Preparation of Calcium Fluoride Nanoparticles by Double-Jet Precipitation

Calcium fluoride nanoparticles were prepared by double-jet precipitation. The influence of the synthesis conditions [solvent (water, alcohols, acetone, acetonitrile), temperature (20-95 degrees C), presence of sodium citrate] on the morphology and size of the CaF2 particles formed was studied. By varying the above factors, it is possible to prepare nonaggregated round or cubic nanoparticles with the mean size from 9 to 180 nm. The presence of sodium citrate in the reaction system leads to the chemical modification of CaF2 and formation of a dense layer of citrate ions on its surface, which favors the formation of stable aqueous dispersions of CaF2. Assumptions concerning the structure of the layer of citrate complexes on the particle surface are made.