CaF2 and CaF2:Ln3+ (Ln = Er, Nd, Yb) hierarchical nanoflowers: hydrothermal synthesis and luminescent properties

Abstract

Highly uniform three-dimensional flower-like CaF₂ and CaF₂:Ln³⁺ (Ln = Er, Nd, Yb) nanostructures have been successfully prepared by a facile hydrothermal method assisted by a chelating reagent, ethylenediamine tetraacetic acid disodium salt (Na₂EDTA). 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.