Preparation and luminescent properties of cubic potassium-erbium fluoride nanoparticles

Cubic phase potassium-erbium fluoride nanoparticles were prepared via the reaction of Er(NO3)3·6H2O, KCl and bmimPF6, which is an ionic liquid that acts as both a solvent and a fluorinating agent. The product was characterized by XRPD, XPS, TEM and luminescence measurements. The prepared nanocrystals had a cubic crystallographic lattice and an under-doped stoichiometry of potassium to KErF4, according to the XPS and AAS measurements. Using the Scherrer equation and the XRPD data, the average size of the nanocrystals was estimated to be 46.2 nm, which was confirmed by TEM. The product was thermally treated at 600 °C to achieve phase transition to the hexagonal phase; however, several new products were observed along with the hexagonal phase. Our simple and safe method can be used for the preparation of nano-sized erbium fluorides for both research and industrial applications.