Judd-Ofelt and structural analysis of colour tunable BaY2ZnO5:Eu3+ nanocrystals for single-phased white LEDs

Abstract

Eu3+ doped BaY2ZnO5 nanophosphor was developed for the very first time via glycine assisted modified combustion synthesis using metal nitrates as initial raw materials. Rietveld refinement was performed over the sample to analyse the qualitative and quantitative aspects of the structural framework. It was found to crystallize in orthorhombic lattice with the Pbnm(62) space group. The photoluminescent spectral study revealed the low phonon nature of the host which in turn was found responsible for colour tunability as a function of dopant concentration and excitation wavelength. The optimum concentration of Eu3+ ion in BaY2ZnO5 for excellent luminescence was found to be 20 mol%. The refractive index of the host and the critical distance for non-radiative energy transfer were calculated to be 2.1766 and 8.43 Å respectively. Refractive index and photoluminescent emission spectra were exploited to calculate Judd-Ofelt intensity parameters. Quadruple–Quadruple (Q–Q) interactions were ascribed as the major factor responsible for concentration quenching arising from the over-doping of the activator ions. The concentration dependence of chromatic behaviour indicates that these nanophosphors are promising candidate for the single-phased white LEDs with near ultra-violet excitation.