Chemical potentials of oxygen for mixtures of CaO (s) + Ca4P2O9 (s) + {CaO + P2O5 + FexO} melts and Ca4P2O9 (s) + Ca3P2O8 (s) + {CaO + P2O5 + FexO} melts

Electrochemical measurements involving stabilized zirconia as solid electrode and Mo + MoO₂ as reference electrode were conducted in order to determine the chemical potentials of oxygen for threephase assemblages of CaO (s) + Ca₄P₂O₉ (s) + liquid and Ca₄P₂O₉ + Ca₃P₂O₈ + liquid within the system CaO + Fe_xO + P₂O₅. The results for the former are $$\log (P_{O_2 } /atm) = 6.22 - 27,900 (T/K)$$ while for the latter, $$\log (P_{O_2 } /atm) = 6.35 - 27,600 (T/K)$$