Conditions and Mechanism for the Formation of CeFeO₃ via Hydrogen Reduction of CeO₂–Fe₂O₃ Mixed Oxides

Herein, we demonstrate that CeFeO₃ with high phase purity can be synthesized from CeO₂–Fe₂O₃ mixed oxides by hydrogen reduction at 1073 K through control of the H₂ partial pressure and gas flow rate.

Powder X-ray diffraction and Rietveld refinement reveal that the phase purity of CeFeO₃ strongly depends on the reducing conditions and increases with decreasing H₂ partial pressure and flow rate. The highest phase purity, 99 mol % by Rietveld analysis, was obtained at PH2 = 1.25% and FH2 = 50.0 cm³ min^–1. Analysis of H₂ consumption, powder XRD patterns of intermediate products, and Fe K-edge and Ce L₃-edge XANES spectra show that CeFeO₃ forms through the reaction of CeO₂ with FeO generated by the stepwise reduction of Fe₂O₃.