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“Isolating hydrogen in hexagonal boron nitride bubbles by a plasma treatment”. He L, Wang H, Chen L, Wang X, Xie H, Jiang C, Li C, Elibol K, Meyer J, Watanabe K, Taniguchi T, Wu Z, Wang W, Ni Z, Miao X, Zhang C, Zhang D, Wang H, Xie X, Nature communications 10, 2815 (2019). http://doi.org/10.1038/s41467-019-10660-9
Abstract: Atomically thin hexagonal boron nitride (h-BN) is often regarded as an elastic film that is impermeable to gases. The high stabilities in thermal and chemical properties allow h-BN to serve as a gas barrier under extreme conditions. Here, we demonstrate the isolation of hydrogen in bubbles of h-BN via plasma treatment. Detailed characterizations reveal that the substrates do not show chemical change after treatment. The bubbles are found to withstand thermal treatment in air, even at 800°C. Scanning transmission electron microscopy investigation shows that the h-BN multilayer has a unique aligned porous stacking nature, which is essential for the character of being transparent to atomic hydrogen but impermeable to hydrogen molecules. In addition, we successfully demonstrated the extraction of hydrogen gases from gaseous compounds or mixtures containing hydrogen element. The successful production of hydrogen bubbles on h-BN flakes has potential for further application in nano/ micro-electromechanical systems and hydrogen storage.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 8
DOI: 10.1038/s41467-019-10660-9
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“Early deformation mechanisms in the shear affected region underneath a copper sliding contact”. Haug C, Ruebeling F, Kashiwar A, Gumbsch P, Kübel C, Greiner C, Nature Communications 11, 839 (2020). http://doi.org/10.1038/S41467-020-14640-2
Abstract: Dislocation mediated plastic deformation decisively influences the friction coefficient and the microstructural changes at many metal sliding interfaces during tribological loading. This work explores the initiation of a tribologically induced microstructure in the vicinity of a copper twin boundary. Two distinct horizontal dislocation traces lines (DTL) are observed in their interaction with the twin boundary beneath the sliding interface. DTL formation seems unaffected by the presence of the twin boundary but the twin boundary acts as an indicator of the occurring deformation mechanisms. Three concurrent elementary processes can be identified: simple shear of the subsurface area in sliding direction, localized shear at the primary DTL and crystal rotation in the layers above and between the DTLs around axes parallel to the transverse direction. Crystal orientation analysis demonstrates a strong compatibility of these proposed processes. Quantitatively separating these different deformation mechanisms is crucial for future predictive modeling of tribological contacts.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
DOI: 10.1038/S41467-020-14640-2
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“Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams”. Guzzinati G, Béché, A, Lourenço-Martins H, Martin J, Kociak M, Verbeeck J, Nature communications 8, 14999 (2017). http://doi.org/10.1038/ncomms14999
Abstract: Plasmonics, the science and technology of the interaction of light with metallic objects, is fundamentally changing the way we can detect, generate and manipulate light. Although the field is progressing swiftly, thanks to the availability of nanoscale manufacturing and analysis methods, fundamental properties such as the plasmonic excitations’ symmetries cannot be accessed directly, leading to a partial, sometimes incorrect, understanding of their properties. Here we overcome this limitation by deliberately shaping the wave function of an electron beam to match a plasmonic excitations’ symmetry in a modified transmission electron microscope. We show experimentally and theoretically that this offers selective detection of specific plasmon modes within metallic nanoparticles, while excluding modes with other symmetries. This method resembles the widespread use of polarized light for the selective excitation of plasmon modes with the advantage of locally probing the response of individual plasmonic objects and a far wider range of symmetry selection criteria.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 84
DOI: 10.1038/ncomms14999
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“Dependence of the shape of graphene nanobubbles on trapped substance”. Ghorbanfekr-Kalashami H, Vasu KS, Nair RR, Peeters FM, Neek-Amal M, Nature communications 8, 15844 (2017). http://doi.org/10.1038/ncomms15844
Abstract: Van der Waals (vdW) interaction between two-dimensional crystals (2D) can trap substances in high pressurized (of order 1 GPa) on nanobubbles. Increasing the adhesion between the 2D crystals further enhances the pressure and can lead to a phase transition of the trapped material. We found that the shape of the nanobubble can depend critically on the properties of the trapped substance. In the absence of any residual strain in the top 2D crystal, flat nanobubbles can be formed by trapped long hydrocarbons (that is, hexadecane). For large nanobubbles with radius 130 nm, our atomic force microscopy measurements show nanobubbles filled with hydrocarbons (water) have a cylindrical symmetry (asymmetric) shape which is in good agreement with our molecular dynamics simulations. This study provides insights into the effects of the specific material and the vdW pressure on the microscopic details of graphene bubbles.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 44
DOI: 10.1038/ncomms15844
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“Imaging of super-fast dynamics and flow instabilities of superconducting vortices”. Embon L, Anahory Y, Jelić, ZL, Lachman EO, Myasoedov Y, Huber ME, Mikitik GP, Silhanek AV, Milošević, MV, Gurevich A, Zeldov E, Nature communications 8, 85 (2017). http://doi.org/10.1038/S41467-017-00089-3
Abstract: Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. Here, we use a nanoscale scanning superconducting quantum interference device to image vortices penetrating into a superconducting Pb film at rates of tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate. These experiments reveal formation of mesoscopic vortex channels which undergo cascades of bifurcations as the current and magnetic field increase. Our numerical simulations predict metamorphosis of fast Abrikosov vortices into mixed Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the fundamental physics of dynamic vortex states of superconductors at high current densities, crucial for many applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 124
DOI: 10.1038/S41467-017-00089-3
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“Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar”. Dubrovinsky L, Dubrovinskaia N, Prakapenka VB, Abakumov AM, Nature communications 3, 1163 (2012). http://doi.org/10.1038/ncomms2160
Abstract: Since invention of the diamond anvil cell technique in the late 1950s for studying materials at extreme conditions, the maximum static pressure generated so far at room temperature was reported to be about 400 GPa. Here we show that use of micro-semi-balls made of nanodiamond as second-stage anvils in conventional diamond anvil cells drastically extends the achievable pressure range in static compression experiments to above 600 GPa. Micro-anvils (10-50 mu m in diameter) of superhard nano-diamond (with a grain size below similar to 50 nm) were synthesized in a large volume press using a newly developed technique. In our pilot experiments on rhenium and gold we have studied the equation of state of rhenium at pressures up to 640 GPa and demonstrated the feasibility and crucial necessity of the in situ ultra high-pressure measurements for accurate determination of material properties at extreme conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 150
DOI: 10.1038/ncomms2160
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“Manipulating topological transformations of polar structures through real-time observation of the dynamic polarization evolution”. Du K, Zhang M, Dai C, Zhou ZN, Xie YW, Ren ZH, Tian H, Chen LQ, Van Tendeloo G, Zhang Z, Nature communications 10, 4864 (2019). http://doi.org/10.1038/S41467-019-12864-5
Abstract: Topological structures based on controllable ferroelectric or ferromagnetic domain configurations offer the opportunity to develop microelectronic devices such as high-density memories. Despite the increasing experimental and theoretical insights into various domain structures (such as polar spirals, polar wave, polar vortex) over the past decade, manipulating the topological transformations of polar structures and comprehensively understanding its underlying mechanism remains lacking. By conducting an in-situ non-contact bias technique, here we systematically investigate the real-time topological transformations of polar structures in PbTiO3/SrTiO3 multilayers at an atomic level. The procedure of vortex pair splitting and the transformation from polar vortex to polar wave and out-of-plane polarization are observed step by step. Furthermore, the redistribution of charge in various topological structures has been demonstrated under an external bias. This provides new insights for the symbiosis of polar and charge and offers an opportunity for a new generation of microelectronic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
DOI: 10.1038/S41467-019-12864-5
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“Independent tuning of size and coverage of supported Pt nanoparticles using atomic layer deposition”. Dendooven J, Ramachandran RK, Solano E, Kurttepeli M, Geerts L, Heremans G, Ronge J, Minjauw MM, Dobbelaere T, Devloo-Casier K, Martens JA, Vantomme A, Bals S, Portale G, Coati A, Detavernier C, Nature communications 8, 1074 (2017). http://doi.org/10.1038/S41467-017-01140-Z
Abstract: Synthetic methods that allow for the controlled design of well-defined Pt nanoparticles are highly desirable for fundamental catalysis research. In this work, we propose a strategy that allows precise and independent control of the Pt particle size and coverage. Our approach exploits the versatility of the atomic layer deposition (ALD) technique by combining two ALD processes for Pt using different reactants. The particle areal density is controlled by tailoring the number of ALD cycles using trimethyl(methylcyclopentadienyl) platinum and oxygen, while subsequent growth using the same Pt precursor in combination with nitrogen plasma allows for tuning of the particle size at the atomic level. The excellent control over the particle morphology is clearly demonstrated by means of in situ and ex situ X-ray fluorescence and grazing incidence small angle X-ray scattering experiments, providing information about the Pt loading, average particle dimensions, and mean center-to-center particle distance.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 88
DOI: 10.1038/S41467-017-01140-Z
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“A redox signalling globin is essential for reproduction in Caenorhabditis elegans”. De Henau S, Tilleman L, Vangheel M, Luyckx E, Trashin S, Pauwels M, Germani F, Vlaeminck C, Vanfleteren JR, Bert W, Pesce A, Nardini M, Bolognesi M, De Wael K, Moens L, Dewilde S, Braeckman BP, Nature communications 6, 8782 (2015). http://doi.org/10.1038/NCOMMS9782
Abstract: Moderate levels of reactive oxygen species (ROS) are now recognized as redox signalling molecules. However, thus far, only mitochondria and NADPH oxidases have been identified as cellular sources of ROS in signalling. Here we identify a globin (GLB-12) that produces superoxide, a type of ROS, which serves as an essential signal for reproduction in C. elegans. We find that GLB-12 has an important role in the regulation of multiple aspects in germline development, including germ cell apoptosis. We further describe how GLB-12 displays specific molecular, biochemical and structural properties that allow this globin to act as a superoxide generator. In addition, both an intra- and extracellular superoxide dismutase act as key partners of GLB-12 to create a transmembrane redox signal. Our results show that a globin can function as a driving factor in redox signalling, and how this signal is regulated at the subcellular level by multiple control layers.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 12.124
Times cited: 20
DOI: 10.1038/NCOMMS9782
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“Direct observation of cation diffusion driven surface reconstruction at van der Waals gaps”. Cui W, Lin W, Lu W, Liu C, Gao Z, Ma H, Zhao W, Van Tendeloo G, Zhao W, Zhang Q, Sang X, Nature communications 14, 554 (2023). http://doi.org/10.1038/S41467-023-35972-9
Abstract: Weak interlayer van der Waals (vdW) bonding has significant impact on the surface/interface structure, electronic properties, and transport properties of vdW layered materials. Unraveling the complex atomistic dynamics and structural evolution at vdW surfaces is therefore critical for the design and synthesis of the next-generation vdW layered materials. Here, we show that Ge/Bi cation diffusion along the vdW gap in layered GeBi2Te4 (GBT) can be directly observed using in situ heating scanning transmission electron microscopy (STEM). The cation concentration variation during diffusion was correlated with the local Te-6 octahedron distortion based on a quantitative analysis of the atomic column intensity and position in time-elapsed STEM images. The in-plane cation diffusion leads to out-of-plane surface etching through complex structural evolutions involving the formation and propagation of a non-centrosymmetric GeTe2 triple layer surface reconstruction on fresh vdW surfaces, and GBT subsurface reconstruction from a septuple layer to a quintuple layer. Our results provide atomistic insight into the cation diffusion and surface reconstruction in vdW layered materials. Weak interlayer van der Waals (vdW) bonding has significant impact on the structure and properties of vdW layered materials. Here authors use in-situ aberration-corrected ADF-STEM for an atomistic insight into the cation diffusion in the vdW gaps and the etching of vdW surfaces at high temperatures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
DOI: 10.1038/S41467-023-35972-9
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“Dislocation-mediated relaxation in nanograined columnar palladium films revealed by on-chip time-resolved HRTEM testing”. Colla M-S, Amin-Ahmadi B, Idrissi H, Malet L, Godet S, Raskin J-P, Schryvers D, Pardoen T, Nature communications 6, 5922 (2015). http://doi.org/10.1038/ncomms6922
Abstract: The high-rate sensitivity of nanostructured metallic materials demonstrated in the recent literature is related to the predominance of thermally activated deformation mechanisms favoured by a large density of internal interfaces. Here we report time-resolved high-resolution electron transmission microscopy creep tests on thin nanograined films using on-chip nanomechanical testing. Tests are performed on palladium, which exhibited unexpectedly large creep rates at room temperature. Despite the small 30-nm grain size, relaxation is found to be mediated by dislocation mechanisms. The dislocations interact with the growth nanotwins present in the grains, leading to a loss of coherency of twin boundaries. The density of stored dislocations first increases with applied deformation, and then decreases with time to drive additional deformation while no grain boundary mechanism is observed. This fast relaxation constitutes a key issue in the development of various micro- and nanotechnologies such as palladium membranes for hydrogen applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 34
DOI: 10.1038/ncomms6922
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“High temperature rise dominated cracking mechanisms in ultra-ductile and tough titanium alloy”. Choisez L, Ding L, Marteleur M, Idrissi H, Pardoen T, Jacques PJ, Nature Communications 11, 2110 (2020). http://doi.org/10.1038/S41467-020-15772-1
Abstract: Extensive use of titanium alloys is partly hindered by a lack of ductility, strain hardening, and fracture toughness. Recently, several beta -metastable titanium alloys were designed to simultaneously activate both transformation-induced plasticity and twinning-induced plasticity effects, resulting in significant improvements to their strain hardening capacity and resistance to plastic localization. Here, we report an ultra-large fracture resistance in a Ti-12Mo alloy (wt.%), that results from a high resistance to damage nucleation, with an unexpected fracture phenomenology under quasi-static loading. Necking develops at a large uniform true strain of 0.3 while fracture initiates at a true fracture strain of 1.0 by intense through-thickness shear within a thin localized shear band. Transmission electron microscopy reveals that dynamic recrystallization occurs in this band, while local partial melting is observed on the fracture surface. Shear band temperatures of 1250-2450 degrees C are estimated by the fusible coating method. The reported high ductility combined to the unconventional fracture process opens alternative avenues toward Ti alloys toughening. Specific titanium alloys combine transformation-induced plasticity and twinning-induced plasticity for improved work hardening. Here, the authors show that these alloys also have an ultra-large fracture resistance and an unexpected fracture mechanism via dynamic recrystallization and local melting in a deformation band.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 1
DOI: 10.1038/S41467-020-15772-1
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“Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation”. Chirayath VA, Callewaert V, Fairchild AJ, Chrysler MD, Gladen RW, Mcdonald AD, Imam SK, Shastry K, Koymen AR, Saniz R, Barbiellini B, Rajeshwar K, Partoens B, Weiss AH, Nature communications 8, 16116 (2017). http://doi.org/10.1038/ncomms16116
Abstract: Auger processes involving the filling of holes in the valence band are thought to make important contributions to the low-energy photoelectron and secondary electron spectrum from many solids. However, measurements of the energy spectrum and the efficiency with which electrons are emitted in this process remain elusive due to a large unrelated background resulting from primary beam-induced secondary electrons. Here, we report the direct measurement of the energy spectra of electrons emitted from single layer graphene as a result of the decay of deep holes in the valence band. These measurements were made possible by eliminating competing backgrounds by employing low-energy positrons (<1.25 eV) to create valence-band holes by annihilation. Our experimental results, supported by theoretical calculations, indicate that between 80 and 100% of the deep valence-band holes in graphene are filled via an Auger transition.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 20
DOI: 10.1038/ncomms16116
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“Epitaxially grown silicon-based single-atom catalyst for visible-light-driven syngas production”. Chen H, Xiong Y, Li J, Abed J, Wang D, Pedrazo-Tardajos A, Cao Y, Zhang Y, Wang Y, Shakouri M, Xiao Q, Hu Y, Bals S, Sargent EHH, Su C-Y, Yang Z, Nature communications 14, 1719 (2023). http://doi.org/10.1038/S41467-023-37401-3
Abstract: Despite the natural abundance and promising properties of Si, there are few examples of crystalline Si-based catalysts. Here, the authors report an epitaxial growth method to construct Co single atoms on Si for light driven CO2 reduction to syngas. Improving the dispersion of active sites simultaneous with the efficient harvest of photons is a key priority for photocatalysis. Crystalline silicon is abundant on Earth and has a suitable bandgap. However, silicon-based photocatalysts combined with metal elements has proved challenging due to silicon's rigid crystal structure and high formation energy. Here we report a solid-state chemistry that produces crystalline silicon with well-dispersed Co atoms. Isolated Co sites in silicon are obtained through the in-situ formation of CoSi2 intermediate nanodomains that function as seeds, leading to the production of Co-incorporating silicon nanocrystals at the CoSi2/Si epitaxial interface. As a result, cobalt-on-silicon single-atom catalysts achieve an external quantum efficiency of 10% for CO2-to-syngas conversion, with CO and H-2 yields of 4.7 mol g((Co))(-1) and 4.4 mol g((Co))(-1), respectively. Moreover, the H-2/CO ratio is tunable between 0.8 and 2. This photocatalyst also achieves a corresponding turnover number of 2 x 10(4) for visible-light-driven CO2 reduction over 6 h, which is over ten times higher than previously reported single-atom photocatalysts.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 6
DOI: 10.1038/S41467-023-37401-3
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“Signatures of enhanced out-of-plane polarization in asymmetric BaTiO3 superlattices integrated on silicon”. Chen B, Gauquelin N, Strkalj N, Huang S, Halisdemir U, Nguyen MD, Jannis D, Sarott MF, Eltes F, Abel S, Spreitzer M, Fiebig M, Trassin M, Fompeyrine J, Verbeeck J, Huijben M, Rijnders G, Koster G, Nature communications 13, 265 (2022). http://doi.org/10.1038/s41467-021-27898-x
Abstract: In order to bring the diverse functionalities of transition metal oxides into modern electronics, it is imperative to integrate oxide films with controllable properties onto the silicon platform. Here, we present asymmetric LaMnO<sub>3</sub>/BaTiO<sub>3</sub>/SrTiO<sub>3</sub>superlattices fabricated on silicon with layer thickness control at the unit-cell level. By harnessing the coherent strain between the constituent layers, we overcome the biaxial thermal tension from silicon and stabilize<italic>c</italic>-axis oriented BaTiO<sub>3</sub>layers with substantially enhanced tetragonality, as revealed by atomically resolved scanning transmission electron microscopy. Optical second harmonic generation measurements signify a predominant out-of-plane polarized state with strongly enhanced net polarization in the tricolor superlattices, as compared to the BaTiO<sub>3</sub>single film and conventional BaTiO<sub>3</sub>/SrTiO<sub>3</sub>superlattice grown on silicon. Meanwhile, this coherent strain in turn suppresses the magnetism of LaMnO<sub>3</sub>as the thickness of BaTiO<sub>3</sub>increases. Our study raises the prospect of designing artificial oxide superlattices on silicon with tailored functionalities.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 11
DOI: 10.1038/s41467-021-27898-x
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“Wien effect in interfacial water dissociation through proton-permeable graphene electrodes”. Cai J, Griffin E, Guarochico-Moreira VH, Barry D, Xin B, Yagmurcukardes M, Zhang S, Geim AK, Peeters FM, Lozada-Hidalgo M, Nature communications 13, 5776 (2022). http://doi.org/10.1038/S41467-022-33451-1
Abstract: Strong electric fields can accelerate molecular dissociation reactions. The phenomenon known as the Wien effect was previously observed using high-voltage electrolysis cells that produced fields of about 10(7) V m(-1), sufficient to accelerate the dissociation of weakly bound molecules (e.g., organics and weak electrolytes). The observation of the Wien effect for the common case of water dissociation (H2O reversible arrow H+ + OH-) has remained elusive. Here we study the dissociation of interfacial water adjacent to proton-permeable graphene electrodes and observe strong acceleration of the reaction in fields reaching above 10(8) V m(-1). The use of graphene electrodes allows measuring the proton currents arising exclusively from the dissociation of interfacial water, while the electric field driving the reaction is monitored through the carrier density induced in graphene by the same field. The observed exponential increase in proton currents is in quantitative agreement with Onsager's theory. Our results also demonstrate that graphene electrodes can be valuable for the investigation of various interfacial phenomena involving proton transport.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 16.6
Times cited: 14
DOI: 10.1038/S41467-022-33451-1
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“Control of switching between metastable superconducting states in delta-MoN nanowires”. Buh J, Kabanov V, Baranov V, Mrzel A, Kovic A, Mihailovic D, Nature communications 6, 10250 (2015). http://doi.org/10.1038/ncomms10250
Abstract: The superconducting state in one-dimensional nanosystems is very delicate. While fluctuations of the phase of the superconducting wave function lead to the spontaneous decay of persistent supercurrents in thin superconducting wires and nanocircuits, discrete phase-slip fluctuations can also lead to more exotic phenomena, such as the appearance of metastable superconducting states in current-bearing wires. Here we show that switching between different metastable superconducting states in d-MoN nanowires can be very effectively manipulated by introducing small amplitude electrical noise. Furthermore, we show that deterministic switching between metastable superconducting states with different numbers of phase-slip centres can be achieved in both directions with small electrical current pulse perturbations of appropriate polarity. The observed current-controlled bi-stability is in remarkable agreement with theoretically predicted trajectories of the system switching between different limit cycle solutions of a model one-dimensional superconductor.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 8
DOI: 10.1038/ncomms10250
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“Transforming solid-state precipitates via excess vacancies”. Bourgeois L, Zhang Y, Zhang Z, Chen Y, Medhekar N V, Nature Communications 11, 1248 (2020). http://doi.org/10.1038/S41467-020-15087-1
Abstract: Many phase transformations associated with solid-state precipitation look structurally simple, yet, inexplicably, take place with great difficulty. A classic case of difficult phase transformations is the nucleation of strengthening precipitates in high-strength lightweight aluminium alloys. Here, using a combination of atomic-scale imaging, simulations and classical nucleation theory calculations, we investigate the nucleation of the strengthening phase theta' onto a template structure in the aluminium-copper alloy system. We show that this transformation can be promoted in samples exhibiting at least one nanoscale dimension, with extremely high nucleation rates for the strengthening phase as well as for an unexpected phase. This template-directed solid-state nucleation pathway is enabled by the large influx of surface vacancies that results from heating a nanoscale solid. Template-directed nucleation is replicated in a bulk alloy as well as under electron irradiation, implying that this difficult transformation can be facilitated under the general condition of sustained excess vacancy concentrations.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 5
DOI: 10.1038/S41467-020-15087-1
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“Efficient long-range conduction in cable bacteria through nickel protein wires”. Boschker HTS, Cook PLM, Polerecky L, Eachambadi RT, Lozano H, Hidalgo-Martinez S, Khalenkow D, Spampinato V, Claes N, Kundu P, Wang D, Bals S, Sand KK, Cavezza F, Hauffman T, Bjerg JT, Skirtach AG, Kochan K, McKee M, Wood B, Bedolla D, Gianoncelli A, Geerlings NMJ, Van Gerven N, Remaut H, Geelhoed JS, Millan-Solsona R, Fumagalli L, Nielsen LP, Franquet A, Manca JV, Gomila G, Meysman FJR, Nature Communications 12, 3996 (2021). http://doi.org/10.1038/s41467-021-24312-4
Abstract: Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 23
DOI: 10.1038/s41467-021-24312-4
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“Asymmetry and non-dispersivity in the Aharonov-Bohm effect”. Becker M, Guzzinati G, Béché, A, Verbeeck J, Batelaan H, Nature communications 10, 1700 (2019). http://doi.org/10.1038/S41467-019-09609-9
Abstract: Decades ago, Aharonov and Bohm showed that electrons are affected by electromagnetic potentials in the absence of forces due to fields. Zeilinger's theorem describes this absence of classical force in quantum terms as the “dispersionless” nature of the Aharonov-Bohm effect. Shelankov predicted the presence of a quantum “force” for the same Aharonov-Bohm physical system as elucidated by Berry. Here, we report an experiment designed to test Shelankov's prediction and we provide a theoretical analysis that is intended to elucidate the relation between Shelankov's prediction and Zeilinger's theorem. The experiment consists of the Aharonov-Bohm physical system; free electrons pass a magnetized nanorod and far-field electron diffraction is observed. The diffraction pattern is asymmetric confirming one of Shelankov's predictions and giving indirect experimental evidence for the presence of a quantum “force”. Our theoretical analysis shows that Zeilinger's theorem and Shelankov's result are both special cases of one theorem.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 12
DOI: 10.1038/S41467-019-09609-9
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“Atomic scale dynamics of ultrasmall germanium clusters”. Bals S, Van Aert S, Romero CP, Lauwaet K, Van Bael MJ, Schoeters B, Partoens B, Yuecelen E, Lievens P, Van Tendeloo G, Nature communications 3, 897 (2012). http://doi.org/10.1038/ncomms1887
Abstract: Starting from the gas phase, small clusters can be produced and deposited with huge flexibility with regard to composition, materials choice and cluster size. Despite many advances in experimental characterization, a detailed morphology of such clusters is still lacking. Here we present an atomic scale observation as well as the dynamical behaviour of ultrasmall germanium clusters. Using quantitative scanning transmission electron microscopy in combination with ab initio calculations, we are able to characterize the transition between different equilibrium geometries of a germanium cluster consisting of less than 25 atoms. Seven-membered rings, trigonal prisms and some smaller subunits are identified as possible building blocks that stabilize the structure.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 90
DOI: 10.1038/ncomms1887
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“Preventing cation intermixing enables 50% quantum yield in sub-15 nm short-wave infrared-emitting rare-earth based core-shell nanocrystals”. Arteaga Cardona F, Jain N, Popescu R, Busko D, Madirov E, Arús BA, Gerthsen D, De Backer A, Bals S, Bruns OT, Chmyrov A, Van Aert S, Richards BS, Hudry D, Nature communications 14, 4462 (2023). http://doi.org/10.1038/s41467-023-40031-4
Abstract: Short-wave infrared (SWIR) fluorescence could become the new gold standard in optical imaging for biomedical applications due to important advantages such as lack of autofluorescence, weak photon absorption by blood and tissues, and reduced photon scattering coefficient. Therefore, contrary to the visible and NIR regions, tissues become translucent in the SWIR region. Nevertheless, the lack of bright and biocompatible probes is a key challenge that must be overcome to unlock the full potential of SWIR fluorescence. Although rare-earth-based core-shell nanocrystals appeared as promising SWIR probes, they suffer from limited photoluminescence quantum yield (PLQY). The lack of control over the atomic scale organization of such complex materials is one of the main barriers limiting their optical performance. Here, the growth of either homogeneous (α-NaYF<sub>4</sub>) or heterogeneous (CaF<sub>2</sub>) shell domains on optically-active α-NaYF<sub>4</sub>:Yb:Er (with and without Ce<sup>3+</sup>co-doping) core nanocrystals is reported. The atomic scale organization can be controlled by preventing cation intermixing only in heterogeneous core-shell nanocrystals with a dramatic impact on the PLQY. The latter reached 50% at 60 mW/cm<sup>2</sup>; one of the highest reported PLQY values for sub-15 nm nanocrystals. The most efficient nanocrystals were utilized for in vivo imaging above 1450 nm.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 1
DOI: 10.1038/s41467-023-40031-4
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“A nanoscale shape memory oxide”. Zhang J, Ke X, Gou G, Seidel J, Xiang B, Yu P, Liang WI, Minor AM, Chu Yh, Van Tendeloo G, Ren X, Ramesh R;, Nature communications 4, 2768 (2013). http://doi.org/10.1038/ncomms3768
Abstract: Stimulus-responsive shape-memory materials have attracted tremendous research interests recently, with much effort focused on improving their mechanical actuation. Driven by the needs of nanoelectromechanical devices, materials with large mechanical strain, particularly at nanoscale level, are therefore desired. Here we report on the discovery of a large shape-memory effect in bismuth ferrite at the nanoscale. A maximum strain of up to ~14% and a large volumetric work density of ~600±90 J cm−3 can be achieved in association with a martensitic-like phase transformation. With a single step, control of the phase transformation by thermal activation or electric field has been reversibly achieved without the assistance of external recovery stress. Although aspects such as hysteresis, microcracking and so on have to be taken into consideration for real devices, the large shape-memory effect in this oxide surpasses most alloys and, therefore, demonstrates itself as an extraordinary material for potential use in state-of-art nanosystems.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 67
DOI: 10.1038/ncomms3768
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“Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling”. Tongay S, Sahin H, Ko C, Luce A, Fan W, Liu K, Zhou J, Huang YS, Ho CH, Yan J, Ogletree DF, Aloni S, Ji J, Li S, Li J, Peeters FM, Wu J;, Nature communications 5, 3252 (2014). http://doi.org/10.1038/ncomms4252
Abstract: Semiconducting transition metal dichalcogenides consist of monolayers held together by weak forces where the layers are electronically and vibrationally coupled. Isolated monolayers show changes in electronic structure and lattice vibration energies, including a transition from indirect to direct bandgap. Here we present a new member of the family, rhenium disulphide (ReS2), where such variation is absent and bulk behaves as electronically and vibrationally decoupled monolayers stacked together. From bulk to monolayers, ReS2 remains direct bandgap and its Raman spectrum shows no dependence on the number of layers. Interlayer decoupling is further demonstrated by the insensitivity of the optical absorption and Raman spectrum to interlayer distance modulated by hydrostatic pressure. Theoretical calculations attribute the decoupling to Peierls distortion of the 1T structure of ReS2, which prevents ordered stacking and minimizes the interlayer overlap of wavefunctions. Such vanishing interlayer coupling enables probing of two-dimensional-like systems without the need for monolayers.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 806
DOI: 10.1038/ncomms4252
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“Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors”. Li J, Ji M, Schwarz T, Ke X, Van Tendeloo G, Yuan J, Pereira PJ, Huang Y, Zhang G, Feng HL, Yuan YH, Hatano T, Kleiner R, Koelle D, Chibotaru LF, Yamaura K, Wang HB, Wu PH, Takayama-Muromachi E, Vanacken J, Moshchalkov VV;, Nature communications 6, 7614 (2015). http://doi.org/10.1038/ncomms8614
Abstract: The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional Swiss cheese-like pattern with in-plane and out-of-plane characteristic lengths slightly below ~1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 12
DOI: 10.1038/ncomms8614
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