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 55nm. The photoluminescence emission of the synthesized nanophosphors exhibits two characteristics peaks i.e. blue (489nm) and yellow (578nm) emissions under excitation of 353nm; assigned to F-4(9/2) H-6(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 (5250K) 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.