Hydrothermal Synthesis, Cubic Structure, and Luminescence Properties of BaYF5:RE (RE = Eu, Ce, Tb) Nanocrystals

BaYF 5 nanocrystals with a mean size of about 24 nm have been prepared via a facile hydrothermal method without the assistance of any surfactant for the first time. The structure investigation reveals that the as-synthesized BaYF 5 nanocrystals are cubic structures instead of the reported tetragonal structures found via a Rietveld refinement method with GSAS, a Rietveld refinement package. The XRD and SEM analyses demonstrate that the size and morphology of the products are insensitive to the variation of experimental conditions. The photoluminescence properties of the Eu 3+, Ce 3+, and Tb 3+ single-doped as well as Ce 3+ -Tb 3+ codoped BaYF 5 nanocrystals were characterized. The results reveal that the existence of the Ce 3+ ions can dramatically enhance the emission intensity of the Tb 3+ ions, due to an efficient energy transfer from the Ce 3+ to Tb 3+ ions in the BaYF 5:Ce 3+,Tb 3+ nanocrystals. The critical energy transfer distance between the Ce 3+ and Tb 3+ ions was calculated by methods of concentration quenching and spectral overlapping. Analysis and calculation reveal that the dipole−quadrupole interaction should be mainly responsible for the energy transfer and the accurate oscillator strength ratio of the electric quadrupole to dipole transitions for the Tb 3+ ion is about 10 −3 .