Lanthanide Doped Nanocrystalline Alkaline Earth Fluorides: Synthesis, Structural, Morphological and Spectroscopic Investigation
Fluoride based materials doped with lanthanide ions are interesting hosts for efficient luminescence. In particular, NaYF4 codoped with Er3+ and Yb3+ ions has been demonstrated to be possibly the material in which upconversion is most efficient.
Fluoride based materials can be prepared in colloidal forms, thus opening the doors to their use in important technological applications, especially in biomedical diagnostic. As an example, interesting investigations have been recently reported on the upconversion imaging of Er3+/Yb3+ codoped NaYF4 nanoparticles located inside HeLa cancer cells .
Lanthanide ions doped CaF2 nanoparticles very recently have raised attention, due to their strong upconversion emission . It must be emphasized that an easy synthesis of aqueous dispersable nanoparticles of binary fluorides is still a challenging task. In this contribution, we have investigated a variety of preparation methods to obtain alkaline earth fluoride nanoparticles of controlled size while maintaining their upconversion properties. In particular, a hydrothermal one-step procedure has been used to prepare nanocrystalline MF2 (M = Ca, Sr) doped with Er3+/Yb3+, Ho3+/Yb3+ and Tm3+/Yb3+. Different temperatures and reaction times have been employed to control the size and morphology of the nanoparticles. Their structural and morphological properties have been investigated by X-Ray diffraction and electron microscopy. The obtained nanocrystalline materials are single phase and can be easily dispersed in water. The colloidal solutions show interesting upconversion properties upon laser excitation at 980 nm.
KeywordsColloidal Solution Nanocrystalline Material Spectroscopic Investigation Dispersable Nanoparticles Efficient Luminescence
- 2.Pedroni M, Piccinelli F, Passuello T, Giarola M, Mariotto G, Polizzi S, Bettinelli M, Speghini A (2011) Lanthanide doped upconverting colloidal CaF2 nanoparticles prepared by a single-step hydrothermal method: toward efficient materials with near infrared-to-near infrared upconversion emission. Nanoscale 3:1456–1460ADSCrossRefGoogle Scholar