Solvothermal synthesis of monodisperse ultrasmall cubic-structure Ba_2YbF_7 nanocrystals with intense upconversion

摘要

A series of monodisperse ultrasmall Ba_2YbF_7 nanocrystals with intense upconversion emission were synthesized via a facile solvothermal method by using oleic acid as capping ligands. X-ray diffraction (XRD) and transmission electron microscopy (TEM) assays revealed that the as-synthesized Ba_2YbF_7 nanocrystals are of cubic structure, rather than the reported tetragonal structure. The eel! parameter of the particles is 5.918 A. The Er~(3+) or Tm~(3+) doped Ba_2YbF_7 nanocrystals with the size of sub-10 nm can give an intense upconversion emission under the 980 nm laser excitation and the upconversion processes were discussed. The Ba_2YbF_7 nanocrystals show a potential application as a bioimaging agent.