Iron sulfide (troilite) inclusion extracted from Sikhote-Alin iron meteorite: Composition, structure and magnetic properties

Iron sulfide (troilite) inclusion extracted from Sikhote-Alin IIAB iron meteorite was examined for its composition, structure and magnetic properties by means of several complementary analytical techniques such as: powder X-ray diffractometry, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, magnetization measurements, ferromagnetic resonance spectroscopy and 57Fe Mössbauer spectroscopy with a high velocity resolution. The applied techniques consistently indicated the presence of daubréelite (FeCr2S4) as a minority phase beside troilite proper (FeS). As revealed by 57Fe Mössbauer spectroscopy, the Fe atoms in troilite were in different microenvironments associated with either the ideal FeS structure or that of a slightly iron deficient Fe1-xS. Phase transitions of troilite were detected above room temperature by ferromagnetic resonance spectroscopy. A novel analysis of 295 and 90 K 57Fe Mössbauer spectra was carried out and the hyperfine parameters associated with the ideal structure of troilite were determined by considering the orientation of the hyperfine magnetic field in the eigensystem of the electric field gradient at the 57Fe nucleus.