“…The perovskite form, CeFeO 3 , is analogous to LaFeO 3 and can be prepared with difficulty as a bulk oxide. , Unfortunately, the bulk perovskite is unstable, as shown by the fact that, after high-temperature oxidation, high-temperature reduction does not bring back the perovskite structure. However, some of us have demonstrated that thin CeFeO x films, formed by atomic layer deposition (ALD) on an alumina support, can reversibly transition from a fluorite structure upon oxidation to a perovskite structure upon reduction . Spectroscopic data suggest that it is the Ce that changes the oxidation state, between +4 and +3 in these films, while Fe remains primarily in the +3-oxidation state.…”