Journal article
Thermodynamic assessment of the La-Fe-O system
Swiss Federal Institute of Technology Zurich1
SMS Concast AG2
Electroceramics, Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark3
Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark4
Risø National Laboratory for Sustainable Energy, Technical University of Denmark5
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.
Language: | English |
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Year: | 2009 |
Pages: | 351-366 |
ISSN: | 18637345 and 15477037 |
Types: | Journal article |
DOI: | 10.1007/s11669-009-9501-6 |
ORCIDs: | Chen, Ming |