Effect of MoO42− partial substitution on optical enhancement of LaNa(MoO4)2:Dy3+ phosphors for white light emitting diodes

Dy3+ doped LaNa(MoO4)2 phosphors with different anionic groups (SO42−, PO43− and BO33−) substitution were prepared through solid state reaction at 1100 °C. X-ray diffraction patterns of the as-prepared phosphors indicate that all samples have the standard LaNa(MoO4)2 structure. The photoluminescence spectra consist of a blue emission at 484 nm and a yellow emission at 576 nm, which corresponding to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions, respectively. The luminescence intensity of LaNa(MoO4)1.9(BO3)0.1:Dy3+, LaNa(MoO4)1.8(PO4)0.2:Dy3+ and LaNa(MoO4)1.9(SO4)0.1:Dy3+ phosphors are 2.8, 1.8 and 3-fold higher than that of LaNa(MoO4)2:Dy3+ phosphor, respectively. In addition, the luminescence lifetime values of LaNa(MoO4)2:Dy3+, LaNa(MoO4)2−x(BO3)x:Dy3+, LaNa(MoO4)2−x(PO4)x:Dy3+, and LaNa(MoO4)2−x(SO4)x:Dy3+ are 0.188, 0.189, 0.186 and 0.183 ms, respectively.