Synthesis and Luminescence Properties of a Novel Yellow-White Emitting NaLa(MoO₄)₂: Dy, Li Phosphor.

Intense yellow-white NaLa(MoO4)2: Dy3+ phosphors co-doped with Li+ ions have been successfully synthesized via facile sol-gel combustion approach. The dependence of the crystal structure and crystallinity, particle morphology, photoluminescence property, fluorescent lifetime and absolute quantum efficiency of the as-prepared phosphors has been investigated. Stable yellow-white emission from 440 nm to 600 nm and higher absolute quantum efficiency were studied on Dy3+ doped NaLa(MoO4)2, Dy3+ and Li+ co-doped NaLa(MoO4)2, respectively. Surprisingly, only a small amount of Li+ can lead to a remarkable increase of the PL intensity and the quantum efficiency. Especially, along with 0.75 mol% Li+ ions induced in the NaLa(MoO4)2: Dy3+ phosphors, the absolute quantum efficiency increased from 13.8% to 22%, and the possible mechanism has been deeply discussed. Outstanding luminescence properties have certified that NaLa(MoO4)2: Dy3+, Li+ phosphors are promising candidates as new yellow-white components for optical devices.