Nickel sulphide (NiS) was characterised using X-ray diffraction, thermal gr
avimetric analysis (TG) and differential scanning calorimetry (DSC). The 'a
s received' Millerite, stoichiometric NiS, observed to be slightly nickel d
eficient, was found to readily decompose in a nitrogen atmosphere at elevat
ed temperatures (450 degrees C max.) to the sulphur deficient Godlevskite,
Ni7S6. DSC and X-ray measurements demonstrated that the high temperature fo
rm of the Godlevskite was readily stabilised at room temperature. The kinet
ics of the alpha-beta re-transformation in Godlevskite were then investigat
ed using DSC and were observed to be first order.