SAXS study of the formation and structure of polynuclear thorium(IV) colloids and thorium dioxide nanoparticles.

Stable actinide colloids and nanoparticles are of interest because of their potential to affect the transportation of radionuclides in the near-field of a nuclear waste repository. At high concentrations, thorium(IV) can precipitate to form intrinsic colloids. In the present study, polynuclear thorium colloids and thorium dioxide crystallites, formed by the condensation of hydrolyzed Th solutions (3 mM; initial pH 5.