The standard Gibbs energy changes for the following reactions have been directly determined from electromotive force (EMF) measurements using CaF 2 as the solid electrolyte at elevated temperatures. Pt(s) + 4CaO(s) + O2(g) = Ca4PtO6(s) ΔrG°/ kJ = -218.5 + 0.1599T (± 0.3) (1273-1313 K) Pt(s) + CaO(s) + O 2(g) = CaPtO3(s) ΔrG°/kJ = -296.8 + 0.2490T (± 0.6) (1123-1173 K) From the preceding results, the standard Gibbs energies of formation of Ca4PtO6 and CaPtO 3 have been evaluated as ΔfG° (Ca 4PtO6)/kJmol-1 = -2790.1 + 0.6055 T (± 3.5) (1273-1313 K) ΔfG° (CaPtO3)/kJmol -1 = -939.7 + 0.3604 T(± 0.88) (1123-1173 K). The phase diagram for the Ca-Pt-O system has been constructed based on the thermodynamic data obtained in the present study.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Physical and Theoretical Chemistry