Thermodynamic data of Ba0.6Sr0.4Co0.8Fe0.2O3−δ SOFC cathode material

• We report relevant data for thermodynamic stability of Ba0.6Sr0.4Co0.8Fe0.2O3−δ perovskite compound.
• Temperature of structural transformations related to the charge compensation of the material system is evidenced.
• The results are discussed based on the properties-defect structure relationship.

The compound Ba0.6Sr0.4Co0.8Fe0.2O3−δ with perovskite structure has been studied focusing mainly on the thermodynamic stability in correlation to the change in the oxygen stoichiometry. The thermochemical behavior has been investigated from room temperature to 1300 K by thermal gravimetry and differential thermal analysis in air and by calorimetry in scanning mode in Argon. The temperature dependence of enthalpy (ΔHT298) in the temperature range of 300–900 K was measured by drop calorimetry. Thermodynamic properties represented by the relative partial molar free energies, enthalpies and entropies of oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressures of oxygen have been obtained in the temperature range of 823–1273 K using solid electrolyte electrochemical cells (EMF). The influence of the oxygen stoichiometry on the thermodynamic properties was examined using a coulometric titration technique coupled with EMF measurements. The results are discussed based on the strong correlation between the energetic parameters and the charge compensation of the material system.

Partial molar energy of oxygen dissolution (ΔG−O2) and equilibrium partial pressure of oxygen (log⁡pO2log⁡pO2) of perovskite material with the composition Ba0.6Sr0.4Co0.8Fe0.2O3−δ as a function of temperature.Figure optionsDownload as PowerPoint slide