Novel Mn4+ doped Ca2GdSbO6 red–emitting phosphor: A potential color converter for light‐emitting diodes

As potential color converter towards white/red light–emitting diodes, novel Ca2GdSbO6:Mn4+ phosphors with excellent optical performances were prepared by a conventional solid–state reaction route. The as–prepared phosphors with monoclinic crystal system had abundant [SbO6] octahedrons for Mn4+ ions to occupy and stably exist. With an excitation of 356 nm, an intense red emission peaking at 676 nm attributed to 2Eg→4A2g transition of Mn4+ ions can be observed in the emission spectrum. The critical concentration of Mn4+ ions was found to be 0.6 mol% and the concentration quenching mechanism was also discussed in detail. Importantly, the Ca2GdSbO6:0.6%Mn4+ phosphors exhibited a high internal quantum efficiency of 38.9%. Novel red phosphors Ca2GdSbO6:Mn4+ with high efficiency were developed.