Colloidal calcium thiophosphates in organic medium: Synthesis and analysis

A colloidal dispersion of calcium thiophosphate in hydrocarbon medium was synthesized by reacting calcium oxide with tetraphosphorus decasulfide and water in the presence of a surfactant under specific conditions. The resulting product can be defined as a distribution of inorganic cores surrounded by a surfactant layer in a reverse-micelle-type association. The chemical composition was determined by P-31 NMR, dialysis, and thermogravimetric analysis. The core particles were found to be a mixture of calcium thiophosphates, consisting mainly of mono- and dithiophosphates, with a small amount of phosphate. Shape, size distribution, and average core radius were investigated using transmission electron microscopy and small angle X-ray scattering. According to these techniques, the colloidal species can be defined as polydisperse spherical micelles with the radius of the mineral cores ranging from 10 to 80 Angstrom. (C) 1997 Academic Press.