“Real‐Time Reconstruction of Arbitrary Slices for Quantitative and In Situ 3D Characterization of Nanoparticles”. Vanrompay H, Buurlage J‐W, Pelt DM, Kumar V, Zhuo X, Liz‐Marzán LM, Bals S, Batenburg KJ, Particle &, Particle Systems Characterization 37, 2000073 (2020). http://doi.org/10.1002/ppsc.202000073
Abstract: A detailed 3D investigation of nanoparticles at a local scale is of great importance to connect their structure and composition to their properties. Electron tomography has therefore become an important tool for the 3D characterization of nanomaterials. 3D investigations typically comprise multiple steps, including acquisition, reconstruction, and analysis/quantification. Usually, the latter two steps are performed offline, at a dedicated workstation. This sequential workflow prevents on-the-fly control of experimental parameters to improve the quality of the 3D reconstruction, to select a relevant nanoparticle for further characterization or to steer an in-situ tomography experiment. Here, we present an efficient approach to overcome these limitations, based on the real-time reconstruction of arbitrary 2D reconstructed slices through a 3D object. Implementation of this method may lead to generalized implementation of electron tomography for routine nanoparticle characterization in 3D.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.7
Times cited: 10
DOI: 10.1002/ppsc.202000073
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“Functionalization of single-layer TaS₂, and formation of ultrathin Janus structures”. Kahraman Z, Yagmurcukardes M, Sahin H, Journal Of Materials Research 35, 1397 (2020). http://doi.org/10.1557/JMR.2020.64
Abstract: Ab initio calculations are performed to investigate the structural, vibrational, electronic, and piezoelectric properties of functionalized single layers of TaS2. We find that single-layer TaS2 is a suitable host material for functionalization via fluorination and hydrogenation. The one-side fluorinated (FTaS2) and hydrogenated (HTaS2) single layers display indirect gap semiconducting behavior in contrast to bare metallic TaS2. On the other hand, it is shown that as both surfaces of TaS2 are saturated anti-symmetrically, the formed Janus structure is a dynamically stable metallic single layer. In addition, it is revealed that out-of-plane piezoelectricity is created in all anti-symmetric structures. Furthermore, the Janus-type single-layer has the highest specific heat capacity to which longitudinal and transverse acoustical phonon modes have contribution at low temperatures. Our findings indicate that single-layer TaS2 is suitable for functionalization via H and F atoms that the formed, anti-symmetric structures display distinctive electronic, vibrational, and piezoelectric properties.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 1
DOI: 10.1557/JMR.2020.64
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“The generalized Gielis geometric equation and its application”. Shi P, Ratkowsky DA, Gielis J, Symmetry-Basel 12, 645 (2020). http://doi.org/10.3390/SYM12040645
Abstract: Many natural shapes exhibit surprising symmetry and can be described by the Gielis equation, which has several classical geometric equations (for example, the circle, ellipse and superellipse) as special cases. However, the original Gielis equation cannot reflect some diverse shapes due to limitations of its power-law hypothesis. In the present study, we propose a generalized version by introducing a link function. Thus, the original Gielis equation can be deemed to be a special case of the generalized Gielis equation (GGE) with a power-law link function. The link function can be based on the morphological features of different objects so that the GGE is more flexible in fitting the data of the shape than its original version. The GGE is shown to be valid in depicting the shapes of some starfish and plant leaves.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.7
Times cited: 4
DOI: 10.3390/SYM12040645
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“Inhomogeneous superconductivity and quasilinear magnetoresistance at amorphous LaTiO₃/SrTiO₃, interfaces”. Lebedev N, Stehno M, Rana A, Gauquelin N, Verbeeck J, Brinkman A, Aarts J, Journal Of Physics-Condensed Matter 33, 055001 (2020). http://doi.org/10.1088/1361-648X/ABC102
Abstract: We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures. In spite of 2D growth observed in reflection high energy electron diffraction, transmission electron microscopy images revealed that the samples tend to amorphize. Still, we observe that the structures are conducting, and some of them exhibit high conductance and/or superconductivity. We established that conductivity arises mainly on the STO side of the interface, and shows all the signs of the two-dimensional electron gas usually observed at interfaces between STO and LTO or LaAlO3, including the presence of two electron bands and tunability with a gate voltage. Analysis of magnetoresistance (MR) and superconductivity indicates the presence of spatial fluctuations of the electronic properties in our samples. That can explain the observed quasilinear out-of-plane MR, as well as various features of the in-plane MR and the observed superconductivity.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.7
Times cited: 1
DOI: 10.1088/1361-648X/ABC102
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“Magnetic field induced vortices in graphene quantum dots”. Lavor IR, da Costa DR, Chaves A, Farias GA, Macedo R, Peeters FM, Journal Of Physics-Condensed Matter 32, 155501 (2020). http://doi.org/10.1088/1361-648X/AB6463
Abstract: The energy spectrum and local current patterns in graphene quantum dots (QD) are investigated for different geometries in the presence of an external perpendicular magnetic field. Our results demonstrate that, for specific geometries and edge configurations, the QD exhibits vortex and anti-vortex patterns in the local current density, in close analogy to the vortex patterns observed in the probability density current of semiconductor QD, as well as in the order parameter of mesoscopic superconductors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 5
DOI: 10.1088/1361-648X/AB6463
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“Strain and electric field tuning of semi-metallic character WCrCO₂, MXenes with dual narrow band gap”. Bafekry A, Akgenc B, Ghergherehchi M, Peeters FM, Journal Of Physics-Condensed Matter 32, 355504 (2020). http://doi.org/10.1088/1361-648X/AB8E88
Abstract: Motivated by the recent successful synthesis of double-M carbides, we investigate structural and electronic properties of WCrC and WCrCO2 monolayers and the effects of biaxial and out-of-plane strain and electric field using density functional theory. WCrC and WCrCO2 monolayers are found to be dynamically stable. WCrC is metallic and WCrCO2 display semi-metallic character with narrow band gap, which can be controlled by strain engineering and electric field. WCrCO2 monolayer exhibits a dual band gap which is preserved in the presence of an electric field. The band gap of WCrCO2 monolayer increases under uniaxial strain while it becomes metallic under tensile strain, resulting in an exotic 2D double semi-metallic behavior. Our results demonstrate that WCrCO2 is a new platform for the study of novel physical properties in two-dimensional Dirac materials and which may provide new opportunities to realize high-speed low-dissipation devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 45
DOI: 10.1088/1361-648X/AB8E88
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“Electrochemical detection of MDMA and 2C-B in ecstasy tablets using a selectivity enhancement strategy by in-situ derivatization”. Van Echelpoel R, Kranenburg R, van Asten A, De Wael K, Forensic chemistry 27, 100383 (2022). http://doi.org/10.1016/J.FORC.2021.100383
Abstract: Forensic drug laboratories are confronted with increasing amounts of drugs and a demand for faster results that are directly available on-site. In addition, the drug market is getting more complex with hundreds of new psychoactive substances (NPS) entering the market in recent years. Rapid and on-scene presumptive drug testing therefore faces a shift from manual colorimetric tests towards approaches that can detect a wider range of components and process results automatically. Electrochemical detection offers these desired characteristics, making it a suitable candidate for on-site drug detection. In this study, a two-step electrochemical sensor is introduced for the detection of MDMA and 2C-B. Firstly, a direct electrochemical analysis was performed to detect MDMA. Validation experiments on over 70 substances revealed that 2C-B was the only frequently encountered drug that gave a false positive result for MDMA in this first analysis. A second step using in-situ derivatization was subsequently introduced. To this end, formaldehyde was used for N-methylation of 2C-B thereby enhancing its electrochemical profile. The enriched electrochemical fingerprint in the second step allowed for clear differentiation between MDMA and 2C-B. The applicability of this approach was demonstrated with 71 ecstasy tablets seized by the Amsterdam Police. The MDMA/2C-B sensor correctly identified all 39 MDMA-containing tablets and 10 out of 11 tablets containing 2C-B. Most notably, correct results were also obtained for dark colored tablets in which both spectroscopic analysis and colorimetric tests failed due to obscured signals.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 2.7
DOI: 10.1016/J.FORC.2021.100383
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“Evidence that supertriangles exist in nature from the vertical projections of Koelreuteria paniculata fruit”. Li Y, Quinn BK, Gielis J, Li Y, Shi P, Symmetry 14, 23 (2022). http://doi.org/10.3390/SYM14010023
Abstract: Many natural radial symmetrical shapes (e.g., sea stars) follow the Gielis equation (GE) or its twin equation (TGE). A supertriangle (three triangles arranged around a central polygon) represents such a shape, but no study has tested whether natural shapes can be represented as/are supertriangles or whether the GE or TGE can describe their shape. We collected 100 pieces of Koelreuteria paniculata fruit, which have a supertriangular shape, extracted the boundary coordinates for their vertical projections, and then fitted them with the GE and TGE. The adjusted root mean square errors (RMSEadj) of the two equations were always less than 0.08, and >70% were less than 0.05. For 57/100 fruit projections, the GE had a lower RMSEadj than the TGE, although overall differences in the goodness of fit were non-significant. However, the TGE produces more symmetrical shapes than the GE as the two parameters controlling the extent of symmetry in it are approximately equal. This work demonstrates that natural supertriangles exist, validates the use of the GE and TGE to model their shapes, and suggests that different complex radially symmetrical shapes can be generated by the same equation, implying that different types of biological symmetry may result from the same biophysical mechanisms.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.7
DOI: 10.3390/SYM14010023
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“A new program to estimate the parameters of Preston's equation, a general formula for describing the egg shape of birds”. Shi P, Wang L, Quinn BKK, Gielis J, Symmetry 15, 231 (2023). http://doi.org/10.3390/SYM15010231
Abstract: Preston's equation is a general model describing the egg shape of birds. The parameters of Preston's equation are usually estimated after re-expressing it as the Todd-Smart equation and scaling the egg's actual length to two. This method assumes that the straight line through the two points on an egg's profile separated by the maximum distance (i.e., the longest axis of an egg's profile) is the mid-line. It hypothesizes that the photographed egg's profile is perfectly bilaterally symmetrical, which seldom holds true because of photographic errors and placement errors. The existing parameter estimation method for Preston's equation considers an angle of deviation for the longest axis of an egg's profile from the mid-line, which decreases prediction errors to a certain degree. Nevertheless, this method cannot provide an accurate estimate of the coordinates of the egg's center, and it leads to sub-optimal parameter estimation. Thus, it is better to account for the possible asymmetry between the two sides of an egg's profile along its mid-line when fitting egg-shape data. In this paper, we propose a method based on the optimization algorithm (optimPE) to fit egg-shape data and better estimate the parameters of Preston's equation by automatically searching for the optimal mid-line of an egg's profile and testing its validity using profiles of 59 bird eggs spanning a wide range of existing egg shapes. We further compared this method with the existing one based on multiple linear regression (lmPE). This study demonstrated the ability of the optimPE method to estimate numerical values of the parameters of Preston's equation and provide the theoretical egg length (i.e., the distance between two ends of the mid-line of an egg's profile) and the egg's maximum breadth. This provides a valuable approach for comparing egg shapes among conspecifics or across different species, or even different classes (e.g., birds and reptiles), in future investigations.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.7
DOI: 10.3390/SYM15010231
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“Effects of the numerical values of the parameters in the Gielis equation on its geometries”. Wang L, Ratkowsky DA, Gielis J, Ricci PE, Shi P, Symmetry 14, 2475 (2022). http://doi.org/10.3390/SYM14122475
Abstract: The Lamé curve is an extension of an ellipse, the latter being a special case. Dr. Johan Gielis further extended the Lamé curve in the polar coordinate system by introducing additional parameters (n1, n2, n3; m): rφ=1Acosm4φn2+1Bsinm4φn3−1/n1, which can be applied to model natural geometries. Here, r is the polar radius corresponding to the polar angle φ; A, B, n1, n2 and n3 are parameters to be estimated; m is the positive real number that determines the number of angles of the Gielis curve. Most prior studies on the Gielis equation focused mainly on its applications. However, the Gielis equation can also generate a large number of shapes that are rotationally symmetric and axisymmetric when A = B and n2 = n3, interrelated with the parameter m, with the parameters n1 and n2 determining the shapes of the curves. In this paper, we prove the relationship between m and the rotational symmetry and axial symmetry of the Gielis curve from a theoretical point of view with the condition A = B, n2 = n3. We also set n1 and n2 to take negative real numbers rather than only taking positive real numbers, then classify the curves based on extremal properties of r(φ) at φ = 0, π/m when n1 and n2 are in different intervals, and analyze how n1, n2 precisely affect the shapes of Gielis curves.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.7
DOI: 10.3390/SYM14122475
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“Intercalation of argon in honeycomb structures towards promising strategy for rechargeable Li-ion batteries”. Duden EI, Savaci U, Turan S, Sevik C, Demiroglu I, Journal of physics : condensed matter 35, 085301 (2023). http://doi.org/10.1088/1361-648X/ACA8E7
Abstract: High-performance rechargeable batteries are becoming very important for high-end technologies with their ever increasing application areas. Hence, improving the performance of such batteries has become the main bottleneck to transferring high-end technologies to end users. In this study, we propose an argon intercalation strategy to enhance battery performance via engineering the interlayer spacing of honeycomb structures such as graphite, a common electrode material in lithium-ion batteries (LIBs). Herein, we systematically investigated the LIB performance of graphite and hexagonal boron nitride (h-BN) when argon atoms were sent into between their layers by using first-principles density-functional-theory calculations. Our results showed enhanced lithium binding for graphite and h-BN structures when argon atoms were intercalated. The increased interlayer space doubles the gravimetric lithium capacity for graphite, while the volumetric capacity also increased by around 20% even though the volume was also increased. The ab initio molecular dynamics simulations indicate the thermal stability of such graphite structures against any structural transformation and Li release. The nudged-elastic-band calculations showed that the migration energy barriers were drastically lowered, which promises fast charging capability for batteries containing graphite electrodes. Although a similar level of battery promise was not achieved for h-BN material, its enhanced battery capabilities by argon intercalation also support that the argon intercalation strategy can be a viable route to enhance such honeycomb battery electrodes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACA8E7
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“Magnus induced diode effect for skyrmions in channels with periodic potentials”. Souza JCB, Vizarim NP, Reichhardt CJO, Reichhardt C, Venegas PA, Journal of physics : condensed matter 35, 015804 (2023). http://doi.org/10.1088/1361-648X/AC9CC5
Abstract: Using a particle based model, we investigate the skyrmion dynamical behavior in a channel where the upper wall contains divots of one depth and the lower wall contains divots of a different depth. Under an applied driving force, skyrmions in the channels move with a finite skyrmion Hall angle that deflects them toward the upper wall for -x direction driving and the lower wall for +x direction driving. When the upper divots have zero height, the skyrmions are deflected against the flat upper wall for -x direction driving and the skyrmion velocity depends linearly on the drive. For +x direction driving, the skyrmions are pushed against the lower divots and become trapped, giving reduced velocities and a nonlinear velocity-force response. When there are shallow divots on the upper wall and deep divots on the lower wall, skyrmions get trapped for both driving directions; however, due to the divot depth difference, skyrmions move more easily under -x direction driving, and become strongly trapped for +x direction driving. The preferred -x direction motion produces what we call a Magnus diode effect since it vanishes in the limit of zero Magnus force, unlike the diode effects observed for asymmetric sawtooth potentials. We show that the transport curves can exhibit a series of jumps or dips, negative differential conductivity, and reentrant pinning due to collective trapping events. We also discuss how our results relate to recent continuum modeling on a similar skyrmion diode system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/AC9CC5
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“Qualitative Comparison of Lock-in Thermography (LIT) and Pulse Phase Thermography (PPT) in Mid-Wave and Long-Wave Infrared for the Inspection of Paintings”. Hillen M, Sels S, Ribbens B, Verspeek S, Janssens K, Van der Snickt G, Steenackers G, Applied Sciences 13, 1 (2023). http://doi.org/10.3390/APP13074094
Abstract: When studying paintings with active infrared thermography (IRT), minimizing the temperature fluctuations and thermal shock during a measurement becomes important. Under these conditions, it might be beneficial to use lock-in thermography instead of the conventionally used pulse thermography (PT). This study compared the observations made with lock-in thermography (LIT) and pulse phase thermography (PPT) with halogen light excitation. Three distinctly different paintings were examined. The LIT measurements caused smaller temperature fluctuations and, overall, the phase images appeared to have a higher contrast and less noise. However, in the PPT phase images, the upper paint layer was less visible, an aspect which is of particular interest when trying to observe subsurface defects or the structure of the support. The influence of the spectral range of the cameras on the results was also investigated. All measurements were taken with a mid-wave infrared (MWIR) and long wave infrared (LWIR) camera. The results show that there is a significant number of direct reflection artifacts, caused by the use of the halogen light sources when using the MWIR camera. Adding a long-pass filter to the MWIR camera eliminated most of these artifacts. All results are presented in a side-by-side comparison.
Keywords: A1 Journal article; Engineering sciences. Technology; Art; Antwerp Cultural Heritage Sciences (ARCHES); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 2.7
DOI: 10.3390/APP13074094
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“Cluster analysis of IR thermography data for differentiating glass types in historical leaded-glass windows”. Hillen M, Legrand S, Dirkx Y, Janssens K, van der Snickt G, Caen J, Steenackers G, Applied Sciences-Basel 10, 4255 (2020). http://doi.org/10.3390/APP10124255
Abstract: Infrared thermography is a fast, non-destructive and contactless testing technique which is increasingly used in heritage science. The aim of this study was to assess the ability of infrared thermography, in combination with a data clustering approach, to differentiate between the different types of historical glass that were included in a colorless leaded-glass windows during previous restoration interventions. Inspection of the thermograms and the application of two data mining techniques on the thermal data, i.e., k-means clustering and hierarchical clustering, allowed identifying different groups of window panes that show a different thermal behavior. Both clustering approaches arrive at similar groupings of the glass with a clear separation of three types. However, the lead cames that hold the glass panes appear to have a substantial impact on the thermal behavior of the surrounding glass, thus preventing classification of the smallest glass panes. For the larger panes, this was not a critical issue as the center of the glass remained unaffected. Subtle visual color differences between panes, implying a variation in coloring metal ions, was not always distinguished by IRT. Nevertheless, data clustering assisted infrared thermography shows potential as an efficient and swift method for documenting the material intervention history of leaded-glass windows during or in preparation of conservation treatments.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Cultural Heritage Sciences (ARCHES); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.7
DOI: 10.3390/APP10124255
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“Formation and stability of conformal spirals in confined 2D crystals”. Silva FCO, Menezes RM, Cabral LRE, de Souza Silva CC, Journal Of Physics-Condensed Matter 32, 505401 (2020). http://doi.org/10.1088/1361-648X/ABB0A7
Abstract: We investigate the ground-state and dynamical properties of nonuniform two-dimensional (2D) clusters of long-range interacting particles. We demonstrate that, when the confining external potential is designed to produce an approximate 1/ r 2 density profile, the particles crystallize into highly ordered structures featuring spiral crystalline lines. Despite the strong inhomogeneity of the observed configurations, most of them are characterized by small density of topological defects, typical of conformal crystals, and the net topological charge induced by the simply-connected geometry of the system is concentrated near the cluster center. These crystals are shown to be robust with respect to thermal fluctuations up to a certain threshold temperature, above which the net charge is progressively redistributed from the center to the rest of the system and the topological order is lost. The crystals are also resilient to the shear stress produced by a small nonuniform azimuthal force field, rotating as a rigid body (RB). For larger forces, topological defects proliferate and the RB rotation gives place to plastic flow.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ABB0A7
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“A superellipse with deformation and its application in describing the cross-sectional shapes of a square bamboo”. Huang W, Li Y, Niklas KJ, Gielis J, Ding Y, Cao L, Shi P, Symmetry-Basel 12, 2073 (2020). http://doi.org/10.3390/SYM12122073
Abstract: Many cross-sectional shapes of plants have been found to approximate a superellipse rather than an ellipse. Square bamboos, belonging to the genus Chimonobambusa (Poaceae), are a group of plants with round-edged square-like culm cross sections. The initial application of superellipses to model these culm cross sections has focused on Chimonobambusa quadrangularis (Franceschi) Makino. However, there is a need for large scale empirical data to confirm this hypothesis. In this study, approximately 750 cross sections from 30 culms of C. utilis were scanned to obtain cross-sectional boundary coordinates. A superellipse exhibits a centrosymmetry, but in nature the cross sections of culms usually deviate from a standard circle, ellipse, or superellipse because of the influences of the environment and terrain, resulting in different bending and torsion forces during growth. Thus, more natural cross-sectional shapes appear to have the form of a deformed superellipse. The superellipse equation with a deformation parameter (SEDP) was used to fit boundary data. We find that the cross-sectional shapes (including outer and inner rings) of C. utilis can be well described by SEDP. The adjusted root-mean-square error of SEDP is smaller than that of the superellipse equation without a deformation parameter. A major finding is that the cross-sectional shapes can be divided into two types of superellipse curves: hyperellipses and hypoellipses, even for cross sections from the same culm. There are two proportional relationships between ring area and the product of ring length and width for both the outer and inner rings. The proportionality coefficients are significantly different, as a consequence of the two different superellipse types (i.e., hyperellipses and hypoellipses). The difference in the proportionality coefficients between hyperellipses and hypoellipses for outer rings is greater than that for inner rings. This work informs our understanding and quantifying of the longitudinal deformation of plant stems for future studies to assess the influences of the environment on stem development. This work is also informative for understanding the deviation of natural shapes from a strict rotational symmetry.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.7
DOI: 10.3390/SYM12122073
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“Nitrogen Oxidation in a Multi-Pin Plasma System in the Presence and Absence of a Plasma/Liquid Interface”. Adhami Sayad Mahaleh M, Narimisa M, Nikiforov A, Gromov M, Gorbanev Y, Bitar R, Morent R, De Geyter N, Applied Sciences 13, 7619 (2023). http://doi.org/10.3390/app13137619
Abstract: The recent energy crisis revealed that there is a strong need to replace hydrocarbon-fueled industrial nitrogen fixation processes by alternative, more sustainable methods. In light of this, plasma-based nitrogen fixation remains one of the most promising options, considering both theoretical and experimental aspects. Lately, plasma interacting with water has received considerable attention in nitrogen fixation applications as it can trigger a unique gas- and liquid-phase chemistry. Within this context, a critical exploration of plasma-assisted nitrogen fixation with or without water presence is of great interest with an emphasis on energy costs, particularly in plasma reactors which have potential for large-scale industrial application. In this work, the presence of water in a multi-pin plasma system on nitrogen oxidation is experimentally investigated by comparing two pulsed negative DC voltage plasmas in metal–metal and metal–liquid electrode configurations. The plasma setups are designed to create similar plasma properties, including plasma power and discharge regime in both configurations. The system energy cost is calculated, considering nitrogen-containing species generated in gas and liquid phases as measured by a gas analyzer, nitrate sensor, and a colorimetry method. The energy cost profile as a function of specific energy input showed a strong dependency on the plasma operational frequency and the gas flow rate, as a result of different plasma operation regimes and initiated reverse processes. More importantly, the presence of the plasma/liquid interface increased the energy cost up to 14 ± 8%. Overall, the results showed that the presence of water in the reaction zone has a negative impact on the nitrogen fixation process.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 2.7
DOI: 10.3390/app13137619
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“Estimation of temperature homogeneity in MEMS-based heating nanochips via quantitative HAADF-STEM tomography”. Chen Q, Skorikov A, van der Hoeven JES, van Blaaderen A, Albrecht W, Perez-Garza HH, Bals S, Particle and particle systems characterization 41, 1 (2023). http://doi.org/10.1002/PPSC.202300070
Abstract: Sample holders for transmission electron microscopy (TEM) based on micro-electro-mechanical systems (MEMS) have recently become popular for investigating the behavior of nanomaterials under in situ or environmental conditions. The accuracy and reproducibility of these in situ holders are essential to ensure the reliability of experimental results. In addition, the uniformity of an applied temperature trigger across the MEMS chip is a crucial parameter. In this work, it is measured the temperature homogeneity of MEMS-based heating sample supports by locally analyzing the dynamics of heat-induced alloying of Au@Ag nanoparticles located in different regions of the support through quantitative fast high-angle annular dark-field scanning TEM tomography. These results demonstrate the superior temperature homogeneity of a microheater design based on a heating element shaped as a circular spiral with a width decreasing outwards compared to a double spiral-shaped designed microheater. The proposed approach to measure the local temperature homogeneity based on the thermal properties of bimetallic nanoparticles will support the future development of MEMS-based heating supports with improved thermal properties and in situ studies where high precision in the temperature at a certain position is required. This schematic delineates an approach to quantifying potential localized temperature deviation within a nanochip. Employing two comparable nanoparticles as thermal probes in discrete nanochip regions, the alloying kinetics of these nanoparticles are monitorable using in situ quantitative high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) tomography, thus enabling the precise estimation of local temperature deviations.image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.7
DOI: 10.1002/PPSC.202300070
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“Ginzburg-Landau surface energy of multiband superconductors : derivation and application to selected systems”. Bekaert J, Bringmans L, Milošević, MV, Journal of physics : condensed matter 35, 325602 (2023). http://doi.org/10.1088/1361-648X/ACD217
Abstract: We determine the energy of an interface between a multiband superconducting and a normal half-space, in presence of an applied magnetic field, based on a multiband Ginzburg-Landau (GL) approach. We obtain that the multiband surface energy is fully determined by the critical temperature, electronic densities of states, and superconducting gap functions associated with the different band condensates. This furthermore yields an expression for the thermodynamic critical magnetic field, in presence of an arbitrary number of contributing bands. Subsequently, we investigate the sign of the surface energy as a function of material parameters, through numerical solution of the GL equations. Here, we consider two distinct cases: (i) standard multiband superconductors with attractive interactions, and (ii) a three-band superconductor with a chiral ground state with phase frustration, arising from repulsive interband interactions. Furthermore, we apply this approach to several prime examples of multiband superconductors, such as metallic hydrogen and MgB2, based on microscopic parameters obtained from first-principles calculations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACD217
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“Valley-polarized and enhanced transmission in graphene with a smooth strain profile”. Wang S, Tian H, Sun M, Journal of physics : condensed matter 35, 304002 (2023). http://doi.org/10.1088/1361-648X/ACCBF9
Abstract: We explore the influence of strain on the valley-polarized transmission of graphene by employing the wave-function matching and the non-equilibrium Green's function technique. When the transmission is along the armchair direction, we show that the valley polarization and transmission can be improved by increasing the width of the strained region and increasing (decreasing) the extensional strain in the armchair (zigzag) direction. It is noted that the shear strain does not affect transmission and valley polarization. Furthermore, when we consider the smooth strain barrier, the valley-polarized transmission can be enhanced by increasing the smoothness of the strain barrier. We hope that our finding can shed new light on constructing graphene-based valleytronic and quantum computing devices by solely employing strain.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACCBF9
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“Soliton motion induced along ferromagnetic skyrmion chains in chiral thin nanotracks”. Souza JCB, Vizarim NP, Reichhardt CJO, Reichhardt C, Venegas PA, Journal of magnetism and magnetic materials 587, 171280 (2023). http://doi.org/10.1016/J.JMMM.2023.171280
Abstract: Using atomistic magnetic simulations we investigate the soliton motion along a pinned skyrmion chain containing an interstitial skyrmion. We find that the soliton can exhibit stable motion along the chain without a skyrmion Hall effect for an extended range of drives. Under a constant drive the solitons have a constant velocity. We also measure the skyrmion velocity-current curves and identify the signatures of different phases including a pinned phase, stable soliton motion, and quasi-free motion at higher drives where all of the skyrmions depin from the pinning centers and move along the rigid wall. In the quasi-free motion regime, the velocity is oscillatory due to the motion of the skyrmions over the pinning sites. For increasing pinning strength, the onset of soliton motion shifts to higher values of current density. We also find that for stronger pinning, the characteristic velocity-current shape is affected by the annihilation of single or multiple skyrmions in the drive interval over which the soliton motion occurs. Our results indicate that stable skyrmion soliton motion is possible and that the solitons could be used as information carriers instead of the skyrmions themselves for technological applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1016/J.JMMM.2023.171280
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“Electron microscopy characterisation of erbium silicide-thin films grown on a Si(111) substrate”. Frangis N, Van Tendeloo G, van Landuyt J, Muret P, Nguyen TTA, Applied surface science 102, 163 (1996). http://doi.org/10.1016/0169-4332(96)00040-2
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.711
Times cited: 9
DOI: 10.1016/0169-4332(96)00040-2
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“High crystalline quality erbium silicide films on (100) silicon grown in high vacuum”. Kaltsas G, Travlos A, Nassiopoulos AG, Frangis N, van Landuyt J, Applied surface science 102, 151 (1996). http://doi.org/10.1016/0169-4332(96)00036-0
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.711
Times cited: 14
DOI: 10.1016/0169-4332(96)00036-0
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“Photoelectric and electrical responses of several erbium silicide/silicon interfaces”. Muret P, Nguyen TTA, Frangis N, Van Tendeloo G, van Landuyt J, Applied surface science
T2 –, International Symposium on Si Heterostructures –, From Physics to Devices, SEP 11-14, 1995, IRAKLION, GREECE 102, 173 (1996). http://doi.org/10.1016/0169-4332(96)00042-6
Abstract: In this work, photoelectric yield and electrical properties of several types of epitaxial erbium silicide on silicon Schottky diodes are studied, Different preparation conditions are used simultaneously on n- and p-Si(111) substrates for the 200 Angstrom thick silicide films. A last type of sample consists in 1.3 monolayer of epitaxial silicide with root 3 X root 3 superstructure on the Si substrate and covered by silver on the top. Photocurrent measurements are done as a function of photon energy at several temperatures. All these samples show barrier heights near 1 eV on p-type Si, even for the interface comprising only 1.3 monolayer of silicide whereas barrier heights on n-rype Si span the range from 0.28 to 0.67 eV for this last kind of sample, the sum of the barriers always exceeding the silicon band gap, These photoelectric results are confirmed by electrical characterisations, All these results show that the Fermi level is pinned 0.1 eV below the conduction band edge on p-type Si but shifts to various positions lower within the band gap on n-type Si. This fact leads to the hypothesis of a density of -7 interface states close to the charge change in the Si depletion zone from p- to n-type, namely 10(12) eV(-1) cm(-2). Although some inhomogeneities and defects at the interface are detected by electron microscopy for samples annealed at 750 degrees C, Fermi level position seems rather insensitive to the structural details of the interface while the silicide thickness plays a role on n-type Si.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.711
Times cited: 3
DOI: 10.1016/0169-4332(96)00042-6
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“Round-robin investigation of silicon-oxide on silicon reference materials for ellipsometry”. Vanhellemont J, Maes HE, Schaekers M, Armigliato A, Cerva H, Cullis A, de Sande J, Dinges H, Hallais J, Nayar V, Pickering C, Stehlé, JL, Van Landuyt J, Walker C, Werner H, Salieri P;, Applied surface science
T2 –, SYMP ON DIAGNOSTIC TECHNIQUES FOR SEMICONDUCTOR MATERIALS ANALYSIS AND, FABRICATION PROCESS CONTROL, AT THE 1992 SPRING CONF OF THE EUROPEAN, MATERIALS RESEARCH SOC, JUN 02-05, 1992, STRASBOURG, FRANCE 63, 45 (1993). http://doi.org/10.1016/0169-4332(93)90062-G
Abstract: The main results and conclusions are presented of a round robin study of silicon oxide on silicon reference samples for ellipsometry. The oxide films with nominal thicknesses of 10, 50 and 120 nm are grown by thermal oxidation. The oxide film thicknesses have been determined by single wavelength ellipsometry (SWE), by spectroscopic ellipsometry (SE) and by cross-sectional conventional and high-resolution transmission electron microscopy (TEM and HREM) in different laboratories. The main conclusions are that special precautions have to be taken in order to use TEM as a reliable thickness measurement technique; that single wavelength ellipsometry can be used with great accuracy and reproducibility for the 50 and 120 nm film thicknesses but that it shows some inherent problems for the 10 nm films; and that spectroscopic ellipsometry showed for all film thicknesses an accuracy and reproducibility which is clearly superior to that of SWE.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.711
Times cited: 13
DOI: 10.1016/0169-4332(93)90062-G
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“Microstructure of adiabatic shear bands in Ti6Al4V”. Peirs J, Tirry W, Amin-Ahmadi B, Coghe F, Verleysen P, Rabet L, Schryvers D, Degrieck J, Materials characterization 75, 79 (2013). http://doi.org/10.1016/j.matchar.2012.10.009
Abstract: Microstructural deformation mechanisms in adiabatic shear bands in Ti6Al4V are studied using traditional TEM and selected area diffraction, and more advanced microstructural characterisation techniques such as energy dispersive X-ray spectroscopy, high angle annular dark field STEM and conical dark field TEM. The shear bands under investigation are induced in Ti6Al4V samples by high strain rate compression of cylindrical and hat-shaped specimens in a split Hopkinson pressure bar setup. Samples from experiments interrupted at different levels of deformation are used to study the evolution of the microstructure in and nearby the shear bands. From the early stages of adiabatic shear band formation, TEM revealed strongly elongated equiaxed grains in the shear band. These band-like grains become narrower towards the centre of the band and start to fraction even further along their elongated direction to finally result in a nano-crystalline region in the core. In fully developed shear bands, twins and a needle-like martensite morphology are observed near the shear band.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 56
DOI: 10.1016/j.matchar.2012.10.009
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“Quantitative study of particle size distribution in an in-situ grown Al-TiB2 composite by synchrotron X-ray diffraction and electron microscopy”. Tang Y, Chen Z, Borbely A, Ji G, Zhong SY, Schryvers D, Ji V, Wang HW, Materials characterization 102, 131 (2015). http://doi.org/10.1016/j.matchar.2015.03.003
Abstract: Synchrotron X-ray diffraction and transmission electron microscopy (TEM) were applied to quantitatively characterize the average particle size and size distribution of free-standing TiB2 particles and TiB2 particles in an insitu grown Al–TiB2 composite. The detailed evaluations were carried out by X-ray line profile analysis using the restrictedmoment method and multiplewhole profile fitting procedure (MWP). Both numericalmethods indicate that the formed TiB2 particles are well crystallized and free of crystal defects. The average particle size determined from different Bragg reflections by the restricted moment method ranges between 25 and 55 nm, where the smallest particle size is determined using the 110 reflection suggesting the highest lateral-growth velocity of (110) facets. TheMWP method has shown that the in-situ grown TiB2 particles have a very low dislocation density (~1011 m−2) and their size distribution can be described by a log-normal distribution. Good agreement was found between the results obtained from the restricted moment and MWP methods, which was further confirmed by TEM.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 41
DOI: 10.1016/j.matchar.2015.03.003
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“Structures in textured Cu-Al-Ni shape memory thin films grown by sputtering”. Espinoza Torres C, Condó, AM, Haberkorn N, Zelaya E, Schryvers D, Guimpel J, Lovey FC, Materials characterization 96, 256 (2014). http://doi.org/10.1016/j.matchar.2014.08.005
Abstract: The structure and texture formation in CuAlNi thin films of different thicknesses (1 μm to 5 μm) grown by DC magnetron sputtering without any intentional heating of the substrate are reported. The as-grown films present grains with an average size of 20 nm. The films with thickness of 1 μm have a single metastable phase with a hexagonal structure and are textured with planes (0002) parallel to the plane of the films. It was observed that thicker films present phase coexistence between metastable hexagonal and body centered cubic structures with a gradual increment of the body centered cubic phase fraction. The films with thickness of 5 μm are textured with planes (0002) and View the MathML source101¯0 in the hexagonal structure, whereas in the body centered cubic structure the films are textured with {110} planes parallel to the plane of the films. This fact can be associated with self-heating of the substrate during the growth of the films and with the relative stability of the metastable phases. Free standing films annealed in a second step (1123 K for 1 h) present austenitic phase with L21 structure and sub-micrometric grains textured with {220}L21 planes parallel to the plane of the films. The martensitic transformation temperature was determined from the analysis of resistance against temperature measurements.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 9
DOI: 10.1016/j.matchar.2014.08.005
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“Triple ion beam cutting of diamond/Al composites for interface characterization”. Ji G, Tan Z, Shabadi R, Li Z, Grünewald W, Addad A, Schryvers D, Zhang D, Materials characterization 89, 132 (2014). http://doi.org/10.1016/j.matchar.2014.01.008
Abstract: A novel triple ion beam cutting technique was employed to prepare high-quality surfaces of diamond/Al composites for interfacial characterization, which has been unachievable so far. Near-perfect and artifact-free surfaces were obtained without mechanical pre-polishing. Hence, the as-prepared surfaces are readily available for further study and also, ready to be employed in a focus ion beam system for preferential selection of transmission electron microscopy samples. Dramatically different diamond/Al interface configurations – sub-micrometer Al2O3 particles and clean interfaces were unambiguously revealed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 9
DOI: 10.1016/j.matchar.2014.01.008
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“Twinning in pure Ti subjected to monotonic simple shear deformation”. Tirry W, Bouvier S, Benmhenni N, Hammami W, Habraken AM, Coghe F, Schryvers D, Rabet L, Materials characterization 72, 24 (2012). http://doi.org/10.1016/j.matchar.2012.07.001
Abstract: The aim of this paper is to provide a thorough study on the occurrence and importance of deformation twinning in simple shear deformed pure α-Ti. A statistically relevant inspection of the morphology of the deformation twins in relation to the applied strain/deformation is performed. The investigated microstructural aspects are the twin volume fraction, the twin thickness distribution and the resolved shear stress distribution on the twin plane. All these aspects are examined as a function of the twin types and two initial textures. Monotonic simple shear experiments are carried out for three different loading directions with respect to a direction linked to the initial crystallographic texture. EBSD and TEM observations reveal the presence of View the MathML source and View the MathML source twins. The statistical analysis reveals that View the MathML source and View the MathML source twins have a similar average thickness around 1.9 nm, but the View the MathML source twins show a far larger spread on their thickness and can grow to almost the size of the original parent grain. Correlation of the twin fractions with the RSS analysis shows that RSS is an acceptable method explaining the difference in twin fractions for different textures and orientations. A detailed analysis shows that View the MathML source twins occur in average with a smaller volume fraction but with a higher RSS, indicating they are more difficult to nucleate or grow compared to View the MathML source twinning. In general a higher RSS value on the twin plane is not connected to a higher twin thickness; only in the case of View the MathML source twins the highest RSS values show clearly thicker twins.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 25
DOI: 10.1016/j.matchar.2012.07.001
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