Impact of oxygen content on preferred localization of p- and n-type carriers in La 0.5 Sr 0.5 Fe 1- x Mn x O 3- δ

• Published in: Dalton transactions : an international journal of inorganic chemistry 2021-12, Vol.50 (48), p.17967-17980
• Main Authors: Nikitin, Sergey S, Markov, Alexey A, Merkulov, Oleg V, Chukin, Andrey V, Patrakeev, Mikhail V
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/D1DT03628A

The oxygen content in La Sr Fe Mn O , measured by coulometric titration in a wide range of oxygen partial pressure at various temperatures, was used for defect chemistry analysis. The obtained data were well approximated by a model assuming defect formation in La Sr Fe Mn O Fe and Mn oxidation reactions and charge disproportionation on Fe and Mn ions. The partial molar enthalpy and entropy of oxygen in La Sr Fe Mn O obtained by statistical thermodynamic calculations were found to be in satisfactory agreement with those obtained using the Gibbs-Helmholtz equations, thus further confirming the adequacy of the model. The impact of manganese substitution on defect equilibrium in La Sr Fe Mn O was shown to be attributed to a lower enthalpy of Mn oxidation reaction ( for the oxidation of Fe ) and the charge disproportionation reaction on Mn ( for that on Fe ). The former makes Mn ions more resistant to reduction than Fe . The latter favors the presence of Mn , Mn , and Mn ions in oxides in comparable concentrations. The distribution of charge carriers over iron and manganese ions was determined as a function of oxygen content in La Sr Fe Mn O .