Oxygen content and thermodynamic stability of YBaCo4O7 ± δ

• YBaCo4O7 ± δ was found to be thermodynamically stable in air at T > 900 °C.
• Thermodynamic stability at 950 °C is limited by the range of − 5.05 ≤ log(pO2/atm) ≤ − 0.5.
• Oxygen content in YBaCo4O7 ± δ at 950 °C slightly decreases from 7.009 to 6.953.

YBaCo4O7 ± δ was found to be thermodynamically stable in air at T > 900 °C whereas its thermodynamic stability at 950 °C is limited by the range of oxygen partial pressures − 5.05 ≤ log(pO2/atm) ≤ − 0.5. Oxygen content in YBaCo4O7 ± δ at 950 °C slightly decreases from 7.009 at log(pO2/atm) = − 0.5 to 6.953 in the atmosphere with log(pO2/atm) = − 5.05. YBaCo4O7 ± δ decomposes into the mixture of YCoO3–δ, BaCoO3–δ and Co3O4 at 950 °C in atmosphere with log(pO2/atm) > − 0.5 whereas in atmosphere with log(pO2/atm) < − 5.05 Y2BaCoO5, BaCoO2 and CoO were identified as the products of YBaCo4O7 ± δ decomposition.