“Reliable pore-size measurements based on a procedure specifically designed for electron tomography measurements of nanoporous samples”. Van Eyndhoven G, Batenburg KJ, van Oers C, Kurttepeli M, Bals S, Cool P, Sijbers J, (2014)
Keywords: P3 Proceeding; Electron microscopy for materials research (EMAT); Vision lab; Laboratory of adsorption and catalysis (LADCA)
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Kurttepeli M (2015) Carbon based materials and hybrid nanostructures investigated by advanced transmission electron microscopy. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“Effect of annealing on mechanical properties and thermal stability of ZrCu/O nanocomposite amorphous films synthetized by pulsed laser deposition”. Bignoli F, Rashid S, Rossi E, Jaddi S, Djemia P, Terraneo G, Li Bassi A, Idrissi H, Pardoen T, Sebastiani M, Ghidelli M, Materials &, design 221, 110972 (2022). http://doi.org/10.1016/J.MATDES.2022.110972
Abstract: Binary ZrCu nanocomposite amorphous films are synthetized by pulsed laser deposition (PLD) under vac-uum (2 x 10-3 Pa) and 10 Pa He pressure, leading to fully amorphous compact and nanogranular mor-phologies, respectively. Then, post-thermal annealing treatments are carried out to explore thermal stability and crystallization phenomena together with the evolution of mechanical properties. Compact films exhibit larger thermal stability with partial crystallization phenomena starting at 420 degrees C, still to be completed at 550 degrees C, while nanogranular films exhibit early-stage crystallization at 300 degrees C and com-pleted at 485 degrees C. The microstructural differences are related to a distinct evolution of mechanical
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.4
DOI: 10.1016/J.MATDES.2022.110972
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“Computation of the thermal expansion coefficient of graphene with Gaussian approximation potentials”. Demiroglu I, Karaaslan Y, Kocabas T, Keceli M, Vazquez-Mayagoitia A, Sevik C, Journal Of Physical Chemistry C 125, 14409 (2021). http://doi.org/10.1021/ACS.JPCC.1C01888
Abstract: Direct experimental measurement of thermal expansion coefficient without substrate effects is a challenging task for two-dimensional (2D) materials, and its accurate estimation with large-scale ab initio molecular dynamics is computationally very expensive. Machine learning-based interatomic potentials trained with ab initio data have been successfully used in molecular dynamics simulations to decrease the computational cost without compromising the accuracy. In this study, we investigated using Gaussian approximation potentials to reproduce the density functional theory-level accuracy for graphene within both lattice dynamical and molecular dynamical methods, and to extend their applicability to larger length and time scales. Two such potentials are considered, GAP17 and GAP20. GAP17, which was trained with pristine graphene structures, is found to give closer results to density functional theory calculations at different scales. Further vibrational and structural analyses verify that the same conclusions can be deduced with density functional theory level in terms of the reasoning of the thermal expansion behavior, and the negative thermal expansion behavior is associated with long-range out-of-plane phonon vibrations. Thus, it is argued that the enabled larger system sizes by machine learning potentials may even enhance the accuracy compared to small-size-limited ab initio molecular dynamics.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
DOI: 10.1021/ACS.JPCC.1C01888
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“The influence of surface functionalization on thermal transport and thermoelectric properties of MXene monolayers”. Sarikurt S, Çakir D, Keceli M, Sevik C, Nanoscale 10, 8859 (2018). http://doi.org/10.1039/C7NR09144C
Abstract: The newest members of a two-dimensional material family, involving transition metal carbides and nitrides (called MXenes), have garnered increasing attention due to their tunable electronic and thermal properties depending on the chemical composition and functionalization. This flexibility can be exploited to fabricate efficient electrochemical energy storage (batteries) and energy conversion (thermoelectric) devices. In this study, we calculated the Seebeck coefficients and lattice thermal conductivity values of oxygen terminated M2CO2 (where M = Ti, Zr, Hf, Sc) monolayer MXene crystals in two different functionalization configurations (model-II (MD-II) and model-III (MD-III)), using density functional theory and Boltzmann transport theory. We estimated the thermoelectric figure-of-merit, zT, of these materials by two different approaches, as well. First of all, we found that the structural model (i.e. adsorption site of oxygen atom on the surface of MXene) has a paramount impact on the electronic and thermoelectric properties of MXene crystals, which can be exploited to engineer the thermoelectric properties of these materials. The lattice thermal conductivity kappa(l), Seebeck coefficient and zT values may vary by 40% depending on the structural model. The MD-III configuration always has the larger band gap, Seebeck coefficient and zT, and smaller kappa(l) as compared to the MD-II structure due to a larger band gap, highly flat valence band and reduced crystal symmetry in the former. The MD-III configuration of Ti2CO2 and Zr2CO2 has the lowest kappa(l) as compared to the same configuration of Hf2CO2 and Sc2CO2. Among all the considered structures, the MD-II configuration of Hf2CO2 has the highest kappa(l), and Ti2CO2 and Zr2CO2 in the MD-III configuration have the lowest kappa(l). For instance, while the band gap of the MD-II configuration of Ti2CO2 is 0.26 eV, it becomes 0.69 eV in MD-III. The zT(max) value may reach up to 1.1 depending on the structural model of MXene.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.1039/C7NR09144C
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“Gaussian approximation potentials for accurate thermal properties of two-dimensional materials”. Kocabas T, Keceli M, Vazquez-Mayagoitia A, Sevik C, Nanoscale 15, 8772 (2023). http://doi.org/10.1039/D3NR00399J
Abstract: Two-dimensional materials (2DMs) continue to attract a lot of attention, particularly for their extreme flexibility and superior thermal properties. Molecular dynamics simulations are among the most powerful methods for computing these properties, but their reliability depends on the accuracy of interatomic interactions. While first principles approaches provide the most accurate description of interatomic forces, they are computationally expensive. In contrast, classical force fields are computationally efficient, but have limited accuracy in interatomic force description. Machine learning interatomic potentials, such as Gaussian Approximation Potentials, trained on density functional theory (DFT) calculations offer a compromise by providing both accurate estimation and computational efficiency. In this work, we present a systematic procedure to develop Gaussian approximation potentials for selected 2DMs, graphene, buckled silicene, and h-XN (X = B, Al, and Ga, as binary compounds) structures. We validate our approach through calculations that require various levels of accuracy in interatomic interactions. The calculated phonon dispersion curves and lattice thermal conductivity, obtained through harmonic and anharmonic force constants (including fourth order) are in excellent agreement with DFT results. HIPHIVE calculations, in which the generated GAP potentials were used to compute higher-order force constants instead of DFT, demonstrated the first-principles level accuracy of the potentials for interatomic force description. Molecular dynamics simulations based on phonon density of states calculations, which agree closely with DFT-based calculations, also show the success of the generated potentials in high-temperature simulations.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 6.7
DOI: 10.1039/D3NR00399J
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“Designer phospholipid capping ligands for soft metal halide nanocrystals”. Morad V, Stelmakh A, Svyrydenko M, Feld LG, Boehme SC, Aebli M, Affolter J, Kaul CJ, Schrenker NJ, Bals S, Sahin Y, Dirin DN, Cherniukh I, Raino G, Baumketner A, Kovalenko MV, Nature 626, 542 (2024). http://doi.org/10.1038/S41586-023-06932-6
Abstract: The success of colloidal semiconductor nanocrystals (NCs) in science and optoelectronics is inextricable from their surfaces. The functionalization of lead halide perovskite NCs1-5 poses a formidable challenge because of their structural lability, unlike the well-established covalent ligand capping of conventional semiconductor NCs6,7. We posited that the vast and facile molecular engineering of phospholipids as zwitterionic surfactants can deliver highly customized surface chemistries for metal halide NCs. Molecular dynamics simulations implied that ligand-NC surface affinity is primarily governed by the structure of the zwitterionic head group, particularly by the geometric fitness of the anionic and cationic moieties into the surface lattice sites, as corroborated by the nuclear magnetic resonance and Fourier-transform infrared spectroscopy data. Lattice-matched primary-ammonium phospholipids enhance the structural and colloidal integrity of hybrid organic-inorganic lead halide perovskites (FAPbBr3 and MAPbBr3 (FA, formamidinium; MA, methylammonium)) and lead-free metal halide NCs. The molecular structure of the organic ligand tail governs the long-term colloidal stability and compatibility with solvents of diverse polarity, from hydrocarbons to acetone and alcohols. These NCs exhibit photoluminescence quantum yield of more than 96% in solution and solids and minimal photoluminescence intermittency at the single particle level with an average ON fraction as high as 94%, as well as bright and high-purity (about 95%) single-photon emission. Phospholipids enhance the structural and colloidal integrity of hybrid organic-inorganic lead halide perovskites and lead-free metal halide nanocrystals, which then exhibit enhanced robustness and optical properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
DOI: 10.1038/S41586-023-06932-6
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“Giant tunability of Rashba splitting at cation-exchanged polar oxide interfaces by selective orbital hybridization”. Xu H, Li H, Gauquelin N, Chen X, Wu W-F, Zhao Y, Si L, Tian D, Li L, Gan Y, Qi S, Li M, Hu F, Sun J, Jannis D, Yu P, Chen G, Zhong Z, Radovic M, Verbeeck J, Chen Y, Shen B, Advanced materials (2024). http://doi.org/10.1002/ADMA.202313297
Abstract: The 2D electron gas (2DEG) at oxide interfaces exhibits extraordinary properties, such as 2D superconductivity and ferromagnetism, coupled to strongly correlated electrons in narrow d-bands. In particular, 2DEGs in KTaO3 (KTO) with 5d t2g orbitals exhibit larger atomic spin-orbit coupling and crystal-facet-dependent superconductivity absent for 3d 2DEGs in SrTiO3 (STO). Herein, by tracing the interfacial chemistry, weak anti-localization magneto-transport behavior, and electronic structures of (001), (110), and (111) KTO 2DEGs, unambiguously cation exchange across KTO interfaces is discovered. Therefore, the origin of the 2DEGs at KTO-based interfaces is dramatically different from the electronic reconstruction observed at STO interfaces. More importantly, as the interface polarization grows with the higher order planes in the KTO case, the Rashba spin splitting becomes maximal for the superconducting (111) interfaces approximately twice that of the (001) interface. The larger Rashba spin splitting couples strongly to the asymmetric chiral texture of the orbital angular moment, and results mainly from the enhanced inter-orbital hopping of the t2g bands and more localized wave functions. This finding has profound implications for the search for topological superconductors, as well as the realization of efficient spin-charge interconversion for low-power spin-orbitronics based on (110) and (111) KTO interfaces. An unambiguous cation exchange is discovered across the interfaces of (001), (110), and (111) KTaO3 2D electron gases fabricated at room temperature. Remarkably, the (111) interfaces with the highest superconducting transition temperature also turn out to show the strongest electron-phonon interaction and the largest Rashba spin splitting. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
DOI: 10.1002/ADMA.202313297
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“Tailoring mechanical properties and shear band propagation in ZrCu metallic glass nanolaminates through chemical heterogeneities and interface density”. Brognara A, Kashiwar A, Jung C, Zhang X, Ahmadian A, Gauquelin N, Verbeeck J, Djemia P, Faurie D, Dehm G, Idrissi H, Best JP, Ghidelli M, Small Structures , 2400011 (2024). http://doi.org/10.1002/SSTR.202400011
Abstract: The design of high‐performance structural thin films consistently seeks to achieve a delicate equilibrium by balancing outstanding mechanical properties like yield strength, ductility, and substrate adhesion, which are often mutually exclusive. Metallic glasses (MGs) with their amorphous structure have superior strength, but usually poor ductility with catastrophic failure induced by shear bands (SBs) formation. Herein, we introduce an innovative approach by synthesizing MGs characterized by large and tunable mechanical properties, pioneering a nanoengineering design based on the control of nanoscale chemical/structural heterogeneities. This is realized through a simplified model Zr 24 Cu 76 /Zr 61 Cu 39 , fully amorphous nanocomposite with controlled nanoscale periodicity ( Λ , from 400 down to 5 nm), local chemistry, and glass–glass interfaces, while focusing in‐depth on the SB nucleation/propagation processes. The nanolaminates enable a fine control of the mechanical properties, and an onset of crack formation/percolation (>1.9 and 3.3%, respectively) far above the monolithic counterparts. Moreover, we show that SB propagation induces large chemical intermixing, enabling a brittle‐to‐ductile transition when Λ ≤ 50 nm, reaching remarkably large plastic deformation of 16% in compression and yield strength ≈2 GPa. Overall, the nanoengineered control of local heterogeneities leads to ultimate and tunable mechanical properties opening up a new approach for strong and ductile materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1002/SSTR.202400011
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“Giant magnetoresistance in the half-metallic double-perovskite ferrimagnet Mn2FeReO6”. Li MR, Retuerto M, Deng Z, Stephens PW, Croft M, Huang Q, Wu H, Deng X, Kotliar G, Sánchez-Benítez J, Hadermann J, Walker D, Greenblatt M;, Angewandte Chemie: international edition in English 54, 12069 (2015). http://doi.org/10.1002/anie.201506456
Abstract: The first transition-metal-only double perovskite compound, Mn2+ Fe-2(3+) Re5+ O-6, with 17 unpaired d electrons displays ferrimagnetic ordering up to 520K and a giant positive magnetoresistance of up to 220% at 5K and 8 T. These properties result from the ferrimagnetically coupled Fe and Re sublattice and are affected by a two-to-one magnetic-structure transition of the Mn sublattice when a magnetic field is applied. Theoretical calculations indicate that the half-metallic state can be mainly attributed to the spin polarization of the Fe and Re sites.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
DOI: 10.1002/anie.201506456
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“Atomic-scale viscoplasticity mechanisms revealed in high ductility metallic glass films”. Idrissi H, Ghidelli M, Béché, A, Turner S, Gravier S, Blandin J-J, Raskin J-P, Schryvers D, Pardoen T, Scientific reports 9, 13426 (2019). http://doi.org/10.1038/s41598-019-49910-7
Abstract: The fundamental plasticity mechanisms in thin freestanding Zr65Ni35 metallic glass films are investigated in order to unravel the origin of an outstanding strength/ductility balance. The deformation process is homogenous until fracture with no evidence of catastrophic shear banding. The creep/relaxation behaviour of the films was characterized by on-chip tensile testing, revealing an activation volume in the range 100–200 Å3. Advanced high-resolution transmission electron microscopy imaging and spectroscopy exhibit a very fine glassy nanostructure with well-defined dense Ni-rich clusters embedded in Zr-rich clusters of lower atomic density and a ~2–3 nm characteristic length scale. Nanobeam electron diffraction analysis reveals that the accumulation of plastic deformation at roomtemperature
correlates with monotonously increasing disruption of the local atomic order. These results provide experimental evidences of the dynamics of shear transformation zones activation in metallic glasses. The impact of the nanoscale structural heterogeneities on the mechanical properties including the rate dependent behaviour is discussed, shedding new light on the governing plasticity mechanisms in metallic glasses with initially heterogeneous atomic arrangement.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.259
DOI: 10.1038/s41598-019-49910-7
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“The rediscovered portrait of Prospero Farinacci by Caravaggio”. Cardinali M, De Ruggieri MB, Leone G, Prohaska W, Alfeld M, Janssens K, Artibus et historiae : an art anthology , 249 (2016)
Abstract: Caravaggio's early production as a portrait painter is still the subject of research and a fount of enigmas. Despite the numerous citations in documents, only rarely have these been linked unequivocally to paintings known to date. This is also the case with the `portrait of Farinaccio criminalist painted on a head-size canvas believed to be by Michelangelo from Caravaggio', that was listed in the 1638 inventory of the Marquis Giustiniani and with `the speaker wearing a robe, painted by Caravaggio' on a head-size canvas, owned in 1652 by Caterina Campani, Onorio Longhi's wife. The present multidisciplinary research examines the rediscovery of the portrait of Prospero Farinacci by Caravaggio. The painting, undisclosed until now, hides an underlying female portrait. The authors investigate both compositions from a technical, iconographical and critical point of view, supporting Caravaggio's attribution. The technical researches allow cross-validation in the brushwork and materials of the picture, compared to Caravaggio's early painting technique and style. The portrait of Maffeo Barberini, recently re-ascribed to Caravaggio, shows a significant similarity, while the underlying woman of the retrieved painting closely resembles the gipsy of the Louvre Fortune Teller. In addition, a newly introduced and advanced imaging technique (MaXRF) has detected on the male portrait the feature of the lawyer's robe, which supports the identification with Prospero Farinacci. The intriguing topic of physiognomic accuracy versus stylizing tendency in Caravaggio's portraiture is considered with the aid of Giulio Mancini's observations. Besides, the possible interpretation of the underlying figure as a religious subject sheds a light on the obscure activity of the young Caravaggio in Lorenzo Carli's workshop, recently brought to scholars' attention by new documents and hypotheses.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Advances in non-equilibrium $$\hbox {CO}_2$$ plasma kinetics: a theoretical and experimental review”. Pietanza LD, Guaitella O, Aquilanti V, Armenise I, Bogaerts A, Capitelli M, Colonna G, Guerra V, Engeln R, Kustova E, Lombardi A, Palazzetti F, Silva T, European Physical Journal D 75, 237 (2021). http://doi.org/10.1140/epjd/s10053-021-00226-0
Abstract: Numerous applications have required the study of CO2 plasmas since the 1960s, from CO2 lasers to spacecraft heat shields. However, in recent years, intense research activities on the subject have restarted because of environmental problems associated with CO2 emissions. The present review provides a synthesis of the current state of knowledge on the physical chemistry of cold CO2 plasmas. In particular, the different modeling approaches implemented to address specific aspects of CO2 plasmas are presented. Throughout the paper, the importance of conducting joint experimental, theoretical and modeling studies to elucidate the complex couplings at play in CO2 plasmas is emphasized. Therefore, the experimental data that are likely to bring relevant constraints to the different modeling approaches are first reviewed. Second, the calculation of some key elementary processes obtained with semi-empirical, classical and quantum methods is presented. In order to describe the electron kinetics, the latest coherent sets of cross section satisfying the constraints of “electron swarm” analyses are introduced, and the need for self-consistent calculations for determining accurate electron energy distribution function (EEDF) is evidenced. The main findings of the latest zero-dimensional (0D) global models about the complex chemistry of CO2 and its dissociation products in different plasma discharges are then given, and full state-to-state (STS) models of only the vibrational-dissociation kinetics developed for studies of spacecraft shields are described. Finally, two important points for all applications using CO2 containing plasma are discussed: the role of surfaces in contact with the plasma, and the need for 2D/3D models to capture the main features of complex reactor geometries including effects induced by fluid dynamics on the plasma properties. In addition to bringing together the latest advances in the description of CO2 non-equilibrium plasmas, the results presented here also highlight the fundamental data that are still missing and the possible routes that still need to be investigated.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 1.288
DOI: 10.1140/epjd/s10053-021-00226-0
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“The role of healed N-vacancy defective BC2N sheet and nanotube by NO molecule in oxidation of NO and CO gas molecules”. Nematollahi P, Esrafili MD, Neyts EC, Surface science : a journal devoted to the physics and chemistry of interfaces 672-673, 39 (2018). http://doi.org/10.1016/J.SUSC.2018.03.002
Abstract: In this study, the healing of N-vacancy boron carbonitride nanosheet (NV-BC2NNS) and nanotube (NV-BC2NNT) by NO molecule is studied by means of density functional theory calculations. Two different N-vacancies are considered in each of these structures in which the vacancy site is surrounded by either three B-atoms (NB) or by two B- and one C-atom (NBC). By means of the healed BC2NNS and BC2NNT as a support, the removal of two toxic gas molecules (NO and CO) are applicable. It should be noted that the obtained energy barriers of both healing and oxidizing processes are significantly lower than those of graphene, carbon nanotubes or boron nitride nanostructures. Also, at the end of the oxidation process, the pure BC2NNS or BC2NNT is obtained without any additional defects. Therefore, by using this method, we can considerably purify the defective BC2NNS/BC2NNT. Moreover, according to the thermochemistry calculations we can further confirm that the healing process of the NV-BC2NNS and NV-BC2NNT by NO are feasible at room temperature. So, we can claim that this study could be very helpful in both purifying the defective BC2NNS/BC2NNT while in the same effort removing toxic NO and CO gases.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.062
Times cited: 1
DOI: 10.1016/J.SUSC.2018.03.002
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“MnFe0.5Ru0.5O3 : an above-room-temperature antiferromagnetic semiconductor”. Tan X, McCabe EE, Orlandi F, Manuel P, Batuk M, Hadermann J, Deng Z, Jin C, Nowik I, Herber R, Segre CU, Liu S, Croft M, Kang C-J, Lapidus S, Frank CE, Padmanabhan H, Gopalan V, Wu M, Li M-R, Kotliar G, Walker D, Greenblatt M, Journal of materials chemistry C : materials for optical and electronic devices 7, 509 (2019). http://doi.org/10.1039/C8TC05059G
Abstract: A transition-metal-only MnFe0.5Ru0.5O3 polycrystalline oxide was prepared by a reaction of starting materials MnO, MnO2, Fe2O3, RuO2 at 6 GPa and 1873 K for 30 minutes. A combination of X-ray and neutron powder diffraction refinements indicated that MnFe0.5Ru0.5O3 adopts the corundum (alpha-Fe2O3) structure type with space group R (3) over barc, in which all metal ions are disordered. The centrosymmetric nature of the MnFe0.5Ru0.5O3 structure is corroborated by transmission electron microscopy, lack of optical second harmonic generation, X-ray absorption near edge spectroscopy, and Mossbauer spectroscopy. X-ray absorption near edge spectroscopy of MnFe0.5Ru0.5O3 showed the oxidation states of Mn, Fe, and Ru to be 2+/3+, 3+, and similar to 4+, respectively. Resistivity measurements revealed that MnFe0.5Ru0.5O3 is a semiconductor. Magnetic measurements and magnetic structure refinements indicated that MnFe0.5Ru0.5O3 orders antiferromagnetically around 400 K, with magnetic moments slightly canted away from the c axis. Fe-57 Mossbauer confirmed the magnetic ordering and Fe3+ (S = 5/2) magnetic hyperfine splitting. First principles calculations are provided to understand the electronic structure more thoroughly. A comparison of synthesis and properties of MnFe0.5Ru0.5O3 and related corundum Mn2BB'O-6 derivatives is discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.256
Times cited: 1
DOI: 10.1039/C8TC05059G
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“Universal a-cation splitting in LiNbO₃-type structure driven by intrapositional multivalent coupling”. Han Y, Zeng Y, Hendrickx M, Hadermann J, Stephens PW, Zhu C, Grams CP, Hemberger J, Frank C, Li S, Wu MX, Retuerto M, Croft M, Walker D, Yao D-X, Greenblatt M, Li M-R, Journal Of The American Chemical Society 142, 7168 (2020). http://doi.org/10.1021/JACS.0C01814
Abstract: Understanding the electric dipole switching in multiferroic materials requires deep insight of the atomic-scale local structure evolution to reveal the ferroelectric mechanism, which remains unclear and lacks a solid experimental indicator in high-pressure prepared LiNbO3-type polar magnets. Here, we report the discovery of Zn-ion splitting in LiNbO3-type Zn2FeNbO6 established by multiple diffraction techniques. The coexistence of a high-temperature paraelectric-like phase in the polar Zn2FeNbO6 lattice motivated us to revisit other high-pressure prepared LiNbO3-type A(2)BB'O-6 compounds. The A-site atomic splitting (similar to 1.0-1.2 angstrom between the split-atom pair) in B/B'-mixed Zn2FeTaO6 and O/N-mixed ZnTaO2N is verified by both powder X-ray diffraction structural refinements and high angle annular dark field scanning transmission electron microscopy images, but is absent in single-B-site ZnSnO3. Theoretical calculations are in good agreement with experimental results and suggest that this kind of A-site splitting also exists in the B-site mixed Mn-analogues, Mn2FeMO6 (M = Nb, Ta) and anion-mixed MnTaO2N, where the smaller A-site splitting (similar to 0.2 angstrom atomic displacement) is attributed to magnetic interactions and bonding between A and B cations. These findings reveal universal A-site splitting in LiNbO3-type structures with mixed multivalent B/B', or anionic sites, and the splitting-atomic displacement can be strongly suppressed by magnetic interactions and/or hybridization of valence bands between d electrons of the A- and B-site cations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 15
Times cited: 1
DOI: 10.1021/JACS.0C01814
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“Inverse heavy-atom effect in near infrared photoluminescent gold nanoclusters”. Pramanik G, Kvakova K, Thottappali MA, Rais D, Pfleger J, Greben M, El-Zoka A, Bals S, Dracinsky M, Valenta J, Cigler P, Nanoscale 12, 10462 (2021). http://doi.org/10.1039/D1NR90138A
Abstract: Fluorophores functionalized with heavy elements show enhanced intersystem crossing due to increased spin-orbit coupling, which in turn shortens the fluorescence decay lifetime (tau(PL)). This phenomenon is known as the heavy-atom effect (HAE). Here, we report the observation of increased tau(PL) upon functionalisation of near-infrared photoluminescent gold nanoclusters with iodine. The heavy atom-mediated increase in tau(PL) is in striking contrast with the HAE and referred to as inverse HAE. Femtosecond and nanosecond transient absorption spectroscopy revealed overcompensation of a slight decrease in lifetime of the transition associated with the Au core (ps) by a large increase in the long-lived triplet state lifetime associated with the Au shell, which contributed to the observed inverse HAE. This unique observation of inverse HAE in gold nanoclusters provides the means to enhance the triplet excited state lifetime.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.367
Times cited: 1
DOI: 10.1039/D1NR90138A
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“Melamine–Formaldehyde Microcapsules: Micro- and Nanostructural Characterization with Electron Microscopy”. Heidari H, Rivero G, Idrissi H, Ramachandran D, Cakir S, Egoavil R, Kurttepeli M, Crabbé, AC, Hauffman T, Terryn H, Du Prez F, Schryvers D, Microscopy and microanalysis 22, 1222 (2016). http://doi.org/10.1017/S1431927616012484
Abstract: A systematic study has been carried out to compare the surface morphology, shell thickness, mechanical properties, and binding behavior of melamine–formaldehyde microcapsules of 5–30 μm diameter size with various amounts of core content by using scanning and transmission electron microscopy including electron tomography, in situ nanomechanical tensile testing, and electron energy-loss spectroscopy. It is found that porosities are present on the outside surface of the capsule shell, but not on the inner surface of the shell. Nanomechanical tensile tests on the capsule shells reveal that Young’s modulus of the shell material is higher than that of bulk melamine–formaldehyde and that the shells exhibit a larger fracture strain compared with the bulk. Core-loss elemental analysis of microcapsules embedded in epoxy indicates that during the curing process, the microcapsule-matrix interface remains uniform and the epoxy matrix penetrates into the surface micro-porosities of the capsule shells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.891
Times cited: 2
DOI: 10.1017/S1431927616012484
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“Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9: in Search of Jahn-Teller Distorted Cr(II) Oxide”. Li M-R, Deng Z, Lapidus SH, Stephens PW, Segre CU, Croft M, Sena RP, Hadermann J, Walker D, Greenblatt M, Inorganic chemistry 55, 10135 (2016). http://doi.org/10.1021/ACS.INORGCHEM.6B01047
Abstract: A novel 6H-type hexagonal perovskite Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9 was prepared at high pressure (6 GPa) and temperature (1773 K). Both transmission electron microscopy and synchrotron powder X-ray diffraction data demonstrate that Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9 crystallizes in P6(3)/mmc with face-shared (Cr0.97(1)Te0.03(1))O-6 octahedral pairs interconnected with TeO6 octahedra via corner-sharing. Structure analysis shows a mixed Cr2+/Cr3+ valence state with similar to 10% Cr2+. The existence of Cr2+ in Ba-3(Cr0.10(1)2+Cr0.87(1)3+Te0.036+)(2)TeO9 is further evidenced by X-ray absorption near-edge spectroscopy. Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy-state curvature at low temperature. In this work, the octahedral Cr2+O6 component is stabilized in an oxide material for the first time; the expected Jahn-Teller distortion of high-spin (d(4)) Cr2+ is not found, which is attributed to the small proportion of Cr2+ (similar to 10%) and the face-sharing arrangement of CrO6 octahedral pairs, which structurally disfavor axial distortion.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 2
DOI: 10.1021/ACS.INORGCHEM.6B01047
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“External costs from fossil electricity generation : a review of the applied impact pathway approach”. Jorli M, Van Passel S, Saghdel HS, Energy &, Environment 29, 635 (2018). http://doi.org/10.1177/0958305X18761616
Abstract: This paper reviews and compares 11 studies that have estimated external costs of fossil electricity generation by benefits transfer. These studies include 13 countries and most of these countries are developing countries. The impact pathway approach is applied to estimate the environmental impact arising from fossil fuel-fired power plant's air emission and the related damages on human health. The estimated damages are used to value the monetary external costs from fossil fuel electricity generation. The estimated external costs in the 13 countries vary from 0.51 to 213.5 USD (2005) per MWh due to differences in fossil fuel quality, location, technology, and efficiency of power plants and additionally differences in assumptions, monetization values, and impact estimations. Accounting for these externalities can indicate the actual costs of fossil energy. The results can be applied by policy makers to take measures to avoid additional costs and to apply newer and cleaner energy sources. The described methods in the selected studies for estimating the external costs with respect to incomplete local data can be applied as a useful example for other developing countries.
Keywords: A1 Journal article; Engineering Management (ENM)
Impact Factor: 0.302
Times cited: 3
DOI: 10.1177/0958305X18761616
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“Random charge fluctuation effect on strongly correlated dust particles confined in two dimensions”. Rouaiguia L, Djebli M, Peeters F, Physics letters : A 372, 4487 (2008). http://doi.org/10.1016/j.physleta.2008.04.020
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.772
Times cited: 4
DOI: 10.1016/j.physleta.2008.04.020
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“Electrostatic force-driven oxide heteroepitaxy for interface control”. Ren Z, Wu M, Chen X, Li W, Li M, Wang F, Tian H, Chen J, Xie Y, Mai J, Li X, Lu X, Lu Y, Zhang H, Van Tendeloo G, Zhang Z, Han G, Advanced materials 30, 1707017 (2018). http://doi.org/10.1002/ADMA.201707017
Abstract: Oxide heterostructure interfaces create a platform to induce intriguing electric and magnetic functionalities for possible future devices. A general approach to control growth and interface structure of oxide heterostructures will offer a great opportunity for understanding and manipulating the functionalities. Here, it is reported that an electrostatic force, originating from a polar ferroelectric surface, can be used to drive oxide heteroepitaxy, giving rise to an atomically sharp and coherent interface by using a low-temperature solution method. These heterostructures adopt a fascinating selective growth, and show a saturation thickness and the reconstructed interface with concentrated charges accumulation. The ferroelectric polarization screening, developing from a solid-liquid interface to the heterostructure interface, is decisive for the specific growth. At the interface, a charge transfer and accumulation take place for electrical compensation. The facile approach presented here can be extremely useful for controlling oxide heteroepitaxy and producing intriguing interface functionality via electrostatic engineering.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 4
DOI: 10.1002/ADMA.201707017
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“Estimating human health impacts and costs due to Iranian fossil fuel power plant emissions through the impact pathway approach”. Jorli M, Van Passel S, Sadeghi H, Nasseri A, Agheli L, Energies 10, 2136 (2017). http://doi.org/10.3390/EN10122136
Abstract: Air pollutants from fossil fuel fired power plants harm the environment and human health. More than 91% of Irans electricity production is from thermal power plants that use natural gas, diesel, and fuel oil. We apply the impact pathway approach to estimate the health impacts arising from Iranian fossil-based electricity generation emission, and in a next step, we calculate monetary costs of the estimated damages, for a one-year period starting from 20 March 2016 through 2017. We use the new version of SIMPACTS (International Atomic Energy Agency, Vienna, Austria) to investigate the health effects from 61 major Iran fossil-based power plants separately. The selected plants represent 95.6% of total Iran fossil-based power generation. Using the individual and different power plant estimates, we avoid extrapolation and our results can be considered more reliable, taking into account spatial differences. The total damage cost is 723.42 million USD (2000). The damage cost per generated electricity varies from 0.06 to 22.41 USD/MWh and average plant damage cost is 2.85 USD/MWh. Accounting for these external costs indicates the actual costs of fossil energy. The results are useful for policy makers to compare the health costs from these plants and to decide on cleaner energy sources and to take measures to increase benefits for society.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 2.262
Times cited: 4
DOI: 10.3390/EN10122136
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“Hole doping and structural transformation in CsTl1-xHgxCl3”. Retuerto M, Yin Z, Emge TJ, Stephens PW, Li MR, Sarkar T, Croft MC, Ignatov A, Yuan Z, Zhang SJ, Jin C, Paria Sena R, Hadermann J, Kotliar G, Greenblatt M;, Inorganic chemistry 54, 1066 (2015). http://doi.org/10.1021/ic502400d
Abstract: CsTlCl3 and CsTlF3 perovskites have been theoretically predicted to be superconductors when properly hole-doped. Both compounds have been previously prepared as pure compounds: CsTlCl3 in a tetragonal (I4/m) and a cubic (Fm3̅m) perovskite polymorph and CsTlF3 as a cubic perovskite (Fm3̅m). In this work, substitution of Tl in CsTlCl3 with Hg is reported, in an attempt to hole-dope the system and induce superconductivity. The whole series CsTl1xHgxCl3 (x = 0.0, 0.1, 0.2, 0.4, 0.6, and 0.8) was prepared. CsTl0.9Hg0.1Cl3 is tetragonal as the more stable phase of CsTlCl3. However, CsTl0.8Hg0.2Cl3 is already cubic with the space group Fm3̅m and with two different positions for Tl+ and Tl3+. For x = 0.4 and 0.5, solid solutions could not be formed. For x ≥ 0.6, the samples are primitive cubic perovskites with one crystallographic position for Tl+, Tl3+, and Hg2+. All of the samples formed are insulating, and there is no signature of superconductivity. X-ray absorption spectroscopy indicates that all of the samples have a mixed-valence state of Tl+ and Tl3+. Raman spectroscopy shows the presence of the active TlClTl stretching mode over the whole series and the intensity of the TlClHg mode increases with increasing Hg content. First-principle calculations confirmed that the phases are insulators in their ground state and that Hg is not a good dopant in the search for superconductivity in this system.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 5
DOI: 10.1021/ic502400d
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“Synthesis of aluminum-containing hierarchical mesoporous materials with columnar mesopore ordering by evaporation induced self assembly”. Kurttepeli M, Locus R, Verboekend D, de Clippel F, Breynaert E, Martens J, Sels B, Bals S, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 234, 186 (2016). http://doi.org/10.1016/J.MICROMESO.2016.07.002
Abstract: The incorporation of aluminum into the silica columns of hierarchical mesoporous materials (HMMs) was studied. The HMMs were synthesized by a combination of hard and soft templating methods, forming mesoporous SBA-15-type silica columns inside the pores of anodic aluminum oxide membranes via evaporation induced self-assembly (EISA). By adding Al-isopropoxide to the EISA-mixture a full tetrahedral incorporation of Al and thus the creation of acid sites was achieved, which was proved by nuclear magnetic resonance spectroscopy. Electron microscopy showed that the use of Al-isopropoxide as an Al source for the HMMs led to a change in the mesopore ordering of silica material from circular hexagonal (donut-like) to columnar hexagonal and a 37% increase in specific surface (BET surface). These results were confirmed by a combination of nitrogen physisorption and small-angle X-ray scattering experiments and can be attributed to a swelling of the P123 micelles with isopropanol. The columnar mesopore ordering of silica is advantageous towards the pore accessibility and therefore preferential for many possible applications including catalysis and adsorption on the acid tetrahedral Al-sites. (C) 2016 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.615
Times cited: 5
DOI: 10.1016/J.MICROMESO.2016.07.002
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“Non-thermal plasma-induced immunogenic cell death in cancer”. Khalili M, Daniels L, Lin A, Krebs FC, Snook AE, Bekeschus S, Bownel WB, Miller V, Journal of physics: D: applied physics 52, 423001 (2019). http://doi.org/10.1088/1361-6463/AB31C1
Abstract: Recent advances in biomedical research in cancer immunotherapy have identified the use of an oxidative stress-based approach to treat cancers, which works by inducing immunogenic cell death (ICD) in cancer cells. Since the anti-cancer effects of non-thermal plasma (NTP) are largely attributed to the reactive oxygen and nitrogen species that are delivered to and generated inside the target cancer cells, it is reasonable to postulate that NTP would be an effective modality for ICD induction. NTP treatment of tumors has been shown to destroy cancer cells rapidly and, under specific treatment regimens, this leads to systemic tumorspecific immunity. The translational benefit of NTP for treatment of cancer relies on its ability to enhance the interactions between NTP-exposed minor cells and local immune cells which initiates subsequent protective immune responses. This review discusses results from recent investigations of NTP application to induce ICD in cancer cells. With further optimization of clinical devices and treatment protocols, NTP can become an essential part of the therapeutic armament against cancer.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 6
DOI: 10.1088/1361-6463/AB31C1
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“Pore REconstruction and Segmentation (PORES) method for improved porosity quantification of nanoporous materials”. Van Eyndhoven G, Kurttepeli M, van Oers CJ, Cool P, Bals S, Batenburg KJ, Sijbers J, Ultramicroscopy 148, 10 (2015). http://doi.org/10.1016/j.ultramic.2014.08.008
Abstract: Electron tomography is currently a versatile tool to investigate the connection between the structure and properties of nanomaterials. However, a quantitative interpretation of electron tomography results is still far from straightforward. Especially accurate quantification of pore-space is hampered by artifacts introduced in all steps of the processing chain, i.e., acquisition, reconstruction, segmentation and quantification. Furthermore, most common approaches require subjective manual user input. In this paper, the PORES algorithm POre REconstruction and Segmentation is introduced; it is a tailor-made, integral approach, for the reconstruction, segmentation, and quantification of porous nanomaterials. The PORES processing chain starts by calculating a reconstruction with a nanoporous-specific reconstruction algorithm: the Simultaneous Update of Pore Pixels by iterative REconstruction and Simple Segmentation algorithm (SUPPRESS). It classifies the interior region to the pores during reconstruction, while reconstructing the remaining region by reducing the error with respect to the acquired electron microscopy data. The SUPPRESS reconstruction can be directly plugged into the remaining processing chain of the PORES algorithm, resulting in accurate individual pore quantification and full sample pore statistics. The proposed approach was extensively validated on both simulated and experimental data, indicating its ability to generate accurate statistics of nanoporous materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab; Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 2.843
Times cited: 7
DOI: 10.1016/j.ultramic.2014.08.008
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“Combined macroscopic, nanoscopic, and atomic-scale characterization of gold-ruthenium bimetallic catalysts for octanol oxidation”. Chinchilla LE, Olmos C, Kurttepeli M, Bals S, Van Tendeloo G, Villa A, Prati L, Blanco G, Calvino JJ, Chen X, Hungría AB, Particle and particle systems characterization 33, 419 (2016). http://doi.org/10.1002/ppsc.201600057
Abstract: A series of gold-ruthenium bimetallic catalysts of increasing Au:Ru molar ratios supported on a Ce0.62Zr0.38O2 mixed oxide are prepared and their structural and chemical features characterized by a combination of macroscopic and atomic-scale techniques based on scanning transmission electron microscopy. The influence of the temperature of the final reduction treatment used as activation step (350-700 degrees C range) is also investigated. The preparation method used allows catalysts to be successfully prepared where a major fraction of the metal nanoparticles is in the size range below 5 nm. The structural complexities characteristic of this type of catalysts are evidenced, as well as the capabilities and limitations of both the macroscopic and microscopic techniques in the characterization of the system of metal nanoparticles. A positive influence of the addition of Ru on both the resistance against sintering and the catalytic performance of the starting supported Au catalyst is evidenced.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.474
Times cited: 7
DOI: 10.1002/ppsc.201600057
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“Inverse heavy-atom effect in near infrared photoluminescent gold nanoclusters”. Pramanik G, Kvakova K, Thottappali MA, Rais D, Pfleger J, Greben M, El-Zoka A, Bals S, Dracinsky M, Valenta J, Cigler P, Nanoscale 13, 10462 (2021). http://doi.org/10.1039/D1NR02440J
Abstract: Fluorophores functionalized with heavy elements show enhanced intersystem crossing due to increased spin–orbit coupling, which in turn shortens the fluorescence decay lifetime (<italic>τ</italic><sup>PL</sup>). This phenomenon is known as the heavy-atom effect (HAE). Here, we report the observation of increased<italic>τ</italic><sup>PL</sup>upon functionalisation of near-infrared photoluminescent gold nanoclusters with iodine. The heavy atom-mediated increase in<italic>τ</italic><sup>PL</sup>is in striking contrast with the HAE and referred to as inverse HAE. Femtosecond and nanosecond transient absorption spectroscopy revealed overcompensation of a slight decrease in lifetime of the transition associated with the Au core (ps) by a large increase in the long-lived triplet state lifetime associated with the Au shell, which contributed to the observed inverse HAE. This unique observation of inverse HAE in gold nanoclusters provides the means to enhance the triplet excited state lifetime.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 7.367
Times cited: 7
DOI: 10.1039/D1NR02440J
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“Deposition of aminosilane coatings on porous Al2O3microspheres by means of dielectric barrier discharges”. Garzia Trulli M, Claes N, Pype J, Bals S, Baert K, Terryn H, Sardella E, Favia P, Vanhulsel A, Plasma processes and polymers 14, 1600211 (2017). http://doi.org/10.1002/ppap.201600211
Abstract: Advances in the synthesis of porous microspheres and in their functionalization are increasing the interest in applications of alumina. This paper deals with coatings plasma deposited from 3-aminopropyltriethoxysilane by means of dielectric barrier discharges on alumina porous microspheres, shaped by a vibrational droplet coagulation technique. Aims of the work are the functionalization of the particles with active amino groups, as well as the evaluation of their surface coverage and of the penetration of the coatings into their pores. A multi-diagnostic approach was used for the chemical/morphological characterization of the particles. It was found that 5 min exposure to plasma discharges promotes the deposition of homogeneous coatings onto the microspheres and within their pores, down to 1 μm.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 2.846
Times cited: 8
DOI: 10.1002/ppap.201600211
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