Radiative transition probability enhancement of white light emitting Dy3+ doped and K+ co-doped BaWO4 phosphors via charge compensation

In this article, Dy3+ doped and K+ co-doped BaWO4 phosphors were synthesized by a solid state reaction method and the effect of Dy3+/K+ doping/co-doping concentration on the structural and photoluminescence (PL) properties were investigated. Rietveld refinement analysis revealed the tetragonal structure of the phosphors and lattice parameter contraction/expansion due to doping/co-doping. The energy band gap reduced with the increasing doping and co-doping concentration in the host materials. Judd-Ofelt (J-O) parameters were calculated from the excitation spectra. J-O parameters described the covalency dependency on the environment around the Dy3+ ion in the lattice. Intense white light was achieved by Dy3+ doping. The PL concentration quenching mechanism was described and the suggested quenching mechanism was dipole-dipole interactions. K+ co-doping with Dy3+ doping suggested that charge compensation improved the colour point and increased the internal quantum efficiency from 56 to 67% owing to a reduction in the non-radiative transitions which was proven by using the J-O theory. A short life time (281.60 mu s) and CCT value (5392 K) very close to day light of the Ba1-x-yDyxKyWO4 (x = 0.10; y = 0.05) indicated the suitability of the tungstate based phosphors for white light emitting diode applications. (C) 2017 Elsevier B.V. All rights reserved.