Thermodynamic assessment of the La-Fe-O system

E. Povoden-Karadeniz, A.N. Grundy, Ming Chen, T. Ivas, L.J. Gauckler

    Research output: Contribution to journalJournal articleResearchpeer-review


    The La-Fe and the La-Fe-O systems are assessed using the Calphad approach, and the Gibbs energy functions of ternary oxides are presented. Oxygen and mutual La and Fe solubilities in body-centered cubic (bcc) and face-centered cubic (fcc) structured metallic phases are considered in the modeling. Oxygen nonstoichiometry of perovskite-structured La1±x Fe1±y O3−δ is modeled using the compound energy formalism (CEF), and the model is submitted to a defect chemistry analysis. The contribution to the Gibbs energy of LaFeO3 due to a magnetic order-disorder transition is included in the model description. Lanthanum-doped hexaferrite, LaFe12O19, is modeled as a stoichiometric phase. Δf,elements°H 298 K (LaFe12O19) = −5745 kJ/mol, °S 298 K (LaFe12O19) = 683 J/mol · K, and Δf,oxides°G (LaFe12O19) = 4634 − 37.071T (J/mol) from 1073 to 1723 K are calculated. The liquid phase is modeled using the two-sublattice model for ionic liquids. The calculated La-Fe phase diagram, LaO1.5-FeO x phase diagrams at different oxygen partial pressures, and phase equilibria of the La-Fe-O system at 873, 1073, and 1273 K as a function of oxygen partial pressures are presented.
    Original languageEnglish
    JournalJournal of Phase Equilibria and Diffusion
    Issue number4
    Pages (from-to)351-366
    Publication statusPublished - 2009


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