Formation of monodispersed spindle-type hematite particles

Procedures have been developed which yield spindle-type colloidal hematite particles of narrow size distribution by forced hydrolysis of ferric chloride solutions at elevated temperatures. It was shown that small additions of phosphate or hypophosphite ions to such systems before aging had a significant effect on the resulting particle shape. Specifically, the axial ratio of the precipitated solids depended on the concentration of these anions in the original solutions.