Variation in magnetic properties during chemical reactions producing Fe_1-xS and FeCl₂

Abstract

 By use of a Hall measurement gaussmeter, the magnetic properties of chemically-reacting iron-sulfur powder mixtures and of iron powder plus hydrochloric acid have been extensively studied. In the case of iron sulfide (non-stoichiometric Fe_1-xS) the measured value of the magnetic (B) field first increased continuously and significantly as the chemical reaction proceeded, then decreased sharply as the reaction neared completion. This behavior was stronger in the presence of an externally applied static magnetic field but was also clearly observed in the absence of an external field. The recovered product of the reaction was bronze-colored pyrrhotite which was in the form of a thin magnetic coating on Fe particles with a narrow conical morphology aligned with the external B field. The magnetic behavior during the Fe+HCl reaction was similar but far less pronounced. The general magnetic field behavior in both systems parallels the character of an activated state energy behavior.