“Mechanical behavior of ultrathin sputter deposited porous amorphous Al2O3 films”. van der Rest A, Idrissi H, Henry F, Favache A, Schryvers D, Proost J, Raskin J-P, Van Overmeere Q, Pardoen T, Acta materialia 125, 27 (2017). http://doi.org/10.1016/j.actamat.2016.11.037
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.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 5
DOI: 10.1016/j.actamat.2016.11.037
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“Homogeneous flow and size dependent mechanical behavior in highly ductile Zr 65 Ni 35 metallic glass films”. Ghidelli M, Idrissi H, Gravier S, Blandin J-J, Raskin J-P, Schryvers D, Pardoen T, Acta materialia 131, 246 (2017). http://doi.org/10.1016/j.actamat.2017.03.072
Abstract: Motivated by recent studies demonstrating a high strength – high ductility potential of nano-scale metallic glass samples, the mechanical response of freestanding Zr65Ni35 film with sub-micron thickness has been investigated by combining advanced on-chip tensile testing and electron microscopy. Large deformation up to 15% is found for specimen thicknesses below 500 nm with variations depending on specimen size and frame compliance. The deformation is homogenous until fracture, with no evidence of shear banding. The yield stress is doubled when decreasing the specimen cross-section, reaching ~3 GPa for small cross-sections. The fracture strain variation is related to both the stability of the test device and to the specimen size. The study concludes on clear disconnect between the mechanisms controlling the onset of plasticity and the fracture process.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 42
DOI: 10.1016/j.actamat.2017.03.072
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“Direct nucleation of hexagonal boron nitride on diamond : crystalline properties of hBN nanowalls”. Hoang D-Q, Korneychuk S, Sankaran KJ, Pobedinskas P, Drijkoningen S, Turner S, Van Bael MK, Verbeeck J, Nicley SS, Haenen K, Acta materialia 127, 17 (2017). http://doi.org/10.1016/J.ACTAMAT2017.01.002
Abstract: Hexagonal boron nitride (hBN) nanowalls were deposited by unbalanced radio frequency sputtering on (100)-oriented silicon, nanocrystalline diamond films, and amorphous silicon nitride (Si3N4) membranes. The hBN nanowall structures were found to grow vertically with respect to the surface of all of the substrates. To provide further insight into the nucleation phase and possible lattice distortion of the deposited films, the structural properties of the different interfaces were characterized by transmission electron microscopy. For Si and Si3N4 substrates, turbostratic and amorphous BN phases form a clear transition zone between the substrate and the actual hBN phase of the bulk nanowalls. However, surprisingly, the presence of these phases was suppressed at the interface with a nanocrystalline diamond film, leading to a direct coupling of hBN with the diamond surface, independent of the vertical orientation of the diamond grain. To explain these observations, a growth mechanism is proposed in which the hydrogen terminated surface of the nanocrystalline diamond film leads to a rapid formation of the hBN phase during the initial stages of growth, contrary to the case of Si and Si3N4 substrates. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT2017.01.002
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“Characterization of (Ti,Mo,Cr)C nanoprecipitates in an austenitic stainless steel on the atomic scale”. Cautaerts N, Delville R, Stergar E, Schryvers D, Verwerft M, Acta materialia 164, 90 (2019). http://doi.org/10.1016/j.actamat.2018.10.018
Abstract: Nanometer sized (Ti,Mo,Cr)C (MX-type) precipitates that grew in a 24% cold worked Ti-stabilized austenitic stainless steel (grade DIN 1.4970, member of the 15-15Ti austenitic stainless steels) after heat treatment were fully characterized with transmission electron microscopy (TEM), probe corrected high angle annular dark field scanning transmission electron microscopy (HR-HAADF STEM), and atom probe tomography (APT). The precipitates shared the cube-on-cube orientation with the matrix and were facetted on {111} planes, yielding octahedral and elongated octahedral shapes. The misfit dislocations were believed to have Burgers vectors a/6<112> which was verified by geometrical phase analysis (GPA) strain mapping of a matrix-precipitate interface. The dislocations were spaced five to seven atomic
planes apart, on average slightly wider than expected for the lattice parameters of steel and TiC. Quantitative atom probe tomography analysis of the precipitates showed that precipitates were significantly enriched in Mo, Cr and V, and that they were hypostoichiometric with respect to C. These findings were consistent with a reduced lattice parameter. The precipitates were found primarily on Shockley
partial dislocations originating from the original perfect dislocation network. These novel findings could contribute to the understanding of how TiC nanoprecipitates interact with point defects and matrix dislocations. This is essential for the application of these Ti-stabilized steels in high temperature environments or fast spectrum nuclear fission reactors.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 2
DOI: 10.1016/j.actamat.2018.10.018
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“Resolving the FCC/HCP interfaces of the \gamma'(Ag2Al) precipitate phase in aluminium”. Zhang Z, Rosalie JM, Medhekar NV, Bourgeois L, Acta materialia 174, 116 (2019). http://doi.org/10.1016/J.ACTAMAT.2019.04.058
Abstract: The gamma'(Ag2Al) phase in the Al-Ag alloy system has served as a textbook example for understanding phase transformations, precipitating hexagonal close-packed (HCP) crystals in the face-centred cubic (FCC) aluminium matrix. The gamma' precipitates display fully coherent interfaces at their broad facets and semicoherent interfaces at their edges. Shockley partial dislocations are expected to decorate the semicoherent interface due to the FCC-HCP structural transformation. Determining the exact locations and core structures of interfacial dislocations, however, remains challenging. In this study, we used aberration-corrected scanning transmission electron microscopy and atomistic simulations to re-visit this classical system. We characterised and explained the Ag segregation at coherent interfaces in the early stage of precipitation. For semicoherent interfaces, interfacial dislocations and reconstructions were revealed by bridging advanced microstructure characterisation and atomistic simulations. In particular, we discovered a new FCC/HCP interfacial structure that displays a unique combination of Shockley partial, Lomer-Cottrell and Hirth dislocations that evolve from the known interfacial structure purely composed by Shockley partial dislocations. Our findings show that the FCC-HCP transformation is more complex than hitherto considered, due to the interplay between structure and composition confined at interfaces. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 3
DOI: 10.1016/J.ACTAMAT.2019.04.058
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“Effect of Ag addition on the precipitation evolution and interfacial segregation for Al-Mg-Si alloy”. Weng Y, Ding L, Zhang Z, Jia Z, Wen B, Liu Y, Muraishi S, Li Y, Liu Q, Acta materialia 180, 301 (2019). http://doi.org/10.1016/J.ACTAMAT.2019.09.015
Abstract: The effect of Ag addition on the precipitation evolution and interfacial segregation for Al-Mg-Si alloys was systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atom probe tomography (APT) and density functional theory (DFT) calculation. At the early aging stage, Ag atoms could enter clusters and refine the distribution of these clusters. Then, Ag atoms preferentially segregate at the GP zone/alpha-Al and beta ''/alpha-Al interfaces at the peak aging stage by the replacement of Al atoms in FCC matrix. With prolonging aging time, Ag atoms generally incorporate into the interior of beta '' precipitate, facilitating the formation of QP lattice (a hexagonal network of Si atomic columns) and the local symmetry substructures, Ag sub-unit (1) and Ag sub-unit (2). At the over-aged stage, the Ag sub-unit (1) and Ag sub-unit (2) could transform to the beta'(Ag) (i.e. beta'(Ag1) and beta'(Ag2).) and Q'(Ag) unit cells, respectively. All the precipitates at the over-aging stage have a composite and disordered structure due to the coexistence of different unit cells (beta'(Ag1), beta'(Ag2), Q'(Ag) and beta') and the non-periodic arrangement of Ag atoms within the precipitate. In the equilibrium stage, the incorporated Ag atoms in the precipitates release into the alpha-Al matrix as solute atoms or form Ag particles. In general, Ag atoms undergo a process of “segregate at the precipitate/matrix interface -> incorporate into the interior of precipitate -> release into the alpha-Al matrix” during the precipitation for Al-Mg-Si-Ag alloys. Besides, Ag segregation is found at the interfaces of almost all metastable phases (including GP zone, beta '', beta'/beta'(Ag) phase) in Al-Mg-Si-Ag alloys. The Ag segregation at the beta'/alpha-Al interface could increase the length/diameter ratio of beta' phase and thus promote the additional strengthening potential of these alloys. These findings provide a new route for precipitation hardening by promoting the nucleation and morphology evolution of precipitates. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT.2019.09.015
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“The role of Ti and TiC nanoprecipitates in radiation resistant austenitic steel: A nanoscale study”. Cautaerts N, Delville R, Stergar E, Pakarinen J, Verwerft M, Yang Y, Hofer C, Schnitzer R, Lamm S, Felfer P, Schryvers D, Acta Materialia 197, 184 (2020). http://doi.org/10.1016/J.ACTAMAT.2020.07.022
Abstract: This work encompasses an in-depth transmission electron microscopy and atom probe tomography study of Ti-stabilized austenitic steel irradiated with Fe-ions. The focus is on radiation induced segregation and precipitation, and in particular on how Ti and TiC affect these processes. A 15-15Ti steel (grade: DIN 1.4970) in two thermo-mechanical states (cold-worked and aged) was irradiated at different temperatures up to a dose of 40 dpa. At low irradiation temperatures, the cold-worked and aged materials evolved to a similar microstructure dominated by small Si and Ni clusters, corresponding to segregation to small point defect clusters. TiC precipitates, initially present in the aged material, were found to be unstable under these irradiation conditions. Elevated irradiation temperatures resulted in the nucleation of nanometer sized Cr enriched TiC precipitates surrounded by Si and Ni enriched shells. In addition, nanometer sized Ti- and Mn-enriched G-phase (M6Ni16Si7) precipitates formed, often attached to TiC precipitates. Post irradiation, larger number densities of TiC were observed in the cold-worked material compared to the aged material. This was correlated with a lower volume fraction of G-phase. The findings suggest that at elevated irradiation temperatures, the precipitate-matrix interface is an important point defect sink and contributes to the improved radiation resistance of this material. The study is a first of its kind on stabilized steel and demonstrates the significance of the small Ti addition to the evolution of the microstructure under irradiation. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/J.ACTAMAT.2020.07.022
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“Novel class of nanostructured metallic glass films with superior and tunable mechanical properties”. Ghidelli M, Orekhov A, Bassi AL, Terraneo G, Djemia P, Abadias G, Nord M, Béché, A, Gauquelin N, Verbeeck J, Raskin J-p, Schryvers D, Pardoen T, Idrissi H, Acta Materialia , 116955 (2021). http://doi.org/10.1016/j.actamat.2021.116955
Abstract: A novel class of nanostructured Zr50Cu50 (%at.) metallic glass films with superior and tunable mechanical
properties is produced by pulsed laser deposition. The process can be controlled to synthetize a wide
range of film microstructures including dense fully amorphous, amorphous embedded with nanocrystals
and amorphous nano-granular. A unique dense self-assembled nano-laminated atomic arrangement
characterized by alternating Cu-rich and Zr/O-rich nanolayers with different local chemical enrichment
and amorphous or amorphous-crystalline composite nanostructure has been discovered, while
significant in-plane clustering is reported for films synthetized at high deposition pressures. This unique
nanoarchitecture is at the basis of superior mechanical properties including large hardness and elastic
modulus up to 10 and 140 GPa, respectively and outstanding total elongation to failure (>9%), leading to
excellent strength/ductility balance, which can be tuned by playing with the film architecture. These
results pave the way to the synthesis of novel class of engineered nanostructured metallic glass films
with high structural performances attractive for a number of applications in microelectronics and
coating industry.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 27
DOI: 10.1016/j.actamat.2021.116955
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“Rheology of amorphous olivine thin films characterized by nanoindentation”. Baral P, Orekhov A, Dohmen R, Coulombier M, Raskin JP, Cordier P, Idrissi H, Pardoen T, Acta Materialia 219, 117257 (2021). http://doi.org/10.1016/J.ACTAMAT.2021.117257
Abstract: The rheological properties of amorphous olivine thin films deposited by pulsed laser deposition have been studied based on ambient temperature nanoindentation under constant strain-rate as well as re-laxation conditions. The amorphous olivine films exhibit a viscoelastic-viscoplastic behavior with a significant rate dependency. The strain-rate sensitivity m is equal to similar to 0 . 05 which is very high for silicates, indicating a complex out-of-equilibrium structure. The minimum apparent activation volume determined from nanoindentation experiments corresponds to Mg and Fe atomic metallic sites in the (Mg,Fe)(2)SiO4 crystalline lattice. The ambient temperature creep behavior of the amorphous olivine films differs very much from the one of single crystal olivine. This behavior directly connects to the recent demonstration of the activation of grain boundary sliding in polycrystalline olivine following grain boundary amorphization under high-stress. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT.2021.117257
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“Shearing and rotation of β'' and β' precipitates in an Al-Mg-Si alloy under tensile deformation : in-situ and ex-situ studies”. Yang M, Orekhov A, Hu Z-Y, Feng M, Jin S, Sha G, Li K, Samaee V, Song M, Du Y, Van Tendeloo G, Schryvers D, Acta Materialia 220, 117310 (2021). http://doi.org/10.1016/J.ACTAMAT.2021.117310
Abstract: The interaction between dislocations and nano-precipitates during deformation directly influences hardening response of precipitation-strengthening metals such as Al-Mg-Si alloys. However, how coherent and semi-coherent nano-precipitates accommodate external deformation applied to an Al alloy remains to be elucidated. In-situ tensile experiments in a transmission electron microscope (TEM) were conducted to study the dynamic process of dislocations cutting through coherent needle-like beta '' precipitates with diameters of 3 similar to 8 nm. Comprehensive investigations using in-situ, ex-situ TEM and atom probe tomography uncovered that beta '' precipitates were firstly sheared into small fragments, and then the rotation of the fragments, via sliding along precipitate/matrix interfaces, destroyed their initially coherent interface with the Al matrix. In contrast, semi-coherent beta' precipitates with sizes similar to beta '' were more difficult to be fragmented and accumulation of dislocations at the interface increased interface misfit between beta' and the Al matrix. Consequently, beta' precipitates could basically maintain their needle-like shape after the tensile deformation. This research gains new insights into the interaction between nano-precipitates and dislocations. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT.2021.117310
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“Shear banding-activated dynamic recrystallization and phase transformation during quasi-static loading of β-metastable Ti &ndash, 12 wt % Mo alloy”. Choisez L, Ding L, Marteleur M, Kashiwar A, Idrissi H, Jacques PJ, Acta materialia 235, 118088 (2022). http://doi.org/10.1016/J.ACTAMAT.2022.118088
Abstract: Dynamic recrystallization (DRX) within adiabatic shear bands forming during the fracture of TRIP-TWIP β−metastable Ti-12Mo (wt %) alloy was recently reported. The formation of 1-3 µm thick-adiabatic shear bands, and of dynamic recrystallization, was quite surprising as their occurrence generally requires high temperature and/or high strain rate loading while these samples were loaded in quasi-static conditions at room temperature. To better understand the fracture mechanism and associated microstructural evolution, thin foils representative of different stages of the fracture process were machined from the fracture surface by Focused Ion Beam (FIB) and analyzed by Transmission Electron Microscopy (TEM) and Automated Crystal Orientation mapping (ACOM-TEM). Complex microstructure transformations involving severe plastic deformed nano-structuration, crystalline rotation and local precipitation of the omega phase were identified. The spatial and temporal evolution of the microstructure during the propagation of the crack was explained through dynamic recovery and continuous dynamic recrystallization, and linked to the modelled distribution of temperature and strain level where TEM samples were extracted.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/J.ACTAMAT.2022.118088
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“The effect of microstructure and film composition on the mechanical properties of linear antenna CVD diamond thin films”. Mary Joy R, Pobedinskas P, Baule N, Bai S, Jannis D, Gauquelin N, Pinault-Thaury M-A, Jomard F, Sankaran KJ, Rouzbahani R, Lloret F, Desta D, D’Haen J, Verbeeck J, Becker MF, Haenen K, Acta materialia 264, 119548 (2024). http://doi.org/10.1016/j.actamat.2023.119548
Abstract: This study reports the impact of film microstructure and composition on the Young’s modulus and residual stress in nanocrystalline diamond (NCD) thin films ( thick) grown on silicon substrates using a linear antenna microwave plasma-enhanced chemical vapor deposition (CVD) system. Combining laser acoustic wave spectroscopy to determine the elastic properties with simple wafer curvature measurements, a straightforward method to determine the intrinsic stress in NCD films is presented. Two deposition parameters are varied: (1) the substrate temperature from 400 °C to 900 °C, and (2) the [P]/[C] ratio from 0 ppm to 8090 ppm in the H2/CH4/CO2/PH3 diamond CVD plasma. The introduction of PH3 induces a transition in the morphology of the diamond film, shifting from NCD with larger grains to ultra-NCD with a smaller grain size, concurrently resulting in a decrease in Young’s modulus. Results show that the highest Young’s modulus of (113050) GPa for the undoped NCD deposited at 800 °C is comparable to single crystal diamond, indicating that NCD with excellent mechanical properties is achievable with our process for thin diamond films. Based on the film stress results, we propose the origins of tensile intrinsic stress in the diamond films. In NCD, the tensile intrinsic stress is attributed to larger grain size, while in ultra-NCD films the tensile intrinsic stress is due to grain boundaries and impurities.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/j.actamat.2023.119548
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“A new healing strategy for metals : programmed damage and repair”. Arseenko M, Hannard F, Ding L, Zhao L, Maire E, Villanova J, Idrissi H, Simar A, Acta materialia 238, 118241 (2022). http://doi.org/10.1016/J.ACTAMAT.2022.118241
Abstract: Self-healing strategies aim at avoiding part repair or even replacement, which is time consuming, expen-sive and generates waste. However, strategies for metallic systems are still under-developed and solid-state solutions for room temperature service are limited to nano-scale damage repair. Here we propose a new healing strategy of micron-sized damage requiring only short and low temperature heating. This new strategy is based on damage localization particles, which can be healed by fast diffusing atoms of the matrix activated during heat treatment. The healing concept was successfully validated with a com-mercial aluminum alloy and manufactured by Friction Stir Processing (FSP). Damage was demonstrated to initiate on particles that were added to the matrix during material processing. In situ 2D and 3D nano -imaging confirmed healing of the damaged material and showed that heating this material for 10 min at 400 degrees C is sufficient to heal incipient damage with complete filling of 70% of all damage (and up to 90% when their initial size is below 0.2 mu m). Furthermore, strength is retained and the work of fracture of the alloy is improved by about 40% after healing. The proposed Programmed Damage and Repair healing strategy could be extended to other metal based systems presenting precipitation. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/J.ACTAMAT.2022.118241
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“On the formation mechanisms of intragranular shear bands in olivine by stress-induced amorphization”. Idrissi H, Béché, A, Gauquelin N, Ul-Haq I, Bollinger C, Demouchy S, Verbeeck J, Pardoen T, Schryvers D, Cordier P, Acta materialia 239, 118247 (2022). http://doi.org/10.1016/J.ACTAMAT.2022.118247
Abstract: Intragranular amorphization shear lamellae are found in deformed olivine aggregates. The detailed trans-mission electron microscopy analysis of intragranular lamella arrested in the core of a grain provides novel information on the amorphization mechanism. The deformation field is complex and heteroge-neous, corresponding to a shear crack type instability involving mode I, II and III loading components. The formation and propagation of the amorphous lamella is accompanied by the formation of crystal defects ahead of the tip. These defects are geometrically necessary [001] dislocations, characteristics of high-stress deformation in olivine, and rotational nanodomains which are tentatively interpreted as disclinations. We show that these defects play an important role in dictating the path followed by the amorphous lamella. Stress-induced amorphization in olivine would thus result from a direct crystal-to -amorphous transformation associated with a shear instability and not from a mechanical destabilization due to the accumulation of high number of defects from an intense preliminary deformation. The pref-erential alignment of some lamellae along (010) is a proof of the lower ultimate mechanical strength of these planes.(c) 2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
Times cited: 5
DOI: 10.1016/J.ACTAMAT.2022.118247
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“On-chip very low strain rate rheology of amorphous olivine films”. Coulombier M, Baral P, Orekhov A, Dohmen R, Raskin JP, Pardoen T, Cordier P, Idrissi H, Acta materialia 266, 119693 (2024). http://doi.org/10.1016/J.ACTAMAT.2024.119693
Abstract: Recent observations made by the authors revealed the activation of stress induced amorphization and sliding at grain boundary in olivine [1], a mechanism which is expected to play a pivotal role in the viscosity drop at the lithosphere-asthenosphere boundary and the brittle -ductile transition in the lithospheric mantle. However, there is a lack of information in the literature regarding the intrinsic mechanical properties and the elementary deformation mechanisms of this material, especially at time scales relevant for geodynamics. In the present work, amorphous olivine films were obtained by pulsed laser deposition (PLD). The mechanical response including the rate dependent behavior are investigated using a tension -on -chip (TOC) method developed at UCLouvain allowing to perform creep/relaxation tests on thin films at extremely low strain rates. In the present work, strain rate down to 10-12 s- 1 was reached which is unique. High strain rate sensitivity of 0.054 is observed together with the activation of relaxation at the very early stage of deformation. Furthermore, digital image correlation (DIC), used for the first time on films deformed by TOC, reveals local strain heterogeneities. The relationship between such heterogeneities, the high strain rate sensitivity and the effect of the electron beam in the scanning electron microscope is discussed and compared to the literature.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/J.ACTAMAT.2024.119693
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“Electron microscopy study of the formation of Ni5Al3 in a Ni62.5Al37.5 B2 alloy: 1: precipitation and growth”. Schryvers D, Ma Y, Toth L, Tanner LE, Acta metallurgica et materialia 43, 4045 (1995). http://doi.org/10.1016/0956-7151(95)00101-Z
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 27
DOI: 10.1016/0956-7151(95)00101-Z
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“Electron microscopy study of the formation of Ni5Al3 in a Ni62.5Al37.5 B2 alloy: 2: plate crystallography”. Schryvers D, Ma Y, Toth L, Tanner LE, Acta metallurgica et materialia 43, 4057 (1995). http://doi.org/10.1016/0956-7151(95)00102-2
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 11
DOI: 10.1016/0956-7151(95)00102-2
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“HREM and ED study of the displacive transformation of the Ni2Al phase in a Ni65Al35 alloy and associated with the martensitic transformation”. Muto S, Schryvers D, Merk N, Tanner LE, Acta metallurgica et materialia 41, 2377 (1993)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 31
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“Structural analysis of CuInSe2, CuInTe2 and CuInSeTe by electron microscopy and X-ray techniques”. Leon M, Merino JM, Van Tendeloo G, Acta Microscopica 18, 128 (2009)
Abstract: A structural research of semiconductor compounds for photovoltaic applications CuInSe(2), CuInTe(2) and CuInSeTe, has been done by x-ray diffraction using the Rietveld analysis of experimental diagrams. Besides, in the CuInSeTe compound the electron diffraction and high resolution microscopy techniques have been used. All the studied compounds were polycrystals with chalcopyrite tetragonal structure, I. 42d. A model for the atomic occupancy in each compound has been proposed, and the results have been compared analyzing the Se-Te substitution effect.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.07
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“Laser microprobe mass analysis (LAMMA) to study lead intoxication at the subcellular level”. Vandeputte DF, Verbueken AH, Jacob WA, Van Grieken RE, Acta pharmacologica et toxicologica 59, 617 (1986). http://doi.org/10.1111/J.1600-0773.1986.TB02840.X
Keywords: A3 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1111/J.1600-0773.1986.TB02840.X
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“Magnetoexcitons in semiconductor quantum rings with complicated (Kane's) dispersion law”. Avetisyan AA, Ghazaryan AV, Djotyan AP, Kirakosyan AA, Moulopoulos K, Acta physica Polonica: A: general physics, solid state physics, applied physics
T2 –, 4th Workshop on Quantum Chaos and Localisation Phenomena, MAY 22-24, 2009, Polish Acad Sci, Ctr Theoret Phys, Inst Phys, Polish Acad Sci, Ctr Theoret Phys, Inst Phys, War 116, 826 (2009). http://doi.org/10.12693/APHYSPOLA.116.826
Abstract: The influence of the nonparabolicity of charge carriers dispersion law (Kane's dispersion) on a magnetoexciton energy spectrum in InSb quantum rings is theoretically investigated The analytical expression for the energy spectrum of exciton in a narrow-gap semiconductor nanoring in a magnetic field is obtained. The Aharonov – Bohm oscillations in the energy of excited states are studied.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.12693/APHYSPOLA.116.826
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“Free-standing Si and Ge, and Ge/Si core-shell semiconductor nanowires”. Peelaers H, Partoens B, Peeters FM, Acta physica Polonica: A: general physics, solid state physics, applied physics
T2 –, WELCOME Scientific Meeting on Hybrid Nanostructures, AUG 28-31, 2011, Torun, POLAND 122, 294 (2012)
Abstract: The properties of free-standing silicon and germanium nanowires oriented along the [110] direction are studied using different first principles methods. We show the corrections due to quasi-particles to the band structures obtained using the local-density approximation. The formation energies of B and P doped nanowires are calculated, both in the absence and presence of dangling bond defects and we link these to experimental results. Furthermore, we report on the phonon properties of pure Si and Ge nanowires, as well as Ge/Si core-shell nanowires, and discuss the differences between them.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.469
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“Classical nature of quantum dots in a magnetic field”. Anisimovas E, Matulis A, Peeters FM, Acta physica Polonica: A: general physics, solid state physics, applied physics 107, 188 (2005)
Abstract: A quasiclassical theory of few-electron quantum dots in a strong magnetic field is developed. The ground state energy and the corresponding many-electron wave function are obtained and used to derive a universal relation of critical magnetic fields and calculate the currents and the density-current correlation function.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.469
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“Electron microscopy and X-ray structural investigations of incommensurate spin-ladder Sr4.1Ca4.7Bi0.3Cu17O29 single crystals”. Dluzewski P, Pietraszko A, Kozlowski M, Szczepanska A, Gorecka J, Baran M, Leonyuk L, Babonas GJ, Lebedev OI, Szymczak R, Acta physica Polonica: A: general physics, solid state physics, applied physics 98, 729 (2000)
Abstract: Transmission electron microscopy and X-ray diffraction proved chain/ladder incommensurate single crystal structure of investigated samples. The incommensurate ratio was determined from the X-ray and electron diffraction being equal to 0.704. Diffuse scattering intensities localised on the planes perpendicular to the c*-axis and passing through the spots originating from the periodicity of chain sublattice were detected. High-angle grain boundary or twinning formed by rotation of 33.3 degrees around [100] direction was observed. High-resolution electron microscopy images revealed the stacking faults in ac planes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.469
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“Interband optical properties of concentric type-I nanorings in a normal magnetic field”. Arsoski V, Tadić, M, Peeters FM, Acta physica Polonica: A: general physics, solid state physics, applied physics 117, 733 (2010)
Abstract: Two concentric two-dimensional GaAs/(Al,Ga)As nanorings in a normal magnetic field are theoretically studied. The single-band effective mass approximation is adopted for both the electron and the hole states, and the analytical solutions are given. We find that the electronic single particle states are arranged in pairs, which exhibit anticrossings and the orbital momentum transitions in the energy spectrum when magnetic field increases. Their period is essentially determined by the radius of the outer ring. The oscillator strength for interband transitions is strongly reduced close to each anticrossing. We show that an optical excitonic Aharonov-Bohm effect may occur in concentric nanorings.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.469
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“The optical excitonic Aharonov-Bohm effect in a few nanometer wide type-I nanorings”. Tadić, M, Arsoski V, Čukarić, N, Peeters FM, Acta physica Polonica: A: general physics, solid state physics, applied physics 117, 974 (2010)
Abstract: The optical excitonic Aharonov-Bohm effect in type-1 three-dimensional (In, Ga)As/GaAs nanorings in theoretically explored. The single-particle states of the electron and the hole are extracted from the effective mass theory in the presence of inhomogeneous strain, and an exact numerical diagonalization approach is used to compute the exciton states and the oscillator strength fx for exciton recombination. We studied both the large lithographically-defined and small self-assembled rings. Only in smaller self-assembled nanorings we found optical excitonic AharonovBohm effect. Those oscillations are established by anticrossings between the optically active exciton states with zero orbital momentum. In lithographically defined rings, whose average radius is 33 nm, fx shows no oscillations, whereas in the smaller self-assembled nanoring with average radius of 11.5 nm oscillations in fx for the ground exciton state are found as function of the magnetic field that is superposed on a linear dependence. These oscillations are smeared out at finite temperature, thus photoluminescence intensity exhibits step-like variation with magnetic field even at temperature as small as 4.2 K.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.469
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“Chemical analysis in metal processing: overview and future needs in refined and ultrapure metals”. Gijbels R, Acta technica Belgica: metallurgie 30, 91 (1991)
Keywords: A3 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Superconducting YBa2Cu3O7-δNanocomposites Using Preformed ZrO2Nanocrystals: Growth Mechanisms and Vortex Pinning Properties”. De Keukeleere K, Cayado P, Meledin A, Vallès F, De Roo J, Rijckaert H, Pollefeyt G, Bruneel E, Palau A, Coll M, Ricart S, Van Tendeloo G, Puig T, Obradors X, Van Driessche I, Advanced Electronic Materials 2, 1600161 (2016). http://doi.org/10.1002/aelm.201600161
Abstract: Although high temperature superconductors are promising for power applications, the production of low-cost coated conductors with high current densities—at high magnetic fields—remains challenging. A superior superconducting YBa2Cu3O7–δ nanocomposite is fabricated via chemical solution deposition (CSD) using preformed nanocrystals (NCs). Preformed, colloidally stable ZrO2 NCs are added to the trifluoroacetic acid based precursor solution and the NCs' stability is confirmed up to 50 mol% for at least 2.5 months. These NCs tend to disrupt the epitaxial growth of YBa2Cu3O7–δ, unless a thin seed layer is applied. A 10 mol% ZrO2 NC addition proved to be optimal, yielding a critical current density JC of 5 MA cm−2 at 77 K in self-field. Importantly, this new approach results in a smaller magnetic field decay of JC(H//c) for the nanocomposite compared to a pristine film. Furthermore, microstructural analysis of the YBa2Cu3O7–δ nanocomposite films reveals that different strain generation mechanisms may occur compared to the spontaneous segregation approach. Yet, the generated nanostrain in the YBa2Cu3O7–δ nanocomposite results in an improvement of the superconducting properties similar to the spontaneous segregation approach. This new approach, using preformed NCs in CSD coatings, can be of great potential for high magnetic field applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 26
DOI: 10.1002/aelm.201600161
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“Hybrid YBa2Cu3O7 superconducting-ferromagnetic nanocomposite thin films prepared from colloidal chemical solutions”. Bartolome E, Cayado P, Solano E, Mocuta C, Ricart S, Mundet B, Coll M, Gazquez J, Meledin A, Van Tendeloo G, Valvidares SM, Herrero-Martin J, Gargiani P, Pellegrin E, Magen C, Puig T, Obradors X, Advanced Electronic Materials 3, 1700037 (2017). http://doi.org/10.1002/AELM.201700037
Abstract: High T-c superconductor-ferromagnetic heterostructures constitute an appealing playground to study the interplay between flux vortices and magnetic moments. Here, the capability of a solution-derived route to grow hybrid YBa2Cu3O7-ferromagnetic nanocomposite epitaxial thin films from preformed spinel ferrite (MFe2O4, M = Mn, Co) nanoparticles (NPs) is explored. The characterization, performed using a combination of structural and magnetic techniques, reveals the complexity of the resulting nanocomposites. Results show that during the YBCO growth process, most of the NPs evolve to ferromagnetic double-perovskite (DP) phases (YBaCu2-x-yFexCoyO5/YBaCoFeO5), while a residual fraction of preformed ferrite NPs may remain in the YBCO matrix. Magnetometry cycles reflect the presence of ferromagnetic structures associated to the DPs embedded in the superconducting films. In addition, a superparamagnetic signal that may be associated with a diluted system of ferromagnetic clusters around complex defects has been detected, as previously observed in standard YBCO films and nanocomposites. The hybrid nanocomposites described in this work will allow studying several fundamental issues like the nucleation of superconductivity and the mechanisms of magnetic vortex pinning in superconducting/ferromagnetic heterostructures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.193
Times cited: 7
DOI: 10.1002/AELM.201700037
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“Exploiting the novel electronic and magnetic structure of C3Nvia functionalization and conformation”. Bafekry A, Stampfl C, Shayesteh SF, Peeters FM, Advanced Electronic Materials 5, 1900459 (2019). http://doi.org/10.1002/AELM.201900459
Abstract: 2D polyaniline, C3N, is of recent high interest due to its unusual properties and potential use in various technological applications. In this work, through systematic first-principles calculations, the atomic, electronic, and magnetic structure of C3N and the changes induced due to functionalization by the adsorption of hydrogen, oxygen, and fluorine, for different coverages and sites, as well as on formation of nanoribbons including the effect of adsorbed hydrogen and oxygen, and the effect of strain, are investigated. Among other interesting phenomena, for hydrogen adsorption, a semiconductor-to-topological insulator transition, where two Dirac-points appear around the Fermi level, as well as ferromagnetic ordering for both hydrogen and oxygen functionalization, is identified. Considering C3N nanoribbons, adsorption of H leads to significant changes in the electronic properties, such as transforming the structures from semiconductor to metallic. Furthermore, investigating the effect of strain on the physical properties, it is found that the band gap can be significantly altered and controlled. The present findings predict that a wide variation in the magnetic and electronic structure of C3N can be achieved by adatom functionalization and conformation indicating its high potential for use in various technological applications, ranging from catalysis, energy storage, and nanoelectronic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.193
Times cited: 39
DOI: 10.1002/AELM.201900459
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