Solution-combustion synthesized highly luminescent CaTiO3:Gd2O3:Eu3+ perovskite nanophosphors for WLED applications

Abstract

A series of Ca (1- x - y ) TiO 3 : x Gd 3+ , y Eu 3+ perovskite nanophosphors were synthesized by the solution combustion employing metal-citrate complexation method. The luminescence enhancement of seven times and the color purity of 97.4% were observed when 5 mol% of Gd 3+ ions were substituted in the Ca 0.93 TiO 3 :0.07Eu 3+ phosphor. The occupancy of Gd 3+ and Eu 3+ ions at Ca 2+ sites were detected by Rietveld refinements and XPS spectroscopy. The characteristic binding energy peaks of Europium and Gadolinium ions evidenced their 3+ oxidation state. Raman shifts observed for these phosphors affirmed the phase purity and the appearance of localized vibrational modes at 803 cm −1 signifying the substitution of rare earth ions in the crystal. The TEM analysis confirmed a high degree of crystallinity. The single exponential nature of the luminescence decay curves vindicated the substitution of the activator ions at a unique site. The thermal activation energy of 0.31 eV obtained for Ca 0.88 Gd 0.05 TiO 3 :0.07Eu 3+ suggested an appreciable stability against thermal quenching due to the cross-over process. The color parameters, luminescence lifetime, Judd–Ofelt parameters and radiative properties have been fairly discussed. • Ca (1-x-y) TiO 3 :xGd 3+ , yEu 3+ nanophosphors were synthesized by solution combustion synthesis. • The optimum doping of Gd 3+ ions in Ca 0.93 TiO 3 :0.07Eu 3+ enhanced luminescence seven times. • The increase in the local asymmetry was denoted by color purity of 97.4% and enhancement of Judd–Ofelt parameter, Ω 2 . • The occupancy of dopants at Ca 2+ sites were detected by Rietveld refinements and XPS spectroscopy. • Raman shifts observed for these phosphors affirmed the phase purity.