High-temperature stabilities of YCuO2, BaCu2O2 and Ba2CuO3 from oxide electrolyte e.m.f. measurements

The oxygen potentials in the system YCuO₂/Y₂O₃/Cu and Y₂O₃/YCuO₂/CuO were measured over the ranges 1113–1255 K and 782–1122 K by employing oxide electrolyte galvanic cells with air/platinum as the reference electrode, and the expression $$\Delta G_{f, ox}^o (YCuO_2 )( \pm 0.19)(kJ mol^{ - 1} ) = - 5.346 + 0.00384{\text{ }}T (K)$$ was determined. Similar e.m.f. measurements were carried out on the electrodes BaCuO₂/BaCu₂O₂/Cu₂O and Ba₂CuO₃/BaCuO₂/BaCu₂O₂ were measured over the ranges 1003–1132 K and 1175–1235 K and from the results, the ΔG _f,ox ^o of BaCu₂O₂ and Ba₂CuO₃ were determined to be $$\begin{gathered} \Delta G_{f, ox}^o (BaCu_2 O_2 )(kJ mol^{ - 1} ) = - 25.09 + 0.01548{\text{ }}T (K) \hfill \\ \Delta G_{f, ox}^o (BaCu_2 O_3 )(kJ mol^{ - 1} ) = - 5.79 - 0.07492{\text{ }}T (K) \hfill \\ \end{gathered} $$