Dealloying of Au-Ag thin films with a composition gradient: Influence on morphology of nanoporous Au |
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Authors: | X Lu TJ Balk R Spolenak E Arzt |
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Affiliation: | a Max Planck Institute for Metals Research, Heisenbergstr. 3, D-70569 Stuttgart, Germany b Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, China c Chemical and Materials Engineering, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, KY 40506, United States d Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerland |
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Abstract: | Nanoporous Au can be formed by dealloying Au-Ag alloys and, depending on the initial alloy composition, produce a variety of microstructural features. We investigated a wide compositional range and found three regimes, based on initial Au content, that yield varying degrees of dealloying in thin films. Between 22 and 26 at.% Au, dealloying produces nearly pure Au with an open nanoporous structure. However, above 36 at.% Au, only the grain boundaries dealloy, leaving islands of retained Au-Ag alloy. For intermediate compositions, a transitional microstructure results, with final Ag concentration ranging from 50 at.% down to 4 at.%. Film cracking was observed after dealloying, and lower initial Au content correlated with a higher degree of cracking and a higher pore fraction. |
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Keywords: | Gold Nanoporous Thin film Dealloy Microstructure Porosity |
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