title: Atomic Structural Evolution during the Reduction of α-Fe2O3Nanowires.
abstract: The atomic-scale reduction mechanism of α-Fe2O3nanowires by H2was followed using transmission electron microscopy to reveal the evolution of atomic structures and the associated transformation pathways for different iron oxides. The reduction commences with the generation of oxygen vacancies that order onto every 10th[Formula: see text] plane. This vacancy ordering is followed by an allotropic transformation of α-Fe2O3→ γ-Fe2O3along with the formation of Fe3O4nanoparticles on the surface of the γ-Fe2O3nanowire by a topotactic transformation process, which shows 3D correspondence between the structures of the product and its host. These observations demonstrate that the partial reduction of α-Fe2O3nanowires results in the formation of a unique hierarchical structure of hybrid oxides consisting of the parent oxide phase, γ-Fe2O3, as the one-dimensional wire and the Fe3O4in the form of nanoparticles decorated on the parent oxide skeleton. We show that the proposed mechanism is consistent with previously published and our density functional theory results on the thermodynamics of surface termination and oxygen vacancy formation in α-Fe2O3. Compared to previous reports of α-Fe2O3directly transformed to Fe3O4, our work provides a more in-depth understanding with substeps of reduction, i.e., the whole reduction process follows: α-Fe2O3→ α-Fe2O3superlattice → γ-Fe2O3+ Fe3O4→ Fe3O4.
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York, Binghamton, NY 13902, USA.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Winterstein
authors.affiliation: Department of Physics, State University of New York, Binghamton, NY 13902, USA.
authors.forename: Itai
authors.initials: I
authors.lastname: Maimon
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York, Binghamton, NY 13902, USA.
authors.forename: Qiyue
authors.initials: Q
authors.lastname: Yin
authors.affiliation: Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York, Binghamton, NY 13902, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Physics, State University of New York, Binghamton, NY 13902, USA.
authors.forename: Aleksey N
authors.initials: AN
authors.lastname: Kolmogorov
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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, NY 13902, USA.
authors.forename: Guangwen
authors.initials: G
authors.lastname: Zhou