Stabilization through precipitation in a system of colloidal iron(III) pyrophosphate salts

► The ionic strength decreases during the precipitation of an insoluble salt. ► The drop in ionic strength can be sufficient to stabilize a system during formation. ► We observe two stages in the aging of colloidal iron(III) pyrophosphate salts. ► While the nanoparticles are unstable, their aggregates remain in dispersion. ► Calculated interaction potentials confirm decreasing ionic strength as the cause.