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Title: Segregation induced order-disorder transition in Cu(Au) surface alloys

Abstract

Using in-situ transmission electron microscopy and atomistic simulations, we report atomic-scale observations of segregation-induced structure changes in the surface and subsurface region of a Cu(Au) solid solution in both reductive and oxidative environments. In a H 2 atmosphere, Au segregation induces the formation of a two-atomic-layer thick ordered surface alloy with an L1 0 terminated surface layer. By switching to an O 2 atmosphere, the outermost surface develops into an Au-missing row reconstruction and simultaneously the second layer experiences an order-disorder transition via intralayer atomic exchanges. The chemical disordering then propagates to the outermost surface, driven by oxygen adsorption induced Cu surface segregation. This transforms the L1 0 missing-row reconstruction into a non-reconstructed, oxygenated surface. Furthermore, these observations provide a mechanistic detail regarding the evolution of the surface and subsurface of this alloy in response to environmental stimuli, and are relevant to a wide range of technologically relevant processes.

Authors:
 [1];  [2];  [2];  [2];  [1];  [1];  [2];  [3];  [3];  [2];  [2]; ORCiD logo [1]
  1. State Univ. at New York at Binghamton, Binghamton, NY (United States)
  2. Univ. of Pittsburgh, Pittsburgh, PA (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1479265
Alternate Identifier(s):
OSTI ID: 1548237
Report Number(s):
[BNL-209332-2018-JAAM]
[Journal ID: ISSN 1359-6454]
Grant/Contract Number:  
[SC0012704; SC0001135]
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
[ Journal Volume: 154; Journal Issue: C]; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Surface segregation; In-situ transmission electron microscopy; Cu(Au); Order-disorder transition

Citation Formats

Zou, Lianfeng, Saidi, Wissam A., Lei, Yinkai, Liu, Zhenyu, Li, Jonathan, Li, Liang, Zhu, Qing, Zakharov, Dmitri N., Stach, Eric A., Yang, Judith C., Wang, Guofeng, and Zhou, Guangwen. Segregation induced order-disorder transition in Cu(Au) surface alloys. United States: N. p., 2018. Web. doi:10.1016/j.actamat.2018.05.040.
Zou, Lianfeng, Saidi, Wissam A., Lei, Yinkai, Liu, Zhenyu, Li, Jonathan, Li, Liang, Zhu, Qing, Zakharov, Dmitri N., Stach, Eric A., Yang, Judith C., Wang, Guofeng, & Zhou, Guangwen. Segregation induced order-disorder transition in Cu(Au) surface alloys. United States. doi:10.1016/j.actamat.2018.05.040.
Zou, Lianfeng, Saidi, Wissam A., Lei, Yinkai, Liu, Zhenyu, Li, Jonathan, Li, Liang, Zhu, Qing, Zakharov, Dmitri N., Stach, Eric A., Yang, Judith C., Wang, Guofeng, and Zhou, Guangwen. Sat . "Segregation induced order-disorder transition in Cu(Au) surface alloys". United States. doi:10.1016/j.actamat.2018.05.040. https://www.osti.gov/servlets/purl/1479265.
@article{osti_1479265,
title = {Segregation induced order-disorder transition in Cu(Au) surface alloys},
author = {Zou, Lianfeng and Saidi, Wissam A. and Lei, Yinkai and Liu, Zhenyu and Li, Jonathan and Li, Liang and Zhu, Qing and Zakharov, Dmitri N. and Stach, Eric A. and Yang, Judith C. and Wang, Guofeng and Zhou, Guangwen},
abstractNote = {Using in-situ transmission electron microscopy and atomistic simulations, we report atomic-scale observations of segregation-induced structure changes in the surface and subsurface region of a Cu(Au) solid solution in both reductive and oxidative environments. In a H2 atmosphere, Au segregation induces the formation of a two-atomic-layer thick ordered surface alloy with an L10 terminated surface layer. By switching to an O2 atmosphere, the outermost surface develops into an Au-missing row reconstruction and simultaneously the second layer experiences an order-disorder transition via intralayer atomic exchanges. The chemical disordering then propagates to the outermost surface, driven by oxygen adsorption induced Cu surface segregation. This transforms the L10 missing-row reconstruction into a non-reconstructed, oxygenated surface. Furthermore, these observations provide a mechanistic detail regarding the evolution of the surface and subsurface of this alloy in response to environmental stimuli, and are relevant to a wide range of technologically relevant processes.},
doi = {10.1016/j.actamat.2018.05.040},
journal = {Acta Materialia},
number = [C],
volume = [154],
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
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Figures / Tables:

Fig. 1 Fig. 1: (A) HRTEM image of a (100) faceted edge showing the formation of an ordered superlattice structure in the two outermost layers by annealing a Cu-10 at.%Au (100) film at 350°C and 1 x 10-3 Torr of H2 flow. Insets are intensity profiles taken along the topmost and secondmore » layer; (b) [001] projected views of the CuAu (L10 ordered) and Cu3Au (L12 ordered) structures; (c) structure model of the ordered surface alloy, where the topmost layer is L10 ordered whereas the second layer consists of alternate columns of pure Cu atoms and columns of half Au and half Cu atoms; (d) simulated HRTEM micrograph of the (100) surface based on the structural model shown in (c).« less

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