title: In Situ Atomic-Scale Probing of the Reduction Dynamics of Two-Dimensional Fe2O3Nanostructures.
abstract: Atomic-scale structural dynamics and phase transformation pathways were probed, in situ, during the hydrogen-induced reduction of Fe2O3nanostructure bicrystals using an environmental transmission electron microscope. Reduction commenced with the α-Fe2O3→ γ-Fe2O3phase transformation of one part of the bicrystal, resulting in the formation of a two-phase structure of α-Fe2O3and γ-Fe2O3. The progression of the phase transformation into the other half of the bicrystalline Fe2O3across the bicrystalline boundary led to the formation of a single-crystal phase of γ-Fe2O3with concomitant oxygen-vacancy ordering on every third {422} plane, followed by transformation into Fe3O4. Further reduction resulted in the coexistence of Fe3O4, FeO, and Fe via the transformation pathway Fe3O4→ FeO → Fe. The series of phase transformations was accompanied by the formation of a Swiss-cheese-like structure, induced by the significant volume shrinkage occurring upon reduction. These results elucidated the atomistic mechanism of the reduction of Fe oxides and demonstrated formation of hybrid structures of Fe oxides via tuning the phase transformation pathway.
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York , Binghamton, New York 13902, United States.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Winterstein
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.|University of Maryland-IREAP , College Park, Maryland 20742, United States.
authors.forename: Wei-Chang David
authors.initials: WD
authors.lastname: Yang
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York , Binghamton, New York 13902, United States.
authors.forename: Lu
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Renu
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York , Binghamton, New York 13902, United States.
authors.forename: Guangwen
authors.identifier: 0000-0002-9243-293X
authors.initials: G
authors.lastname: Zhou
keywords: in situ TEM; phase transformation; reduction; α-Fe2O3