| Records |
| Author |
Abakumov, A.M.; Van Tendeloo, G.; Scheglov, A.A.; Shpanchenko, R.V.; Antipov, E.V. |
| Title |
The crystal structure of Ba8Ta6NiO24: cation ordering in hexagonal perovskites |
Type |
A1 Journal article |
| Year |
1996 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
Volume  |
125 |
Issue |
|
Pages |
102-107 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
|
| Address |
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| Corporate Author |
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Thesis |
|
| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
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Wos |
A1996VB31300015 |
Publication Date |
2002-10-07 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0022-4596; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.133 |
Times cited |
38 |
Open Access |
|
| Notes |
|
Approved |
no |
| Call Number |
UA @ lucian @ c:irua:16868 |
Serial |
569 |
| Permanent link to this record |
| |
|
| |
| Author |
Lichtert, S.; Verbeeck, J. |
| Title |
Statistical consequences of applying a PCA noise filter on EELS spectrum images |
Type |
A1 Journal article |
| Year |
2013 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
| Volume |
125 |
Issue |
|
Pages |
35-42 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Principal component analysis (PCA) noise filtering is a popular method to remove noise from experimental electron energy loss (EELS) spectrum images. Here, we investigate the statistical behaviour of this method by applying it on a simulated data set with realistic noise levels. This phantom data set provides access to the true values contained in the data set as well as to many different realizations of the noise. Using least squares fitting and parameter estimation theory, we demonstrate that even though the precision on the estimated parameters can be better as the CramérRao lower bound, a significant bias is introduced which can alter the conclusions drawn from experimental data sets. The origin of this bias is in the incorrect retrieval of the principal loadings for noisy data. Using an expression for the bias and precision of the singular values from literature, we present an evaluation criterion for these singular values based on the noise level and the amount of information present in the data set. This criterion can help to judge when to avoid PCA noise filtering in practical situations. Further we show that constructing elemental maps of PCA noise filtered data using the background subtraction method, does not guarantee an increase in the signal to noise ratio due to correlation of the spectral data as a result of the filtering process. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Amsterdam |
Editor |
|
| Language |
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Wos |
000314679700006 |
Publication Date |
2012-10-27 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0304-3991; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.843 |
Times cited |
54 |
Open Access |
|
| Notes |
Fwo; Countatoms; Vortex; Esteem 312483; esteem2jra3 ECASJO; |
Approved |
Most recent IF: 2.843; 2013 IF: 2.745 |
| Call Number |
UA @ lucian @ c:irua:105293 |
Serial |
3153 |
| Permanent link to this record |
| |
|
| |
| Author |
Ivanov, V.A.; Misko, V.R.; Fomin, V.M.; Devreese, J.T. |
| Title |
Superconductivity in mesoscopic high-Tc superconducting particles |
Type |
A1 Journal article |
| Year |
2003 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun |
| Volume |
125 |
Issue |
|
Pages |
439-444 |
| Keywords |
A1 Journal article; Electron Microscopy for Materials Science (EMAT); |
| Abstract |
|
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
New York, N.Y. |
Editor |
|
| Language |
|
Wos |
000181023700017 |
Publication Date |
2003-01-30 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0038-1098; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
1.554 |
Times cited |
3 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 1.554; 2003 IF: 1.602 |
| Call Number |
UA @ lucian @ c:irua:40871 |
Serial |
3372 |
| Permanent link to this record |
| |
|
| |
| 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 |
|
Editor |
|
| Language |
|
Wos |
000394201500003 |
Publication Date |
2016-12-02 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
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 |
| |
|
| |
| Author |
Mohammed, M.; Verhulst, A.S.; Verreck, D.; Van de Put, M.L.; Magnus, W.; Sorée, B.; Groeseneken, G. |
| Title |
Phonon-assisted tunneling in direct-bandgap semiconductors |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
1 |
Pages |
015701 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
In tunnel field-effect transistors, trap-assisted tunneling (TAT) is one of the probable causes for degraded subthreshold swing. The accurate quantum-mechanical (QM) assessment of TAT currents also requires a QM treatment of phonon-assisted tunneling (PAT) currents. Therefore, we present a multi-band PAT current formalism within the framework of the quantum transmitting boundary method. An envelope function approximation is used to construct the electron-phonon coupling terms corresponding to local Frohlich-based phonon-assisted inter-band tunneling in direct-bandgap III-V semiconductors. The PAT current density is studied in up to 100 nm long and 20 nm wide p-n diodes with the 2- and 15-band material description of our formalism. We observe an inefficient electron-phonon coupling across the tunneling junction. We further demonstrate the dependence of PAT currents on the device length, for our non-self-consistent formalism which neglects changes in the electron distribution function caused by the electron-phonon coupling. Finally, we discuss the differences in doping dependence between direct band-to-band tunneling and PAT current. Published under license by AIP Publishing. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000455350200021 |
Publication Date |
2019-01-02 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
2 |
Open Access |
|
| Notes |
; This work was supported by Imec's Industrial Affiliation Program. ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:156735 |
Serial |
5224 |
| Permanent link to this record |
| |
|
| |
| Author |
Milovanović, S.P.; Covaci, L.; Peeters, F.M. |
| Title |
Strain fields in graphene induced by nanopillar mesh |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
8 |
Pages |
082534 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The mechanical and electronic properties of a graphene membrane placed on top of a triangular superlattice of nanopillars are investigated. We use molecular dynamics simulations to access the deformation fields and the tight-binding approaches to calculate the electronic properties. Ripples form in the graphene layer that span across the unit cell, connecting neighboring pillars, in agreement with recent experiments. We find that the resulting pseudo-magnetic field (PMF) varies strongly across the unit cell. We investigate the dependence of PMF on unit cell boundary conditions, height of the pillars, and the strength of the van der Waals interaction between graphene and the substrate. We find direct correspondence with typical experiments on pillars, showing intrinsic “slack” in the graphene membrane. PMF values are confirmed by the local density of states calculations performed at different positions of the unit cell showing pseudo-Landau levels with varying spacings. Our findings regarding the relaxed membrane configuration and the induced strains are transferable to other flexible 2D 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 |
|
Editor |
|
| Language |
|
Wos |
000460033800038 |
Publication Date |
2019-01-16 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
5 |
Open Access |
|
| Notes |
; S.P.M. is supported by the Flemish Science Foundation (FWO). ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:158605 |
Serial |
5231 |
| Permanent link to this record |
| |
|
| |
| Author |
Gu, J.-G.; Zhang, Y.; Gao, M.-X.; Wang, H.-Y.; Zhang, Q.-Z.; Yi, L.; Jiang, W. |
| Title |
Enhancement of surface discharge in catalyst pores in dielectric barrier discharges |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
15 |
Pages |
153303 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
The generation of high-density plasmas on the surface of porous catalysts is very important for plasma catalysis, as it determines the active surface of the catalyst that is available for the reaction. In this work, we investigate the mechanism of surface and volume plasma streamer formation and propagation near micro-sized pores in dielectric barrier discharges operating in air at atmospheric pressure. A two-dimensional particle-in-cell/ Monte Carlo collision model is used to model the individual kinetic behavior of plasma species. Our calculations indicate that the surface discharge is enhanced on the surface of the catalyst pores compared with the microdischarge inside the catalyst pores. The reason is that the surface ionization wave induces surface charging along the catalyst pore sidewalls, leading to a strong electric field along the pore sidewalls, which in turn further enhances the surface discharge. Therefore, highly concentrated reactive species occur on the surfaces of the catalyst pores, indicating high-density plasmas on the surface of porous catalysts. Indeed, the maximum electron impact excitation and ionization rates occur on the pore surface, indicating the more pronounced production of excited state and electron-ion pairs on the pore surface than inside the pore, which may profoundly affect the plasma catalytic process. Published under license by AIP Publishing. |
| Address |
|
| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000465441200022 |
Publication Date |
2019-04-15 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
4 |
Open Access |
Not_Open_Access |
| Notes |
|
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:160397 |
Serial |
5273 |
| Permanent link to this record |
| |
|
| |
| Author |
Vohra, A.; Khanam, A.; Slotte, J.; Makkonen, I.; Pourtois, G.; Loo, R.; Vandervorst, W. |
| Title |
Evolution of phosphorus-vacancy clusters in epitaxial germanium |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
2 |
Pages |
025701 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
The E centers (dopant-vacancy pairs) play a significant role in dopant deactivation in semiconductors. In order to gain insight into dopant-defect interactions during epitaxial growth of in situ phosphorus doped Ge, positron annihilation spectroscopy, which is sensitive to open-volume defects, was performed on Ge layers grown by chemical vapor deposition with different concentrations of phosphorus (similar to 1 x 10(18)-1 x 10(20) cm(-3)). Experimental results supported by first-principles calculations based on the two component density-functional theory gave evidence for the existence of mono-vacancies decorated by several phosphorus atoms as the dominant defect type in the epitaxial Ge. The concentration of vacancies increases with the amount of P-doping. The number of P atoms around the vacancy also increases, depending on the P concentration. The evolution of P-n-V clusters in Ge contributes significantly to the dopant deactivation. Published under license by AIP Publishing. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000455922100057 |
Publication Date |
2019-01-08 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
5 |
Open Access |
Not_Open_Access |
| Notes |
|
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:156722 |
Serial |
5274 |
| Permanent link to this record |
| |
|
| |
| Author |
Piorra, A.; Hrkac, V.; Wolff, N.; Zamponi, C.; Duppel, V.; Hadermann, J.; Kienle, L.; Quandt, E. |
| Title |
(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 thin films prepared by PLD : relaxor properties and complex microstructure |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
24 |
Pages |
244103 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Ferroelectric lead-free thin films of the composition (Ba0.85Ca0.15)(Ti0.9Zr0.1)O-3 (BCZT) were deposited by pulsed laser deposition on Pt/TiO2/SiO2/Si substrates using a ceramic BCZT target prepared by a conventional solid state reaction. The target material itself shows a piezoelectric coefficient of d(33)=640pm/V. The (111) textured thin films possess a thickness of up to 1.1 mu m and exhibit a clamped piezoelectric response f of up to 190pm/V, a dielectric coefficient of (r)=2000 at room temperature, and a pronounced relaxor behavior. As indicated by transmission electron microscopy, the thin films are composed of longitudinal micrometersized columns with similar to 100nm lateral dimension that are separated at twin- and antiphase boundaries. The superposition phenomena according to this columnar growth were simulated based on suitable supercells. The major structural component is described as a tetragonal distorted variant of the perovskite parent type; however, frequently coherently intergrown nanodomains were observed indicating a much more complex structure that is characterized by a 7-layer modulation along the growth direction of the 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 |
|
| Language |
|
Wos |
000474439600002 |
Publication Date |
2019-06-25 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
|
Open Access |
|
| Notes |
; The authors want to thank Dr. Martina Luysberg and Dr. Lothar Houben from the Ernst Ruska Centre in Julich for discussion and CS-corrected microscopy. Funding of this work via the DFG (No. CRC1261) “Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics” and the PAK902 is gratefully acknowledged. ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:161310 |
Serial |
5399 |
| Permanent link to this record |
| |
|
| |
| Author |
Chen, Q.; Li, L.L.; Peeters, F.M. |
| Title |
Inner and outer ring states of MoS2 quantum rings : energy spectrum, charge and spin currents |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
24 |
Pages |
244303 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We investigate the energy levels and persistent currents of MoS2 quantum rings having different shapes and edge types in the presence of a perpendicular magnetic field by means of the tight-binding approach. We find states localized at the inner and outer boundaries of the ring. These energy levels exhibit different magnetic field dependences for the inner and outer ring states due to their different localization properties. They both exhibit the usual Aharanov-Bohm oscillations but with different oscillation periods. In the presence of spin-orbit coupling, we show distinct spin and charge persistent currents for inner and outer ring states. We find well-defined spin currents with negligibly small charge currents. This is because the local currents of spin-up and -down states flow in opposite directions. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000474439600026 |
Publication Date |
2019-06-25 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
10 |
Open Access |
|
| Notes |
; This work was supported by the Hunan Provincial Natural Science Foundation of China (Nos. 2015JJ2040, 2018JJ2080, and 2018JJ4047), the National Natural Science Foundation of China (NNSFC) (No. 51502087), the Scientific Research Fund of Hunan Provincial Education Department (Nos. 15A042, 15B056, and 17B060), and the Flemish Science Foundation (FWO-VI). ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:161309 |
Serial |
5417 |
| Permanent link to this record |
| |
|
| |
| Author |
Vohra, A.; Khanam, A.; Slotte, J.; Makkonen, I.; Pourtois, G.; Porret, C.; Loo, R.; Vandervorst, W. |
| Title |
Heavily phosphorus doped germanium : strong interaction of phosphorus with vacancies and impact of tin alloying on doping activation |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
125 |
Issue |
22 |
Pages |
225703 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
We examined the vacancy trapping proficiency of Sn and P atoms in germanium using positron annihilation spectroscopy measurements, sensitive to the open-volume defects. Epitaxial Ge1 xSnx films were grown by chemical vapor deposition with different P concentrations in the 3: 0 1019-1: 5 1020 cm 3 range. We corroborate our findings with first principles simulations. Codoping of Ge with a Sn concentration of up to 9% is not an efficient method to suppress the free vacancy concentration and the formation of larger phosphorus-vacancy complexes. Experimental results confirm an increase in the number of P atoms around the monovacancy with P-doping, leading to dopant deactivation in epitaxial germanium-tin layers with similar Sn content. Vice versa, no impact on the improvement of maximum achieved P activation in Ge with increasing Sn-doping has been observed. Theoretical calculations also confirm that Pn-V (vacancy) complexes are energetically more stable than the corresponding SnmPn-V and Snm-V defect structures with the same number of alien atoms (Sn or P) around the monovacancy. he strong attraction of vacancies to the phosphorus atoms remains the dominant dopant deactivation mechanism in Ge as well as in Ge1 xSnx. Published under license by AIP Publishing. |
| 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 |
|
Wos |
000471698600044 |
Publication Date |
2019-06-10 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
1 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:161333 |
Serial |
6300 |
| Permanent link to this record |
| |
|
| |
| Author |
Idrissi, H.; Samaee, V.; Lumbeeck, G.; Werf, T.; Pardoen, T.; Schryvers, D.; Cordier, P. |
| Title |
In Situ Quantitative Tensile Testing of Antigorite in a Transmission Electron Microscope |
Type |
A1 Journal article |
| Year |
2020 |
Publication |
Journal Of Geophysical Research-Solid Earth |
Abbreviated Journal |
J Geophys Res-Sol Ea |
| Volume |
125 |
Issue |
3 |
Pages |
|
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The determination of the mechanical properties of serpentinites is essential toward the understanding of the mechanics of faulting and subduction. Here we present the first in situ tensile tests on antigorite in a transmission electron microscope. A push‐to‐pull deformation device is used to perform quantitative tensile tests, during which force and displacement are measured, while the evolving microstructure is imaged with the microscope. The experiments have been performed at room temperature on 2 × 1 × 0.2 μm3 beams prepared by focused ion beam. The specimens are not single crystals despite their small sizes. Orientation mapping indicated that several grains were well oriented for plastic slip. However, no dislocation activity has been observed even though the engineering tensile stress went up to 700 MPa. We show also that antigorite does not exhibit a purely elastic‐brittle behavior since, despite the presence of defects, the specimens accumulate permanent deformation and did not fail within the elastic regime. Instead, we observe that strain localizes at grain boundaries. All observations concur to show that under these experimental conditions, grain boundary sliding is the dominant deformation mechanism. This study sheds a new light on the mechanical properties of antigorite and calls for further studies on the structure and properties of grain boundaries in antigorite and more generally in phyllosilicates. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000530895800023 |
Publication Date |
2020-02-20 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2169-9313 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.9 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
We thank S. Guillot for having kindly provided us with the two antigorite samples investigated in this study. We acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under Grant Agreement 787198—TimeMan. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR‐FNRS). We acknowledge fruitful discussions with A. Baronnet. We thank J. Gasc and an anonymous reviewer for their critical comments. Data (movies of the three in situ deformation experiments) can be downloaded (from https://doi.org/10.5281/zenodo.3583135). |
Approved |
Most recent IF: 3.9; 2020 IF: 3.35 |
| Call Number |
EMAT @ emat @c:irua:167594 |
Serial |
6355 |
| Permanent link to this record |
| |
|
| |
| Author |
Loenders, B.; Engelmann, Y.; Bogaerts, A. |
| Title |
Plasma-Catalytic Partial Oxidation of Methane on Pt(111): A Microkinetic Study on the Role of Different Plasma Species |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
5 |
Pages |
2966-2983 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Movement Antwerp (MOVANT) |
| Abstract |
We use microkinetic modeling to examine the potential of plasma-catalytic partial oxidation (POX) of CH4 as a promising new approach to produce oxygenates. We study how different plasma species affect POX of CH4 on the Pt(111) surface, and we discuss the associated kinetic and mechanistic changes. We discuss the effect of vibrationally excited CH4 and O2, as well as plasma-generated radicals and stable intermediates. Our results show that vibrational excitation enhances the turnover frequency (TOF) of catalytic CH4 dissociation and has good potential for improving the selectivities toward CH3OH, HCOOH, and C2 hydrocarbons. Nevertheless, when also considering plasma-generated radicals, we find that these species mainly govern the surface chemistry. Additionally, we find that plasma-generated radicals and stable intermediates enhance the TOFs of COx and oxygenates, increase the selectivity toward oxygenates, and make the formation of HCOOH more significant on Pt(111). We also briefly illustrate the potential impact of Eley−Rideal reactions that involve plasma-generated radicals. Finally, we reveal how various radicals affect the catalyst surface chemistry and we link this to the formation of different products. This allows us to make suggestions on how the plasma composition should be altered to improve the formation of desired products. |
| 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 |
|
| Language |
|
Wos |
000619760700017 |
Publication Date |
2021-02-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
Universiteit Antwerpen; Fonds Wetenschappelijk Onderzoek, S001619N ; H2020 European Research Council, 810182 ; We thank Tom Butterworth for the interesting discussions regarding the calculation of the vibrational populations of methane and for taking the time to share his thoughts and experiences on the matter. This research is supported by the FWO-SBO project PLASMACATDesign (grant number S001619N). We also acknowledge financial support from the TOP-BOF project of the University of Antwerp and from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program (grant agreement no. 810182SCOPE ERC Synergy project). The calculations were carried out using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen, a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (Department EWI), and the University of Antwerp. |
Approved |
Most recent IF: 4.536 |
| Call Number |
PLASMANT @ plasmant @c:irua:175873 |
Serial |
6672 |
| Permanent link to this record |
| |
|
| |
| Author |
Renero-Lecuna, C.; Herrero, A.; Jimenez de Aberasturi, D.; Martínez-Flórez, M.; Valiente, R.; Mychinko, M.; Bals, S.; Liz-Marzán, L.M. |
| Title |
Nd3+-Doped Lanthanum Oxychloride Nanocrystals as Nanothermometers |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
36 |
Pages |
19887-19896 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
The development of optical nanothermometers operating in the near-infrared (NIR) is of high relevance toward temperature measurements in biological systems. We propose herein the use of Nd3+-doped lanthanum oxychloride nanocrystals as an efficient system with intense photoluminescence under NIR irradiation in the first biological transparency window and emission in the second biological window with excellent emission stability over time under 808 nm excitation, regardless of Nd3+ concentration, which can be considered as a particular strength of our system. Additionally, surface passivation through overgrowth of an inert LaOCl shell around optically active LaOCl/Nd3+ cores was found to further enhance the photoluminescence intensity and also the lifetime of the 1066 nm, 4F3/2 to 4I11/2 transition, without affecting its (ratiometric) sensitivity toward temperature changes. As required for biological applications, we show that the obtained (initially hydrophobic) nanocrystals can be readily transferred into aqueous solvents with high, long-term stability, through either ligand exchange or encapsulation with an amphiphilic polymer. |
| 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 |
|
| Language |
|
Wos |
000697335100031 |
Publication Date |
2021-09-16 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
9 |
Open Access |
OpenAccess |
| Notes |
The authors thank the financial support of the European Research Council (ERC-AdG-2017 787510, ERC-CoG-2019 815128) and of the European Commission (EUSMI, Grant 731019). This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency−Grant MDM-2017−0720. Realnano; sygmaSB |
Approved |
Most recent IF: 4.536 |
| Call Number |
EMAT @ emat @c:irua:181671 |
Serial |
6831 |
| Permanent link to this record |
| |
|
| |
| Author |
Sanchez-Iglesias, A.; Jenkinson, K.; Bals, S.; Liz-Marzan, L.M. |
| Title |
Kinetic regulation of the synthesis of pentatwinned gold nanorods below room temperature |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
43 |
Pages |
23937-23944 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
The synthesis of gold nanorods requires the presence of symmetry-breaking and shape-directing additives, among which bromide ions and quaternary ammonium surfactants have been reported as essential. As a result, hexadecyltrimethylammonium bromide (CTAB) has been selected as the most efficient surfactant to direct anisotropic growth. One of the difficulties arising from this selection is the low solubility of CTAB in water at room temperature, and therefore the seeded growth of gold nanorods is usually performed at 25 degrees C or above, which has restricted so far the analysis of kinetic effects derived from lower temperatures. We report a systematic study of the synthesis of gold nanorods from pentatwinned seeds using hexadecyltrimethylammonium chloride (CTAC) as the principal surfactant and a low concentration of bromide as shape-directing agent. Under these conditions, the synthesis can be performed at temperatures as low as 8 degrees C, and the corresponding kinetic effects can be studied, resulting in temperature-controlled aspect ratio tunability. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
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Editor |
|
| Language |
|
Wos |
000716453300038 |
Publication Date |
2021-10-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
6 |
Open Access |
OpenAccess |
| Notes |
realnano; sygmaSB; This work was supported by the National Science Foundation (NSF) under award NSF CHE-1808502 (P.C. and I.J.). This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-1720139). D.A E. and S.B. acknowledge funding from the European Research Council under the European Union's Horizon 2020 research and innovation program (ERC Consolidator Grants No. 815128 REALNANO and Grant Agreement No. 731019 EUSMI). |
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:184104 |
Serial |
6868 |
| Permanent link to this record |
| |
|
| |
| Author |
Zhou, X.-G.; Yang, C.-Q.; Sang, X.; Li, W.; Wang, L.; Yin, Z.-W.; Han, J.-R.; Li, Y.; Ke, X.; Hu, Z.-Y.; Cheng, Y.-B.; Van Tendeloo, G. |
| Title |
Probing the electron beam-induced structural evolution of halide perovskite thin films by scanning transmission electron microscopy |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
19 |
Pages |
10786-10794 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
A deep understanding of the fine structure at the atomic scale of halide perovskite materials has been limited by their sensitivity to the electron beam that is widely used for structural characterization. The sensitivity of a gamma-CsPbIBr2 perovskite thin film under electron beam irradiation is revealed by scanning transmission electron microscopy (STEM) through a universal large-range electron dose measurement, which is based on discrete single-electron events in the STEM mode. Our research indicates that the gamma-CsPbIBr2 thin film undergoes structural changes with increasing electron overall dose (e(-).A(-2)) rather than dose rate (e(-).A(-2).s(-1)), which suggests that overall dose is the key operative parameter. The electron beam-induced structural evolution of gamma-CsPbIBr2 is monitored by fine control of the electron beam dose, together with the analysis of high-resolution (S)TEM, diffraction, and energy-dispersive X-ray spectroscopy. Our results show that the gamma-CsPbIBr2 phase first forms an intermediate phase [e.g., CsPb(1-x)(IBr)((3-y))] with a superstructure of ordered vacancies in the pristine unit cell, while a fraction of Pb2+ is reduced to Pb-0. As the electron dose increases, Pb nanoparticles precipitate, while the remaining framework forms the Cs2IBr phase, accompanied by some amorphization. This work provides guidelines to minimize electron beam irradiation artifacts for atomic-resolution imaging on CsPbIBr2 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 |
|
Wos |
000655640900061 |
Publication Date |
2021-05-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
Not_Open_Access |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:179187 |
Serial |
6880 |
| Permanent link to this record |
| |
|
| |
| Author |
Altantzis, T.; Wang, D.; Kadu, A.; van Blaaderen, A.; Bals, S. |
| Title |
Optimized 3D Reconstruction of Large, Compact Assemblies of Metallic Nanoparticles |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
47 |
Pages |
26240-26246 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT) |
| Abstract |
3D characterization of assemblies of nanoparticles is of great importance to determine their structure-property connection. Such investigations become increasingly more challenging when the assemblies become larger and more compact. In this paper, we propose an optimized approach for electron tomography to minimize artefacts related to beam broadening in High Angle Annular Dark-Field Scanning Transmission Electron Microscopy mode. These artefacts are typically present at one side of the reconstructed 3D data set for thick nanoparticle assemblies. To overcome this problem, we propose a procedure in which two tomographic tilt series of the same sample are acquired. After acquiring the first series, the sample is flipped over 180o, and a second tilt series is acquired. By merging the two reconstructions, blurring in the reconstructed volume is minimized. Next, this approach is combined with an advanced three-dimensional reconstruction algorithm yielding quantitative structural information. Here, the approach is applied to a thick and compact assembly of spherical Au nanoparticles, but the methodology can we used to investigate a broad range of samples. |
| 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 |
|
| Language |
|
Wos |
000752810100031 |
Publication Date |
2021-12-02 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
4 |
Open Access |
OpenAccess |
| Notes |
This work was supported by the European Research Council (grant No. 815128−REALNANO to S.B.). T.A. acknowledges the University of Antwerp Research fund (BOF). D.W. and A.v.B. acknowledge partial financial support from the European Research Council under the European Union’s Seventh Framework Program (FP-2007-2013)/ERC Advanced Grant Agreement 291667 HierarSACol. D.W. acknowledges an Individual Fellowship funded by the Marie Sklodowska-Curie Actions (MSCA) in Horizon 2020 program (grant 894254 SuprAtom).; sygmaSB |
Approved |
Most recent IF: 4.536 |
| Call Number |
EMAT @ emat @c:irua:185224 |
Serial |
6904 |
| Permanent link to this record |
| |
|
| |
| Author |
Akbali, B.; Yagmurcukardes, M.; Peeters, F.M.; Lin, H.-Y.; Lin, T.-Y.; Chen, W.-H.; Maher, S.; Chen, T.-Y.; Huang, C.-H. |
| Title |
Determining the molecular orientation on the metal nanoparticle surface through surface-enhanced Raman spectroscopy and density functional theory simulations |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
29 |
Pages |
16289-16295 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
We report here the efficacy of surface-enhanced Raman spectroscopy (SERS) measurements as a probe for molecular orientation. 4-Aminobenzoic acid (PABA) on a surface consisting of silver (Ag) nanoparticles (NPs) is investigated. We find that the orientation of the PABA molecule on the SERS substrate is estimated based on the relative change in the magnitude of the C-H stretching bands on the SERS substrate, and it is found that the molecule assumes a horizontal orientation on the Ag-NP surface. The strong molecule-metal interaction is determined by an abnormal enhanced SERS band appearing at 980 cm(-1), and the peak is assigned to an out-of-plane amine vibrational mode, which is supported by our ab initio calculations. DFT-based Raman activity calculations corroborate the SERS results, revealing that (i) the PABA molecule attaches to the surface of Ag-NPs with its alpha dimers rather than single-molecule binding and (ii) the molecule preserves its alpha dimers in an aqueous environment. Our results demonstrate that SERS can be used to gain deeper insights into the molecular orientation on metal nanoparticle surfaces. |
| 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 |
|
| Language |
|
Wos |
000680445800055 |
Publication Date |
2021-07-19 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
2 |
Open Access |
Not_Open_Access |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:180455 |
Serial |
6978 |
| Permanent link to this record |
| |
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| |
| Author |
Bafekry, A.; Faraji, M.; Fadlallah, M.M.; Mortazavi, B.; Ziabari, A.A.; Khatibani, A.B.; Nguyen, C., V; Ghergherehchi, M.; Gogova, D. |
| Title |
Point defects in a two-dimensional ZnSnN₂ nanosheet : a first-principles study on the electronic and magnetic properties |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
23 |
Pages |
13067-13075 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
The reduction of dimensionality is a very effective way to achieve appealing properties in two-dimensional materials (2DMs). First-principles calculations can greatly facilitate the prediction of 2DM properties and find possible approaches to enhance their performance. We employed first-principles calculations to gain insight into the impact of different types of point defects (vacancies and substitutional dopants) on the electronic and magnetic properties of a ZnSnN2 (ZSN) monolayer. We show that Zn, Sn, and N + Zn vacancy-defected structures are p-type conducting, while the defected ZSN with a N vacancy is n-type conducting. For substitutional dopants, we found that all doped structures are thermally and energetically stable. The most stable structure is found to be B-doping at the Zn site. The highest work function value (5.0 eV) has been obtained for Be substitution at the Sn site. Li-doping (at the Zn site) and Be-doping (at the Sn site) are p-type conducting, while B-doping (at the Zn site) is n-type conducting. We found that the considered ZSN monolayer-based structures with point defects are magnetic, except those with the N vacancy defects and Be-doped structures. The ab initio molecular dynamics simulations confirm that all substitutionally doped and defected structures are thermally stable. Thus, our results highlight the possibility of tuning the magnetism in ZnSnN2 monolayers through defect engineering. |
| 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 |
000664312500063 |
Publication Date |
2021-06-03 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
Not_Open_Access |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:179741 |
Serial |
7012 |
| Permanent link to this record |
| |
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| |
| Author |
Canossa, S.; Ferrari, E.; Sippel, P.; Fischer, J.K.H.; Pfattner, R.; Frison, R.; Masino, M.; Mas-Torrent, M.; Lunkenheimer, P.; Rovira, C.; Girlando, A. |
| Title |
Tetramethylbenzidine-TetrafluoroTCNQ (TMB-TCNQF(4)) : a narrow-gap semiconducting salt with room-temperature relaxor ferroelectric behavior |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
46 |
Pages |
25816-25824 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
We present an extension and revision of the spectroscopic and structural data of the mixed-stack charge-transfer (CT) crystal 3,3 ',5,5 '-tetramethylbenzidine-tetrafluorotetracyano-quinodimethane (TMB-TCNQF4), associated with new electric and dielectric measurements. Refinement of synchrotron structural data at low temperature has led to revise the previously reported C2/m structure. The revised structure is P2(1)/m, with two dimerized stacks per unit cell, and is consistent with the low temperature vibrational data. However, polarized Raman data in the low-frequency region also indicate that by increasing temperature above 200 K, the structure presents an increasing degree of disorder, mainly along the stack axis. X-ray diffraction data at room temperature have confirmed that the correct structure is P2(1)/ m -no phase transitions -but did not allow substantiating the presence of disorder. On the other hand, dielectric measurements have evidenced a typical relaxor ferroelectric behavior already at room temperature, with a peak in the real part of dielectric constant epsilon'(T,v) around 200 K and 0.1 Hz. The relaxor behavior is explained in terms of the presence of spin solitons separating domains of opposite polarity that yield to ferroelectric nanodomains. TMB-TCNQF(4) is confirmed to be a narrow-gap band semiconductor (Ea similar to 0.3 eV) with a room-temperature conductivity of similar to 10(-4) Omega(-1) cm(-1). |
| 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 |
000731170500008 |
Publication Date |
0000-00-00 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
Not_Open_Access |
| Notes |
A.G. thanks Prof. Pascale Foury-Leylekian for very helpful discussions about the crystallographic issues. R.F. thanks Prof. Anthony Linden for his help in the X-ray diffraction data collection. J.K.H.F. and P.L. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) via the Transregional Collaborative Research Center TRR80 (Augsburg, Munich). R.P. and M.M.-T. acknowledge support from the Marie Curie Cofund, Beatriu de Pinós Fellowships (Grant nos. AGAUR 2017 BP 00064). This work was also supported by the Spanish Ministry project GENESIS PID2019-111682RBI00, the “Severo Ochoa” Programme for Centers of Excellence in R&D (FUNFUTURE, CEX2019-000917-S), and the Generalitat de Catalunya (2017-SGR-918). The Elettra Synchrotron (CNR Trieste) is acknowledged for granting the beamtime at the single-crystal diffraction beamline XRD1 (Proposal ID 20185483). In Parma, the work has benefited from the equipment and support of the COMP-HUB Initiative, funded by the “Departments of Excellence” program of the |
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:184866 |
Serial |
7066 |
| Permanent link to this record |
| |
|
| |
| Author |
Demiroglu, I.; Karaaslan, Y.; Kocabas, T.; Keceli, M.; Vazquez-Mayagoitia, A.; Sevik, C. |
| Title |
Computation of the thermal expansion coefficient of graphene with Gaussian approximation potentials |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
26 |
Pages |
14409-14415 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Direct experimental measurement of thermal expansion coefficient without substrate effects is a challenging task for two-dimensional (2D) materials, and its accurate estimation with large-scale ab initio molecular dynamics is computationally very expensive. Machine learning-based interatomic potentials trained with ab initio data have been successfully used in molecular dynamics simulations to decrease the computational cost without compromising the accuracy. In this study, we investigated using Gaussian approximation potentials to reproduce the density functional theory-level accuracy for graphene within both lattice dynamical and molecular dynamical methods, and to extend their applicability to larger length and time scales. Two such potentials are considered, GAP17 and GAP20. GAP17, which was trained with pristine graphene structures, is found to give closer results to density functional theory calculations at different scales. Further vibrational and structural analyses verify that the same conclusions can be deduced with density functional theory level in terms of the reasoning of the thermal expansion behavior, and the negative thermal expansion behavior is associated with long-range out-of-plane phonon vibrations. Thus, it is argued that the enabled larger system sizes by machine learning potentials may even enhance the accuracy compared to small-size-limited ab initio molecular dynamics. |
| 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 |
000672734100027 |
Publication Date |
2021-06-24 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:179850 |
Serial |
7719 |
| Permanent link to this record |
| |
|
| |
| Author |
Van de Sompel, P.; Khalilov, U.; Neyts, E.C. |
| Title |
Contrasting H-etching to OH-etching in plasma-assisted nucleation of carbon nanotubes |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
14 |
Pages |
7849-7855 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
To gain full control over the growth of carbon nanotubes (CNTs) using plasma-enhanced chemical vapor deposition (PECVD), a thorough understanding of the underlying plasma-catalyst mechanisms is required. Oxygen-containing species are often used as or added to the growth precursor gas, but these species also yield various radicals and ions, which may simultaneously etch the CNT during the growth. At present, the effect of these reactive species on the growth onset has not yet been thoroughly investigated. We here report on the etching mechanism of incipient CNT structures from OH and O radicals as derived from combined (reactive) molecular dynamics (MD) and force-bias Monte Carlo (tfMC) simulations. Our results indicate that the oxygen-containing radicals initiate a dissociation process. In particular, we show how the oxygen species weaken the interaction between the CNT and the nanocluster. As a result of this weakened interaction, the CNT closes off and dissociates from the cluster in the form of a fullerene. Beyond the specific systems studied in this work, these results are generically important in the context of PECVD-based growth of CNTs using oxygen-containing precursors. |
| 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 |
|
| Language |
|
Wos |
000641307100032 |
Publication Date |
2021-04-06 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:178393 |
Serial |
7729 |
| Permanent link to this record |
| |
|
| |
| Author |
Nematollahi, P.; Ma, H.; Schneider, W.F.; Neyts, E.C. |
| Title |
DFT and microkinetic comparison of ru-doped porphyrin-like graphene and nanotubes toward catalytic formic acid decomposition and formation |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
34 |
Pages |
18673-18683 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
Immobilization of single metal atoms on a solid host opens numerous possibilities for catalyst designs. If that host is a two-dimensional sheet, sheet curvature becomes a design parameter potentially complementary to host and metal composition. Here, we use a combination of density functional theory calculations and microkinetic modeling to compare the mechanisms and kinetics of formic acid decomposition and formation, chosen for their relevance as a potential hydrogen storage medium, over single Ru atoms anchored to pyridinic nitrogen in a planar graphene flake (RuN4-G) and curved carbon nanotube (RuN4-CNT). Activation barriers are lowered and the predicted turnover frequencies are increased over RuN4-CNT relative to RuN4-CNT. The results highlight the potential of curvature control as a means to achieve high performance and robust catalysts. |
| 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 |
|
| Language |
|
Wos |
000693413400013 |
Publication Date |
2021-08-22 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:181538 |
Serial |
7805 |
| Permanent link to this record |
| |
|
| |
| Author |
Korkmaz, Y.A.; Bulutay, C.; Sevik, C. |
| Title |
k · p parametrization and linear and circular dichroism in strained monolayer (Janus) transition metal dichalcogenides from first-principles |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
125 |
Issue |
13 |
Pages |
7439-7450 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Semiconductor monolayer transition metal dichalcogenides (TMDs) have brought a new paradigm by introducing optically addressable valley degree of freedom. Concomitantly, their high flexibility constitutes a unique platform that links optics to mechanics via valleytronics. With the intention to expedite the research in this direction, we investigated ten TMDs, namely MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, MoSSe, MoSeTe, WSSe, and WSeTe, which particularly includes their so-called janus types (JTMDs). First, we obtained their electronic band structures using regular and hybrid density functional theory (DFT) calculations in the presence of the spin-orbit coupling and biaxial or uniaxial strain. Our DFT results indicated that against the expectations based on their reported piezoelectric behavior, JTMDs typically interpolated between the standard band properties of the constituent TMDs without producing a novel feature. Next, by fitting to our DFT data we generated both spinless and spinful k center dot p parameter sets which are quite accurate over the K valley where the optical activity occurs. As an important application of this parametrization, we considered the circular and linear dichroism under strain. Among the studied (J)TMDs, WTe2 stood out with its largest linear dichroism under uniaxial strain because of its narrower band gap and large K valley uniaxial deformation potential. This led us to suggest WTe2 monolayer membranes for optical polarization-based strain measurements, or conversely, as strain tunable optical polarizers. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000639044400045 |
Publication Date |
2021-03-26 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447; 1932-7455 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.536 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
|
Approved |
Most recent IF: 4.536 |
| Call Number |
UA @ admin @ c:irua:178264 |
Serial |
8136 |
| Permanent link to this record |
| |
|
| |
| Author |
Beckers, A.; Thewissen, M.; Sorée, B. |
| Title |
Energy filtering in silicon nanowires and nanosheets using a geometric superlattice and its use for steep-slope transistors |
Type |
A1 Journal article |
| Year |
2018 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
124 |
Issue |
14 |
Pages |
144304 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
This paper investigates energy filtering in silicon nanowires and nanosheets by resonant electron tunneling through a geometric superlattice. A geometric superlattice is any kind of periodic geometric feature along the transport direction of the nanowire or nanosheet. Multivalley quantum-transport simulations are used to demonstrate the manifestation of minibands and minibandgaps in the transmission spectra of such a superlattice. We find that the presence of different valleys in the conduction band of silicon favors a nanowire with a rectangular cross section for effective energy filtering. The obtained energy filter can consequently be used in the source extension of a field-effect transistor to prevent high-energy electrons from contributing to the leakage current. Self-consistent Schrodinger-Poisson simulations in the ballistic limit show minimum subthreshold swings of 6 mV/decade for geometric superlattices with indentations. The obtained theoretical performance metrics for the simulated devices are compared with conventional III-V superlatticeFETs and TunnelFETs. The adaptation of the quantum transmitting boundary method to the finite-element simulation of 3-D structures with anisotropic effective mass is presented in Appendixes A and B. Our results bare relevance in the search for steep-slope transistor alternatives which are compatible with the silicon industry and can overcome the power-consumption bottleneck inherent to standard CMOS technologies. Published by AIP Publishing. |
| Address |
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| Corporate Author |
|
Thesis |
|
| Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
|
| Language |
|
Wos |
000447148100011 |
Publication Date |
2018-10-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
3 |
Open Access |
|
| Notes |
; ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ lucian @ c:irua:154729UA @ admin @ c:irua:154729 |
Serial |
5099 |
| Permanent link to this record |
| |
|
| |
| 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 |
|
| Language |
|
Wos |
000453254000025 |
Publication Date |
2018-12-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| 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 |
| |
|
| |
| Author |
Verreck, D.; Verhulst, A.S.; Van de Put, M.L.; Sorée, B.; Magnus, W.; Collaert, N.; Mocuta, A.; Groeseneken, G. |
| Title |
Self-consistent procedure including envelope function normalization for full-zone Schrodinger-Poisson problems with transmitting boundary conditions |
Type |
A1 Journal article |
| Year |
2018 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
| Volume |
124 |
Issue |
20 |
Pages |
204501 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
In the quantum mechanical simulation of exploratory semiconductor devices, continuum methods based on a k.p/envelope function model have the potential to significantly reduce the computational burden compared to prevalent atomistic methods. However, full-zone k.p/envelope function simulation approaches are scarce and existing implementations are not self-consistent with the calculation of the electrostatic potential due to the lack of a stable procedure and a proper normalization of the multi-band envelope functions. Here, we therefore present a self-consistent procedure based on a full-zone spectral k.p/envelope function band structure model. First, we develop a proper normalization for the multi-band envelope functions in the presence of transmitting boundary conditions. This enables the calculation of the free carrier densities. Next, we construct a procedure to obtain self-consistency of the carrier densities with the electrostatic potential. This procedure is stabilized with an adaptive scheme that relies on the solution of Poisson's equation in the Gummel form, combined with successive underrelaxation. Finally, we apply our procedure to homostructure In0.53Ga0.47As tunnel field-effect transistors (TFETs) and staggered heterostructure GaAs0.5Sb0.5/In0.53Ga0.47As TFETs and show the importance of self-consistency on the device predictions for scaled dimensions. Published by AIP Publishing. |
| 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 |
|
Wos |
000451743900015 |
Publication Date |
2018-11-30 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.068 |
Times cited |
1 |
Open Access |
|
| Notes |
; This work was supported by imec's Industrial Affiliation Program. ; |
Approved |
Most recent IF: 2.068 |
| Call Number |
UA @ admin @ c:irua:156291 |
Serial |
5228 |
| Permanent link to this record |
| |
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| |
| Author |
Van Alphen, S.; Vermeiren, V.; Butterworth, T.; van den Bekerom, D.C.M.; van Rooij, G.J.; Bogaerts, A. |
| Title |
Power Pulsing To Maximize Vibrational Excitation Efficiency in N2Microwave Plasma: A Combined Experimental and Computational Study |
Type |
A1 Journal article |
| Year |
2020 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
| Volume |
124 |
Issue |
3 |
Pages |
1765-1779 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
Plasma is gaining increasing interest for N2 fixation, being a flexible, electricity-driven alternative for the current conventional fossil fuel-based N2 fixation processes. As the vibrational-induced dissociation of N2 is found to be an energy-efficient pathway to acquire atomic N for the fixation processes, plasmas that are in vibrational nonequilibrium seem promising for this application. However, an important challenge in using nonequilibrium plasmas lies in preventing vibrational−translational (VT) relaxation processes, in which vibrational energy crucial for N2 dissociation is lost to gas heating. We present here both experimental and modeling results for the vibrational and gas temperature in a microsecond-pulsed microwave (MW) N2 plasma, showing how power pulsing can suppress this unfavorable VT relaxation and achieve a maximal vibrational nonequilibrium. By means of our kinetic model, we demonstrate that pulsed plasmas take advantage of the long time scale on which VT processes occur, yielding a very pronounced nonequilibrium over the whole N2 vibrational ladder. Additionally, the effect of pulse parameters like the pulse frequency and pulse width are investigated, demonstrating that the advantage of pulsing to inhibit VT relaxation diminishes for high pulse frequencies (around 7000 kHz) and long power pulses (above 400 μs). Nevertheless, all regimes studied here demonstrate a clear vibrational nonequilibrium while only requiring a limited power-on time, and thus, we may conclude that a pulsed plasma seems very interesting for energyefficient vibrational excitation. |
| 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 |
|
Wos |
000509438600001 |
Publication Date |
2020-01-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1932-7447 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.7 |
Times cited |
|
Open Access |
|
| Notes |
Fonds Wetenschappelijk Onderzoek, 30505023 GoF9618n ; This research was supported by the Excellence of Science FWO-FNRS project (FWO Grant ID GoF9618n, EOS ID 30505023). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. |
Approved |
Most recent IF: 3.7; 2020 IF: 4.536 |
| Call Number |
PLASMANT @ plasmant @c:irua:165586 |
Serial |
5443 |
| Permanent link to this record |
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| |
| Author |
van der Snickt, G.; Legrand, S.; Caen, J.; Vanmeert, F.; Alfeld, M.; Janssens, K. |
| Title |
Chemical imaging of stained-glass windows by means of macro X-ray fluorescence (MA-XRF) scanning |
Type |
A1 Journal article |
| Year |
2016 |
Publication |
Microchemical journal |
Abbreviated Journal |
Microchem J |
| Volume |
124 |
Issue |
|
Pages |
615-622 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES) |
| Abstract |
Since the recent development of a mobile setup, MA-XRF scanning proved a valuable tool for the non-invasive, technical study of paintings. In this work, the applicability of MA-XRF scanning for investigating stained-glass windows inside a conservation studio is assessed by analysis of a high-profile, well-studied late-mediaeval panel. Although accurate quantification of components is not feasible with this analytical imaging technique, plotting the detected intensities of K versus Ca in a scatter plot allowed distinguishing glass fragments of different compositional types within the same panel. In particular, clusters in the Ca/K correlation plot revealed the presence of two subtypes of potash glass and three subtypes of high lime low alkali glass. MA-XRF results proved consistent with previous quantitative SEM-EDX analysis on two samples and analytical-based theories on glass production in the Low Countries formulated in literature. A bi-plot of the intensities of the more energetic Rb-K versus Sr-K emission lines yielded a similar glass type differentiation and is here presented as suitable alternative in case the Ca/K signal ratio is affected by superimposed weathering crusts. Apart from identification of the chromophores responsible for the green, blue and red glass colors, contrasting the associated elemental distribution maps obtained on the exterior and interior side of the glass permitted discriminating between colored pot metal glass and multi-layered flashed glass as well. Finally, the benefit of obtaining compositional information from the entire surface, as opposed to point analysis, was illustrated by the discovery of what appears to be a green cobalt glass a feature that was previously missed on this well-studied stained-glass window, both by connoisseurs and spectroscopic sample analysis. (C) 2015 Elsevier B.V. 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 |
|
Wos |
000367755600074 |
Publication Date |
2015-10-25 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0026-265x; 0026-265x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.034 |
Times cited |
22 |
Open Access |
|
| Notes |
; The staff of the Museums of the City of Bruges, i.e. Director Till-Holger Borchert and Deputy Curator Kristel Van Audenaeren, are acknowledged for this pleasant collaboration and the authorization for the publication of the images in this article. This research was supported by the InBev-Baillet Latour fund. ; |
Approved |
Most recent IF: 3.034 |
| Call Number |
UA @ admin @ c:irua:131100 |
Serial |
5514 |
| Permanent link to this record |
| |
|
| |
| Author |
Monico, L.; Janssens, K.; Cotte, M.; Sorace, L.; Vanmeert, F.; Brunetti, B.G.; Miliani, C. |
| Title |
Chromium speciation methods and infrared spectroscopy for studying the chemical reactivity of lead chromate-based pigments in oil medium |
Type |
A1 Journal article |
| Year |
2016 |
Publication |
Microchemical journal
T2 – TECHNART Conference, APR 27-30, 2015, Catania, ITALY |
Abbreviated Journal |
Microchem J |
| Volume |
124 |
Issue |
|
Pages |
272-282 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic pigments (e.g., vermilion, cadmium yellows, zinc yellows, chrome yellows) are mainly activated by light-exposure. In view of the optimization of the long-term conservation and restoration strategies of paintings it is of relevant interest to establish the consequences of thermal parameters (temperature and relative humidity) on the chemical/photochemical-reactivity and the nature of the alteration products of light sensitive-pigments in oil medium. To this aim here we propose a multi-method analytical approach based on the combination of diffuse reflectance UV-Vis, FTIR, synchrotron radiation (SR)-based micro X-ray fluorescence (mu-XRF)/micro-X-ray absorption neat edge structure ()CANES) and electron paramagnetic resonance (EPR) spectroscopies for studying the effects of different relative humidity conditions before and after light exposure on the reactivity of a series of lead chromate-based pigments [such as PbCrO4 center dot PbO (monoclinic), PbCrO4 (monoclinic) and PbCr0.2S0.8O4 (orthorhombic)] in an oil medium. The investigation of paint models was also compared to that of a late 19th century historical orthorhombic PbCr0.4S0.6O4 oil paint. Diffuse reflectance UV-Vis and FTIR spectroscopies were used to obtain information associated with chromatic changes and the formation of organo-metal degradation products at the paint surface. SR-based Cr K-edge mu-XANES/mu-XRF mapping analysis and EPR spectroscopy were employed in a complementary fashion to determine the amount, nature and distribution of Cr(III) and Cr(V)-based alteration compounds within the paints with micrometric spatial resolution. Under the employed thermal aging conditions, lead(II)-carboxylates and reduced Cr-compounds (in abundance of up to about 35% at the surface) have been identified in the lead chromate-based paints. The tendency of chromates to become reduced increased with increasing moisture levels and was favored for the orthorhombic PbCr0.2S0.8O4 compounds. The redox process gave rise to the formation of Cr(V)-species in relative amount much higher than that was formed in the equivalent paint which was exposed only to light. After light-exposure of the thermally aged paints, compounds ascribable to the oxidation of the organic binder were detected for all the types of pigments. Nevertheless, the previous thermal treatment increased the tendency toward photo-reduction of only the PbCr0.2S0.8O4 pigment. For this light-sensitive compound, the thickness variation of the reduced Cr-rich (ca. 70%) photo-alteration layer with moisture levels could be ascribed to a surface passivation phenomenon that had already occurred before photochemical aging. (C) 2015 Elsevier B.V. All rights reserved. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000367755600042 |
Publication Date |
2015-09-12 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0026-265x; 0026-265x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.034 |
Times cited |
23 |
Open Access |
|
| Notes |
; ; |
Approved |
Most recent IF: 3.034 |
| Call Number |
UA @ admin @ c:irua:131099 |
Serial |
5519 |
| Permanent link to this record |
