Synthesis of Small Ce 3+ -Er 3+ -Yb 3+ Tri-Doped BaLuF 5 Active-Core-Active-Shell-Active-Shell Nanoparticles with Strong Down Conversion Luminescence at 1.5 μm

摘要

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF 5 :Yb 3+ ,Er 3+ NPs by way of combining doping Ce 3+ ions and coating multiple BaLuF 5 : Yb 3+ active-shells. We prepared the BaLuF 5 :18%Yb 3+ ,2%Er 3+ ,2%Ce 3+ NPs through a high-boiling solvent method. The effect of Ce 3+ concentration on the DC luminescence was systematically investigated in the BaLuF 5 :Yb 3+ ,Er 3+ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF 5 :18%Yb 3+ ,2%Er 3+ ,2%Ce 3+ NPs was enhanced by 2.6 times comparing to that of BaLuF 5 :18%Yb 3+ ,2%Er 3+ NPs since the energy transfer between Er 3+ and Ce 3+ ions: Er 3+ : 4 I 11/2 (Er 3+ ) + 2 F 5/2 (Ce 3+ ) → 4 I 13/2 (Er 3+ ) + 2 F 7/2 (Ce 3+ ). Then, we synthesized BaLuF 5 :18%Yb 3+ ,2%Er 3+ ,2%Ce 3+ @BaLuF 5 :5%Yb 3+ @BaLuF 5 :5%Yb 3+ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF 5 :Yb 3+ active-shell around BaLuF 5 :Yb 3+ ,Er 3+ ,Ce 3+ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF 5 :Yb 3+ ,Er 3+ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb 3+ ions inside the active-shells.