Phase Transformations in Iron Oxide under the Action of Microwave Radiation

It has been shown that microwave radiation induces structural and, as a consequence, magnetic phase transformations in iron oxide α-Fe2O3 (hematite). After microwave irradiation of fine-dispersed partially amorphized Fe2O3 particles for 10 min in wet air, the percentage of crystalline hematite drops by 40% but the total amount of crystalline components increases owing to the formation of a new ferromagnetic modification, α-Fe2O3 maghemite. The initial antiferromagnetic and final ferromagnetic Fe2O3 samples are powders consisting of spherical particles with nearly equisized (40–60 nm) domains of X-ray coherent scattering.