System Pr-Pd-O: Phase diagram and thermodynamic properties of ternary oxides using solid-state cells with special features

Isothermal section of the phase diagram of the system Pr-Pd-O at 1223 K was established by phase analysis of samples quenched after equilibration at high temperature. Based on the phase diagram, two solid state cells were designed to measure the chemical potential of oxygen corresponding to two phase-fields in the ternary, each involving three condensed phases. From accurate measurements on cells incorporating buffer electrodes, the Gibbs energies, enthalpies and entropies of formation of the ternary oxides Pr4PdO7, Pr2Pd2O5, and Pr2PdO4 were deduced. Chemical potential diagrams were developed based on the thermodynamic data obtained in the study and auxiliary information from the literature. Isobaric phase diagrams were also computed.