Thermodynamic properties and phase boundaries of Co--O solutions

Abstract

The thermodynamic properties of liquid unsaturated Co--O solutions have been determined by electrochemical measurements using (Y₂O₃)ThO₂ as solid electrolyte. The cell can be represented as, Pt. MoO₂+Mo| (Y₂O₃)ThO₂|O_Co ,tungsten, Pt, Emf of the cell was measured as a function of oxygen concentration in liquid Co at 1798, 1873 and 1973K. Least-mean squares regression analysis of the experimental data gives for the free energy of solution of diatomic oxygen in liquid Co Delta G exp 0_O(Co) = --84935--7.61 T ( plus/minus 400) J/g-atom and self interaction parameter for oxygen epsilon exp O_O= --97240/T+40.52(plus/minus 1) where the standard state for O is an infinitely dilute solution in which the activity is equal to atomic percent. The present data are discussed in comparison with those reported in the literature and the phase diagram for the Co--O system.