title: In Situ Study of Fe3Pt-Fe2O3 Core-Shell Nanoparticle Formation.
abstract: We report an in situ study of Fe3Pt-Fe2O3 core-shell nanoparticle growth using liquid cell transmission electron microscopy. By controlling the Fe-to-Pt ratio in the precursor solution, we achieved the growth of nanoparticles with the formation of an iron-platinum alloy core followed by an iron oxide shell in the electron beam-induced reactions. There was no substantial change in the growth kinetics of the iron oxide shell after the Fe-Pt alloy core stopped growing. The core growth was arrested by depletion of the Pt precursor. Heteroepitaxy of Fe3Pt [101] (core)||α-Fe2O3 [111] (shell) was observed in most of the nanoparticles, while a polycrystalline iron oxide shell is developed eventually for strain relaxation. Our studies suggest that Pt atoms catalyze the reduction of Fe ions to form the Fe3Pt alloy core, and when Pt is depleted, a direct precipitation of iron oxide results in the core-shell nanostructure formation.
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University , Hsinchu 300, Taiwan.|Materials Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Wen-I
authors.initials: WI
authors.lastname: Liang
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Centre of Advanced Microstructures, Nanjing University , Nanjing 210093, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University , Shanghai 200030, China.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Zan
authors.affiliation: Gatan, Inc. , 5794 West Las Positas Boulevard, Pleasanton, California 94588, United States.
authors.forename: Ming
authors.initials: M
authors.lastname: Pan
authors.affiliation: Gatan, Inc. , 5794 West Las Positas Boulevard, Pleasanton, California 94588, United States.
authors.forename: Cory
authors.initials: C
authors.lastname: Czarnik
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Karen
authors.initials: K
authors.lastname: Bustillo
authors.affiliation: National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Centre of Advanced Microstructures, Nanjing University , Nanjing 210093, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University , Hsinchu 300, Taiwan.|Institute of Physics, Academia Sinica , Taipei 105, Taiwan.
authors.forename: Ying-Hao
authors.initials: YH
authors.lastname: Chu
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
authors.forename: Haimei
authors.initials: H
authors.lastname: Zheng