Sol–gel synthesis and characterisation of nanoscopic strontium fluoride

Strontium fluoride nanoparticles have been successfully synthesized via the fluorolytic sol–gel synthesis. The investigation by DLS, XRD, TEM and N2 adsorption/desorption measurements (BET) revealed the existence of sol particles with a hydrodynamic diameter of approximately 6 nm, crystallite sizes below 10 nm and high surface area of 180 m2 g−1. The sols are highly transparent and stable for a few months, however, with time all sols tend to undergo gelation. The ageing process of these sols was investigated using WAXS. As a result, Ostwald ripening as a reason for gel formation can be excluded. By following the reaction progress fluorine-containing crystalline species were detected by XRD and solid state 19F MAS NMR spectroscopy indicating the formation of an intermediate phase during the fluorolysis reaction.