Metastable iron sulfides

Data on various iron sulfides are analyzed with special reference to the presence of a ferrimagnetic phase with a Curie temperature of 580 degrees C in pyrrhotine. X-ray diffraction studies and magnetic measurements provide substantial evidence for the existence of a metastable phase Fe2S3 with a hexagonal structure, embedded in the structure of pyrrhotine. The exchange integrals and temperature-dependent relative magnetization of iron sulfides are calculated in the molecular-field approximation for two-sublattice ferrimagnets. The calculation results agree well with experimental data.