| CaY2(MoO4)4 with tetragonal scheelite structure has good thermal stability, high quenching concentration and strong charge transfer absorption band in ultraviolet region. It is a promising matrix material for ultraviolet-excited white LED's. Dy3+ is a potential white light center, and Eu3+ is a red light center. Therefore, CaY2(MoO4)4:Dy3+ and CaY2(MoO4)4:Eu3+molybdate phosphors have attracted great attentions. Ultraviolet LED chip has large band gap and low efficiency and it is a hot spot in this field about how to improve the emission intensity and particle morphology of CaY2(MoO4)4:Dy3+ and CaY2(MoO4)4:Eu3+ phosphors.In this paper, Al3+,Zn2+ doped CaY2(MoO4)4:Dy3+ and Al3+,Bi3+, Si4+, BO33-, SO42- doped CaY2(MoO4)4:Eu3+ phosphors were synthesized by sol-gel combustion method. The as-synthesized phosphors were characterized by XRD, SEM, EDS, UV-Vis, FT-IR and PL. The effect of Al3+,Zn2+, Bi3+,Si4+,BO33-, SO42- on properties of CaY2(MoO4)4:Dy3+ and CaY2(MoO4)4:Eu3+ phosphors were investigated. The results showed that:(1) CaY2-x(MoO4)4:xDy3+ phosphors emits yellow-green light under UV excitation and the emission intensity of phosphors reach the maximum at x=0.12. The emission intensity of CaY1.88(MoO4)4:0.12Dy3+ phosphor can be enhanced by appropriate addition of Al3+ and Zn2+.With the increase of Al3+ and Zn2+ amount, the luminescence intensity of CaY1.88-xMex(MoO4)4:0.12Dy3+(Me=Al, Zn) phosphors showed a tendency to increase first and then decrease, reaching the maximum at x=0.06 and 0.04, respectively, which are improved then decrease, reaching the maximum at x=0.06 and 0.04, respectively, which are improved 2.68 and 1.87 times compared with un-doped sample.(2) Eu3+ doped CaY2-x(MoO4)4:xEu3+ phosphors show red emitting at 613nm under UV excitation, and the emission intensity of phosphors reach the maximum at x=1.2. The emission intensity of CaY0.8-xMex(MoO4)4:1.2Eu3+(Me=Al, Bi) can be significantly improved by Al3+and Bi3+ partly replacement the Y3+ under UV excitation, which are increased 2.36 times and 2.41 times at x=0.08 and 0.01,respectively. The maximum of CT band for CaY2(MoO4)4:Eu3+phosphor remarkably shifted from 321nm to 333nm by doping Bi3+.(3) The covalency of Mo-O bond was strengthened and the luminescence intensity of Eu3+ was enhanced by doping BO33- and SO42- under UV excitation. The emission intensity of CaY0.8(MoO4)4-x(BO3)x:1.2Eu3+ and CaY0.8(MoO4)4-x(SO4)x:1.2Eu3+ phosphors are improved 1.76 times and 2.66 times at x=0.02 and 0.02, respectively.(4) The dispersibility of CaY2(MoO4)4:Eu3+ phosphor can be significantly improved and the particle size can be reduced by doping Si4+. With the increase of Si4+ amount, the maximum of CT band for CaY0.8(Mo1-xSixO4)4:1.2Eu3+ phosphors remarkably shifted from 321nm to 311nm and the luminescence intensity reach the maximum at x=0.02, which is improved 1.49 times conpared with un-doped sample. |
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