ACTIVITY OF NIO IN (NI,MG)O SOLID-SOLUTIONS

Disagreement exists in the literature concerning the activity of NO in (Ni,Mg)O solid solutions. Ideal behavior, as well as strong positive deviations and strong negative deviations from ideality, has been repo rted. In the present study, the activity of NiO was determined by elec tromotive force measurements using the solid-state cell Pt/Ni-NiO/0.92 ZrO(2)-, 0.08Y(2)O(3)/Ni-(Ni,Mg)O/Pt. The compositions studied had NiO mole fractions of 0.1, 0.3, 0.5, 0.7, and 0.9. In agreement with theo retical expectations, the solid solutions exhibited ideal behavior at 882 degrees and 982 degrees C. Possible reasons for the conflicting re sults in the literature are presented.