Lanthanide fluorides and oxyfluorides are ideal as fluorescent hosts owing to their low vibrational energies and wide band gap (>10 eV). Systematic research on the morphology-controlled synthesis of nano/micromaterials has been driven by their intrinsic morphology/size-dependent properties. Among the lanthanide derivatives with diversiform morphologies, porous spheres are more desirable for biomedical and energy-related applications owing to their high drug-loading space and high specific surface.

Hongpeng You, Chinese Academy of Sciences, Changchun, China, and colleagues have synthesized monodisperse YF₃ and YOF porous sub-microspheres by a sacrificing template method using amorphous Y(OH)CO₃·xH₂O as precursors as well as the template. The luminescence properties of the as-synthesized YF₃:Ln³⁺ (Ln = Eu, Tb, Ce, Ce/Tb, Yb/Er, Yb/Ho, and Yb/Tm) showed strong multicolor emissions including down/upconversion and energy-transfer processes. YF₃ and YOF inherited the spherical shapes and monodispersity of their precursors, while the final products had different pore structures by tuning the amounts of the fluorine source.

A series of contrast experiments on the formation processes of these pore structures showed that the difference in the initial concentration of HF gas was responsible for the YF₃ homogeneous porous structure and YOF yolk-shell like structure. Moreover, YOX (X = Cl and Br) could be obtained when the calcination atmosphere was a halogen. This strategy was also extended to other lanthanide fluorides (REF3, RE = Gd, Lu), which may open a facile way to fabricate other porous nanostructures.

• Facile Synthesis of Lanthanides (Ce, Eu, Tb, Ce/Tb, Yb/Er, Yb/Ho, and Yb/Tm) Doped LnF₃ and LnOF Porous Sub-microspheres with Multicolor Emissions,
  Shuang Zhao, Baiqi Shao, Yang Feng, Senwen Yuan, Jiansheng Huo, Wei Lv, Kai Liu, Hongpeng You,
  Chem. Asian J. 2017.
  DOI: 10.1002/asia.201701142