alpha-beta phase re-transformation kinetics in nickel sulphide

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.