Structural and Luminescence Analysis of Low Temperature Solution Combustion Derived White Light Emitting Y2(1-x)Dy2xZr2O7 Nanophosphors for WLEDs

Abstract

White light emitting dysprosium doped rare-earth zirconate Y2(1-x)Dy2xZr2O7 (x = 0.5 to 5 mol%) crystalline phosphors in nano-regime were obtained using urea supported solution combustion methodology at low temperature 650 ºC. Presence of fluorite structure having cubic symmetry with Fm3m space group was analyzed by powder X-ray diffraction patterns. Spherical shaped nanoparticles with clear boundaries were observed by surface morphological studies. Diverse elements Y, Zr, Dy and O were present in the optimized nanophosphors as examined by energy dispersive X-ray analysis. Upon near ultraviolet (NUV) excitation at 354 nm wavelength, the Y2(1-x)Dy2xZr2O7 phosphors displayed the characteristic white light emanation resulted from blue and yellow emission owing to 4F9/2→6H15/2 (450-525 nm) and 4F9/2→6H13/2 (525-650) transitions, respectively. With the doping of 1.5 mol% amount of Dy3+ ions in Y2(1-x)Dy2xZr2O7 powders showed maximum photoluminescence emission, above which intensity was quenched due to dipole-dipole interactions. In addition, Y1.97Dy0.03Zr2O7 nanopowders exhibit CIE colour coordinates (0.2605, 0.3145) residing in white region. The closeness of this value to the white emission coordinates of the National Television System Committee (NTSC) endorsed Y2(1-x)Dy2xZr2O7 nanophosphors as fascinating candidate for displays and white light emitting diodes.