Thermal Analysis of Iron Sulfides at the Temperature Range of α-transformation

The specific heat of iron sulfides near stoichiometric composition from FeS 1.00 to FeS 1.07 at the temperature range of α-transformation was measured. It was found that the curves of specific heat versus temperature had a comparatively sharp \(\)-shaped maximum. Both the temperature for such a maximum and the peak values of specific heat decreased with the increase of sulfur contents. It was also found that the heat absorption due to this transition also decreased with the increase of excess sulfur, its value being about 550 cal mol -1 at the stoichiometric compound, and vanishing at the composition FeS 1.07 . The several possible models for the mechanism of this transition are discussed taking into account the above experimental results.