title: A Second Amorphous Layer Underneath Surface Oxide.
abstract: Formation of a nanometer-scale oxide surface layer is common when a material is exposed to oxygen-containing environment. Employing aberration-corrected analytical transmission electron microscopy and using single crystal SnSe as an example, we show that for an alloy, a second thin amorphous layer can appear underneath the outmost oxide layer. This inner amorphous layer is not oxide based, but instead originates from solid-state amorphization of the base alloy when its free energy rises to above that of the metastable amorphous state; which is a result of the composition shift due to the preferential depletion of the oxidizing species, in our case, the outgoing Sn reacting with the oxygen atmosphere.
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: 2College of Physics,Chongqing University,Chongqing 401331,China.
authors.forename: Kunlin
authors.initials: K
authors.lastname: Peng
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Xuechao
authors.initials: X
authors.lastname: Sha
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.affiliation: 2College of Physics,Chongqing University,Chongqing 401331,China.
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Zhou
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Chen
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: QingSong
authors.initials: Q
authors.lastname: Deng
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Dingfeng
authors.initials: D
authors.lastname: Yang
authors.affiliation: 3Department of Materials Science and Engineering,Johns Hopkins University,Baltimore,MD 21218,USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Ma
authors.affiliation: 1Beijing Key Laboratory of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100024,China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Han
keywords: SnSe single crystal; high angle annular dark field (HAADF) imaging; interdiffusion; solid-state amorphization; surface oxidation