Oxygen intercalation in Ruddlesden-Popper type Sr3LaFe3O10-δ

The oxygen nonstoichiometry of Ruddlesden-Popper type Sr3LaFe3O10-δ, a promising parent material for mixed-conducting electrodes and membranes, was studied in the oxygen partial pressure range from 10−24 to 0.5 atm at 973-1223 K by coulometric titration and thermogravimetry. The p(O2)-T-δ diagram can be described using a statistical thermodynamic model relating the non-ideal behavior in oxidizing and strongly reducing atmospheres to the coulombic interaction between oxygen vacancies and electronic charge carriers. The results confirm a strong energetic affinity of anion vacancies to the central perovskite-like layers of the Ruddlesden-Popper structure, whilst the difference between crystallographic iron sites has no significant effects on the oxygen intercalation thermodynamics at elevated temperatures. No indications of long-range ordering in the oxygen sublattice were observed.