Temperature Dependence of Hyperfine Interactions in Near‐Stoichiometric FeS I. Experiment

Abstract
Mössbauer measurements as a function of temperature are presented for three synthetic 57Fe‐enriched polycrystalline samples of FeS in the composition region near stoichiometry. The independence of the Morin and α‐transitions, previously concluded from neutron diffraction measurements, has been verified. A low‐temperature transition has been found near 200 °K. It appears necessary to postulate the existence of a reversible, crystallographic two‐phase region between the α‐transition and about 200 °K in order to explain the Mössbauer measurements. This hypothesis also seems to provide a logical explanation of several anomalies in FeS.