“The conversion mechanism of amorphous silicon to stoichiometric WS2”. Heyne MH, de Marneffe J-F, Nuytten T, Meersschaut J, Conard T, Caymax M, Radu I, Delabie A, Neyts EC, De Gendt S, Journal of materials chemistry C : materials for optical and electronic devices 6, 4122 (2018). http://doi.org/10.1039/C8TC00760H
Abstract: The deposition of ultra-thin tungsten films and their related 2D chalcogen compounds on large area dielectric substrates by gas phase reactions is challenging. The lack of nucleation sites complicates the adsorption of W-related precursors and subsequent sulfurization usually requires high temperatures. We propose here a technique in which a thin solid amorphous silicon film is used as reductant for the gas phase precursor WF6 leading to the conversion to metallic W. The selectivity of the W conversion towards the underlying dielectric surfaces is demonstrated. The role of the Si surface preparation, the conversion temperature, and Si thickness on the formation process is investigated. Further, the in situ conversion of the metallic tungsten into thin stoichiometric WS2 is achieved by a cyclic approach based on WF6 and H2S pulses at the moderate temperature of 450 1C, which is much lower than usual oxide sulfurization processes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.256
Times cited: 4
DOI: 10.1039/C8TC00760H
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“Increased Performance Improvement of Lithium-Ion Batteries by Dry Powder Coating of High-Nickel NMC with Nanostructured Fumed Ternary Lithium Metal Oxides”. Herzog MJ, Gauquelin N, Esken D, Verbeeck J, Janek J, ACS applied energy materials 4, 8832 (2021). http://doi.org/10.1021/acsaem.1c00939
Abstract: Dry powder coating is an effective approach to protect the surfaces of layered cathode active materials (CAMs) in lithium-ion batteries. Previous investigations indicate an incorporation of lithium ions in fumed Al2O3, ZrO2, and TiO2 coatings on LiNi0.7Mn0.15Co0.15O2 during cycling, improving the cycling performance. Here, this coating approach is transferred for the first time to fumed ternary LiAlO2, Li4Zr3O8, and Li4Ti5O12 and directly compared with their lithium-free equivalents. All materials could be processed equally and their nanostructured small aggregates accumulate on the CAM surfaces to quite homogeneous coating layers with a certain porosity. The LiNixMnyCozO2 (NMC) coated with lithium-containing materials shows an enhanced improvement in overall capacity, capacity retention, rate performance, and polarization behavior during cycling, compared to their lithium-free analogues. The highest rate performance was achieved with the fumed ZrO2 coating, while the best long-term cycling stability with the highest absolute capacity was obtained for the fumed LiAlO2-coated NMC. The optimal coating agent for NMC to achieve a balanced system is fumed Li4Ti5O12, providing a good compromise between high rate capability and good capacity retention. The coating agents prevent CAM particle cracking and degradation in the order LiAlO2 ≈ Al2O3 > Li4Ti5O12 > Li4Zr3O8 > ZrO2 > TiO2. A schematic model for the protection and electrochemical performance enhancement of high-nickel NMC with fumed metal oxide coatings is sketched. It becomes apparent that physical and chemical characteristics of the coating significantly influence the performance of NMC. A high degree of coating-layer porosity is favorable for the rate capability, while a high coverage of the surface, especially in vulnerable grain boundaries, enhances the long-term cycling stability and improves the cracking behavior of NMCs. While zirconium-containing coatings possess the best chemical properties for high rate performances, aluminum-containing coatings feature a superior chemical nature to protect high-nickel NMCs.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 15
DOI: 10.1021/acsaem.1c00939
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“Monoclinic microdomains and clustering in the colossal magnetoresistance manganites Pr0.7Ca0.25Sr0.05MnO3 and Pr0.75Sr0.25MnO3”. Hervieu M, Van Tendeloo G, Caignaert V, Maignan A, Raveau B, Physical review : B : condensed matter and materials physics 53, 14274 (1996)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.736
Times cited: 75
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“Mécanismes de la non-stoechiométrie dans les nouveaux supraconducteurs à, haute Tc”. Hervieu M, Michel C, Martin C, Huvé, M, Van Tendeloo G, Maignan A, Pelloquin D, Goutenoire F, Raveau B, Journal de physique: 3: applied physics, materials science, fluids, plasma and instrumentation 4, 2057 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Structural and magnetotransport transitions in the electron-doped Pr1-xSrxMnO3(0.85\leq x\leq1) manganites”. Hervieu M, Martin C, Maignan A, Van Tendeloo G, Jirak Z, Hejtmanek J, Barnabe A, Thopart D, Raveau B, Chemistry and materials 12, 1456 (2000). http://doi.org/10.1021/cm000016o
Abstract: The exploration of the Mn4+-rich side of the Pr1-xSrxMnO3 system has allowed the extension of the domain of the cubic perovskite, by using a two-step process, combining synthesis under Ar flow at high temperature and O-2 pressure annealing at lower temperature. We show that these Pr-doped cubic perovskites exhibit a coupled structural (cubic-tetragonal) and magnetic (para-antiferro) transition connected with a resistivity jump at the same temperature. The strong interplay between lattice, charges, and spins for these oxides results from the appearance at low temperature of the distorted C-type antiferromagnetic structure. The Pr1-xSrxMnO3 magnetic phase diagram shows, for 0.9 less than or equal to x less than or equal to 1 (i.e., on the Mn4+-rich side), the existence at low temperature of C- and G-type antiferromagnetism. The absence of ferromagnetic-antiferromagnetic competition explains that magnetoresistante properties are not observed in this system, in contrast to Mn4+-rich Ln(1-x)Ca(x)MnO(3) systems.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 24
DOI: 10.1021/cm000016o
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“Electronic and magnetic properties of superlattices of graphene/graphane nanoribbons with different edge hydrogenation”. Hernández-Nieves AD, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 82, 165412 (2010). http://doi.org/10.1103/PhysRevB.82.165412
Abstract: Zigzag graphene nanoribbons patterned on graphane are studied using spin-polarized ab initio calculations. We found that the electronic and magnetic properties of the graphene/graphane superlattice strongly depends on the degree of hydrogenation at the interfaces between the two materials. When both zigzag interfaces are fully hydrogenated, the superlattice behaves like a freestanding zigzag graphene nanoribbon, and the magnetic ground state is antiferromagnetic. When one of the interfaces is half hydrogenated, the magnetic ground state becomes ferromagnetic, and the system is very close to being a half metal with possible spintronics applications whereas the magnetic ground state of the superlattice with both interfaces half hydrogenated is again antiferromagnetic. In this last case, both edges of the graphane nanoribbon also contribute to the total magnetization of the system. All the spin-polarized ground states are semiconducting, independent of the degree of hydrogenation of the interfaces. The ab initio results are supplemented by a simple tight-binding analysis that captures the main qualitative features. Our ab initio results show that patterned hydrogenation of graphene is a promising way to obtain stable graphene nanoribbons with interesting technological applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 46
DOI: 10.1103/PhysRevB.82.165412
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“Effects of thermal fluctuations on the magnetic behavior of mesoscopic superconductors”. Hernández AD, Baelus BJ, Domínguez D, Peeters FM, Physical review : B : condensed matter and materials physics 71, 214524 (2005). http://doi.org/10.1103/PhysRevB.71.214524
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PhysRevB.71.214524
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“Chemical and structural analysis of etching residue layers in semiconductor devices with energy filtering transmission electron microscopy”. Hens S, van Landuyt J, Bender H, Boullart W, Vanhaelemeersch S, Materials science in semiconductor processing 4, 109 (2001). http://doi.org/10.1016/S1369-8001(00)00147-5
Abstract: The use of an energy-filtering held emission gun transmission electron microscope (CM30 FEG Ultratwin) allows, apart from imaging morphologies down to nanometer scale, the fast acquisition of high-resolution element distributions. Electrons that have lost energy corresponding to characteristic inner-shell loss edges are used to form the element maps. The production of Ultra Large-Scale Integration (ULSI) devices with dimensions below 0.25 mum requires among others the formation of a multilayer metallization scheme by means of repeatedly applying the deposition and etching of dielectrics and metals. In this work the evolution of the surface chemical species on etched Al lines in a post-etch cleaning process has been investigated by energy filtering transmission electron microscopy, with the aim to understand the role of each process step on the removal of the etching residues. (C) 2001 Elsevier Science Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.359
DOI: 10.1016/S1369-8001(00)00147-5
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“EFTEM study of plasma etched low-k Si-O-C dielectrics”. Hens S, Bender H, Donaton RA, Maex K, Vanhaelemeersch S, van Landuyt J, Institute of physics conference series
T2 –, Royal-Microscopical-Society Conference on Microscopy of Semiconducting, Materials, MAR 25-29, 2001, UNIV OXFORD, OXFORD, ENGLAND , 415 (2001)
Abstract: Materials with low dielectric constant ("low-k'') in combination with Cu metallization are replacing the oxide based dielectrics with Al metallization in future generations of micro-electronic devices. In this work, a carbon doped oxide low-k dielectric material is studied after different kinds of etch/strip steps in single damascene Cu. filled line structures. Interline capacitance measurements indicate a dependence of the dielectric constant on the strip conditions. EFTEM is used to study the composition of the dielectric material and the modification of the low-k material at the sidewall of the etched structures for the various treatment conditions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“The influence of synthesis method on the local structure and electrochemical properties of Li-rich/Mn-rich NMC cathode materials for Li-Ion batteries”. Hendrickx M, Paulus A, Kirsanova MA, Van Bael MK, Abakumov AM, Hardy A, Hadermann J, Nanomaterials 12, 2269 (2022). http://doi.org/10.3390/NANO12132269
Abstract: Electrochemical energy storage plays a vital role in combating global climate change. Nowadays lithium-ion battery technology remains the most prominent technology for rechargeable batteries. A key performance-limiting factor of lithium-ion batteries is the active material of the positive electrode (cathode). Lithium- and manganese-rich nickel manganese cobalt oxide (LMR-NMC) cathode materials for Li-ion batteries are extensively investigated due to their high specific discharge capacities (>280 mAh/g). However, these materials are prone to severe capacity and voltage fade, which deteriorates the electrochemical performance. Capacity and voltage fade are strongly correlated with the particle morphology and nano- and microstructure of LMR-NMCs. By selecting an adequate synthesis strategy, the particle morphology and structure can be controlled, as such steering the electrochemical properties. In this manuscript we comparatively assessed the morphology and nanostructure of LMR-NMC (Li1.2Ni0.13Mn0.54Co0.13O2) prepared via an environmentally friendly aqueous solution-gel and co-precipitation route, respectively. The solution-gel (SG) synthesized material shows a Ni-enriched spinel-type surface layer at the {200} facets, which, based on our post-mortem high-angle annual dark-field scanning transmission electron microscopy and selected-area electron diffraction analysis, could partly explain the retarded voltage fade compared to the co-precipitation (CP) synthesized material. In addition, deviations in voltage fade and capacity fade (the latter being larger for the SG material) could also be correlated with the different particle morphology obtained for both materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.3
DOI: 10.3390/NANO12132269
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“Measurement of the size of embedded metal clusters by mass spectrometry, transmission electron microscopy, and small-angle X-ray scattering”. Hendrich C, Favre L, Ievlev DN, Dobrynin AN, Bras W, Hörmann U, Piscopiello E, Van Tendeloo G, Lievens P, Temst K, Applied physics A : materials science &, processing 86, 533 (2007). http://doi.org/10.1007/s00339-006-3808-5
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.455
Times cited: 11
DOI: 10.1007/s00339-006-3808-5
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“Far-infrared spectroscopy of minibands and confined donors in GaAs/AlxGa1-xAs superlattices”. Helm M, Peeters FM, DeRosa F, Colas E, Harbison JP, Florez LT, Physical review : B : condensed matter and materials physics 43, 13983 (1991)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 77
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“Infrared absorption in superlattices: a probe of the miniband dispersion and the structure of the impurity band”. Helm M, Hilber W, Fromherz T, Peeters FM, Alavi K, Pathak R, Physical review : B : condensed matter and materials physics 48, 1601 (1993). http://doi.org/10.1103/PhysRevB.48.1601
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 61
DOI: 10.1103/PhysRevB.48.1601
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“Reactions of high FeO-olivine rock with groundwater and redox-sensitive elements studied by surface-analytical methods and autoradiography”. Hellmuth KH, Siitari-Kaupi M, Rauhala E, Johansson B, Zilliacus R, Gijbels R, Adriaens A, Materials Research Society symposium proceedings 333, 947 (1994)
Keywords: P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 6
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“CO2 conversion in a microwave plasma reactor in the presence of N2 : elucidating the role of vibrational levels”. Heijkers S, Snoeckx R, Kozák T, Silva T, Godfroid T, Britun N, Snyders R, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 119, 12815 (2015). http://doi.org/10.1021/acs.jpcc.5b01466
Abstract: A chemical kinetics model is developed for a CO2/N2 microwave plasma, focusing especially on the vibrational levels of both CO2 and N2. The model is used to calculate the CO2 and N2 conversion as well as the energy efficiency of CO2 conversion for different power densities and for N2 fractions in the CO2/N2 gas mixture ranging from 0 to 90%. The calculation results are compared with measurements, and agreements within 23% and 33% are generally found for the CO2 conversion and N2 conversion, respectively. To explain the observed trends, the destruction and formation processes of both CO2 and N2 are analyzed, as well as the vibrational distribution functions of both CO2 and N2. The results indicate that N2 contributes in populating the lower asymmetric levels of CO2, leading to a higher absolute CO2 conversion upon increasing N2 fraction. However, the effective CO2 conversion drops because there is less CO2 initially present in the gas mixture; thus, the energy efficiency also drops with rising N2 fraction.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 56
DOI: 10.1021/acs.jpcc.5b01466
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“Nanosecond Pulsed Discharge for CO2Conversion: Kinetic Modeling To Elucidate the Chemistry and Improve the Performance”. Heijkers S, Martini LM, Dilecce G, Tosi P, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 123, 12104 (2019). http://doi.org/10.1021/acs.jpcc.9b01543
Abstract: We study the mechanisms of CO2 conversion in a nanosecond repetitively pulsed (NRP) discharge, by means of a chemical kinetics model. The calculated conversions and energy efficiencies are in reasonable agreement with experimental results over a wide range of specific energy input values, and the same applies to the evolution of gas temperature and CO2 conversion as a function of time in the afterglow, indicating that our model provides a realistic picture of the underlying mechanisms in the NRP discharge and can be used to identify its limitations and thus to suggest further improvements. Our model predicts that vibrational excitation is very important in the NRP discharge, explaining why this type of plasma yields energy-efficient CO2 conversion. A significant part of the CO2 dissociation occurs by electronic excitation from the lower vibrational levels toward repulsive electronic states, thus resulting in dissociation. However, vibration−translation (VT) relaxation (depopulating the higher vibrational levels) and CO + O recombination (CO + O + M → CO2 + M), as well as mixing of the converted gas with fresh gas entering the plasma in between the pulses, are limiting factors for the conversion and energy efficiency. Our model predicts that extra cooling, slowing down the rate of VT relaxation and of the above recombination reaction, thus enhancing the contribution of the highest vibrational levels to the overall CO2 dissociation, can further improve the performance of the NRP discharge for energy-efficient CO2 conversion.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 4
DOI: 10.1021/acs.jpcc.9b01543
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“CO2Conversion in a Gliding Arc Plasmatron: Elucidating the Chemistry through Kinetic Modeling”. Heijkers S, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 22644 (2017). http://doi.org/10.1021/acs.jpcc.7b06524
Abstract: By means of chemical kinetics modeling, it is possible to elucidate the main dissociation mechanisms of CO2 in a gliding arc plasmatron (GAP). We obtain good agreement between the calculated and experimental conversions and energy efficiencies, indicating that the model can indeed be used to study the underlying mechanisms. The calculations predict that vibration-induced dissociation is the main dissociation mechanism of CO2, but it occurs mainly from the lowest vibrational levels because of fast thermalization of the vibrational distribution. Based on these findings, we propose ideas for improving the performance of the GAP, but testing of these ideas in the simulations reveals that they do not always lead to significant enhancement, because of other side effects, thus illustrating the complexity of the process. Nevertheless, the model allows more insight into the underlying mechanisms to be obtained and limitations to be identified.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 6
DOI: 10.1021/acs.jpcc.7b06524
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“Iron catalysts for the growth of carbon nanofibers : Fe, Fe3C or both?”.He Z, Maurice J-L, Gohier A, Lee CS, Pribat D, Cojocaru CS, Chemistry of materials 23, 5379 (2011). http://doi.org/10.1021/cm202315j
Abstract: Iron is a widely used catalyst for the growth of carbon nanotubes (CNTs) or carbon nanofibers (CNFs) by catalytic chemical vapor deposition. However, both Fe and FeC compounds (generally, Fe3C) have been found to catalyze the growth of CNTs/CNFs, and a comparison study of their respective catalytic activities is still missing. Furthermore, the control of the crystal structure of iron-based catalysts, that is α-Fe or Fe3C, is still a challenge, which not only obscures our understanding of the growth mechanisms of CNTs/CNFs, but also complicates subsequent procedures, such as the removal of catalysts for better industrial applications. Here, we show a partial control of the phase of iron catalysts (α-Fe or Fe3C), obtained by varying the growth temperatures during the synthesis of carbon-based nanofibers/nanotubes in a plasma-enhanced chemical vapor deposition reactor. We also show that the structure of CNFs originating from Fe3C is bamboo-type, while that of CNFs originating from Fe is not. Moreover, we directly compare the growth rates of carbon-based nanofibers/nanotubes during the same experiments and find that CNFs/CNTs grown by α-Fe nanoparticles are longer than CNFs grown from Fe3C nanoparticles. The influence of the type of catalyst on the growth of CNFs is analyzed and the corresponding possible growth mechanisms, based on the different phases of the catalysts, are discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 91
DOI: 10.1021/cm202315j
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“Photoluminescence of negatively charged excitons in high magnetic fields”. Hayne M, Jones CL, Bogaerts R, Riva C, Usher A, Peeters FM, Herlach F, Moshchalkov VV, Henini M, Physical review : B : condensed matter and materials physics 59, 2927 (1999). http://doi.org/10.1103/PhysRevB.59.2927
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 86
DOI: 10.1103/PhysRevB.59.2927
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“Chlorinated phosphorene for energy application”. Hassani N, Yagmurcukardes M, Peeters FM, Neek-Amal M, Computational materials science 231, 112625 (2024). http://doi.org/10.1016/J.COMMATSCI.2023.112625
Abstract: The influence of decoration with impurities and the composition dependent band gap in 2D materials has been the subject of debate for a long time. Here, by using Density Functional Theory (DFT) calculations, we systematically disclose physical properties of chlorinated phosphorene having the stoichiometry of PmCln. By analyzing the adsorption energy, charge density, migration energy barrier, structural, vibrational, and electronic properties of chlorinated phosphorene, we found that (I) the Cl-P bonds are strong with binding energy Eb =-1.61 eV, decreases with increasing n. (II) Cl atoms on phosphorene have anionic feature, (III) the migration path of Cl on phosphorene is anisotropic with an energy barrier of 0.38 eV, (IV) the phonon band dispersion reveal that chlorinated phosphorenes are stable when r <= 0.25 where r = m/n, (V) chlorinated phosphorenes is found to be a photonic crystal in the frequency range of 280 cm-1 to 325 cm-1, (VI) electronic band structure of chlorinated phosphorenes exhibits quasi-flat bands emerging around the Fermi level with widths in the range of 22 meV to 580 meV, and (VII) Cl adsorption causes a semiconducting to metallic/semi-metallic transition which makes it suitable for application as an electroactive material. To elucidate this application, we investigated the change in binding energy (Eb), specific capacity, and open-circuit voltage as a function of the density of adsorbed Cl. The theoretical storage capacity of the chlorinated phosphorene is found to be 168.19 mA h g-1with a large average voltage (similar to 2.08 V) which is ideal number as a cathode in chloride-ion batteries.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.3
Times cited: 2
DOI: 10.1016/J.COMMATSCI.2023.112625
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“Two new members of the covalent organic frameworks family : crystalline 2D-oxocarbon and 3D-borocarbon structures”. Hassani N, Movafegh-Ghadirli A, Mahdavifar Z, Peeters FM, Neek-Amal M, Computational materials science 241, 1 (2024). http://doi.org/10.1016/J.COMMATSCI.2024.113022
Abstract: Oxocarbons, known for over two centuries, have recently revealed a long-awaited facet: two-dimensional crystalline structures. Employing an intelligent global optimization algorithm (IGOA) alongside densityfunctional calculations, we unearthed a quasi -flat oxocarbon (C 6 0 6 ), featuring an oxygen -decorated hole, and a novel 3D-borocarbon. Comparative analyses with recently synthesized isostructures, such as 2D -porous carbon nitride (C 6 N 6 ) and 2D -porous boroxine (B 6 0 6 ), highlight the unique attributes of these compounds. All structures share a common stoichiometry of X 6 Y 6 (which we call COF-66), where X = B, C, and Y = B, N, O (with X not equal Y), exhibiting a 2D -crystalline structure, except for borocarbon C 6 B 6 , which forms a 3D crystal. In our comprehensive study, we conducted a detailed exploration of the electronic structure of X 6 Y 6 compounds, scrutinizing their thermodynamic properties and systematically evaluating phonon stability criteria. With expansive surface areas, diverse pore sizes, biocompatibility, pi-conjugation, and distinctive photoelectric properties, these structures, belonging to the covalent organic framework (COF) family, present enticing prospects for fundamental research and hold potential for biosensing applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.3
DOI: 10.1016/J.COMMATSCI.2024.113022
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“Properties and thermal stability of solution processed ultrathin, high-k bismuth titanate (Bi2Ti2O7) films”. Hardy A, Van Elshocht S, De Dobbelaere C, Hadermann J, Pourtois G, De Gendt S, Afanas'ev VV, Van Bael MK, Materials research bulletin 47, 511 (2012). http://doi.org/10.1016/j.materresbull.2012.01.001
Abstract: Ultrathin bismuth titanate films (Bi2Ti2O7, 5-25 nm) are deposited onto SiO2/Si substrates by aqueous chemical solution deposition and their evolution during annealing is studied. The films crystallize into a preferentially oriented, pure pyrochlore phase between 500 and 700 degrees C, depending on the film thickness and the total thermal budget. Crystallization causes a strong increase of surface roughness compared to amorphous films. An increase of the interfacial layer thickness is observed after anneal at 600 degrees C, together with intermixing of bismuth with the substrate as shown by TEM-EDX. The band gap was determined to be similar to 3 eV from photoconductivity measurements and high dielectric constants between 30 and 130 were determined from capacitance voltage measurements, depending on the processing conditions. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.446
DOI: 10.1016/j.materresbull.2012.01.001
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“From 2D to 3D : bridging self-assembled monolayers to a substrate-induced polymorph in a molecular semiconductor”. Hao Y, Velpula G, Kaltenegger M, Bodlos WR, Vibert F, Mali KS, De Feyter S, Resel R, Geerts YH, Van Aert S, Beljonne D, Lazzaroni R, Chemistry of materials 34, 2238 (2022). http://doi.org/10.1021/ACS.CHEMMATER.1C04038
Abstract: In this study, a new bottom-up approach is proposed to predict the crystal structure of the substrate-induced polymorph (SIP) of an archetypal molecular semiconductor. In spite of intense efforts, the formation mechanism of SIPs is still not fully understood, and predicting their crystal structure is a very delicate task. Here, we selected lead phthalocyanine (PbPc) as a prototypical molecular material because it is a highly symmetrical yet nonplanar molecule and we demonstrate that the growth and crystal structure of the PbPc SIPs can be templated by the corresponding physisorbed self-assembled molecular networks (SAMNs). Starting from SAMNs of PbPc formed at the solution/graphite interface, the structural and energetic aspects of the assembly were studied by a combination of in situ scanning tunneling microscopy and multiscale computational chemistry approach. Then, the growth of a PbPc SIP on top of the physisorbed monolayer was modeled without prior experimental knowledge, from which the crystal structure of the SIP was predicted. The theoretical prediction of the SIP was verified by determining the crystal structure of PbPc thin films using X-ray diffraction techniques, revealing the formation of a new polymorph of PbPc on the graphite substrate. This study clearly illustrates the correlation between the SAMNs and SIPs, which are traditionally considered as two separate but conceptually connected research areas. This approach is applicable to molecular materials in general to predict the crystal structure of their SIPs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.6
DOI: 10.1021/ACS.CHEMMATER.1C04038
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“Orbital-hybridization-driven charge density wave transition in CsV₃Sb₅, kagome superconductor”. Han S, Tang CS, Li L, Liu Y, Liu H, Gou J, Wu J, Zhou D, Yang P, Diao C, Ji J, Bao J, Zhang L, Zhao M, Milošević, MV, Guo Y, Tian L, Breese MBH, Cao G, Cai C, Wee ATS, Yin X, Advanced materials , 1 (2022). http://doi.org/10.1002/ADMA.202209010
Abstract: Owing to its inherent non-trivial geometry, the unique structural motif of the recently discovered kagome topological superconductor AV(3)Sb(5) (A = K, Rb, Cs) is an ideal host of diverse topologically non-trivial phenomena, including giant anomalous Hall conductivity, topological charge order, charge density wave (CDW), and unconventional superconductivity. Despite possessing a normal-state CDW order in the form of topological chiral charge order and diverse superconducting gaps structures, it remains unclear how fundamental atomic-level properties and many-body effects including Fermi surface nesting, electron-phonon coupling, and orbital hybridization contribute to these symmetry-breaking phenomena. Here, the direct participation of the V3d-Sb5p orbital hybridization in mediating the CDW phase transition in CsV3Sb5 is reported. The combination of temperature-dependent X-ray absorption and first-principles studies clearly indicates the inverse Star-of-David structure as the preferred reconstruction in the low-temperature CDW phase. The results highlight the critical role that Sb orbitals play and establish orbital hybridization as the direct mediator of the CDW states and structural transition dynamics in kagome unconventional superconductors. This is a significant step toward the fundamental understanding and control of the emerging correlated phases from the kagome lattice through the orbital interactions and provides promising approaches to novel regimes in unconventional orders and topology.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 29.4
Times cited: 1
DOI: 10.1002/ADMA.202209010
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“Bioactive Nonthermal Biocompatible Plasma Enhances Migration on Human Gingival Fibroblasts”. Han I, Song IS, Choi SA, Lee T, Yusupov M, Shaw P, Bogaerts A, Choi EH, Ryu JJ, Advanced healthcare materials 12, 2200527 (2023). http://doi.org/10.1002/adhm.202200527
Abstract: This study hypothesizes that the application of low-dose nonthermal biocompatible dielectric barrier discharge plasma (DBD-NBP) to human gingival fibroblasts (HGFs) will inhibit colony formation but not cell death and induce matrix metalloproteinase (MMP) expression, extracellular matrix (ECM) degradation, and subsequent cell migration, which can result in enhanced wound healing. HGFs treated with plasma for 3 min migrate to each other across the gap faster than those in the control and 5-min treatment groups on days 1 and 3. The plasma-treated HGFs show significantly high expression levels of the cell cycle arrest-related p21 gene and enhanced MMP activity. Focal adhesion kinase (FAK) mediated attenuation of wound healing or actin cytoskeleton rearrangement, and plasma-mediated reversal of this attenuation support the migratory effect of DBD-NBP. Further, this work performs computer simulations to investigate the effect of oxidation on the stability and conformation of the catalytic kinase domain (KD) of FAK. It is found that the oxidation of highly reactive amino acids (AAs) Cys427, Met442, Cys559, Met571, Met617, and Met643 changes the conformation and increases the structural flexibility of the FAK protein and thus modulates its function and activity. Low-dose DBD-NBP-induces host cell cycle arrest, ECM breakdown, and subsequent migration, thus contributing to the enhanced wound healing process.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 10
DOI: 10.1002/adhm.202200527
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“ELNES study of carbon K-edge spectra of plasma deposited carbon films”. Hamon A-L, Verbeeck J, Schryvers D, Benedikt J, van den Sanden RMCM, Journal of materials chemistry 14, 2030 (2004). http://doi.org/10.1039/b406468m
Abstract: Electron energy loss spectroscopy was used to investigate the bonding of plasma deposited carbon films. The experimental conditions include the use of a specific collection angle for which the shape of the spectra is free of the orientation dependency usually encountered in graphite due to its anisotropic structure. The first quantification process of the energy loss near-edge structure was performed by a standard fit of the collected spectrum, corrected for background and multiple scattering, with three Gaussian functions followed by a comparison with the graphite spectrum obtained under equivalent experimental conditions. In a second approach a fitting model directly incorporating the background subtraction and multiple scattering removal was applied. The final numerical results are interpreted in view of the deposition conditions of the films and the actual fitting procedure with the related choice of parameters.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.626
Times cited: 61
DOI: 10.1039/b406468m
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“Existence of superstructures due to large amounts of Fe vacancies in the LiFePO4-type framework”. Hamelet S, Casas-Cabanas M, Dupont L, Davoisne C, Tarascon JM, Masquelier C, Chemistry of materials 23, 32 (2011). http://doi.org/10.1021/cm102511m
Abstract: LiFePO4 has been under intense scrutiny over the past decade because it stands as an attractive positive electrode material for the next generation of Li-ion batteries to power electric vehicles and hybrid electric vehicles, hence the importance of its thermal behavior. The reactivity of LiFePO4 with air at moderate temperatures is shown to be dependent on its particle size. For nanosized materials, a progressive displacement of Fe from the core structure leading to a composite made of nanosize Fe2O3 and highly defective, oxidized LixFeyPO4 compositions, among which the “ideal” formula LiFe2/3PO4. Herein we report, from both temperature-controlled X-ray diffraction and electronic diffraction microscopy, that these off-stoichiometry olivine-type compounds show a defect ordering resulting in the formation of a superstructure. Such a finding shows striking similarities with the temperature-driven oxidation of fayalite Fe2SiO4 (another olivine) to structurally defective laihunite, reported in the literature three decades ago.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 30
DOI: 10.1021/cm102511m
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“Electron-mobility in 2 coupled delta-layers”. Hai, Studart, Peeters FM, Physical review : B : condensed matter and materials physics 52, 11273 (1995). http://doi.org/10.1103/PhysRevB.52.11273
Abstract: The low-temperature transport properties are studied for electrons confined in delta-doped semiconductor structures with two sheets in parallel. The subband quantum mobility and transport mobility are calculated numerically for the Si delta-doped GaAs systems. The effect of coupling of the two delta layers on the electron transport is investigated. Our calculations are in good agreement with experimental results.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 25
DOI: 10.1103/PhysRevB.52.11273
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“Multisubband electron-transport in delta-doped semiconductor systems”. Hai, Studart, Peeters FM, Physical review : B : condensed matter and materials physics 52, 8363 (1995). http://doi.org/10.1103/PhysRevB.52.8363
Abstract: The electron transport properties in delta-doped semiconductor systems-are studied. The subband electronic structure of the delta-doped system is obtained by solving the coupled Schrodinger and Poisson equations. The screening of the quasi-two-dimensional electron gas is taken into account for the ionized impurity scattering through the matrix dielectric function within the random-phase approximation. The quantum and transport mobilities are calculated numerically as a function of the total electron density and the width of the doped layer at zero temperature. The intersubband scattering and the effect of empty subbands above the Fermi level on the electron mobilities are investigated. The calculated mobilities are in reasonable agreement with the available experimental results.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 67
DOI: 10.1103/PhysRevB.52.8363
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“Electron mobility in two coupled &delta, layers”. Hai GQ, Studart N, Peeters FM, Physical review : B : condensed matter and materials physics 52, 11273 (1995)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 24
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