e. blue (489 nm) and yellow (578 nm) emissions under excitation of 353 nm; assigned to ⁴F_9/2 → ⁶H_J (J = 15/2, 13/2) transitions of dysprosium ions, respectively. The calculated CIE chromaticity coordinates for optimum luminescent composition (x = 0.3378, y = 0.3297) were found to be very close to the standard white emission recommended by National Television Standard Committee. The values of CIE chromaticity coordinates and correlated color temperature (5250 K) recommend the cool white-light emission from the phosphor. This study discovers that Dy³⁺ doped Ba₅Zn₄Y₈O₂₁ phosphor may be a credible candidate for near ultra-violet excited white-LED applications with cool light components.