White-emission in single-phase Ba₂Gd₂Si₄O₁₃:Ce³⁺,Eu²⁺,Sm³⁺ phosphor for white-LEDs

To develop new white-light-emitting phosphor, a series of Ce³⁺-Eu²⁺-Sm³⁺ doped Ba₂Gd₂Si₄O₁₃ (BGS) phosphors were prepared by the solid-state reaction method, and their photoluminescence properties were studied. The Ce³⁺ and Eu²⁺ single-doped BGS show broad emission bands around in the region of 350-550 and 420-650nm, respectively. By co-doping Ce³⁺-Eu²⁺ into BGS, the energy transfer (ET) from Ce³⁺ to Eu²⁺ is inefficient, which could be due to the competitive absorption between the two activator ions. The Sm³⁺-activated BGS exhibits an orangey-red emission in the region of 550-750nm. To achieve white emission, the BGS:0.06Ce³⁺,0.04Eu²⁺,ySm³⁺ (0≤y≤0.18) phosphors were designed, in which the ET from Ce³⁺/Eu²⁺ to Sm³⁺ was observed. The emission color can be tuned by controlling the Sm³⁺ concentration, and white emission was obtained in the BGS:0.06Ce³⁺,0.04Eu²⁺,0.06Sm³⁺ sample. The investigation of thermal luminescence stability for the typical BGS:0.06Ce³⁺,0.04Eu²⁺,0.06Sm³⁺ sample reveals that the emission intensities of both Eu²⁺ and Sm³⁺ demonstrate continuous decrease but the Ce³⁺ emission is enhanced gradually with increasing temperature. The corresponding reason has been discussed.