Synthesis and photoluminescence properties of red emitting phosphor La2-x Eux Li0.5 Al0.5 O4 [x=0.2-2] with K2 NiF4 structure.

Abstract

Europium (Eu)3+ -substituted La2 Li0.5 Al0.5 O4 red emitting phosphors were prepared by a conventional high-temperature solid-state reaction method. Powder X-ray diffraction, diffuse reflectance spectra and spectrofluorometry were used as vital characterizing tools for the phosphors. The Eu concentration dependence luminescence properties and Judd-Ofelt intensity parameters were investigated and calculated, respectively. All compositions showed an orange red emission (due to the magnetic and electric dipole transitions of the Eu3+ ion) with the appropriate Commission Internationale de l'Eclairage (CIE) colour gamut under near ultraviolet or blue ray light excitation. The calculated critical distance showed that the energy transfer occured between Eu to Eu via an exchange mechanism. The Eu1.4 La0.6 Li0.5 Al0.5 O4 composition showed the highest red emission intensity with CIE colour saturation compared with that of the commercial Eu-activated yttrium oxysulfide red phosphor.