THERMODYNAMIC STUDY OF THE NIO-MGO SYSTEM IN THE TEMPERATURE-RANGE 1073 TO 1473 K BY A GALVANIC CELL TECHNIQUE

In the present work, the thermodynamic activities of NiO in NiO-MgO so lid solutions were measured by means of the ZrO2-CaO solid-electrolyte galvanic cell method in the temperature range 1073 to 1473 K. The sys tem shows a near-ideal behavior, while at lower temperatures, the resu lts are anomalous at a high MgO content. Lattice parameter measurement s show that the system conforms to Vegard's law. The enthalpies estima ted from the present results are compared with previous work as well a s those estimated from theoretical models. A complete thermodynamic de scription and a calculation of the phase diagram of the NiO-MgO system are enabled by the application of a two-sublattice model.