In Situ Transmission Electron Microscopy of Disorder–Order Transition in Epitaxially Stabilized FeGe2

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Date
2021
Volume
125
Issue
4
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Publisher
Washington, DC : Soc.
Abstract

Isothermal crystallization of amorphous Ge deposited on a cubic Fe3Si/GaAs(001) substrate is performed by in situ annealing within a transmission electron microscope. It was found that the formation of epitaxially aligned tetragonal FeGe2 is associated with a disorder–order phase transition mainly consisting of a rearrangement of the Fe/vacancy sublattice from a random distribution to alternating filled and empty layers. Additionally, atomically resolved high-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy demonstrated that the vertical lattice spacing of the Ge sublattice reduces across vacancy layers, indicating that strain minimization plays a role in the phase transition process. Crystallization and ordering are both found to proceed layer-by-layer and with square-root-shaped kinetics with a smaller transition rate for the latter.

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Keywords
Energy dispersive spectroscopy, Germanium, Germanium compounds, High resolution transmission electron microscopy, In situ processing, Iron compounds, Isothermal annealing, Scanning electron microscopy, Transmissions, Disorder-order phase transitions, Disorder-order transitions, Energy dispersive X ray spectroscopy, Epitaxially stabilized, High-angle annular dark fields, In-situ transmission electron microscopies, Isothermal crystallization, Random distribution, Germanium metallography
Citation
Terker, M., Nicolai, L., Gaucher, S., Herfort, J., & Trampert, A. (2021). In Situ Transmission Electron Microscopy of Disorder–Order Transition in Epitaxially Stabilized FeGe2. 125(4). https://doi.org//10.1021/acs.jpcc.0c10716
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CC BY-NC-ND 4.0 Unported