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Lumbeeck, G.; Delvaux, A.; Idrissi, H.; Proost, J.; Schryvers, D. |
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Title |
Analysis of internal stress build-up during deposition of nanocrystalline Ni thin films using transmission electron microscopy |
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A1 Journal article |
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Year  |
2020 |
Publication |
Thin solid films : an international journal on the science and technology of thin and thick films |
Abbreviated Journal |
Thin Solid Films |
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Volume |
707 |
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Pages |
138076 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Ni thin films sputter-deposited at room temperature with varying Ar pressures were investigated with automated crystal orientation mapping in a transmission electron microscope to uncover the mechanisms controlling the internal stress build-up recorded in-situ during deposition. Large grains were found to induce behaviour similar to a stress-free nucleation layer. The measurements of grain size in most of the Ni thin films are in agreement with the island coalescence model. Low internal stress was observed at low Ar pressure and was explained by the presence of large grains. Relaxation of high internal stress was also noticed at the highest Ar pressure, which was attributed to a decrease of Σ3 twin boundary density due to a low deposition rate. The results provide insightful information to better understand the relationship between structural boundaries and the evolution of internal stress upon deposition of thin films. |
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Wos |
000539312200011 |
Publication Date |
2020-05-12 |
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UA library record; WoS full record; WoS citing articles |
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OpenAccess |
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Notes |
This work was supported by the Hercules Foundation [Grant No. AUHA13009], the Flemish Research Fund (FWO) [Grant No. G.0365.15N], and the Flemish Strategic Initiative for Materials (SIM) under the project InterPoCo. Thin film deposition has been realised as part of the WallonHY project, funded by the Public Service of Wallonia – Department of Energy and Sustainable Building. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). |
Approved |
Most recent IF: NA |
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Call Number |
EMAT @ emat @c:irua:169708 |
Serial |
6370 |
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Author |
Delvaux, A.; Lumbeeck, G.; Idrissi, H.; Proost, J. |
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Title |
Effect of microstructure and internal stress on hydrogen absorption into Ni thin film electrodes during alkaline water electrolysis |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Electrochimica Acta |
Abbreviated Journal |
Electrochim Acta |
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Volume |
340 |
Issue |
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Pages |
135970-10 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Efforts to improve the cell efficiency of hydrogen production by water electrolysis continue to address the electrochemical kinetics of the oxygen and hydrogen evolution reactions in detail. The objective of this work is to study a parasitic reaction occurring during the hydrogen evolution reaction (HER), namely the absorption of hydrogen atoms into the bulk electrode. Effects of the electrode microstructure and internal stress on this reaction have been addressed as well in this paper. Ni thin film samples were deposited on a Si substrate by sputter deposition with different deposition pressures, resulting in different microstructures and varying levels of internal stress. These microstructures were first analyzed in detail by Transmission Electron Microscopy (TEM). Cathodic chrono-amperometric measurements and cyclic voltammetries have then been performed in a homemade electrochemical cell. These tests were coupled to a multi-beam optical sensor (MOS) in order to obtain in-situ curvature measurements during hydrogen absorption. Indeed, since hydrogen absorption in the thin film geometry results in a constrained volume expansion, internal stress generation during HER can be monitored by means of curvature measurements. Our results show that different levels of internal stress, grain size and twin boundary density can be obtained by varying the deposition parameters. From an electrochemical point of view, this paper highlights the fact that the electrochemical surface mechanisms during HER are the same for all the electrodes, regardless of their microstructure. However it is shown that the absolute amount of hydrogen being absorbed into the Ni thin films increases when the grain size is reduced, due to a higher grain boundaries density which are favourite absorption sites for hydrogen. At the same time, it was concluded that H-2 evolution is favoured at electrodes having a more compressive (i.e. a less tensile) internal stress. Finally, the subtle effect of microstructure on the hydrogen absorption rate will be discussed as well. (C) 2020 Elsevier Ltd. All rights reserved. |
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000521531800011 |
Publication Date |
2020-02-26 |
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ISSN |
0013-4686 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.6 |
Times cited |
2 |
Open Access |
Not_Open_Access |
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Notes |
; The authors gratefully acknowledge financial support of the Public Service of Wallonia e Department of Energy and Sustainable Building, through the project WallonHY. The ACOM-TEM work was supported by the Hercules Foundation [Grant No. AUHA13009], the Flemish Research Fund (FWO) [Grant No. G.0365.15 N], and the Flemish Strategic Initiative for Materials (SIM) under the project InterPoCo. We also like to cordially thank Ronny Santoro for carrying out the ICP-OES measurements. ; |
Approved |
Most recent IF: 6.6; 2020 IF: 4.798 |
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Call Number |
UA @ admin @ c:irua:168536 |
Serial |
6497 |
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