“Plasma-based conversion of CO2 and CH4 into syngas: A dive into the effect of adding water”. Wanten B, Gorbanev Y, Bogaerts A, Fuel 374, 132355 (2024). http://doi.org/10.1016/j.fuel.2024.132355
Abstract: Plasma technology can play a vital role in the electrification and decarbonization of chemical processes. In this work, we carried out the bi-reforming of methane (BRM), producing syngas out of H2O vapor and the greenhouse gases CO2 and CH4, in an atmospheric pressure glow discharge reactor. Compared to dry reforming of methane (DRM), the addition of H2O helps in counteracting soot formation, and thus avoids severe destabilization of the generated plasma. A mixture of 14–41-45 vol% (CO2-CH4-H2O) leads to the overall best results in terms of stable plasma and performance metrics. We obtained a CO2 and CH4 conversion of 49 % and 74 %, respectively, at a SEI of 210 kJ/mol. The energy cost is 390 kJ/mol converted reactants, which is below the target defined for plasmabased syngas production to be competitive with other technologies. Moreover, we reached CO and H2 yields of
59 % and 49 %, and a syngas ratio (SR) of 2, which is ideal for further methanol synthesis.
Keywords: A1 Journal Article; Plasma Bi-reforming of methane Atmospheric pressure glow discharge Hydrogen-rich syngas; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2024.132355
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“Effect of O2on Plasma-Based Dry Reforming of Methane: Revealing the Optimal Gas Composition via Experiments and Modeling of an Atmospheric Pressure Glow Discharge”. Maerivoet S, Wanten B, De Meyer R, Van Hove M, Van Alphen S, Bogaerts A, ACS Sustainable Chemistry &, Engineering 12, 11419 (2024). http://doi.org/10.1021/acssuschemeng.4c04283
Abstract: Plasma technology is gaining increasing interest for the conversion of greenhouse gases, such as CO2 and CH4, into value-added chemicals using (renewable) electricity. In this paper, we study the effect of O2 addition to the combined conversion of CO2 and CH4 in an atmospheric pressure glow discharge plasma. This process is called “oxidative CO2 reforming of methane”, and we search for the optimal gas mixing ratio in terms of conversion, energy cost, product output and plasma stability. A mixing ratio of 42.5:42.5:15 CO2/CH4/O2 yields the best performance, with a CO2 and CH4 conversion of 50 and 74%, respectively, and an energy cost as low as 2 eV molecule−1 (corresponding to 7.9 kJ L−1 and 190 kJ mol−1), i.e., clearly below the target defined to be competitive with other technologies. The syngas components (CO and H2) are the most important products, with a syngas ratio, H2/CO, being 0.8. Plasma destabilization at high CH4 fractions due to solid carbon formation is the limiting factor for further improving this syngas ratio. The solid carbon material is found to be contaminated with steel particles originating from the electrode material, rendering it unappealing as a side product. Therefore, O2 addition helps to remove the carbon formation. Besides the experiments, we developed a 2D axisymmetric fluid dynamics model, which can successfully predict the experimental trends in conversion, product composition and temperatures, while providing unique insights in the formation of CxHy species.
Keywords: A1 Journal Article; plasma-based conversion, thermal plasma, syngas production, CO2 conversion, CH4 conversio; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.4c04283
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“Effect of Gas Composition on Temperature and CO2Conversion in a Gliding Arc Plasmatron reactor: Insights for Post‐Plasma Catalysis from Experiments and Computation”. Xu W, Van Alphen S, Galvita VV, Meynen V, Bogaerts A, ChemSusChem (2024). http://doi.org/10.1002/cssc.202400169
Abstract: Plasma‐based CO<sub>2</sub>conversion has attracted increasing interest. However, to understand the impact of plasma operation on post‐plasma processes, we studied the effect of adding N<sub>2</sub>, N<sub>2</sub>/CH<sub>4</sub>and N<sub>2</sub>/CH<sub>4</sub>/H<sub>2</sub>O to a CO<sub>2</sub>gliding arc plasmatron (GAP) to obtain valuable insights into their impact on exhaust stream composition and temperature, which will serve as feed gas and heat for post‐plasma catalysis (PPC). Adding N<sub>2</sub>improves the CO<sub>2</sub>conversion from 4 % to 13 %, and CH<sub>4</sub>addition further promotes it to 44 %, and even to 61 % at lower gas flow rate (6 L/min), allowing a higher yield of CO and hydrogen for PPC. The addition of H<sub>2</sub>O, however, reduces the CO<sub>2</sub>conversion from 55 % to 22 %, but it also lowers the energy cost, from 5.8 to 3 kJ/L. Regarding the temperature at 4.9 cm post‐plasma, N<sub>2</sub>addition increases the temperature, while the CO<sub>2</sub>/CH<sub>4</sub>ratio has no significant effect on temperature. We also calculated the temperature distribution with computational fluid dynamics simulations. The obtained temperature profiles (both experimental and calculated) show a decreasing trend with distance to the exhaust and provide insights in where to position a PPC bed.
Keywords: A1 Journal Article; CO2 conversion · Plasma · Gliding arc plasmatron · Temperature profiles · Computational modelling; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 8.4
DOI: 10.1002/cssc.202400169
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“Sorption-Enhanced Dry Reforming of Methane in a DBD Plasma Reactor for Single-Stage Carbon Capture and Utilization”. Vertongen R, De Felice G, van den Bogaard H, Gallucci F, Bogaerts A, Li S, ACS Sustainable Chemistry &, Engineering 12, 10841 (2024). http://doi.org/10.1021/acssuschemeng.4c02502
Abstract: Plasma−sorbent systems are a novel technology for single-stage carbon capture and utilization (CCU), where the plasma enables the desorption of CO2 from a sorbent and the simultaneous conversion to CO. In this study, we test the flexibility of a plasma−sorbent system in a single unit, specifically for sorption-enhanced dry reforming of methane (DRM). The experimental results indicate the selective adsorption of CO2 by the sorbent zeolite 5A in the first step, and CH4 addition during the plasma-based desorption of CO2 enables DRM to various value-added products in the second step, such as H2, CO, hydrocarbons, and the byproduct H2O. Furthermore, our work also demonstrates that zeolite has the potential to increase the conversion of CO2 and CH4, attributed to its capability to capture H2O. Aside from the notable carbon deposition, material analysis shows that the zeolite remains relatively stable under plasma exposure.
Keywords: A1 Journal Article; plasma, dry reforming of methane, dielectric barrier discharge, sorbent, carbon capture and utilization, zeolite; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.4c02502
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“Photoluminescence of germanium-vacancy centers in nanocrystalline diamond films : implications for quantum sensing applications”. Joy RM, Pobedinskas P, Bourgeois E, Chakraborty T, Goerlitz J, Herrmann D, Noel C, Heupel J, Jannis D, Gauquelin N, D'Haen J, Verbeeck J, Popov C, Houssiau L, Becher C, Nesladek M, Haenen K, ACS applied nano materials 7, 3873 (2024). http://doi.org/10.1021/ACSANM.3C05491
Abstract: Point defects in diamond, promising candidates for nanoscale pressure- and temperature-sensing applications, are potentially scalable in polycrystalline diamond fabricated using the microwave plasma-enhanced chemical vapor deposition (MW PE CVD) technique. However, this approach introduces residual stress in the diamond films, leading to variations in the characteristic zero phonon line (ZPL) of the point defect in diamond. Here, we report the effect of residual stress on germanium-vacancy (GeV) centers in MW PE CVD nanocrystalline diamond (NCD) films fabricated using single crystal Ge as the substrate and solid dopant source. GeV ensemble formation indicated by the zero phonon line (ZPL) at similar to 602 nm is confirmed by room temperature (RT) photoluminescence (PL) measurements. PL mapping results show spatial nonuniformity in GeV formation along with other defects, including silicon-vacancy centers in the diamond films. The residual stress in NCD results in shifts in the PL peak positions. By estimating a stress shift coefficient of (2.9 +/- 0.9) nm/GPa, the GeV PL peak position in the NCD film is determined to be between 598.7 and 603.2 nm. A larger ground state splitting due to the strain on a GeV-incorporated NCD pillar at a low temperature (10 K) is also reported. We also report the observation of intense ZPLs at RT that in some cases could be related to low Ge concentration and the surrounding crystalline environment. In addition, we also observe thicker microcrystalline diamond (MCD) films delaminate from the Ge substrate due to film residual stress and graphitic phase at the diamond/Ge substrate interface (confirmed by electron energy loss spectroscopy). Using this approach, a free-standing color center incorporated MCD film with dimensions up to 1 x 1 cm(2) is fabricated. Qualitative analysis using time-of-flight secondary ion mass spectroscopy reveals the presence of impurities, including Ge and silicon, in the MCD film. Our experimental results will provide insights into the scalability of GeV fabrication using the MW PE CVD technique and effectively implement NCD-based nanoscale-sensing applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.9
DOI: 10.1021/ACSANM.3C05491
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“On central focusing for contrast optimization in direct electron ptychography of thick samples”. Gao C, Hofer C, Pennycook TJ, Ultramicroscopy 256, 113879 (2024). http://doi.org/10.1016/J.ULTRAMIC.2023.113879
Abstract: Ptychography provides high dose efficiency images that can reveal light elements next to heavy atoms. However, despite ptychography having an otherwise single signed contrast transfer function, contrast reversals can occur when the projected potential becomes strong for both direct and iterative inversion ptychography methods. It has recently been shown that these reversals can often be counteracted in direct ptychography methods by adapting the focus. Here we provide an explanation of why the best contrast is often found with the probe focused to the middle of the sample. The phase contribution due to defocus at each sample slice above and below the central plane in this configuration effectively cancels out, which can prevent contrast reversals when dynamical scattering effects are not overly strong. In addition we show that the convergence angle can be an important consideration for removal of contrast reversals in relatively thin samples.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.2
DOI: 10.1016/J.ULTRAMIC.2023.113879
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“Floquet engineering of axion and high-Chern number phases in a topological insulator under illumination”. Shafiei M, Fazileh F, Peeters FM, Milošević, MV, SciPost Physics Core 7, 024 (2024). http://doi.org/10.21468/SCIPOSTPHYSCORE.7.2.024
Abstract: Quantum anomalous Hall, high-Chern number, and axion phases in topological insulators are characterized by its Chern invariant C (respectively, C = 1, integer C > 1, and C = 0 with half-quantized Hall conductance of opposite signs on top and bottom surfaces). They are of recent interest because of novel fundamental physics and prospective applications, but identifying and controlling these phases has been challenging in practice. Here we show that these states can be created and switched between in thin films of Bi2Se3 by Floquet engineering, using irradiation by circularly polarized light. We present the calculated phase diagrams of encountered topological phases in Bi2Se3, as a function of wavelength and amplitude of light, as well as sample thickness, after properly taking into account the penetration depth of light and the variation of the gap in the surface states. These findings open pathways towards energy-efficient optoelectronics, advanced sensing, quantum information processing and metrology.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.21468/SCIPOSTPHYSCORE.7.2.024
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Zhang Y, Grü,newald L, Cao X, Abdelbarey D, Zheng X, Rugeramigabo EP, Zopf M, Verbeeck J, Ding F (2024) Supplementary Information and Data for “Unveiling the 3D Morphology of Epitaxial GaAs/AlGaAs Quantum Dots”
Abstract: Raw and processed TEM and AFM data for the article Unveiling the 3D Morphology of Epitaxial GaAs/AlGaAs Quantum Dots.
Keywords: Dataset; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
DOI: 10.5281/ZENODO.11449864
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“Capillary Condensation of Water in Graphene Nanocapillaries”. Faraji F, Neyts EC, Milošević, MV, Peeters FM, Nano Letters 24, 5625 (2024). http://doi.org/10.1021/acs.nanolett.4c01088
Abstract: Recent experiments have revealed that the macroscopic Kelvin equation remains surprisingly accurate even for nanoscale capillaries. This phenomenon was so far explained by the oscillatory behavior of the solid−liquid interfacial free energy. We here demonstrate thermodynamic and capillarity inconsistencies with this explanation. After revising the Kelvin equation, we ascribe its validity at nanoscale confinement to the effect of disjoining pressure.
To substantiate our hypothesis, we employed molecular dynamics simulations to evaluate interfacial heat transfer and wetting properties. Our assessments unveil a breakdown in a previously established proportionality between the work of adhesion and the Kapitza conductance at capillary heights below 1.3 nm, where the dominance of the work of adhesion shifts primarily from energy to entropy. Alternatively, the peak density of the initial water layer can effectively probe the work of adhesion. Unlike under bulk conditions, high confinement renders the work of adhesion entropically unfavorable.
Keywords: A1 Journal Article; CMT
Impact Factor: 10.8
DOI: 10.1021/acs.nanolett.4c01088
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“On-chip very low strain rate rheology of amorphous olivine films”. Coulombier M, Baral P, Orekhov A, Dohmen R, Raskin JP, Pardoen T, Cordier P, Idrissi H, Acta materialia 266, 119693 (2024). http://doi.org/10.1016/J.ACTAMAT.2024.119693
Abstract: Recent observations made by the authors revealed the activation of stress induced amorphization and sliding at grain boundary in olivine [1], a mechanism which is expected to play a pivotal role in the viscosity drop at the lithosphere-asthenosphere boundary and the brittle -ductile transition in the lithospheric mantle. However, there is a lack of information in the literature regarding the intrinsic mechanical properties and the elementary deformation mechanisms of this material, especially at time scales relevant for geodynamics. In the present work, amorphous olivine films were obtained by pulsed laser deposition (PLD). The mechanical response including the rate dependent behavior are investigated using a tension -on -chip (TOC) method developed at UCLouvain allowing to perform creep/relaxation tests on thin films at extremely low strain rates. In the present work, strain rate down to 10-12 s- 1 was reached which is unique. High strain rate sensitivity of 0.054 is observed together with the activation of relaxation at the very early stage of deformation. Furthermore, digital image correlation (DIC), used for the first time on films deformed by TOC, reveals local strain heterogeneities. The relationship between such heterogeneities, the high strain rate sensitivity and the effect of the electron beam in the scanning electron microscope is discussed and compared to the literature.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.4
DOI: 10.1016/J.ACTAMAT.2024.119693
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“Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity”. Verbeelen T, Fernandez CA, Nguyen TH, Gupta S, Aarts R, Tabury K, Leroy B, Wattiez R, Vlaeminck SE, Leys N, Ganigué, R, Mastroleo F, NPJ microgravity 10, 3 (2024). http://doi.org/10.1038/S41526-024-00345-Z
Abstract: Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1038/S41526-024-00345-Z
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“Plasma-assisted NH3 cracking in warm plasma reactors for green H2 production”. Fedirchyk I, Tsonev I, Quiroz Marnef R, Bogaerts A, Chemical Engineering Journal 499, 155946 (2024). http://doi.org/10.1016/j.cej.2024.155946
Abstract: renewable energy. Plasma technology is promising for this purpose, as it can crack NH3 without the need for a catalyst and is highly compatible with renewable electricity, reducing the environmental footprint of the cracking process. This work investigates the NH3 cracking performance of four different warm plasma reactors with different configurations and operating in a wide range of conditions. We show that the NH3 conversion in warm plasma reactors is primarily determined by the specific energy input, with the main difference observed in the energy cost (EC) of cracking. The lowest EC obtained is 146 kJ/mol but at a conversion of only 8 %. A more reasonable conversion of around 50 % yields an EC of around 200 kJ/mol in two of the reactors investigated. Plasma reactors operating at higher feed flow rates are more efficient and yield a higher H2 production rate. Our data indicate that NH3 cracking in these warm plasma reactors occurs mainly via thermal chemistry, with nonthermal plasma chemistry playing a less prominent role. NH3 decomposes not only inside the plasma core but also in a hot volume around it, which reduces the EC. Our study shows that warm plasmas are significantly more efficient for NH3 cracking than cold plasmas, even when the latter are combined with catalysts.
Keywords: A1 Journal Article; Plasma-assisted NH3 cracking Plasma reactors Warm plasma H2 production from NH3; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 15.1
DOI: 10.1016/j.cej.2024.155946
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“Unraveling microbial processes involved in carbon and nitrogen cycling and greenhouse gas emissions in rewetted peatlands by molecular biology”. Gios E, Verbruggen E, Audet J, Burns R, Butterbach-Bahl K, Espenberg M, Fritz C, Glatzel S, Jurasinski G, Larmola T, Mander U, Nielsen C, Rodriguez AF, Scheer C, Zak D, Silvennoinen HM, Biogeochemistry (2024). http://doi.org/10.1007/S10533-024-01122-6
Abstract: Restoration of drained peatlands through rewetting has recently emerged as a prevailing strategy to mitigate excessive greenhouse gas emissions and re-establish the vital carbon sequestration capacity of peatlands. Rewetting can help to restore vegetation communities and biodiversity, while still allowing for extensive agricultural management such as paludiculture. Belowground processes governing carbon fluxes and greenhouse gas dynamics are mediated by a complex network of microbial communities and processes. Our understanding of this complexity and its multi-factorial controls in rewetted peatlands is limited. Here, we summarize the research regarding the role of soil microbial communities and functions in driving carbon and nutrient cycling in rewetted peatlands including the use of molecular biology techniques in understanding biogeochemical processes linked to greenhouse gas fluxes. We emphasize that rapidly advancing molecular biology approaches, such as high-throughput sequencing, are powerful tools helping to elucidate the dynamics of key biogeochemical processes when combined with isotope tracing and greenhouse gas measuring techniques. Insights gained from the gathered studies can help inform efficient monitoring practices for rewetted peatlands and the development of climate-smart restoration and management strategies.
Keywords: A1 Journal article; Plant and Ecosystems (PLECO) – Ecology in a time of change
Impact Factor: 4
DOI: 10.1007/S10533-024-01122-6
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“Rhodotorula kratochvilovae outperforms Cutaneotrichosporon oleaginosum in the valorisation of lignocellulosic wastewater to microbial oil”. Broos W, Wittner N, Dries J, Vlaeminck SE, Gunde-Cimerman N, Cornet I, Process biochemistry (1991) 137, 229 (2024). http://doi.org/10.1016/J.PROCBIO.2024.01.009
Abstract: Rhodotorula kratochvilovae has shown to be a promising species for microbial oil production from lignin-derived compounds. Yet, information on R. kratochvilovae’s detoxification and microbial oil production is scarce. This study investigated the growth and microbial oil production on the phenolic-containing effluent from poplar steam explosion and its detoxification with five R. kratochvilovae strains (EXF11626, EXF9590, EXF7516, EXF3697, EXF3471) and compared them with Cutaneotrichosporon oleaginosum. The R. kratochvilovae strains reached a maximum growth rate up to four times higher than C. oleaginosum. Furthermore, all R. kratochvilovae strains generally degraded phenolics more rapidly and to a larger extent than C. oleaginosum. However, the diluted substrate limited the lipid production by all strains as the maximum lipid content and titre were 10.5% CDW and 0.40 g/L, respectively. Therefore, future work should focus on increasing lipid production by using advanced fermentation strategies and stimulating the enzyme excretion by the yeasts for complex substrate breakdown.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Biochemical Wastewater Valorization & Engineering (BioWaVE)
Impact Factor: 4.4
DOI: 10.1016/J.PROCBIO.2024.01.009
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“Incommensurate Modulations and Perovskite Growth in LaxSr2–xMnO4−δAffecting Solid Oxide Fuel Cell Conductivity”. Vandemeulebroucke D, Batuk M, Hajizadeh A, Wastiaux M, Roussel P, Hadermann J, Chemistry of materials (2024). http://doi.org/10.1021/acs.chemmater.3c03199
Abstract: Ruddlesden-Popper La????Sr2−????MnO4−???? materials are interesting symmetric solid oxide
fuel cell electrodes due to their good redox stability, mixed ionic and electronic conducting behavior and thermal expansion that matches well with common electrolytes. In reducing environments – as at a solid oxide fuel cell anode – the x = 0.5 member, i.e. La0.5Sr1.5MnO4−????, has a much higher total conductivity than compounds with a different La/Sr ratio, although all those compositions have the same K2NiF4-type I4/mmm structure. The origin for this conductivity difference is not yet known in literature. Now, a combination of in-situ and ex-situ 3D electron diffraction, high-resolution imaging, energy-dispersive X-ray analysis and electron energy-loss spectroscopy uncovered clear differences between x=0.25 and x=0.5 in the pristine structure, as well as in the transformations upon high-temperature reduction. In La0.5Sr1.5MnO4−????, Ruddlesden-Popper n=2 layer defects and an amorphous surface layer are present, but not in La0.25Sr1.75MnO4−????. After annealing at 700°C in 5% H2/Ar, La0.25Sr1.75MnO4−???? transforms to a tetragonal 2D incommensurately modulated structure with modulation vectors ⃗????1 = 0.2848(1) · (⃗????* +⃗????*) and ⃗????2 =0.2848(1) · (⃗????* – ⃗????*), whereas La0.5Sr1.5MnO4−???? only partially transforms to an orthorhombic 1D incommensurately modulated structure,
with ⃗???? = 0.318(2) · ⃗????*. Perovskite domains grow at the crystal edge at 700°C in 5%
H2 or vacuum, due to the higher La concentration on the surface compared to the bulk, which leads to a different thermodynamic equilibrium. Since it is known that a lower degree of oxygen vacancy ordering and a higher amount of perovskite blocks enhance oxygen mobility, those differences in defect structure and structural transformation upon reduction, might all contribute to the higher conductivity of La0.5Sr1.5MnO4−???? in solid oxide fuel cell anode conditions compared to other La/Sr ratios.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.6
DOI: 10.1021/acs.chemmater.3c03199
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“Atomically dispersed ruthenium hydride on beta zeolite as catalysts for the isomerization of muconates”. Khalil I, Rigamonti MG, Janssens K, Bugaev A, Arenas Esteban D, Robijns S, Donckels T, Beydokhti MT, Bals S, De Vos D, Dusselier M, Nature Catalysis 7, 921 (2024). http://doi.org/10.1038/S41929-024-01205-5
Abstract: Searching for sustainable polymers requires access to biomass-based monomers. In that sense, glucose-derived cis,cis-muconic acid stands as a high-potential intermediate. However, to unlock its potential, an isomerization to the value-added trans,trans-isomer, trans,trans-muconic acid, is required. Here we develop atomically dispersed low-loaded Ru on beta zeolite catalysts that produce trans,trans-muconate in ethanol with total conversion (to equilibrium) and a selectivity of >95%. We reach very high turnovers per Ru and productivity rates of 427 mM h(-1) (similar to 85 g l(-1) h(-1)), surpassing the bio-based cis,cis-muconic acid production rates by an order of magnitude. By coupling isomerization to Diels-Alder cycloaddition, terephthalate intermediates are produced in around 90% yields, circumventing the isomer equilibrium. Isomerization is promoted by Ru hydride species where the hydrides are generated from the alcohol solvent, as evidenced by Fourier transform infrared spectroscopy. Beyond isomerization, the Ru-zeolite and its hydride-forming capacity could be of use as a heterogeneous catalyst for other hydride chemistries, demonstrated by a successful hydride transfer hydrogenation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 37.8
DOI: 10.1038/S41929-024-01205-5
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“Recurrent multi-stressor floc treatments with sulphide and free ammonia enabled mainstream partial nitritation/anammox”. Van Tendeloo M, Baptista MC, Van Winckel T, Vlaeminck SE, The science of the total environment 912, 169449 (2024). http://doi.org/10.1016/J.SCITOTENV.2023.169449
Abstract: Selective suppression of nitrite-oxidising bacteria (NOB) over aerobic and anoxic ammonium-oxidising bacteria (AerAOB and AnAOB) remains a major challenge for mainstream partial nitritation/anammox implementation, a resource-efficient nitrogen removal pathway. A unique multi-stressor floc treatment was therefore designed and validated for the first time under lab-scale conditions while staying true to full-scale design principles. Two hybrid (suspended + biofilm growth) reactors were operated continuously at 20.2 ± 0.6 °C. Recurrent multi-stressor floc treatments were applied, consisting of a sulphide-spiked deoxygenated starvation followed by a free ammonia shock. A good microbial activity balance with high AnAOB (71 ± 21 mg N L−1 d−1) and low NOB (4 ± 17 % of AerAOB) activity was achieved by combining multiple operational strategies: recurrent multi-stressor floc treatments, hybrid sludge (flocs & biofilm), short floc age control, intermittent aeration, and residual ammonium control. The multi-stressor treatment was shown to be the most important control tool and should be continuously applied to maintain this balance. Excessive NOB growth on the biofilm was avoided despite only treating the flocs to safeguard the AnAOB activity on the biofilm. Additionally, no signs of NOB adaptation were observed over 142 days. Elevated effluent ammonium concentrations (25 ± 6 mg N L−1) limited the TN removal efficiency to 39 ± 9 %, complicating a future full-scale implementation. Operating at higher sludge concentrations or reducing the volumetric loading rate could overcome this issue. The obtained results ease the implementation of mainstream PN/A by providing and additional control tool to steer the microbial activity with the multi-stressor treatment, thus advancing the concept of energy neutrality in sewage treatment plants.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.8
DOI: 10.1016/J.SCITOTENV.2023.169449
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“Goodenough-Kanamori-Anderson high-temperature ferromagnetism in tetragonal transition-metal xenes”. Yorulmaz U, Šabani D, Sevik C, Milošević, MV, 2D materials 11, 035013 (2024). http://doi.org/10.1088/2053-1583/AD3E08
Abstract: Seminal Goodenough-Kanamori-Anderson (GKA) rules provide an inceptive understanding of the superexchange interaction of two magnetic metal ions bridged with an anion, and suggest fostered ferromagnetic interaction for orthogonal bridging bonds. However, there are no examples of two-dimensional (2D) materials with structure that optimizes the GKA arguments towards enhanced ferromagnetism and its critical temperature. Here we reveal that an ideally planar GKA ferromagnetism is indeed stable in selected tetragonal transition-metal xenes (tTMXs), with Curie temperature above 300 K found in CrC and MnC. We provide the general orbitally-resolved analysis of magnetic interactions that supports the claims and sheds light at the mechanisms dominating the magnetic exchange process in these structures. Furthermore, we propose the set of three GKA-like rules that will guarantee room temperature ferromagetnism. With recent advent of epitaxially-grown tetragonal 2D materials, our findings earmark tTMXs for facilitated spintronic and magnonic applications, or as a desirable magnetic constituent of functional 2D heterostructures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 5.5
DOI: 10.1088/2053-1583/AD3E08
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“Soil warming increases the number of growing bacterial taxa but not their growth rates”. Metze D, Schnecker J, Le Noir de Carlan C, Bhattarai B, Verbruggen E, Ostonen I, Janssens IA, Sigurdsson BD, Hausmann B, Kaiser C, Richter A, Science Advances 10, eadk6295 (2024). http://doi.org/10.1126/SCIADV.ADK6295
Abstract: Soil microorganisms control the fate of soil organic carbon. Warming may accelerate their activities putting large carbon stocks at risk of decomposition. Existing knowledge about microbial responses to warming is based on community-level measurements, leaving the underlying mechanisms unexplored and hindering predictions. In a long-term soil warming experiment in a Subarctic grassland, we investigated how active populations of bacteria and archaea responded to elevated soil temperatures (+6°C) and the influence of plant roots, by measuring taxon-specific growth rates using quantitative stable isotope probing and 18 O water vapor equilibration. Contrary to prior assumptions, increased community growth was associated with a greater number of active bacterial taxa rather than generally faster-growing populations. We also found that root presence enhanced bacterial growth at ambient temperatures but not at elevated temperatures, indicating a shift in plant-microbe interactions. Our results, thus, reveal a mechanism of how soil bacteria respond to warming that cannot be inferred from community-level measurements.
Keywords: A1 Journal article; Plant and Ecosystems (PLECO) – Ecology in a time of change
Impact Factor: 13.6
DOI: 10.1126/SCIADV.ADK6295
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“Cs3Bi2Br9 nanoparticles decorated C3N4 nanotubes composite photocatalyst for highly selective oxidation of benzylic alcohol”. Ding Y, Wang C, Bandaru S, Pei L, Zheng R, Hau Ng Y, Arenas Esteban D, Bals S, Zhong J, Hofkens J, Van Tendeloo G, Roeffaers MBJ, Chen L-H, Su B-L, Journal of Colloid and Interface Science 672, 600 (2024). http://doi.org/10.1016/j.jcis.2024.06.017
Abstract: Solar-light driven oxidation of benzylic alcohols over photocatalysts endows significant prospects in value-added organics evolution owing to its facile, inexpensive and sustainable process. However, the unsatisfactory performance of actual photocatalysts due to the inefficient charge separation, low photoredox potential and sluggish surface reaction impedes the practical application of this process. Herein, we developed an innovative Z-Scheme Cs3BiBr9 nanoparticles@porous C3N4 tubes (CBB-NP@P-tube-CN) heterojunction photocatalyst for highly selective benzyl alcohol oxidation. Such composite combining increased photo-oxidation potential, Z-Scheme charge migration route as well as the structural advantages of porous tubular C3N4 ensures the accelerated mass and ions diffusion kinetics, the fast photoinduced carriers dissociation and sufficient photoredox potentials. The CBB-NP@P-tube-CN photocatalyst demonstrates an exceptional performance for selective photo-oxidation of benzylic alcohol into benzaldehyde with 19, 14 and 3 times higher benzylic alcohols conversion rate than those of C3N4 nanotubes, Cs3Bi2Br9 and Cs3Bi2Br9@bulk C3N4 photocatalysts, respectively. This work offers a sustainable photocatalytic system based on lead-free halide perovskite toward large scale solar-light driven value-added chemicals production.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 9.9
DOI: 10.1016/j.jcis.2024.06.017
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“Spin-orbit torque vector quantification in nanoscale magnetic tunnel junctions”. Sethu KKV, Yasin F, Swerts J, Sorée B, De Boeck J, Kar GS, Garello K, Couet S, ACS nano 18, 13506 (2024). http://doi.org/10.1021/ACSNANO.3C11289
Abstract: Spin-orbit torques (SOT) allow ultrafast, energy-efficient toggling of magnetization state by an in-plane charge current for applications such as magnetic random-access memory (SOT-MRAM). Tailoring the SOT vector comprising of antidamping (T-AD) and fieldlike (T-FL) torques could lead to faster, more reliable, and low-power SOT-MRAM. Here, we establish a method to quantify the longitudinal (T-AD) and transverse (T-FL) components of the SOT vector and its efficiency chi(AD) and chi(FL), respectively, in nanoscale three-terminal SOT magnetic tunnel junctions (SOT-MTJ). Modulation of nucleation or switching field (B-SF) for magnetization reversal by SOT effective fields (B-SOT) leads to the modification of SOT-MTJ hysteresis loop behavior from which chi(AD) and chi(FL) are quantified. Surprisingly, in nanoscale W/CoFeB SOT-MTJ, we find chi(FL) to be (i) twice as large as chi(AD) and (ii) 6 times as large as chi(FL) in micrometer-sized W/CoFeB Hall-bar devices. Our quantification is supported by micromagnetic and macrospin simulations which reproduce experimental SOT-MTJ Stoner-Wohlfarth astroid behavior only for chi(FL) > chi(AD). Additionally, from the threshold current for current-induced magnetization switching with a transverse magnetic field, we show that in SOT-MTJ, T-FL plays a more prominent role in magnetization dynamics than T-AD. Due to SOT-MRAM geometry and nanodimensionality, the potential role of nonlocal spin Hall spin current accumulated adjacent to the SOT-MTJ in the mediation of T-FL and chi(FL) amplification merits to be explored.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 17.1
DOI: 10.1021/ACSNANO.3C11289
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“Progress in spin logic devices based on domain-wall motion”. Vermeulen BB, Sorée B, Couet S, Temst K, Van Nguyen D, Micromachines 15, 696 (2024). http://doi.org/10.3390/MI15060696
Abstract: Spintronics, utilizing both the charge and spin of electrons, benefits from the nonvolatility, low switching energy, and collective behavior of magnetization. These properties allow the development of magnetoresistive random access memories, with magnetic tunnel junctions (MTJs) playing a central role. Various spin logic concepts are also extensively explored. Among these, spin logic devices based on the motion of magnetic domain walls (DWs) enable the implementation of compact and energy-efficient logic circuits. In these devices, DW motion within a magnetic track enables spin information processing, while MTJs at the input and output serve as electrical writing and reading elements. DW logic holds promise for simplifying logic circuit complexity by performing multiple functions within a single device. Nevertheless, the demonstration of DW logic circuits with electrical writing and reading at the nanoscale is still needed to unveil their practical application potential. In this review, we discuss material advancements for high-speed DW motion, progress in DW logic devices, groundbreaking demonstrations of current-driven DW logic, and its potential for practical applications. Additionally, we discuss alternative approaches for current-free information propagation, along with challenges and prospects for the development of DW logic.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.3390/MI15060696
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“Evaluation of corrosion impeding concretion layers formed on shipwreck steel in the Belgian North Sea”. Laureys A, Richardson P, Verhasselt K, Chaves IA, Melchers RE, Van Den Bergh K, Depover T, Verbeken K, Potters G, De Baere K, Corrosion 80, 539 (2024). http://doi.org/10.5006/4341
Abstract: Steel shipwrecks buried along the Belgian and French North Sea coast have proven to show very low corrosion rates due to concretion. This work aims to provide an in-depth analysis of the formed concretion layers and gain a more complete understanding of the gradual deposition processes in the North Sea. Detailed microstructural characterization by scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction of two different specimens demonstrates that the concretion includes a complex structure of multiple layers. Closest to the metal surface, a layer of 100% akaganeite is found. It forms from corrosion products exhibiting high Cl- ions concentrations at the metal surface. Next, other iron oxides, such as goethite, lepidocrocite, and magnetite, are observed. Then, layers that both contain corrosion products and compounds from the environment are present. These layers contain calcium carbonates (calcite and aragonite), calcium sulfate (gypsum), and quartz (sand). Moreover, due to a displacement of calcium by iron, an additional phase is formed consisting out of hard, dense siderite mixed into calcite. Finally, the surface of the concretion is covered by a biofilm.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp engineering, PhotoElectroChemistry & Sensing (A-PECS)
Impact Factor: 1.6
DOI: 10.5006/4341
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“Unveiling the 3D morphology of epitaxial GaAs/AlGaAs quantum dots”. Zhang Y, Grunewald L, Cao X, Abdelbarey D, Zheng X, Rugeramigabo EP, Verbeeck J, Zopf M, Ding F, Nano letters 24, 10106 (2024). http://doi.org/10.1021/ACS.NANOLETT.4C02182
Abstract: Strain-free GaAs/AlGaAs semiconductor quantum dots (QDs) grown by droplet etching and nanohole infilling (DENI) are highly promising candidates for the on-demand generation of indistinguishable and entangled photon sources. The spectroscopic fingerprint and quantum optical properties of QDs are significantly influenced by their morphology. The effects of nanohole geometry and infilled material on the exciton binding energies and fine structure splitting are well-understood. However, a comprehensive understanding of GaAs/AlGaAs QD morphology remains elusive. To address this, we employ high-resolution scanning transmission electron microscopy (STEM) and reverse engineering through selective chemical etching and atomic force microscopy (AFM). Cross-sectional STEM of uncapped QDs reveals an inverted conical nanohole with Al-rich sidewalls and defect-free interfaces. Subsequent selective chemical etching and AFM measurements further reveal asymmetries in element distribution. This study enhances the understanding of DENI QD morphology and provides a fundamental three-dimensional structural model for simulating and optimizing their optoelectronic properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 10.8
DOI: 10.1021/ACS.NANOLETT.4C02182
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“Unconventional superconducting diode effects via antisymmetry and antisymmetry breaking”. Li C, Lyu Y-Y, Yue W-C, Huang P, Li H, Li T, Wang C-G, Yuan Z, Dong Y, Ma X, Tu X, Tao T, Dong S, He L, Jia X, Sun G, Kang L, Wang H, Peeters FM, Milošević, MV, Wu P, Wang Y-L, Nano letters 24, 4108 (2024). http://doi.org/10.1021/ACS.NANOLETT.3C05008
Abstract: Symmetry breaking plays a pivotal role in unlocking intriguing properties and functionalities in material systems. For example, the breaking of spatial and temporal symmetries leads to a fascinating phenomenon: the superconducting diode effect. However, generating and precisely controlling the superconducting diode effect pose significant challenges. Here, we take a novel route with the deliberate manipulation of magnetic charge potentials to realize unconventional superconducting flux-quantum diode effects. We achieve this through suitably tailored nanoengineered arrays of nanobar magnets on top of a superconducting thin film. We demonstrate the vital roles of inversion antisymmetry and its breaking in evoking unconventional superconducting effects, namely a magnetically symmetric diode effect and an odd-parity magnetotransport effect. These effects are nonvolatilely controllable through in situ magnetization switching of the nanobar magnets. Our findings promote the use of antisymmetry (breaking) for initiating unconventional superconducting properties, paving the way for exciting prospects and innovative functionalities in superconducting electronics.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 10.8
DOI: 10.1021/ACS.NANOLETT.3C05008
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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)
Impact Factor: 29.4
DOI: 10.1002/ADMA.202313297
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“Control of proton transport and hydrogenation in double-gated graphene”. Tong J, Fu Y, Domaretskiy D, Della Pia F, Dagar P, Powell L, Bahamon D, Huang S, Xin B, Costa Filho RN, Vega LF, Grigorieva IV, Peeters FM, Michaelides A, Lozada-Hidalgo M, Nature 630, 619 (2024). http://doi.org/10.1038/s41586-024-07435-8
Abstract: The basal plane of graphene can function as a selective barrier that is permeable to protons but impermeable to all ions and gases, stimulating its use in applications such as membranes, catalysis and isotope separation. Protons can chemically adsorb on graphene and hydrogenate it, inducing a conductor–insulator transition that has been explored intensively in graphene electronic devices. However, both processes face energy barriersand various strategies have been proposed to accelerate proton transport, for example by introducing vacancies, incorporating catalytic metalsor chemically functionalizing the lattice. But these techniques can compromise other properties, such as ion selectivity or mechanical stability. Here we show that independent control of the electric field,<italic>E</italic>, at around 1 V nm<sup>−1</sup>, and charge-carrier density,<italic>n</italic>, at around 1 × 10<sup>14</sup> cm<sup>−2</sup>, in double-gated graphene allows the decoupling of proton transport from lattice hydrogenation and can thereby accelerate proton transport such that it approaches the limiting electrolyte current for our devices. Proton transport and hydrogenation can be driven selectively with precision and robustness, enabling proton-based logic and memory graphene devices that have on–off ratios spanning orders of magnitude. Our results show that field effects can accelerate and decouple electrochemical processes in double-gated 2D crystals and demonstrate the possibility of mapping such processes as a function of<italic>E</italic>and<italic>n</italic>, which is a new technique for the study of 2D electrode–electrolyte interfaces.
Keywords: A1 Journal Article; Condensed Matter Theory (CMT) ;
Impact Factor: 64.8
DOI: 10.1038/s41586-024-07435-8
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“Obtaining 3D Atomic Reconstructions from Electron Microscopy Images Using a Bayesian Genetic Algorithm: Possibilities, Insights, and Limitations”. Stoops T, De Backer A, Lobato I, Van Aert S, Microscopy and Microanalysis (2024). http://doi.org/10.1093/mam/ozae090
Abstract: The Bayesian genetic algorithm (BGA) is a powerful tool to reconstruct the 3D structure of mono-atomic single-crystalline metallic nanoparticles imaged using annular dark field scanning transmission electron microscopy. The number of atoms in a projected atomic column in the image is used as input to obtain an accurate and atomically precise reconstruction of the nanoparticle, taking prior knowledge and the finite precision of atom counting into account. However, as the number of parameters required to describe a nanoparticle with atomic detail rises quickly with the size of the studied particle, the computational costs of the BGA rise to prohibitively expensive levels. In this study, we investigate these computational costs and propose methods and control parameters for efficient application of the algorithm to nanoparticles of at least up to 10 nm in size.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 2.8
DOI: 10.1093/mam/ozae090
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“Multiferroic ScLaX₂, (X = P, As, and Sb) monolayers : bidirectional negative Poisson's ratio effects and phase transformations driven by rare-earth (main-group) elements”. Tian X, Xie X, Li J, Kong X, Gong W-J, Peeters FM, Li L, Physical review materials 8, 084407 (2024). http://doi.org/10.1103/PHYSREVMATERIALS.8.084407
Abstract: The combination of auxetic property, ferroelasticity, and ferroelectricity in two-dimensional materials offers new avenues for next-generation multifunctional devices. However, two-dimensional materials that simultaneously exhibit those properties are rarely reported. Here, we present a class of two-dimensional Janus-like structures ScLaX2 X 2 (X X = P, As, and Sb) with a rectangular lattice based on first-principles calculations. We predict that those ScLaX2 X 2 monolayers are stable semiconductors with both intrinsic in-plane and out-of-plane auxetic properties, showing a bidirectional negative Poisson's ratio effect. The value of the out-of-plane negative Poisson's ratio effect can reach – 2.28 /- 3.06 /- 3.89. By applying uniaxial strain engineering, two transition paths can be found, including the VA main group element path and the rare-earth metal element path, corresponding to the ferroelastic and the multiferroic (ferroelastic and ferroelectric) phase transition, respectively. For the ScLaSb2 2 monolayer, the external force field can not only control the ferroelastic phase transition, but it can also lead to the reversal of the out-of-plane polarization, exhibiting potential multiferroicity. The coupling between the bidirectional negative Poisson's ratio effect and multiferroicity makes the ScLaX2 X 2 monolayers promising for future device applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
DOI: 10.1103/PHYSREVMATERIALS.8.084407
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“Plasma catalysis in ammonia production and decomposition: Use it, or lose it?”.Gorbanev Y, Fedirchyk I, Bogaerts A, Current Opinion in Green and Sustainable Chemistry 47, 100916 (2024). http://doi.org/10.1016/j.cogsc.2024.100916
Abstract: The combination of plasma with catalysis for the synthesis and decomposition of NH3 is an attractive route to the production of carbon-neutral fertiliser and energy carriers and its conversion into H2. Recent years have seen fast developments in the field of plasma-catalytic NH3 life cycle. This work summarises the most recent advances in plasma-catalytic and related NH3-focussed processes, identifies some of the most important discoveries, and addresses plausible strategies for future developments in plasma-based NH3 technology.
Keywords: A1 Journal Article; Plasma Nitrogen fixation Ammonia Plasma catalysis Production and decomposition; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 9.3
DOI: 10.1016/j.cogsc.2024.100916
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