CaF2 and CaF2:Ln(3+) (Ln = Er, Nd, Yb) hierarchical nanoflowers: hydrothermal synthesis and luminescent properties

Highly uniform three-dimensional flower-like CaF2 and CaF2:Ln(3+) (Ln = Er, Nd, Yb) nanostructures have been successfully prepared by a facile hydrothermal method assisted by a chelating reagent, ethylenediamine tetraacetic acid disodium salt (Na(2)EDTA). The nanoflowers with size about 550 nm are assembled by numerous nanoflakes with a thickness of 10 nm. X-Ray diffraction, scanning electron microscopy, transmission electron microscopy, electron diffraction and photoluminescence spectra were used to characterize these materials. The formation process of the hierarchical CaF2 nanoflowers has been investigated in detail. It is found that reaction time and chelating reagent play a key role in forming the hierarchical nanoflowers. Furthermore, the near-infrared luminescence of lanthanide ion (Er, Nd, and Yb) doped CaF2 nanostructures, especially in the 1300-1600 nm region, is discussed and is of particular interest for telecommunications applications.