THERMODYNAMIC INVESTIGATION OF THE SYSTEM NI-FE-O

A thermodynamic investigation has been performed on the solid ternary system Ni - Fe-O, using the high temperature in-situ method of coulometric titration with a solid oxygen ion electrolyte. The boundaries of the wustite field and the spinel field have been determined, and are compared with calculations based on solid solution models. In addition, the nonstoichiometry δ for (Ni, Fe)1-δO3 has been determined experimentally and is interpreted in terms of point defect thermodynamics, assuming singly ionizedcation vacancies and trivalent compensating iron ions to exist in this wustite phase. © R. Oldenbourg Verlag