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Author Gonnissen, J.; de Backer, A.; den Dekker, A.J.; Martinez, G.T.; Rosenauer, A.; Sijbers, J.; Van Aert, S.
Title Optimal experimental design for the detection of light atoms from high-resolution scanning transmission electron microscopy images Type A1 Journal article
Year 2014 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume (up) 105 Issue 6 Pages 063116
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract We report an innovative method to explore the optimal experimental settings to detect light atoms from scanning transmission electron microscopy (STEM) images. Since light elements play a key role in many technologically important materials, such as lithium-battery devices or hydrogen storage applications, much effort has been made to optimize the STEM technique in order to detect light elements. Therefore, classical performance criteria, such as contrast or signal-to-noise ratio, are often discussed hereby aiming at improvements of the direct visual interpretability. However, when images are interpreted quantitatively, one needs an alternative criterion, which we derive based on statistical detection theory. Using realistic simulations of technologically important materials, we demonstrate the benefits of the proposed method and compare the results with existing approaches.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000341188700073 Publication Date 2014-08-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951;1077-3118; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 12 Open Access
Notes FWO (G.0393.11; G.0064.10; and G.0374.13); European Union Seventh Framework Programme [FP7/2007-2013] under Grant Agreement No. 312483 (ESTEEM2); esteem2_jra2 Approved Most recent IF: 3.411; 2014 IF: 3.302
Call Number UA @ lucian @ c:irua:118333 Serial 2482
Permanent link to this record
 
 
Author Croitoru, M.D.; van Dyck, D.; Van Aert, S.; Bals, S.; Verbeeck, J.
Title An efficient way of including thermal diffuse scattering in simulation of scanning transmission electron microscopic images Type A1 Journal article
Year 2006 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 106 Issue 10 Pages 933-940
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Vision lab
Abstract We propose an improved image simulation procedure for atomic-resolution annular dark-field scanning transmission electron microscopy (STEM) based on the multislice formulation, which takes thermal diffuse scattering fully into account. The improvement with regard to the classical frozen phonon approach is realized by separating the lattice configuration statistics from the dynamical scattering so as to avoid repetitive calculations. As an example, the influence of phonon scattering on the image contrast is calculated and investigated. STEM image simulation of crystals can be applied with reasonable computing times to problems involving a large number of atoms and thick or large supercells.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000240397200006 Publication Date 2006-05-10
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 18 Open Access
Notes Fwo; Fwo-V Approved Most recent IF: 2.843; 2006 IF: 1.706
Call Number UA @ lucian @ c:irua:87604UA @ admin @ c:irua:87604 Serial 876
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Author Verbeeck, J.; Van Aert, S.; Bertoni, G.
Title Model-based quantification of EELS spectra: including the fine structure Type A1 Journal article
Year 2006 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 106 Issue 11-12 Pages 976-980
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract An extension to model-based electron energy loss spectroscopy (EELS) quantification is reported to improve the possibility of modelling fine structure changes in electron energy loss spectra. An equalisation function is used in the energy loss near edge structure (ELNES) region to model the differences between a single atom differential cross section and the cross section for an atom in a crystal. The equalisation function can be shown to approximate the relative density of unoccupied states for the given excitation edge. On a set of 200 experimental h-BN spectra, this technique leads to statistically acceptable models resulting into unbiased estimates of relative concentrations and making the estimated precisions come very close to the Cramer-Rao lower bound (CRLB). The method greatly expands the useability of model-based EELS quantification to spectra with pronounced fine structure. Another benefit of this model is that one also gets an estimate of the unoccupied density of states for a given excitation edge, without having to do background removal and deconvolution, making the outcome intrinsically more reliable and less noisy. (c) 2006 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000241592900004 Publication Date 2006-07-04
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 38 Open Access
Notes Goa; Fwo Iap-V Approved Most recent IF: 2.843; 2006 IF: 1.706
Call Number UA @ lucian @ c:irua:61379UA @ admin @ c:irua:61379 Serial 2102
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Author Van Aert, S.; Geuens, P.; van Dyck, D.; Kisielowski, C.; Jinschek, J.R.
Title Electron channelling based crystallography Type A1 Journal article
Year 2007 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 107 Issue 6/7 Pages 551-558
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000245341300015 Publication Date 2006-12-13
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 32 Open Access
Notes Approved Most recent IF: 2.843; 2007 IF: 1.996
Call Number UA @ lucian @ c:irua:64286 Serial 913
Permanent link to this record
 
 
Author Van Aert, S.; Chang, L.Y.; Bals, S.; Kirkland, A.I.; Van Tendeloo, G.
Title Effect of amorphous layers on the interpretation of restored exit waves Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 109 Issue 3 Pages 237-246
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The effects of amorphous layers on the quality of exit wave restorations have been investigated. Two independently developed software implementations for exit wave restoration have been used to simulated focal series of images of SrTiO3 with amorphous carbon layers incorporated. The restored exit waves have been compared both qualitatively and quantitatively. We have shown that amorphous layers have a strong impact on the quantitative measurements of atomic column positions, however, the error in the position measurements is still in the picometer range.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000264280200005 Publication Date 2008-11-15
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 10 Open Access
Notes Fwo; Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:76421 Serial 796
Permanent link to this record
 
 
Author van den Broek, W.; Van Aert, S.; van Dyck, D.
Title A model based atomic resolution tomographic algorithm Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 109 Issue 12 Pages 1485-1490
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Tomography with high angular annular dark field scanning transmission electron microscopy at atomic resolution can be greatly improved if one is able to take advantage of prior knowledge. In this paper we present a reconstruction technique that explicitly takes into account the microscope parameters and the atomic nature of the projected object. This results in a more accurate estimate of the atomic positions and in a good resistance to noise. The reconstruction is a maximum likelihood estimator of the object. Moreover, the limits to the precision have been explored, allowing for a prediction of the amount of expected noise in the reconstruction for a certain experimental setup. We believe that the proposed reconstruction technique can be generalized to other tomographic experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000271840200010 Publication Date 2009-08-28
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 17 Open Access
Notes Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:78588 Serial 2097
Permanent link to this record
 
 
Author Van Aert, S.; Verbeeck, J.; Erni, R.; Bals, S.; Luysberg, M.; van Dyck, D.; Van Tendeloo, G.
Title Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 109 Issue 10 Pages 1236-1244
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000270015200004 Publication Date 2009-05-28
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 166 Open Access
Notes Fwo; Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:78585UA @ admin @ c:irua:78585 Serial 2748
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Author Wang, A.; Chen, F.R.; Van Aert, S.; van Dyck, D.
Title Direct structure inversion from exit waves: part 1: theory and simulations Type A1 Journal article
Year 2010 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 110 Issue 5 Pages 527-534
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract In order to interpret the amplitude and phase of the exit wave in terms of mass and position of the atoms, one has to invert the dynamic scattering of the electrons in the object so as to obtain a starting structure which can then be used as a seed for further quantitative structure refinement. This is especially challenging in case of a zone axis condition when the interaction of the electrons with the atom column is very strong. Based on the channelling theory we will show that the channelling map not only yields a circle on the Argand plot but also a circular defocus curve for every column. The former gives the number of atoms in each column, while the latter provides the defocus value for each column, which reveals the surface roughness at the exit plane with single atom sensitivity.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000279065700019 Publication Date 2009-12-12
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 25 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2010 IF: 2.063
Call Number UA @ lucian @ c:irua:83691 Serial 723
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Author Van Aert, S.; Chen, J.H.; van Dyck, D.
Title Linear versus non-linear structural information limit in high-resolution transmission electron microscopy Type A1 Journal article
Year 2010 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 110 Issue 11 Pages 1404-1410
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract A widely used performance criterion in high-resolution transmission electron microscopy (HRTEM) is the information limit. It corresponds to the inverse of the maximum spatial object frequency that is linearly transmitted with sufficient intensity from the exit plane of the object to the image plane and is limited due to partial temporal coherence. In practice, the information limit is often measured from a diffractogram or from Young's fringes assuming a weak phase object scattering beyond the inverse of the information limit. However, for an aberration corrected electron microscope, with an information limit in the sub-angstrom range, weak phase objects are no longer applicable since they do not scatter sufficiently in this range. Therefore, one relies on more strongly scattering objects such as crystals of heavy atoms observed along a low index zone axis. In that case, dynamical scattering becomes important such that the non-linear and linear interaction may be equally important. The non-linear interaction may then set the experimental cut-off frequency observed in a diffractogram. The goal of this paper is to quantify both the linear and the non-linear information transfer in terms of closed form analytical expressions. Whereas the cut-off frequency set by the linear transfer can be directly related with the attainable resolution, information from the non-linear transfer can only be extracted using quantitative, model-based methods. In contrast to the historic definition of the information limit depending on microscope parameters only, the expressions derived in this paper explicitly incorporate their dependence on the structure parameters as well. In order to emphasize this dependence and to distinguish from the usual information limit, the expressions derived for the inverse cut-off frequencies will be referred to as the linear and non-linear structural information limit. The present findings confirm the well-known result that partial temporal coherence has different effects on the transfer of the linear and non-linear terms, such that the non-linear imaging contributions are damped less than the linear imaging contributions at high spatial frequencies. This will be important when coherent aberrations such as spherical aberration and defocus are reduced.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000282562100008 Publication Date 2010-07-15
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 6 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2010 IF: 2.063
Call Number UA @ lucian @ c:irua:83689 Serial 1821
Permanent link to this record
 
 
Author van den Broek, W.; Van Aert, S.; van Dyck, D.
Title A model based reconstruction technique for depth sectioning with scanning transmission electron microscopy Type A1 Journal article
Year 2010 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 110 Issue 5 Pages 548-554
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Depth sectioning in high angular annular dark field scanning transmission electron microscopy is considered a candidate for three-dimensional characterization on the atomic scale. However at present the depth resolution is still far from the atomic level, due to strong limitations in the opening angle of the beam. In this paper we introduce a new, parameter based tomographic reconstruction algorithm that allows to make maximal use of the prior knowledge about the constituent atom types and the microscope settings, so as to retrieve the atomic positions and push the resolution to the atomic level in all three dimensions.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000279065700022 Publication Date 2009-09-21
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 16 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2010 IF: 2.063
Call Number UA @ lucian @ c:irua:83690 Serial 2104
Permanent link to this record
 
 
Author de Backer, A.; Van Aert, S.; van Dyck, D.
Title High precision measurements of atom column positions using model-based exit wave reconstruction Type A1 Journal article
Year 2011 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 111 Issue 9/10 Pages 1475-1482
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract In this paper, it has been investigated how to measure atom column positions as accurately and precisely as possible using a focal series of images. In theory, it is expected that the precision would considerably improve using a maximum likelihood estimator based on the full series of focal images. As such, the theoretical lower bound on the variances of the unknown atom column positions can be attained. However, this approach is numerically demanding. Therefore, maximum likelihood estimation has been compared with the results obtained by fitting a model to a reconstructed exit wave rather than to the full series of focal images. Hence, a real space model-based exit wave reconstruction technique based on the channelling theory is introduced. Simulations show that the reconstructed complex exit wave contains the same amount of information concerning the atom column positions as the full series of focal images. Only for thin samples, which act as weak phase objects, this information can be retrieved from the phase of the reconstructed complex exit wave.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000300461200004 Publication Date 2011-07-28
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 8 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2011 IF: 2.471
Call Number UA @ lucian @ c:irua:91879 Serial 1438
Permanent link to this record
 
 
Author Wang, A.; Chen, F.R.; Van Aert, S.; van Dyck, D.
Title A method to determine the local surface profile from reconstructed exit waves Type A1 Journal article
Year 2011 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 111 Issue 8 Pages 1352-1359
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Reconstructed exit waves are useful to quantify unknown structure parameters such as the position and composition of the atom columns at atomic scale. Existing techniques provide a complex wave in a flat plane which is close to the plane where the electrons leave the atom columns. However, due to local deviation in the flatness of the exit surface, there will be an offset between the plane of reconstruction and the actual exit of a specific atom column. Using the channelling theory, it has been shown that this defocus offset can in principle be determined atom column-by-atom column. As such, the surface roughness could be quantified at atomic scale. However, the outcome strongly depends on the initial plane of reconstruction especially in a crystalline structure. If this plane is further away from the true exit, the waves of the atom columns become delocalized and interfere mutually which strongly complicates the interpretation of the exit wave in terms of the local structure. In this paper, we will study the delocalization with defocus using the channelling theory in a more systematic way.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000300461100049 Publication Date 2011-05-03
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 3 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2011 IF: 2.471
Call Number UA @ lucian @ c:irua:88941 Serial 2017
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Author van den Broek, W.; Van Aert, S.; Goos, P.; van Dyck, D.
Title Throughput maximization of particle radius measurements by balancing size and current of the electron probe Type A1 Journal article
Year 2011 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 111 Issue 7 Pages 940-947
Keywords A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Abstract In thispaperweinvestigatewhichprobesizemaximizesthethroughputwhenmeasuringtheradiusof nanoparticlesinhighangleannulardarkfieldscanningtransmissionelectronmicroscopy(HAADFSTEM). The sizeandthecorrespondingcurrentoftheelectronprobedeterminetheprecisionoftheestimateofa particlesradius.Maximizingthroughputmeansthatamaximumnumberofparticlesshouldbeimaged withinagiventimeframe,sothataprespecifiedprecisionisattained.WeshowthatBayesianstatistical experimentaldesignisaveryusefulapproachtodeterminetheoptimalprobesizeusingacertainamount of priorknowledgeaboutthesample.Thedependenceoftheoptimalprobesizeonthedetectorgeometry and thediameter,variabilityandatomicnumberoftheparticlesisinvestigated.Anexpressionforthe optimalprobesizeintheabsenceofanykindofpriorknowledgeaboutthespecimenisderivedaswell.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000300461000026 Publication Date 2010-11-25
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 7 Open Access
Notes Approved Most recent IF: 2.843; 2011 IF: 2.471
Call Number UA @ lucian @ c:irua:89657 Serial 3659
Permanent link to this record
 
 
Author Wang, A.; Van Aert, S.; Goos, P.; van Dyck, D.
Title Precision of three-dimensional atomic scale measurements from HRTEM images : what are the limits? Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 114 Issue Pages 20-30
Keywords A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Abstract In this paper, we investigate to what extent high resolution transmission electron microscopy images can be used to measure the mass, in terms of thickness, and surface profile, corresponding to the defocus offset, of an object at the atomic scale. Therefore, we derive an expression for the statistical precision with which these object parameters can be estimated in a quantitative analysis. Evaluating this expression as a function of the microscope settings allows us to derive the optimal microscope design. Acquiring three-dimensional structure information in terms of thickness turns out to be much more difficult than obtaining two-dimensional information on the projected atom column positions. The attainable precision is found to be more strongly affected by processes influencing the image contrast, such as phonon scattering, than by the specific choice of microscope settings. For a realistic incident electron dose, it is expected that atom columns can be distinguished with single atom sensitivity up to a thickness of the order of the extinction distance. A comparable thickness limit is determined to measure surface steps of one atom. An increase of the electron dose shifts the limiting thickness upward due to an increase in the signal-to-noise ratio.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000301954300003 Publication Date 2012-01-06
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 5 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:94116 Serial 2692
Permanent link to this record
 
 
Author Liao, Z.; Gauquelin, N.; Green, R.J.; Müller-Caspary, K.; Lobato, I.; Li, L.; Van Aert, S.; Verbeeck, J.; Huijben, M.; Grisolia, M.N.; Rouco, V.; El Hage, R.; Villegas, J.E.; Mercy, A.; Bibes, M.; Ghosez, P.; Sawatzky, G.A.; Rijnders, G.; Koster, G.
Title Metal–insulator-transition engineering by modulation tilt-control in perovskite nickelates for room temperature optical switching Type A1 Journal article
Year 2018 Publication America Abbreviated Journal P Natl Acad Sci Usa
Volume (up) 115 Issue 38 Pages 9515-9520
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract In transition metal perovskites ABO3 the physical properties are largely driven by the rotations of the BO6 octahedra, which can be tuned in thin films through strain and dimensionality control. However, both approaches have fundamental and practical limitations due to discrete and indirect variations in bond angles, bond lengths and film symmetry by using commercially available substrates. Here, we introduce modulation tilt control as a new approach to tune the ground state of perovskite oxide thin films by acting explicitly on the oxygen octahedra rotation modes, i.e. directly on the bond angles. By intercalating the prototype SmNiO3 target material with a tilt-control layer, we cause the system to change the natural amplitude of a given rotation mode without affecting the interactions. In contrast to strain and dimensionality engineering, our method enables a continuous fine-tuning of the materials properties. This is achieved through two independent adjustable parameters: the nature of the tilt-control material (through its symmetry, elastic constants and oxygen rotation angles) and the relative thicknesses of the target and tilt-control materials. As a result, a magnetic and electronic phase diagram can be obtained, normally only accessible by A-site element substitution, within the single SmNiO3 compound. With this unique approach, we successfully adjusted the metal-insulator transition (MIT) to room temperature to fulfill the desired conditions for optical switching applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000447224900057 Publication Date 2018-09-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0027-8424 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 9.661 Times cited 50 Open Access OpenAccess
Notes We would like to acknowledge Prof. Z. Zhong for stimulated discussion. M.H., G.K. and G.R. acknowledge funding from DESCO program of the Dutch Foundation for Fundamental Research on Matter (FOM) with financial support from the Netherlands Organization for Scientific Research (NWO). This work was funded by the European Union Council under the 7th Framework Program (FP7) grant nr NMP3-LA-2010-246102 IFOX. J.V., S.V.A, N.G. and K.M.C. acknowledge funding from FWO projects G.0044.13N, G.0374.13N, G. 0368.15N, and G.0369.15N. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. N.G. acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant 278510 VORTEX. N.G. and J.V. acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483- ESTEEM2). The Canadian work was supported by NSERC and the Max Planck-UBC Centre for Quantum Materials. Some experiments for this work were performed at the Canadian Light Source, which is funded by the Canada Foundation for Innovation, NSERC, the National Research Council of Canada, the Canadian Institutes of Health Research, the Government of Saskatchewan, Western Economic Diversification Canada, and the University of Saskatchewan. MB acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC CoG grant MINT #615759. A.M. and Ph.G. were supported by the ARC project AIMED and F.R.S-FNRS PDR project HiT4FiT and acknowledge access to Céci computing facilities funded by F.R.S-FNRS (Grant No 2.5020.1), Tier-1 supercomputer of the Fédération Wallonie-Bruxelles funded by the Walloon Region (Grant No 1117545) and HPC resources from the PRACE project Megapasta. Approved Most recent IF: 9.661
Call Number EMAT @ emat @c:irua:154784UA @ admin @ c:irua:154784 Serial 5059
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Author van den Broek, W.; Rosenauer, A.; Goris, B.; Martinez, G.T.; Bals, S.; Van Aert, S.; van Dyck, D.
Title Correction of non-linear thickness effects in HAADF STEM electron tomography Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 116 Issue Pages 8-12
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract In materials science, high angle annular dark field scanning transmission electron microscopy is often used for tomography at the nanometer scale. In this work, it is shown that a thickness dependent, non-linear damping of the recorded intensities occurs. This results in an underestimated intensity in the interior of reconstructions of homogeneous particles, which is known as the cupping artifact. In this paper, this non-linear effect is demonstrated in experimental images taken under common conditions and is reproduced with a numerical simulation. Furthermore, an analytical derivation shows that these non-linearities can be inverted if the imaging is done quantitatively, thus preventing cupping in the reconstruction.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000304473700002 Publication Date 2012-03-09
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 67 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:96558 Serial 518
Permanent link to this record
 
 
Author Wang, A.; Chen, F.R.; Van Aert, S.; van Dyck, D.
Title Direct structure inversion from exit waves : part 2 : a practical example Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 116 Issue Pages 77-85
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract This paper is the second part of a two-part paper on direct structure inversion from exit waves. In the first part, a method has been proposed to quantitatively determine structure parameters with atomic resolution such as atom column positions, surface profile and the number of atoms in the atom columns. In this part, the theory will be demonstrated by means of a Au[110] exit wave reconstructed from a set of focal-series images. The procedures to analyze the experimentally reconstructed exit wave in terms of quantitative structure information are described in detail.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000304473700011 Publication Date 2012-03-28
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 8 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:96660 Serial 724
Permanent link to this record
 
 
Author van den Bos, K.H. W.; De Backer, A.; Martinez, G.T.; Winckelmans, N.; Bals, S.; Nellist, P.D.; Van Aert, S.
Title Unscrambling Mixed Elements using High Angle Annular Dark Field Scanning Transmission Electron Microscopy Type A1 Journal article
Year 2016 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume (up) 116 Issue 116 Pages 246101
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The development of new nanocrystals with outstanding physicochemical properties requires a full threedimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000378059500010 Publication Date 2016-06-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 46 Open Access OpenAccess
Notes The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through Projects No. G.0374.13N, No. G.0368.15N, and No. G.0369.15N, and by grants to K. H.W. van den Bos and A. De Backer. S. Bals and N. Winckelmans acknowledge funding from the European Research Council (Starting Grant No. COLOURATOMS 335078). The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant No. 312483—ESTEEM2. The authors are grateful to A. Rosenauer for providing the STEMsim program.; esteem2jra2; ECASSara; (ROMEO:green; preprint:; postprint:can ; pdfversion:can); Approved Most recent IF: 8.462
Call Number c:irua:133954 c:irua:133954 Serial 4084
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Author Fatermans, J.; den Dekker, A. J.; Müller-Caspary, K.; Lobato, I.; O’Leary, C. M.; Nellist, P. D.; Van Aert, S.
Title Single Atom Detection from Low Contrast-to-Noise Ratio Electron Microscopy Images Type A1 Journal article
Year 2018 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume (up) 121 Issue 5 Pages 056101
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Single atom detection is of key importance to solving a wide range of scientific and technological problems. The strong interaction of electrons with matter makes transmission electron microscopy one of the most promising techniques. In particular, aberration correction using scanning transmission electron microscopy has made a significant step forward toward detecting single atoms. However, to overcome radiation damage, related to the use of high-energy electrons, the incoming electron dose should be kept low enough. This results in images exhibiting a low signal-to-noise ratio and extremely weak contrast, especially for light-element nanomaterials. To overcome this problem, a combination of physics-based model fitting and the use of a model-order selection method is proposed, enabling one to detect single atoms with high reliability.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000440143200007 Publication Date 2018-07-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 6 Open Access OpenAccess
Notes The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through Project fundings (No. WO.010.16N, No. G.0368.15N, No. G.0502.18N). The authors are grateful to M. Van Bael and P. Lievens (KU Leuven) and to L. M. Liz-Marzán (CIC biomaGUNE and Ikerbasque) for providing the samples. This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme (Grant Agreement No. 770887). Approved Most recent IF: 8.462
Call Number EMAT @ emat @c:irua:152819 Serial 5004
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Author Van Aert, S.; De Backer, A.; Jones, L.; Martinez, G.T.; Béché, A.; Nellist, P.D.
Title Control of Knock-On Damage for 3D Atomic Scale Quantification of Nanostructures: Making Every Electron Count in Scanning Transmission Electron Microscopy Type A1 Journal article
Year 2019 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume (up) 122 Issue 6 Pages 066101
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Understanding nanostructures down to the atomic level is the key to optimizing the design of advancedmaterials with revolutionary novel properties. This requires characterization methods capable of quantifying the three-dimensional (3D) atomic structure with the highest possible precision. A successful approach to reach this goal is to count the number of atoms in each atomic column from 2D annular dark field scanning transmission electron microscopy images. To count atoms with single atom sensitivity, a minimum electron dose has been shown to be necessary, while on the other hand beam damage, induced by the high energy electrons, puts a limit on the tolerable dose. An important challenge is therefore to develop experimental strategies to optimize the electron dose by balancing atom-counting fidelity vs the risk of knock-on damage. To achieve this goal, a statistical framework combined with physics-based modeling of the dose-dependent processes is here proposed and experimentally verified. This model enables an investigator to theoretically predict, in advance of an experimental measurement, the optimal electron dose resulting in an unambiguous quantification of nanostructures in their native state with the highest attainable precision.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000458824200008 Publication Date 2019-02-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 3 Open Access OpenAccess
Notes This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 770887). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (WO.010.16N, G.0934.17N, G.0502.18N, G.0267.18N), and a grant to A. D. B. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 312483— ESTEEM2 (Integrated Infrastructure Initiative-I3) and the UK EPSRC (Grant No. EP/M010708/1). Approved Most recent IF: 8.462
Call Number EMAT @ emat @UA @ admin @ c:irua:157175 Serial 5156
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Author Müller-Caspary, K.; Grieb, T.; Müßener, J.; Gauquelin, N.; Hille, P.; Schörmann, J.; Verbeeck, J.; Van Aert, S.; Eickhoff, M.; Rosenauer, A.
Title Electrical Polarization in AlN/GaN Nanodisks Measured by Momentum-Resolved 4D Scanning Transmission Electron Microscopy Type A1 Journal article
Year 2019 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume (up) 122 Issue 10 Pages 106102
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We report the mapping of polarization-induced internal electric fields in AlN/GaN nanowire heterostructures at unit cell resolution as a key for the correlation of optical and structural phenomena in semiconductor optoelectronics. Momentum-resolved aberration-corrected scanning transmission electron microscopy is employed as a new imaging mode that simultaneously provides four-dimensional data in real and reciprocal space. We demonstrate how internal mesoscale and atomic electric fields can be separated in an experiment, which is verified by comprehensive dynamical simulations of multiple electron scattering. A mean difference of 5.3 +- 1.5 MV/cm is found for the polarization-induced electric fields in AlN and GaN, being in accordance with dedicated simulations and photoluminescence measurements in previous publications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000461067700007 Publication Date 2019-03-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 26 Open Access OpenAccess
Notes The authors gratefully acknowledge the help of Natalie Claes for analyzing the EDX data. K. M.-C. acknowledges funding from the Initiative and Network Fund of the Helmholtz Association within the Helmholtz Young Investigator Group moreSTEM under Contract No. VHNG- 1317 at Forschungszentrum Jülich in Germany. The direct electron detector (Medipix3, Quantum Detectors) was funded by the Hercules fund from the Flemish Government. N. G. and J. V. acknowledge funding from the Geconcentreerde Onderzoekacties project Solarpaint of the University of Antwerp. T. G. and A. R. acknowledge support from the Deutsche Forschungsgemeinschaft (Germany) under Contract No. RO2057/8-3. This work also received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Contract No. 770887). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project funding (G.0368.15N).; Helmholtz Association, VH-NG-1317 ; Forschungszentrum Jülich; Flemish Government; Universiteit Antwerpen; Deutsche Forschungsgemeinschaft, RO2057/8-3 ; H2020 European Research Council, 770887 ; Fonds Wetenschappelijk Onderzoek, G.0368.15N ; Approved Most recent IF: 8.462
Call Number UA @ lucian @UA @ admin @ c:irua:158120 Serial 5157
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Author De wael, A.; De Backer, A.; Jones, L.; Varambhia, A.; Nellist, P.D.; Van Aert, S.
Title Measuring Dynamic Structural Changes of Nanoparticles at the Atomic Scale Using Scanning Transmission Electron Microscopy Type A1 Journal article
Year 2020 Publication Physical Review Letters Abbreviated Journal Phys Rev Lett
Volume (up) 124 Issue 10 Pages 106105
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We propose a new method to measure atomic scale dynamics of nanoparticles from experimental high-resolution annular dark field scanning transmission electron microscopy images. By using the so-called hidden Markov model, which explicitly models the possibility of structural changes, the number of atoms in each atomic column can be quantified over time. This newly proposed method outperforms the current atom-counting procedure and enables the determination of the probabilities and cross sections for surface diffusion. This method is therefore of great importance for revealing and quantifying the atomic structure when it evolves over time via adatom dynamics, surface diffusion, beam effects, or during in situ experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000519718100015 Publication Date 2020-03-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.6 Times cited Open Access OpenAccess
Notes This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 770887 and No. 823717 ESTEEM3). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through grants to A.D.w. and A.D.B. and projects G.0502.18N and EOS 30489208. L.J. acknowledges the SFI AMBER Centre for support. A.V. and P.D.N. acknowledge the UK Engineering and Physical Sciences Council (EPSRC) for support (EP/K040375/1 and 1772738). A.V. also acknowledges Johnson-Matthey for support. We would like to thank Brian Theobald and Jonathan Sharman from JMTC Sonning for provision of the Pt sample. Approved Most recent IF: 8.6; 2020 IF: 8.462
Call Number EMAT @ emat @c:irua:167148 Serial 6347
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Author van Thiel, T. c.; Brzezicki, W.; Autieri, C.; Hortensius, J. r.; Afanasiev, D.; Gauquelin, N.; Jannis, D.; Janssen, N.; Groenendijk, D. j.; Fatermans, J.; Van Aert, S.; Verbeeck, J.; Cuoco, M.; Caviglia, A. d.
Title Coupling Charge and Topological Reconstructions at Polar Oxide Interfaces Type A1 Journal article
Year 2021 Publication Physical Review Letters Abbreviated Journal Phys Rev Lett
Volume (up) 127 Issue 12 Pages 127202
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract In oxide heterostructures, different materials are integrated into a single artificial crystal, resulting in a breaking of inversion symmetry across the heterointerfaces. A notable example is the interface between polar and nonpolar materials, where valence discontinuities lead to otherwise inaccessible charge and spin states. This approach paved the way for the discovery of numerous unconventional properties absent in the bulk constituents. However, control of the geometric structure of the electronic wave functions in correlated oxides remains an open challenge. Here, we create heterostructures consisting of ultrathin SrRuO3, an itinerant ferromagnet hosting momentum-space sources of Berry curvature, and

LaAlO3, a polar wide-band-gap insulator. Transmission electron microscopy reveals an atomically sharp LaO/RuO2/SrO interface configuration, leading to excess charge being pinned near the LaAlO3/SrRuO3 interface. We demonstrate through magneto-optical characterization, theoretical calculations and transport measurements that the real-space charge reconstruction drives a reorganization of the topological charges in the band structure, thereby modifying the momentum-space Berry curvature in SrRuO3. Our results illustrate how the topological and magnetic features of oxides can be manipulated by engineering charge discontinuities at oxide interfaces.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000704665000010 Publication Date 2021-09-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 17 Open Access OpenAccess
Notes The authors thank E. Lesne, M. Lee, H. Barakov, M. Matthiesen and U. Filippozzi for discussions. The authors are grateful to E.J.S. van Thiel for producing the illustration in Fig. 4a. This work was supported by the European Research Council under the European Unions Horizon 2020 programme/ERC Grant agreements No. [677458], [770887] and No. [731473] (Quantox of QuantERA ERA-NET Cofund in Quantum Technologies) and by the Netherlands Organisation for Scientific Research (NWO/OCW) as part of the Frontiers of Nanoscience (NanoFront) and VIDI program. The authors acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. [823717] – ESTEEM3. N. G., J. V., and S. V. A. acknowledge funding from the University of Antwerp through the Concerted Research Actions (GOA) project Solarpaint and the TOP project. C. A. and W. B. are supported by the Foundation for Polish Science through the International Research Agendas program co-financed by the European Union within the Smart Growth Operational Programme. C. A. acknowledges access to the computing facilities of the Interdisciplinary Center of Modeling at the University of Warsaw, Grant No. G73-23 and G75-10. W.B. acknowledges support from the Narodowe Centrum Nauk (NCN, National Science Centre, Poland) Project No. 2019/34/E/ST3/00404'; esteem3TA; esteem3reported Approved Most recent IF: 8.462
Call Number EMAT @ emat @c:irua:182595 Serial 6824
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Author Teunissen, J.L.; Braeckevelt, T.; Skvortsova, I.; Guo, J.; Pradhan, B.; Debroye, E.; Roeffaers, M.B.J.; Hofkens, J.; Van Aert, S.; Bals, S.; Rogge, S.M.J.; Van Speybroeck, V.
Title Additivity of Atomic Strain Fields as a Tool to Strain-Engineering Phase-Stabilized CsPbI3Perovskites Type A1 Journal Article
Year 2023 Publication The Journal of Physical Chemistry C Abbreviated Journal J. Phys. Chem. C
Volume (up) 127 Issue 48 Pages 23400-23411
Keywords A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract CsPbI3 is a promising perovskite material for photovoltaic applications in its photoactive perovskite or black phase. However, the material degrades to a photovoltaically inactive or yellow phase at room temperature. Various mitigation strategies are currently being developed to increase the lifetime of the black phase, many of which rely on inducing strains in the material that hinder the black-to-yellow phase transition. Physical insight into how these strategies exactly induce strain as well as knowledge of the spatial extent over which these strains impact the material is crucial to optimize these approaches but is still lacking. Herein, we combine machine learning potential-based molecular dynamics simulations with our in silico strain engineering approach to accurately quantify strained large-scale atomic structures on a nanosecond time scale. To this end, we first model the strain fields introduced by atomic substitutions as they form the most elementary strain sources. We demonstrate that the magnitude of the induced strain fields decays exponentially with the distance from the strain source, following a decay rate that is largely independent of the specific substitution. Second, we show that the total strain field induced by multiple strain sources can be predicted to an excellent approximation by summing the strain fields of each individual source. Finally, through a case study, we illustrate how this additive character allows us to explain how complex strain fields, induced by spatially extended strain sources, can be predicted by adequately combining the strain fields caused by local strain sources. Hence, the strain additivity proposed here can be adopted to further our insight into the complex strain behavior in perovskites and to design strain from the atomic level onward to enhance their sought-after phase stability.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001116862000001 Publication Date 2023-12-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access OpenAccess
Notes This work was supported by iBOF-21-085 PERsist (Special Research Fund of Ghent University, KU Leuven Research Fund, and the Research Fund of the University of Antwerp). S.M.J.R., T.B., and B.P. acknowledge financial support from the Research Foundation-Flanders (FWO) through two postdoctoral fellow- ships [grant nos. 12T3522N (S.M.J.R.) and 1275521N (B.P.)] and an SB-FWO fellowship [grant no. 1SC1319 (T.B.)]. E.D., M.B.J.R., and J.H. acknowledge financial support from the Research Foundation-Flanders (FWO, grant nos. G.0B39.15, G.0B49.15, G098319N, S002019N, S004322N, and ZW15_09- GOH6316). J.H. acknowledges support from the Flemish government through long-term structural funding Methusalem (CASAS2, Meth/15/04) and the MPI as an MPI fellow. S.V.A. and S.B. acknowledge financial support from the Research Foundation-Flanders (FWO, grant no. G0A7723N). S.M.J.R. and V.V.S. acknowledge funding from the Research Board of Ghent University (BOF). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation- Flanders (FWO) and the Flemish Government�department EWI.; KU Leuven, iBOF-21-085 PERsist ; Universiteit Antwerpen, iBOF-21-085 PERsist ; Universiteit Gent, iBOF-21-085 PERsist ; Vlaamse regering, CASAS2, Meth/15/04 ; Fonds Wetenschappelijk Onderzoek, G.0B39.15 G098319N G.0B49.15 1SC1319 12T3522N ZW15 09-GOH6316 G0A7723N 1275521N S004322N S002019N ; Approved Most recent IF: 3.7; 2023 IF: 4.536
Call Number EMAT @ emat @c:irua:202124 Serial 8985
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Author Delfino, C.L.; Hao, Y.; Martin, C.; Minoia, A.; Gopi, E.; Mali, K.S.; Van der Auweraer, M.; Geerts, Y.H.; Van Aert, S.; Lazzaroni, R.; De Feyter, S.
Title Conformation-Dependent Monolayer and Bilayer Structures of an Alkylated TTF Derivative Revealed using STM and Molecular Modeling Type A1 Journal Article
Year 2023 Publication The Journal of Physical Chemistry C Abbreviated Journal J. Phys. Chem. C
Volume (up) 127 Issue 47 Pages 23023-23033
Keywords A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract In this study, the multi-layer self-assembled molecular network formation of an alkylated tetrathiafulvalene compound is studied at the liquid-solid interface between 1-phenyloctane and graphite. A combined theoretical/experimental approach associating force-field and quantum-chemical calculations with scanning tunnelling microscopy is used to determine the two-dimensional self-assembly beyond the monolayer, but also to further the understanding of the molecular adsorption conformation and its impact on the molecular packing within the assemblies at the monolayer and bilayer level.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001111637100001 Publication Date 2023-11-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access OpenAccess
Notes Financial support from the Research Foundation-Flanders (FWO G081518N, G0A3220N) and KU Leuven–Internal Funds (C14/19/079) is acknowledged. This work was in part supported by FWO and F. R. S.-FNRS under the Excellence of Science EOS program (project 30489208 and 40007495). C.M. acknowledges the financial support: Grants PID2021-128761OA-C22 and CNS2022-136052 funded by MCIN/AEI/10.13039/501100011033 by the “European Union” and SBPLY/21/180501/000127 funded by JCCM and by the EU through “Fondo Europeo de Desarollo Regional” (FEDER). Research in Mons is also supported by the Belgian National Fund for Scientific Research (FRS-FNRS) within the Consortium des Équipements de Calcul Intensif – CÉCI, under Grant 2.5020.11, and by the Walloon Region (ZENOBE Tier-1 supercomputer, under grant 1117545). Approved Most recent IF: 3.7; 2023 IF: 4.536
Call Number EMAT @ emat @c:irua:201671 Serial 8974
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Author Wang, A.; Turner, S.; Van Aert, S.; van Dyck, D.
Title An alternative approach to determine attainable resolution directly from HREM images Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 133 Issue Pages 50-61
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract The concept of resolution in high-resolution electron microscopy (HREM) is the power to resolve neighboring atoms. Since the resolution is related to the width of the point spread function of the microscope, it could in principle be determined from the image of a point object. However, in electron microscopy there are no ideal point objects. The smallest object is an individual atom. If the width of an atom is much smaller than the resolution of the microscope, this atom can still be considered as a point object. As the resolution of the microscope enters the sub-Å regime, information about the microscope is strongly entangled with the information about the atoms in HREM images. Therefore, we need to find an alternative method to determine the resolution in an object-independent way. In this work we propose to use the image wave of a crystalline object in zone axis orientation. Under this condition, the atoms of a column act as small lenses so that the electron beam channels through the atom column periodically. Because of this focusing, the image wave of the column can be much more peaked than the constituting atoms and can thus be a much more sensitive probe to measure the resolution. Our approach is to use the peakiness of the image wave of the atom column to determine the resolution. We will show that the resolution can be directly linked to the total curvature of the atom column wave. Moreover, we can then directly obtain the resolution of the microscope given that the contribution from the object is known, which is related to the bounding energy of the atom. The method is applied on an experimental CaTiO3 image wave.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000324471800007 Publication Date 2013-05-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record
Impact Factor 2.843 Times cited Open Access
Notes FWO; Hercules; Esteem2; esteem2_jra2 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109919 Serial 90
Permanent link to this record
 
 
Author de Backer, A.; Martinez, G.T.; Rosenauer, A.; Van Aert, S.
Title Atom counting in HAADF STEM using a statistical model-based approach : methodology, possibilities, and inherent limitations Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 134 Issue Pages 23-33
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract In the present paper, a statistical model-based method to count the number of atoms of monotype crystalline nanostructures from high resolution high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images is discussed in detail together with a thorough study on the possibilities and inherent limitations. In order to count the number of atoms, it is assumed that the total scattered intensity scales with the number of atoms per atom column. These intensities are quantitatively determined using model-based statistical parameter estimation theory. The distribution describing the probability that intensity values are generated by atomic columns containing a specific number of atoms is inferred on the basis of the experimental scattered intensities. Finally, the number of atoms per atom column is quantified using this estimated probability distribution. The number of atom columns available in the observed STEM image, the number of components in the estimated probability distribution, the width of the components of the probability distribution, and the typical shape of a criterion to assess the number of components in the probability distribution directly affect the accuracy and precision with which the number of atoms in a particular atom column can be estimated. It is shown that single atom sensitivity is feasible taking the latter aspects into consideration.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000324474900005 Publication Date 2013-05-17
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 48 Open Access
Notes FWO; Esteem2; FP 2007-2013; esteem2_jra2 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109916 Serial 162
Permanent link to this record
 
 
Author den Dekker, A.J.; Gonnissen, J.; de Backer, A.; Sijbers, J.; Van Aert, S.
Title Estimation of unknown structure parameters from high-resolution (S)TEM images : what are the limits? Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 134 Issue Pages 34-43
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Statistical parameter estimation theory is proposed as a quantitative method to measure unknown structure parameters from electron microscopy images. Images are then purely considered as data planes from which structure parameters have to be determined as accurately and precisely as possible using a parametric statistical model of the observations. For this purpose, an efficient algorithm is proposed for the estimation of atomic column positions and intensities from high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. Furthermore, the so-called CramérRao lower bound (CRLB) is reviewed to determine the limits to the precision with which continuous parameters such as atomic column positions and intensities can be estimated. Since this lower bound can only be derived for continuous parameters, alternative measures using the principles of detection theory are introduced for problems concerning the estimation of discrete parameters such as atomic numbers. An experimental case study is presented to show the practical use of these measures for the optimization of the experiment design if the purpose is to decide between the presence of specific atom types using STEM images.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000324474900006 Publication Date 2013-06-01
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 31 Open Access
Notes FWO; FP 2007-2013; Esteem2; esteem2_jra2 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109240 Serial 1083
Permanent link to this record
 
 
Author Dunin-Borkowski, R.E.; Lichte, H.; Tillmann, K.; Van Aert, S.; Van Tendeloo, G.
Title Introduction to a special issue in honour of W. Owen Saxton, David J. Smith and Dirk Van Dyck on the occasion of their 65th birthdays Type Editorial
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 134 Issue Pages 1-1
Keywords Editorial; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Elsevier science bv Place of Publication Amsterdam Editor
Language Wos 000324474900001 Publication Date 2013-07-24
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 1 Open Access
Notes Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109917 Serial 1721
Permanent link to this record
 
 
Author Martinez, G.T.; Rosenauer, A.; de Backer, A.; Verbeeck, J.; Van Aert, S.
Title Quantitative composition determination at the atomic level using model-based high-angle annular dark field scanning transmission electron microscopy Type A1 Journal article
Year 2014 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume (up) 137 Issue Pages 12-19
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract High angle annular dark field scanning transmission electron microscopy (HAADF STEM) images provide sample information which is sensitive to the chemical composition. The image intensities indeed scale with the mean atomic number Z. To some extent, chemically different atomic column types can therefore be visually distinguished. However, in order to quantify the atomic column composition with high accuracy and precision, model-based methods are necessary. Therefore, an empirical incoherent parametric imaging model can be used of which the unknown parameters are determined using statistical parameter estimation theory (Van Aert et al., 2009, [1]). In this paper, it will be shown how this method can be combined with frozen lattice multislice simulations in order to evolve from a relative toward an absolute quantification of the composition of single atomic columns with mixed atom types. Furthermore, the validity of the model assumptions are explored and discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000331092200003 Publication Date 2013-11-09
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 74 Open Access
Notes FWO; FP7; ERC Countatoms; ESTEEM2; esteem2_ta Approved Most recent IF: 2.843; 2014 IF: 2.436
Call Number UA @ lucian @ c:irua:111579UA @ admin @ c:irua:111579 Serial 2749
Permanent link to this record