Magnetite in soils: I. The synthesis of single-domain and superparamagnetic magnetite

Abstract A series of experiments has been carried out to investigate the possible formation of magnetite, Fe 3 O 4 , under ambient soil-forming conditions. Rapid and easy synthesis of magnetite was achieved through controlled oxidation of Fe 2+ solutions at room temperatures and near neutral pH values. The synthetic products were found to range in size between 0·01–0·07 µ m (mean diameter) and hence span the theoretical superparamagnetic-single-domain grain-size boundary.