Records |
Author |
Delmelle, R.; Amin-Ahmadi, B.; Sinnaeve, M.; Idrissi, H.; Pardoen, T.; Schryvers, D.; Proost, J. |
Title |
Effect of structural defects on the hydriding kinetics of nanocrystalline Pd thin films |
Type |
A1 Journal article |
Year |
2015 |
Publication |
International journal of hydrogen energy |
Abbreviated Journal |
Int J Hydrogen Energ |
Volume |
40 |
Issue |
40 |
Pages |
7335-7347 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
While the microstructure of a metal is well-known to affect its equilibrium hydrogen uptake and therefore the hydriding thermodynamics, microstructural effects on the hydriding kinetics are much less documented. Moreover, for thin film systems, such microstructural effects are difficult to separate from the internal stress effect, since most defects generate internal stresses. Such a decoupling has been achieved in this paper for nanocrystalline Pd thin film model systems through the use of a high-resolution, in-situ curvature measurement set-up during Pd deposition, annealing and hydriding. This set-up allowed producing Pd thin films with similar internal stress levels but significantly different microstructures. This was evidenced from detailed defect statistics obtained by transmission electron microscopy, which showed that the densities of grain boundaries, dislocations and twin boundaries have all been lowered by annealing. The same set-up was then used to study the hydriding equilibrium and kinetic behaviour of the resulting films at room temperature. A full quantitative analysis of their hydriding cycles showed that the rate constants of both the adsorption- and absorption-limited kinetic regimes were strongly affected by microstructure. Defect engineering was thereby shown to increase the rate constants for hydrogen adsorption and absorption in Pd by a factor 40 and 30, respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000355884300012 |
Publication Date |
2015-05-02 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0360-3199; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.582 |
Times cited |
13 |
Open Access |
|
Notes |
Iap 7/21 |
Approved |
Most recent IF: 3.582; 2015 IF: 3.313 |
Call Number |
c:irua:126429 |
Serial |
838 |
Permanent link to this record |
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Author |
Amin-Ahmadi, B.; Idrissi, H.; Delmelle, R.; Pardoen, T.; Proost, J.; Schryvers, D. |
Title |
High resolution transmission electron microscopy characterization of fcc -> 9R transformation in nanocrystalline palladium films due to hydriding |
Type |
A1 Journal article |
Year |
2013 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
Volume |
102 |
Issue |
7 |
Pages |
071911-71914 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Sputtered nanocrystalline palladium thin films with nanoscale growth twins have been subjected to hydriding cycles. The evolution of the twin boundaries has been investigated using high resolution transmission electron microscopy. Surprisingly, the Sigma 3{112} incoherent twin boundaries dissociate after hydriding into two phase boundaries bounding a 9R phase. This phase which corresponds to single stacking faults located every three {111} planes in the fcc Pd structure was not expected because of the high stacking fault energy of Pd. This observation is connected to the influence of the Hydrogen on the stacking fault energy of palladium and the high compressive stresses building up during hydriding. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4793512] |
Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000315596700023 |
Publication Date |
2013-02-26 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
0003-6951; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.411 |
Times cited |
14 |
Open Access |
|
Notes |
Iap |
Approved |
Most recent IF: 3.411; 2013 IF: 3.515 |
Call Number |
UA @ lucian @ c:irua:108303 |
Serial |
1462 |
Permanent link to this record |
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Author |
Proost, J.; Blaffart, F.; Turner, S.; Idrissi, H. |
Title |
On the Origin of Damped Electrochemical Oscillations at Silicon Anodes (Revisited) |
Type |
A1 Journal article |
Year |
2014 |
Publication |
ChemPhysChem : a European journal of chemical physics and physical chemistry |
Abbreviated Journal |
Chemphyschem |
Volume |
15 |
Issue |
14 |
Pages |
3116-3124 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Electrochemical oscillations accompanying the formation of anodic silica have been shown in the past to be correlated with rather abrupt changes in the mechanical stress state of the silica film, commonly associated with some kind of fracture or porosification of the oxide. To advance the understanding on the origin of such oscillations in fluoride-free electrolytes, we have revisited a seminal experiment reported by Lehmann almost two decades ago. We thereby demonstrate that the oscillations are not stress-induced, and do not originate from a morphological transformation of the oxide in the course of anodisation. Alternatively, the mechanical features accompanying the oscillations can be explained by a partial relaxation of the field-induced electrostrictive stress. Furthermore, our observations suggest that the oscillation mechanism more likely results from a periodic depolarisation of the anodic silica. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Weinheim |
Editor |
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Language |
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Wos |
000342770500029 |
Publication Date |
2014-08-27 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1439-4235; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.075 |
Times cited |
5 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 3.075; 2014 IF: 3.419 |
Call Number |
UA @ lucian @ c:irua:121086 |
Serial |
2444 |
Permanent link to this record |
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Author |
Vanhumbeeck, J.-F.; Tian, H.; Schryvers, D.; Proost, J. |
Title |
Stress-assisted crystallisation in anodic titania |
Type |
A1 Journal article |
Year |
2011 |
Publication |
Corrosion science |
Abbreviated Journal |
Corros Sci |
Volume |
53 |
Issue |
4 |
Pages |
1269-1277 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The relationship between the microstructural and internal stress evolution during Ti anodising is discussed. Samples anodised galvanostatically to 12 V and 40 V, corresponding to different stages of the internal stress evolution, were examined by in-plane and cross-section transmission electron microscopy. Electron diffraction patterns have been complemented with stoichiometry data obtained from energy loss near edge structure spectra. The sample anodised to 40 V was observed to consist of two regions, with a crystallised inner region adjacent to the metal/oxide interface. Crystallisation of this region is associated with the presence of large compressive internal stresses which build up during anodising up to 12 V. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000288972000016 |
Publication Date |
2010-12-31 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0010-938X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
5.245 |
Times cited |
11 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 5.245; 2011 IF: 3.734 |
Call Number |
UA @ lucian @ c:irua:88385 |
Serial |
3177 |
Permanent link to this record |
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Author |
Amin-Ahmadi, B.; Connétable, D.; Fivel, M.; Tanguy, D.; Delmelle, R.; Turner, S.; Malet, L.; Godet, S.; Pardoen, T.; Proost, J.; Schryvers, D.; Idrissi, H. |
Title |
Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films |
Type |
A1 Journal article |
Year |
2016 |
Publication |
Acta materialia |
Abbreviated Journal |
Acta Mater |
Volume |
111 |
Issue |
111 |
Pages |
253-261 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000375812100027 |
Publication Date |
2016-04-06 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1359-6454 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
5.301 |
Times cited |
14 |
Open Access |
|
Notes |
This work was carried out in the framework of the IAP program of the Belgian State Federal Office for Scientific, Technical and Cultural Affairs, under Contract No. P7/21. The support of the FWO research project G012012N “Understanding nanocrystalline mechanical behaviour from structural investigations” for B. Amin-Ahmadi is also gratefully acknowledged. This work was granted access to the HPC resources of CALMIP (CICT Toulouse, France) under the allocations 2014-p0912 and 2014-p0749. |
Approved |
Most recent IF: 5.301 |
Call Number |
c:irua:132678 |
Serial |
4054 |
Permanent link to this record |
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Author |
van der Rest, A.; Idrissi, H.; Henry, F.; Favache, A.; Schryvers, D.; Proost, J.; Raskin, J.-P.; Van Overmeere, Q.; Pardoen, T. |
Title |
Mechanical behavior of ultrathin sputter deposited porous amorphous Al2O3 films |
Type |
A1 Journal article |
Year |
2017 |
Publication |
Acta materialia |
Abbreviated Journal |
Acta Mater |
Volume |
125 |
Issue |
125 |
Pages |
27-37 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
The determination of the mechanical properties of porous amorphous Al2O3 thin films is essential to address reliability issues in wear-resistant, optical and electronic coating applications. Testing the mechanical properties of Al2O3 films thinner than 200 nm is challenging, and the link between the mechanical behavior and the microstructure of such films is largely unknown. Herein, we report on the elastic and viscoplastic mechanical properties of amorphous Al2O3 thin films synthesized by reactive magnetron sputtering using a combination of internal stress, nanoindentation, and on-chip uniaxial tensile testing, together with mechanical homogenization models to separate the effect of porosity from intrinsic variations of the response of the sound material. The porosity is made of voids with 2e30 nm diameter. The Young's modulus and hardness of the films decrease by a factor of two when the deposition pressure increases from 1.2 to 8 mTorr. The contribution of porosity was found to be small, and a change in the atomic structure of the amorphous Al2O3 matrix is hypothesized to be the main contributing factor. The activation volume associated to the viscoplastic deformation mechanism is around 100 Å3. Differences in the atomic structure of the films could not be revealed by electron diffraction, pointing to a minute effect of atomic arrangement on the elastic properties. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000394201500003 |
Publication Date |
2016-12-02 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1359-6454 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
5.301 |
Times cited |
5 |
Open Access |
OpenAccess |
Notes |
This work has been funded by the Belgian Science Policy through the IAP 7/21 project. The support of the ‘Fonds Belge pour la Recherche dans l’Industrie et l’Agriculture (FRIA)’ for A.v.d.R. is also gratefully acknowledged, as well as the support of FNRS through the grant PDR T.0122.13 “Mecano”. |
Approved |
Most recent IF: 5.301 |
Call Number |
EMAT @ emat @ c:irua:138990 |
Serial |
4330 |
Permanent link to this record |
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Author |
Lumbeeck, G.; Idrissi, H.; Amin-Ahmadi, B.; Favache, A.; Delmelle, R.; Samaee, V.; Proost, J.; Pardoen, T.; Schryvers, D. |
Title |
Effect of hydriding induced defects on the small-scale plasticity mechanisms in nanocrystalline palladium thin films |
Type |
A1 Journal Article |
Year |
2018 |
Publication |
Journal Of Applied Physics |
Abbreviated Journal |
J Appl Phys |
Volume |
124 |
Issue |
22 |
Pages |
225105 |
Keywords |
A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; |
Abstract |
Nanoindentation tests performed on nanocrystalline palladium films subjected to hydriding/dehydriding cycles demonstrate a significant softening when compared to the as-received material. The origin of this softening is unraveled by combining in situ TEM nanomechanical testing with automated crystal orientation mapping in TEM and high resolution TEM. The softening is attributed to the presence of a high density of stacking faults and of Shockley partial dislocations after hydrogen loading. The hydrogen induced defects affect the elementary plasticity mechanisms and the mechanical response by acting as preferential sites for twinning/detwinning during deformation. These results are analyzed and compared to previous experimental and simulation works in the literature. This study provides new insights into the effect of hydrogen on the atomistic deformation and cracking mechanisms as well as on the mechanical properties of nanocrystalline thin films and membranes. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000453254000025 |
Publication Date |
2018-12-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.068 |
Times cited |
2 |
Open Access |
Not_Open_Access |
Notes |
This work was supported by the Hercules Foundation under Grant No. AUHA13009, the Flemish Research Fund (FWO) under Grant No. G.0365.15N, and the Flemish Strategic Initiative for Materials (SIM) under the project InterPoCo. Dr. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). We would like to thank Dr. Hadi Pirgazi from UGent for his technical support to process the ACOM data in the OIM Analysis software. |
Approved |
Most recent IF: 2.068 |
Call Number |
EMAT @ emat @c:irua:155742 |
Serial |
5135 |
Permanent link to this record |
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Author |
Lumbeeck, G.; Delvaux, A.; Idrissi, H.; Proost, J.; Schryvers, D. |
Title |
Analysis of internal stress build-up during deposition of nanocrystalline Ni thin films using transmission electron microscopy |
Type |
A1 Journal article |
Year |
2020 |
Publication |
Thin solid films : an international journal on the science and technology of thin and thick films |
Abbreviated Journal |
Thin Solid Films |
Volume |
707 |
Issue |
|
Pages |
138076 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000539312200011 |
Publication Date |
2020-05-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
|
Open Access |
OpenAccess |
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 |
Call Number |
EMAT @ emat @c:irua:169708 |
Serial |
6370 |
Permanent link to this record |
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Author |
Delvaux, A.; Lumbeeck, G.; Idrissi, H.; Proost, J. |
Title |
Effect of microstructure and internal stress on hydrogen absorption into Ni thin film electrodes during alkaline water electrolysis |
Type |
A1 Journal article |
Year |
2020 |
Publication |
Electrochimica Acta |
Abbreviated Journal |
Electrochim Acta |
Volume |
340 |
Issue |
|
Pages |
135970-10 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000521531800011 |
Publication Date |
2020-02-26 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0013-4686 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
6.6 |
Times cited |
2 |
Open Access |
Not_Open_Access |
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 |
Call Number |
UA @ admin @ c:irua:168536 |
Serial |
6497 |
Permanent link to this record |
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Author |
Poulain, R.; Lumbeeck, G.; Hunka, J.; Proost, J.; Savolainen, H.; Idrissi, H.; Schryvers, D.; Gauquelin, N.; Klein, A. |
Title |
Electronic and chemical properties of nickel oxide thin films and the intrinsic defects compensation mechanism |
Type |
A1 Journal article |
Year |
2022 |
Publication |
ACS applied electronic materials |
Abbreviated Journal |
|
Volume |
4 |
Issue |
6 |
Pages |
2718-2728 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Although largely studied, contradictory results on nickel oxide (NiO) properties can be found in the literature. We herein propose a comprehensive study that aims at leveling contradictions related to NiO materials with a focus on its conductivity, surface properties, and the intrinsic charge defects compensation mechanism with regards to the conditions preparation. The experiments were performed by in situ photo-electron spectroscopy, electron energy loss spectroscopy, and optical as well as electrical measurements on polycrystalline NiO thin films prepared under various preparation conditions by reactive sputtering. The results show that surface and bulk properties were strongly related to the deposition temperature with in particular the observation of Fermi level pinning, high work function, and unstable oxygen-rich grain boundaries for the thin films produced at room temperature but not at high temperature (>200 degrees C). Finally, this study provides substantial information about surface and bulk NiO properties enabling to unveil the origin of the high electrical conductivity of room temperature NiO thin films and also for supporting a general electronic charge compensation mechanism of intrinsic defects according to the deposition temperature. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000819431200001 |
Publication Date |
2022-06-07 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
2637-6113 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
|
Open Access |
Not_Open_Access |
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ admin @ c:irua:189555 |
Serial |
7081 |
Permanent link to this record |