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“DSC cycling effects on phase transformation temperatures of micron and submicron grain Ni50.8Ti49.2 microwires”. Pourbabak S, Verlinden B, Van Humbeeck J, Schryvers D, Shape memory and superelasticity , 1 (2020). http://doi.org/10.1007/S40830-020-00278-Y
Abstract: The effect of thermal cycling parameters on the phase transformation temperatures of micron and submicron grain size recrystallized Ni-Ti microwires was investigated. The suppression of martensitic transformation by thermal cycling was found to enhance when combined with room temperature aging between the cycles and enhances even more when aged at elevated temperature of 100 degrees C. While aging at room temperature alone has no clear effect on the martensitic transformation, elevated temperature aging at 100 degrees C alone suppresses the martensitic transformation. All aforementioned effects were found to be stronger in large grain samples than in small grain samples. Martensitic transformation suppression in all cases was in line with the formation of Ni4Ti3 precursors in the form of < 111 & rang;(B2) Ni clusters as concluded from the observed diffuse intensity in the electron diffraction patterns revealing short-range ordering enhancement. Performing thermal cycling in some different temperature ranges to separate the effect of martensitic transformation and high temperature range of DSC cycling revealed that both high temperature- and martensitic transformation-included cycles enhance the short-range ordering.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1007/S40830-020-00278-Y
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“Doubling the critical temperature of La1.9Sr0.1CuO4 using epitaxial strain”. Loquet J-P, Perret J, Fompeyrine J, Mächler E, Seo JW, Van Tendeloo G, Nature 394, 453 (1998). http://doi.org/10.1038/28810
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 40.137
Times cited: 404
DOI: 10.1038/28810
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“Double moiré, with a twist : supermoiré, in encapsulated graphene”. Andelkovic M, Milovanović, SP, Covaci L, Peeters FM, Nano Letters 20, 979 (2020). http://doi.org/10.1021/ACS.NANOLETT.9B04058
Abstract: A periodic spatial modulation, as created by a moire pattern, has been extensively studied with the view to engineer and tune the properties of graphene. Graphene encapsulated by hexagonal boron nitride (hBN) when slightly misaligned with the top and bottom hBN layers experiences two interfering moire patterns, resulting in a so-called supermoire (SM). This leads to a lattice and electronic spectrum reconstruction. A geometrical construction of the nonrelaxed SM patterns allows us to indicate qualitatively the induced changes in the electronic properties and to locate the SM features in the density of states and in the conductivity. To emphasize the effect of lattice relaxation, we report band gaps at all Dirac-like points in the hole doped part of the reconstructed spectrum, which are expected to be enhanced when including interaction effects. Our result is able to distinguish effects due to lattice relaxation and due to the interfering SM and provides a clear picture on the origin of recently experimentally observed effects in such trilayer heterostuctures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 10.8
Times cited: 48
DOI: 10.1021/ACS.NANOLETT.9B04058
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“Double modulation and microstructure of the thermoelectric misfit compound \left[Ca2-yLnyCu0.7+yCo1.3-yO4\right]\left[CoO2\right]b_{1/b2} (Ln = Pr, Y and 0\leq y\leq1/3)”. Créon N, Pérez O, Hadermann J, Klein Y, Hébert S, Hervieu M, Raveau B, Chemistry of materials 18, 5355 (2006). http://doi.org/10.1021/cm061163a
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 6
DOI: 10.1021/cm061163a
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“Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting”. de Backer A, Martinez GT, MacArthur KE, Jones L, Béché, A, Nellist PD, Van Aert S, Ultramicroscopy 151, 56 (2015). http://doi.org/10.1016/j.ultramic.2014.11.028
Abstract: Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.843
Times cited: 29
DOI: 10.1016/j.ultramic.2014.11.028
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“Doping of interfaces in (La0.7Sr0.3MnO3)1-x:(MgO)x composite films”. Köster S, Moshnyaga V, Samwer K, Lebedev OI, Van Tendeloo G, Shapoval O, Belenchuk A, Applied physics letters 81, 1648 (2002). http://doi.org/10.1063/1.1503849
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 35
DOI: 10.1063/1.1503849
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“Doping of Bi4Fe5O13F with pentagonal Cairo lattice with Cr and Mn: Synthesis, structure and magnetic properties”. Rozova MG, Grigoriev VV, Tyablikov OA, Filimonov DS, Zakharov KV, Volkova OS, Vasiliev AN, Antipov EV, Abakumov AM, Materials research bulletin 87, 54 (2017). http://doi.org/10.1016/J.MATERRESBULL.2016.11.018
Abstract: The substitution of Cr3+ and Mn3+ for Fe3+ in the Bi4Fe6O13F oxyfluoride featuring the magnetically frustrated pentagonal Cairo lattice is reported. Bi4Fe4.1Cr0.9O13F and BiFe4.2Mn0.8O13F have been prepared using a solid state reaction in inert atmosphere. Their crystal structures were studied with transmission electron microscopy, powder X-ray diffraction and Fe-57 Mossbauer spectroscopy (S.G. P4(2)/mbc, a = 8.27836(2)angstrom, c = 18.00330(9) angstrom, R-F = 0.031 (Bi4Fe4.1Cr0.9O13F)), a= 8.29535(3)angstrom, c= 18.0060(1)angstrom, R-F = 0.027 (Bi4Fe4.1Cr0.9O13F)). The structures are formed by infinite rutile-like chains of the edge sharing BO6 octahedra (B transition metal cations) linked by the Fe2O7 groups of two corner-sharing tetrahedra. The"voids in thus formed framework are occupied by the Bi4F tetrahedra. The Fe-57 Mossbauer spectroscopy reveals that Cr3+ and Mn3+ replace Fe3+. exclusively at the octahedral positions. The Mn- and Cr-doped compounds demonstrate antiferromagnetic ordering below T-N =165 K and 120 K, respectively. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.446
Times cited: 1
DOI: 10.1016/J.MATERRESBULL.2016.11.018
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“Doping anatase TiO2with group V-b and VI-b transition metal atoms: a hybrid functional first-principles study”. Matsubara M, Saniz R, Partoens B, Lamoen D, Physical chemistry, chemical physics 19, 1945 (2017). http://doi.org/10.1039/C6CP06882K
Abstract: We investigate the role of transition metal atoms of group V-b (V, Nb, Ta) and VI-b (Cr, Mo, W) as n- or p-type dopants in anatase TiO$_2$ using thermodynamic
principles and density functional theory with the Heyd-Scuseria-Ernzerhof HSE06 hybrid functional. The HSE06 functional provides a realistic value for the band gap, which ensures a correct classification of dopants as shallow or deep donors or acceptors. Defect formation energies and thermodynamic transition levels are calculated taking into account the constraints imposed by the stability of TiO$_2$ and the solubility limit of the impurities.
Nb, Ta, W and Mo are identified as shallow donors. Although W provides two electrons, Nb and Ta show a considerable lower formation energy, in particular under O-poor conditions. Mo donates in principle one electron, but under specific conditions can turn into a double donor. V impurities are deep donors and Cr
shows up as an amphoteric defect, thereby acting as an electron trapping center in n-type TiO$_2$ especially under O-rich conditions. A comparison with the available experimental data yields excellent agreement.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 4.123
Times cited: 19
DOI: 10.1039/C6CP06882K
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“Dopant-induced electron localization drives CO2 reduction to C2 hydrocarbons”. Zhou Y, Che F, Liu M, Zou C, Liang Z, De Luna P, Yuan H, Li J, Wang Z, Xie H, Li H, Chen P, Bladt E, Quintero-Bermudez R, Sham T-K, Bals S, Hofkens J, Sinton D, Chen G, Sargent EH, Nature chemistry 10, 974 (2018). http://doi.org/10.1038/S41557-018-0092-X
Abstract: The electrochemical reduction of CO2 to multi-carbon products has attracted much attention because it provides an avenue to the synthesis of value-added carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the efficiency of CO2 conversion to C-2 products remains below that necessary for its implementation at scale. Modifying the local electronic structure of copper with positive valence sites has been predicted to boost conversion to C-2 products. Here, we use boron to tune the ratio of Cu delta+ to Cu-0 active sites and improve both stability and C-2-product generation. Simulations show that the ability to tune the average oxidation state of copper enables control over CO adsorption and dimerization, and makes it possible to implement a preference for the electrosynthesis of C-2 products. We report experimentally a C-2 Faradaic efficiency of 79 +/- 2% on boron-doped copper catalysts and further show that boron doping leads to catalysts that are stable for in excess of similar to 40 hours while electrochemically reducing CO2 to multi-carbon hydrocarbons.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 25.87
Times cited: 700
DOI: 10.1038/S41557-018-0092-X
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“Domain Selectivity in BiFeO3Thin Films by Modified Substrate Termination”. Solmaz A, Huijben M, Koster G, Egoavil R, Gauquelin N, Van Tendeloo G, Verbeeck J, Noheda B, Rijnders G, Advanced functional materials 26, 2882 (2016). http://doi.org/10.1002/adfm.201505065
Abstract: Ferroelectric domain formation is an essential feature in ferroelectric thin films. These domains and domain walls can be manipulated depending on the growth conditions. In rhombohedral BiFeO3 thin films, the ordering of the domains and the presence of specific types of domain walls play a crucial role in attaining unique ferroelectric and magnetic properties. In this study, controlled ordering of domains in BiFeO3 film is presented, as well as a controlled selectivity between two types of domain walls is presented, i.e., 71° and 109°, by modifying the substrate termination. The experiments on two different substrates, namely SrTiO3 and TbScO3, strongly indicate that the domain selectivity is determined by the growth kinetics of the initial BiFeO3 layers.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 34
DOI: 10.1002/adfm.201505065
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“Does a monochromator improve the precision in quantitative HRTEM?”.den Dekker AJ, Van Aert S, van Dyck D, van den Bos A, Geuens P, Ultramicroscopy 89, 275 (2001). http://doi.org/10.1016/S0304-3991(01)00089-4
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 22
DOI: 10.1016/S0304-3991(01)00089-4
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“Do you believe that atoms stay in place when you observe them in HREM?”.van Dyck D, Lobato I, Chen F-R, Kisielowski C, Micron 68, 158 (2015). http://doi.org/10.1016/j.micron.2014.09.003
Abstract: Recent advancements in aberration-corrected electron microscopy allow for an evaluation of unexpectedly large atom displacements beyond a resolution limit of similar to 0.5 angstrom, which are found to be dose-rate dependent in high resolution images. In this paper we outline a consistent description of the electron scattering process, which explains these unexpected phenomena. Our approach links thermal diffuse scattering to electron beam-induced object excitation and relaxation processes, which strongly contribute to the image formation process. The effect can provide an explanation for the well-known contrast mismatch (“Stobbs factor”) between image calculations and experiments. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.98
Times cited: 11
DOI: 10.1016/j.micron.2014.09.003
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“Do smaller probes in a scanning transmission electron microscope result in more precise measurement of the distances between atom columns?”.Van Aert S, van Dyck D, Philosophical magazine: B: physics of condensed matter: electronic, optical and magnetic properties 81, 1833 (2001). http://doi.org/10.1080/13642810108223121
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 11
DOI: 10.1080/13642810108223121
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“Do Binary Supracrystals Enhance the Crystal Stability?”.Yang Z, Altantzis T, Bals S, Tendeloo GV, Pileni M-P, The journal of physical chemistry: C : nanomaterials and interfaces 122, 13515 (2018). http://doi.org/10.1021/acs.jpcc.7b12373
Abstract: We study the oxygen thermal stability of two binary
systems. The larger particles are magnetic amorphous Co (7.2 nm) or
Fe3O4 (7.5 nm) nanocrystals, whereas the smaller ones (3.7 nm) are
Au nanocrystals. The nanocrystal ordering as well as the choice of the
magnetic nanoparticles very much influence the stability of the binary
system. A perfect crystalline structure is obtained with the Fe3O4/Au
binary supracrystals. For the Co/Au binary system, oxidation of Co
results in the chemical transformation from Co to CoO, where the size
of the amorphous Co nanoparticles increases from 7.2 to 9.8 nm in
diameter. During the volume expansion of the Co nanoparticles, Au
nanoparticles within the binary assemblies coalesce and are at the
origin of the instability of the binary nanoparticle supracrystals. On the
other hand, for the Fe3O4/Au binary system, the oxidation of Fe3O4 to
γ-Fe2O3 does not lead to a size change of the nanoparticles, which
maintains the stability of the binary nanoparticle supracrystals. A similar behavior is observed for an AlB2-type Co−Ag binary
system: The crystalline structure is maintained, whereas in disordered assemblies, coalescence of Ag nanocrystals is observed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 5
DOI: 10.1021/acs.jpcc.7b12373
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“Distribution of fields and charge carriers in cylindrical nanosize silicon-based metal-oxide-semiconductor structures”. Pokatilov EP, Fomin VM, Balaban SN, Gladilin VN, Klimin SN, Devreese JT, Magnus W, Schoenmaker W, Collaert N, van Rossum M, de Meyer K, Journal Of Applied Physics 85, 6625 (1999). http://doi.org/10.1063/1.370171
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 2.068
Times cited: 16
DOI: 10.1063/1.370171
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“Dissolution study of potassium feldspars using hydrothermally treated sanidine as an example”. Adriaens A, Goossens D, Pijpers A, Van Tendeloo G, Gijbels R, Surface and interface analysis 27, 8 (1999). http://doi.org/10.1002/(SICI)1096-9918(199901)27:1<8::AID-SIA456>3.0.CO;2-Z
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Electron microscopy for materials research (EMAT)
Impact Factor: 1.132
Times cited: 4
DOI: 10.1002/(SICI)1096-9918(199901)27:1<8::AID-SIA456>3.0.CO;2-Z
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“Dissolution corrosion of 316L austenitic stainless steels in contact with static liquid lead-bismuth eutectic (LBE) at 500 °C”. Lambrinou K, Charalampopoulou E, Van der Donck T, Delville R, Schryvers D, Journal of nuclear materials 490, 9 (2017). http://doi.org/10.1016/j.jnucmat.2017.04.004
Abstract: This work addresses the dissolution corrosion behaviour of 316L austenitic stainless steels. For this purpose, solution-annealed and cold-deformed 316L steels were simultaneously exposed to oxygen-poor (<10-8 mass%) static liquid lead-bismuth eutectic (LBE) for 253e3282 h at 500 °C. Corrosion was consistently more severe for the cold-drawn steels than the solution-annealed steel, indicating the importance of the steel thermomechanical state. The thickness of the dissolution-affected zone was nonuniform, and sites of locally-enhanced dissolution were occasionally observed. The progress of LBE dissolution attack was promoted by the interplay of certain steel microstructural features (grain boundaries, deformation twin laths, precipitates) with the dissolution corrosion process. The identified dissolution mechanisms were selective leaching leading to steel ferritization, and non-selective leaching; the latter was mainly observed in the solution-annealed steel. The maximum corrosion rate decreased with exposure time and was found to be inversely proportional to the depth of dissolution attack.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.048
Times cited: 24
DOI: 10.1016/j.jnucmat.2017.04.004
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“Disproportionation of Co2+ in the topochemically reduced oxide LaSrCoRuO₅”. Liang Z, Batuk M, Orlandi F, Manuel P, Hadermann J, Hayward MA, Angewandte Chemie: international edition in English 63, e202313067 (2024). http://doi.org/10.1002/ANIE.202313067
Abstract: Complex transition-metal oxides exhibit a wide variety of chemical and physical properties which are a strong function the local electronic states of the transition-metal centres, as determined by a combination of metal oxidation state and local coordination environment. Topochemical reduction of the double perovskite oxide, LaSrCoRuO6, using Zr, yields LaSrCoRuO5. This reduced phase contains an ordered array of apex-linked square-based pyramidal Ru3+O5, square-planar Co1+O4 and octahedral Co3+O6 units, consistent with the coordination-geometry driven disproportionation of Co2+. Coordination-geometry driven disproportionation of d(7) transition-metal cations (e.g. Rh2+, Pd3+, Pt3+) is common in complex oxides containing 4d and 5d metals. However, the weak ligand field experienced by a 3d transition-metal such as cobalt leads to the expectation that d(7+) Co2+ should be stable to disproportionation in oxide environments, so the presence of Co1+O4 and Co3+O6 units in LaSrCoRuO5 is surprising. Low-temperature measurements indicate LaSrCoRuO5 adopts a ferromagnetically ordered state below 120 K due to couplings between S=(1)/(2) Ru3+ and S=1 Co1+.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
DOI: 10.1002/ANIE.202313067
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“Displacive-replacive phase transformation in a Ni62.5Al37.5 phase studies by HREM and microdiffraction”. Muto S, Merk N, Schryvers D, Tanner LE, Philosophical magazine: B: physics of condensed matter: electronic, optical and magnetic properties 67, 673 (1993). http://doi.org/10.1080/13642819308219316
Abstract: The structure of the metastable Ni2Al phase, which has long been a matter of controversy, has been carefully re-examined by means of high-resolution transmission electron microscopy (HREM) and electron microdiffraction. First, it is concluded that theas-quenched NixAl100-x(60 less-than-or-equal-to x less-than-or-equal-to 65) material already exhibits a partial omega-type collapse in a one-dimensional fashion which and is consistent with the anomalous dip in the phonon dispersion curve. Ni2Al precipitates are formed on annealing by thermal decomposition of the high-temperature NixAl100-xB2 phase and still retain the small omega-type shuffle. The amount of displacement in the well developed Ni2Al phase was estimated to be between 20 and 50% of the ideal omega collapse; this was determined by means of a combined technique of HREM and microdiffraction together with dynamical calculations of HREM images and diffraction intensities.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 16
DOI: 10.1080/13642819308219316
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“Displacive and diffusive components in the formation of the Ni2Al structure studied by HREM, SAED and micro-ED”. Muto S, Merk N, Schryvers D, Tanner LE, Monterey Institute for Advances Studies , 101 (1992)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
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“Dispersion in the wake of a rectangular building : validation of two Reynolds-averaged Navier-Stokes modelling approaches”. Gorlé, C, van Beeck J, Rambaud P, Boundary-layer meteorology 137, 115 (2010). http://doi.org/10.1007/s10546-010-9521-0
Abstract: When modelling the turbulent dispersion of a passive tracer using Reynolds-averaged Navier-Stokes (RANS) simulations, two different approaches can be used. The first consists of solving a transport equation for a scalar, where the governing parameters are the mean velocity field and the turbulent diffusion coefficient, given by the ratio of the turbulent viscosity and the turbulent Schmidt number Sc (t) . The second approach uses a Lagrangian particle tracking algorithm, where the governing parameters are the mean velocity and the fluctuating velocity field, which is determined from the turbulence kinetic energy and the Lagrangian time T (L) . A comparison between the two approaches and wind-tunnel data for the dispersion in the wake of a rectangular building immersed in a neutral atmospheric boundary layer (ABL) is presented. Particular attention was paid to the influence of turbulence model parameters on the flow and concentration field. In addition, an approach to estimate Sc (t) and T (L) based on the calculated flow field is proposed. The results show that applying modified turbulence model constants to enable correct modelling of the ABL improves the prediction for the velocity and concentration fields when the modification is restricted to the region for which it was derived. The difference between simulated and measured concentrations is smaller than 25% or the uncertainty of the data on 76% of the points when solving the transport equation for a scalar with the proposed formulation for Sc (t) , and on 69% of the points when using the Lagrangian particle tracking with the proposed formulation for T (L) .
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.573
Times cited: 16
DOI: 10.1007/s10546-010-9521-0
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“Dislocations in diamond : dissociation into partials and their glide motion”. Blumenau AT, Jones R, Frauenheim T, Willems B, Lebedev OI, Van Tendeloo G, Fisher D, Martineau PM, Physical review : B : condensed matter and materials physics 68, 014115 (2003). http://doi.org/10.1103/PhysRevB.68.014115
Abstract: The dissociation of 60degrees and screw dislocations in diamond is modeled in an approach combining isotropic elasticity theory with ab initio-based tight-binding total-energy calculations. Both dislocations are found to dissociate with a substantial lowering of their line energies. For the 60degrees dislocation, however, an energy barrier to dissociation is found. We investigate the core structure of a screw dislocation distinguishing “shuffle,” “mixed,” and “glide” cores. The latter is found to be the most stable undissociated screw dislocation. Further, the glide motion of 90degrees and 30degrees partials is discussed in terms of a process involving the thermal formation and subsequent migration of kinks along the dislocation line. The calculated activation barriers to dislocation motion show that the 30degrees partial is less mobile than the 90degrees partial. Finally, high-resolution electron microscopy is performed on high-temperature, high-pressure annealed natural brown diamond, allowing the core regions of 60degrees dislocations to be imaged. The majority of dislocations are found to be dissociated. However, in some cases, undissociated 60degrees dislocations were also observed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 39
DOI: 10.1103/PhysRevB.68.014115
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“Dislocations and plasticity of experimentally deformed coesite”. Idrissi H, Cordier P, Jacob D, Walte N, European journal of mineralogy 20, 665 (2008). http://doi.org/10.1127/0935-1221/2008/0020-1849
Abstract: Dislocation microstructures have been characterized by transmission electron microscopy in polycrystalline coesite deformed experimentally at 4 GPa, 1200 degrees C. Burgers vectors have been determined by large-angle convergent-beam electron diffraction. Sample orientation was assisted by precession electron diffraction to overcome difficulties arising from pseudo-hexagonal symmetry. The results are explained by using a pseudo-hexagonal setting. We found that most dislocations observed are of the 1/3 < 2 (1) over bar(1) over bar0 > type. No clear glide plane was identified, suggesting that climb is activated under these conditions. This conclusion is supported by the observation of numerous subgrain boundaries. We have also observed some [00011 dislocations. Finally, the C12/cl space group to which coesite belongs being centred, an additional slip system is observed: 1/6[(1) over bar2 (1) over bar3](01 (1) over bar1) (1/2[(1) over bar 10](110) in the monoclinic setting).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.362
Times cited: 5
DOI: 10.1127/0935-1221/2008/0020-1849
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“Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films”. Amin-Ahmadi B, Connétable D, Fivel M, Tanguy D, Delmelle R, Turner S, Malet L, Godet S, Pardoen T, Proost J, Schryvers D, Idrissi H, Acta materialia 111, 253 (2016). http://doi.org/10.1016/j.actamat.2016.03.054
Abstract: The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 14
DOI: 10.1016/j.actamat.2016.03.054
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“Dislocation-mediated relaxation in nanograined columnar palladium films revealed by on-chip time-resolved HRTEM testing”. Colla M-S, Amin-Ahmadi B, Idrissi H, Malet L, Godet S, Raskin J-P, Schryvers D, Pardoen T, Nature communications 6, 5922 (2015). http://doi.org/10.1038/ncomms6922
Abstract: The high-rate sensitivity of nanostructured metallic materials demonstrated in the recent literature is related to the predominance of thermally activated deformation mechanisms favoured by a large density of internal interfaces. Here we report time-resolved high-resolution electron transmission microscopy creep tests on thin nanograined films using on-chip nanomechanical testing. Tests are performed on palladium, which exhibited unexpectedly large creep rates at room temperature. Despite the small 30-nm grain size, relaxation is found to be mediated by dislocation mechanisms. The dislocations interact with the growth nanotwins present in the grains, leading to a loss of coherency of twin boundaries. The density of stored dislocations first increases with applied deformation, and then decreases with time to drive additional deformation while no grain boundary mechanism is observed. This fast relaxation constitutes a key issue in the development of various micro- and nanotechnologies such as palladium membranes for hydrogen applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 34
DOI: 10.1038/ncomms6922
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Blumenau AT, Frauenheim T, Ö,berg S, Willems B, Van Tendeloo G (2004) Dislocation structures in diamond: density-functional based modelling and high resolution electron microscopy. Trans Tech Publications, s.l
Keywords: MA1 Book as author; Electron microscopy for materials research (EMAT)
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“Dislocation structures and the role of grain boundaries in cyclically deformed Ni micropillars”. Samaee V, Sandfeld S, Idrissi H, Groten J, Pardoen T, Schwaiger R, Schryvers D, Materials Science And Engineering A-Structural Materials Properties Microstructure And Processing 769, 138295 (2020). http://doi.org/10.1016/j.msea.2019.138295
Abstract: Transmission electron microscopy and finite element-based dislocation simulations were combined to study the development of dislocation microstructures after cyclic deformation of single crystal and bicrystal Ni micropillars oriented for multi-slip. A direct correlation between large accumulation of plastic strain and the presence of dislocation cell walls in the single crystal micropillars was observed, while the presence of the grain boundary hampered the formation of wall-like structures in agreement with a smaller accumulated plastic strain. Automated crystallographic orientation and nanostrain mapping using transmission electron microscopy revealed the presence of lattice heterogeneities associated to the cell walls including long range elastic strain fields. By combining the nanostrain mapping with an inverse modelling approach, information about dislocation density, line orientation and Burgers vector direction was derived, which is not accessible otherwise in such dense dislocation structures. Simulations showed that the image forces associated with the grain boundary in this specific bicrystal configuration have only a minor influence on dislocation behavior. Thus, the reduced occurrence of “mature” cell walls in the bicrystal can be attributed to the available volume, which is too small to accommodate cell structures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.4
Times cited: 1
DOI: 10.1016/j.msea.2019.138295
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“Dislocation driven nanosample plasticity: new insights from quantitative in-situ TEM tensile testing”. Samaee V, Gatti R, Devincre B, Pardoen T, Schryvers D, Idrissi H, Scientific Reports 8, 12012 (2018). http://doi.org/10.1038/s41598-018-30639-8
Abstract: Intrinsic dislocation mechanisms in the vicinity of free surfaces of an almost FIB damage-free single crystal Ni sample have been quantitatively investigated owing to a novel sample preparation method combining twin-jet electro-polishing, in-situ TEM heating and FIB. The results reveal that the small-scale plasticity is mainly controlled by the conversion of few tangled dislocations, still present after heating, into stable single arm sources (SASs) as well as by the successive operation of these sources. Strain hardening resulting from the operation of an individual SAS is reported and attributed to the decrease of the length of the source. Moreover, the impact of the shortening of the dislocation source on the intermittent plastic flow, characteristic of SASs, is discussed. These findings provide essential information for the understanding of the regime of ‘dislocation source’ controlled plasticity and the related mechanical size effect.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 4.259
Times cited: 9
DOI: 10.1038/s41598-018-30639-8
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“Dislocation distributions in brown diamond”. Willems B, Martineau PM, Fisher D, van Royen J, Van Tendeloo G, Physica status solidi: A: applied research 203, 3076 (2006). http://doi.org/10.1002/pssa.200671129
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.775
Times cited: 21
DOI: 10.1002/pssa.200671129
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“Dislocation and back stress dominated viscoplasticity in freestanding sub-micron Pd films”. Lemoine G, Delannay L, Idrissi H, Colla M-S, Pardoen T, Acta materialia 111, 10 (2016). http://doi.org/10.1016/j.actamat.2016.03.038
Abstract: A dislocation-based crystal plasticity model is developed in order to study the mechanical and creep/ relaxation behaviour of polycrystalline metallic thin films. The model accounts for the confinement of plasticity due to grain boundaries and for the anisotropy of individual grains, as well as for the significant viscoplastic effects associated to dislocation dominated thermally activated mechanisms. Numerical predictions are assessed based on experimental tensile test followed by relaxation on freestanding Pd films, based on an on-chip test technique. The dislocation-based mechanism assumption captures all the experimental trends, including the stress strain response, the relaxation behaviour and the dislocation density evolution, confirming the dominance of a dislocation driven deformation mechanism for the present Pd films with high defects density. The model has also been used to address some original experimental evidences involving back stresses, Bauschinger effect, backward creep and strain recovery. (C) 2016 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: 6
DOI: 10.1016/j.actamat.2016.03.038
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