Synthesis and luminescence properties of double perovskite Gd₂MgTiO₆:Eu³⁺ red phosphors for white light-emitting diodes

A series of double perovskite Gd_2(1−x)MgTiO₆:xEu³⁺ (x = 0.01, 0.05, 0.1, 0.15, 0.2, 0.3 and 0.5) phosphors were successfully synthesized. Two rare earth ions occupy the A-site in this host, which benefits the doping of Eu³⁺ ions. The crystal structure, microstructure were examined by X-ray diffraction and scanning electron microscopy. Luminescence properties, such as excitation and emission spectra, CIE coordinates and concentration quenching were systematically investigated. A weak magnetic dipole transition (⁵D₀–⁷F₁, 590 nm) and a strong electric dipole transition (⁵D₀–⁷F₂, 616 nm) existed in the emission spectra. The quenching concentration for hypersensitive electric dipole transition of Eu³⁺ reached up to 15.0 mol%. The delayed concentration quenching was observed in Gd₂MgTiO₆:Eu³⁺ phosphors. The theoretical quenching concentration was obtained based on Ozawa’s theory, and the quenching mechanism on Dexter’s theory. All the results indicate that Gd₂MgTiO₆:Eu³⁺ has great potential in solid state lighting.