The dependence of oxygen stoichiometry on the oxygen partial pressure and the temperature for La- and Nb-doped strontium ferrite La0.4Sr0.6Fe0.95Nb0.05O3 – δ (LSFNb5) was studied by quasi-equilibrium oxygen release (QEOR) method. The equilibrium diagram in the coordinates “T – lg(pO2 ) – 3 – δ” in the temperature range of 700–900°C and oxygen partial pressures pO2 = 10–4 – 0.2 atm was obtained. The range of stoichiometry deviation was determined, and the thermodynamic parameters of the oxygen release process were analyzed.
