@article{14435,
abstract = {Low‐cost, safe, and environmental‐friendly rechargeable aqueous zinc‐ion batteries (ZIBs) are promising as next‐generation energy storage devices for wearable electronics among other applications. However, sluggish ionic transport kinetics and the unstable electrode structure during ionic insertion/extraction hampers their deployment. Herein, we propose a new cathode material based on a layered metal chalcogenide (LMC), bismuth telluride (Bi2Te3), coated with polypyrrole (PPy). Taking advantage of the PPy coating, the Bi2Te3@PPy composite presents strong ionic absorption affinity, high oxidation resistance, and high structural stability. The ZIBs based on Bi2Te3@PPy cathodes exhibit high capacities and ultra‐long lifespans of over 5000 cycles. They also present outstanding stability even under bending. In addition, we analyze here the reaction mechanism using in situ X‐ray diffraction, X‐ray photoelectron spectroscopy, and computational tools and demonstrate that, in the aqueous system, Zn2+ is not inserted into the cathode as previously assumed. In contrast, proton charge storage dominates the process. Overall, this work not only shows the great potential of LMCs as ZIBs cathode materials and the advantages of PPy coating, but also clarifies the charge/discharge mechanism in rechargeable ZIBs based on LMCs.},
author = {Zeng, Guifang and Sun, Qing and Horta, Sharona and Wang, Shang and Lu, Xuan and Zhang, Chaoyue and Li, Jing and Li, Junshan and Ci, Lijie and Tian, Yanhong and Ibáñez, Maria and Cabot, Andreu},
issn = {1521-4095},
journal = {Advanced Materials},
keywords = {Mechanical Engineering, Mechanics of Materials, General Materials Science},
number = {1},
publisher = {Wiley},
title = {{A layered Bi2Te3@PPy cathode for aqueous zinc ion batteries: Mechanism and application in printed flexible batteries}},
doi = {10.1002/adma.202305128},
volume = {36},
year = {2024},
}
@article{14733,
abstract = {Redox flow batteries (RFBs) rely on the development of cheap, highly soluble, and high-energy-density electrolytes. Several candidate quinones have already been investigated in the literature as two-electron anolytes or catholytes, benefiting from fast kinetics, high tunability, and low cost. Here, an investigation of nitrogen-rich fused heteroaromatic quinones was carried out to explore avenues for electrolyte development. These quinones were synthesized and screened by using electrochemical techniques. The most promising candidate, 4,8-dioxo-4,8-dihydrobenzo[1,2-d:4,5-d′]bis([1,2,3]triazole)-1,5-diide (−0.68 V(SHE)), was tested in both an asymmetric and symmetric full-cell setup resulting in capacity fade rates of 0.35% per cycle and 0.0124% per cycle, respectively. In situ ultraviolet-visible spectroscopy (UV–Vis), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) spectroscopies were used to investigate the electrochemical stability of the charged species during operation. UV–Vis spectroscopy, supported by density functional theory (DFT) modeling, reaffirmed that the two-step charging mechanism observed during battery operation consisted of two, single-electron transfers. The radical concentration during battery operation and the degree of delocalization of the unpaired electron were quantified with NMR and EPR spectroscopy.},
author = {Jethwa, Rajesh B and Hey, Dominic and Kerber, Rachel N. and Bond, Andrew D. and Wright, Dominic S. and Grey, Clare P.},
issn = {2574-0962},
journal = {ACS Applied Energy Materials},
keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)},
number = {2},
pages = {414--426},
publisher = {American Chemical Society},
title = {{Exploring the landscape of heterocyclic quinones for redox flow batteries}},
doi = {10.1021/acsaem.3c02223},
volume = {7},
year = {2024},
}
@article{14802,
abstract = {Frequency-stable lasers form the back bone of precision measurements in science and technology. Such lasers typically attain their stability through frequency locking to reference cavities. State-of-the-art locking performances to date had been achieved using frequency modulation based methods, complemented with active drift cancellation systems. We demonstrate an all passive, modulation-free laser-cavity locking technique (squash locking) that utilizes changes in spatial beam ellipticity for error signal generation, and a coherent polarization post-selection for noise resilience. By comparing two identically built proof-of-principle systems, we show a frequency locking instability of 5×10−7 relative to the cavity linewidth at 10 s averaging. The results surpass the demonstrated performances of methods engineered over the last five decades, potentially enabling an advancement in the precision control of lasers, while creating avenues for bridging the performance gaps between industrial grade lasers with scientific ones due to the afforded simplicity and scalability.},
author = {Diorico, Fritz R and Zhutov, Artem and Hosten, Onur},
issn = {2334-2536},
journal = {Optica},
keywords = {Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials},
number = {1},
pages = {26--31},
publisher = {Optica Publishing Group},
title = {{Laser-cavity locking utilizing beam ellipticity: accessing the 10−7 instability scale relative to cavity linewidth}},
doi = {10.1364/optica.507451},
volume = {11},
year = {2024},
}
@article{14828,
abstract = {Production of hydrogen at large scale requires development of non-noble, inexpensive, and high-performing catalysts for constructing water-splitting devices. Herein, we report the synthesis of Zn-doped NiO heterostructure (ZnNiO) catalysts at room temperature via a coprecipitation method followed by drying (at 80 °C, 6 h) and calcination at an elevated temperature of 400 °C for 5 h under three distinct conditions, namely, air, N2, and vacuum. The vacuum-synthesized catalyst demonstrates a low overpotential of 88 mV at −10 mA cm–2 and a small Tafel slope of 73 mV dec–1 suggesting relatively higher charge transfer kinetics for hydrogen evolution reactions (HER) compared with the specimens synthesized under N2 or O2 atmosphere. It also demonstrates an oxygen evolution (OER) overpotential of 260 mV at 10 mA cm–2 with a low Tafel slope of 63 mV dec–1. In a full-cell water-splitting device, the vacuum-synthesized ZnNiO heterostructure demonstrates a cell voltage of 1.94 V at 50 mA cm–2 and shows remarkable stability over 24 h at a high current density of 100 mA cm–2. It is also demonstrated in this study that Zn-doping, surface, and interface engineering in transition-metal oxides play a crucial role in efficient electrocatalytic water splitting. Also, the results obtained from density functional theory (DFT + U = 0–8 eV), where U is the on-site Coulomb repulsion parameter also known as Hubbard U, based electronic structure calculations confirm that Zn doping constructively modifies the electronic structure, in both the valence band and the conduction band, and found to be suitable in tailoring the carrier’s effective masses of electrons and holes. The decrease in electron’s effective masses together with large differences between the effective masses of electrons and holes is noticed, which is found to be mainly responsible for achieving the best water-splitting performance from a 9% Zn-doped NiO sample prepared under vacuum.},
author = {Kiran, Gundegowda Kalligowdanadoddi and Singh, Saurabh and Mahato, Neelima and Sreekanth, Thupakula Venkata Madhukar and Dillip, Gowra Raghupathy and Yoo, Kisoo and Kim, Jonghoon},
issn = {2574-0962},
journal = {ACS Applied Energy Materials},
keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)},
number = {1},
pages = {214--229},
publisher = {American Chemical Society},
title = {{Interface engineering modulation combined with electronic structure modification of Zn-doped NiO heterostructure for efficient water-splitting activity}},
doi = {10.1021/acsaem.3c02519},
volume = {7},
year = {2024},
}
@article{15018,
abstract = {The epitaxial growth of a strained Ge layer, which is a promising candidate for the channel material of a hole spin qubit, has been demonstrated on 300 mm Si wafers using commercially available Si0.3Ge0.7 strain relaxed buffer (SRB) layers. The assessment of the layer and the interface qualities for a buried strained Ge layer embedded in Si0.3Ge0.7 layers is reported. The XRD reciprocal space mapping confirmed that the reduction of the growth temperature enables the 2-dimensional growth of the Ge layer fully strained with respect to the Si0.3Ge0.7. Nevertheless, dislocations at the top and/or bottom interface of the Ge layer were observed by means of electron channeling contrast imaging, suggesting the importance of the careful dislocation assessment. The interface abruptness does not depend on the selection of the precursor gases, but it is strongly influenced by the growth temperature which affects the coverage of the surface H-passivation. The mobility of 2.7 × 105 cm2/Vs is promising, while the low percolation density of 3 × 1010 /cm2 measured with a Hall-bar device at 7 K illustrates the high quality of the heterostructure thanks to the high Si0.3Ge0.7 SRB quality.},
author = {Shimura, Yosuke and Godfrin, Clement and Hikavyy, Andriy and Li, Roy and Aguilera Servin, Juan L and Katsaros, Georgios and Favia, Paola and Han, Han and Wan, Danny and de Greve, Kristiaan and Loo, Roger},
issn = {1369-8001},
journal = {Materials Science in Semiconductor Processing},
keywords = {Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science},
number = {5},
publisher = {Elsevier},
title = {{Compressively strained epitaxial Ge layers for quantum computing applications}},
doi = {10.1016/j.mssp.2024.108231},
volume = {174},
year = {2024},
}
@phdthesis{18667,
abstract = {Many chemical and physical properties of materials are determined by the material’s shape,
for example the size of its pores and the width of its tunnels. This makes materials science
a prime application area for geometrical and topological methods. Nevertheless many
methods in topological data analysis have not been satisfyingly extended to the needs of
materials science. This thesis provides new methods and new mathematical theorems
targeted at those specific needs by answering four different research questions. While the
motivation for each of the research questions arises from materials science, the methods
are versatile and can be applied in different areas as well.
The first research question is concerned with image data, for example a three-dimensional
computed tomography (CT) scan of a material, like sand or stone. There are two commonly
used topologies for digital images and depending on the application either of them might be
required. However, software for computing the topological data analysis method persistence
homology, usually supports only one of the two topologies. We answer the question how to
compute persistent homology of an image with respect to one of the two topologies using
software that is intended for the other topology.
The second research question is concerned with image data as well, and asks how much
of the topological information of an image is lost when the resolution is coarsened. As
computer tomography scanners are more expensive the higher the resolution, it is an
important question in materials science to know which resolution is enough to get satisfying
persistent homology. We give theoretical bounds on the information loss based on different
geometrical properties of the object to be scanned. In addition, we conduct experiments on
sand and stone CT image data.
The third research question is motivated by comparing crystalline materials efficiently. As
the atoms within a crystal repeat periodically, crystalline materials are either modeled by
unmanageable infinite periodic point sets, or by one of their fundamental domains, which is
unstable under perturbation. Therefore a fingerprint of crystalline materials is needed, with
appropriate properties such that comparing the crystals can be eased by comparing the
fingerprints instead. We define the density fingerprint and prove the necessary properties.
The fourth research question is motivated by studying the hole-structure or connectedness,
i.e. persistent homology or merge trees, of crystalline materials. A common way to deal
with periodicity is to take a fundamental domain and identify opposite boundaries to form a
torus. However, computing persistent homology or merge trees on that torus loses some
of the information materials scientists are interested in and is additionally not stable under
certain noise. We therefore decorate the merge tree stemming from the torus with additional
information describing the density and growth rate of the periodic copies of a component
within a growing spherical window. We prove all desired properties, like stability and efficient
computability.},
author = {Heiss, Teresa},
isbn = {978-3-99078-052-7},
issn = {2663-337X},
keywords = {persistent homology, topological data analysis, periodic, crystalline materials, images, fingerprint},
pages = {111},
publisher = {Institute of Science and Technology Austria},
title = {{New methods for applying topological data analysis to materials science}},
doi = {10.15479/at:ista:18667},
year = {2024},
}
@article{13988,
abstract = {Most permissionless blockchains inherently suffer from throughput limitations. Layer-2 systems, such as side-chains or Rollups, have been proposed as a possible strategy to overcome this limitation. Layer-2 systems interact with the main-chain in two ways. First, users can move funds from/to the main-chain to/from the layer-2. Second, layer-2 systems periodically synchronize with the main-chain to keep some form of log of their activity on the main-chain - this log is key for security. Due to this interaction with the main-chain, which is necessary and recurrent, layer-2 systems impose some load on the main-chain. The impact of such load on the main-chain has been, so far, poorly understood. In addition to that, layer-2 approaches typically sacrifice decentralization and security in favor of higher throughput. This paper presents an experimental study that analyzes the current state of Ethereum layer-2 projects. Our goal is to assess the load they impose on Ethereum and to understand their scalability potential in the long-run. Our analysis shows that the impact of any given layer-2 on the main-chain is the result of both technical aspects (how state is logged on the main-chain) and user behavior (how often users decide to transfer funds between the layer-2 and the main-chain). Based on our observations, we infer that without efficient mechanisms that allow users to transfer funds in a secure and fast manner directly from one layer-2 project to another, current layer-2 systems will not be able to scale Ethereum effectively, regardless of their technical solutions. Furthermore, from our results, we conclude that the layer-2 systems that offer similar security guarantees as Ethereum have limited scalability potential, while approaches that offer better performance, sacrifice security and lead to an increase in centralization which runs against the end-goals of permissionless blockchains.},
author = {Neiheiser, Ray and Inacio, Gustavo and Rech, Luciana and Montez, Carlos and Matos, Miguel and Rodrigues, Luis},
issn = {2169-3536},
journal = {IEEE Access},
keywords = {General Engineering, General Materials Science, General Computer Science, Electrical and Electronic Engineering},
pages = {8651--8662},
publisher = {Institute of Electrical and Electronics Engineers},
title = {{Practical limitations of Ethereum’s layer-2}},
doi = {10.1109/access.2023.3237897},
volume = {11},
year = {2023},
}
@article{14434,
abstract = {High entropy alloys (HEAs) are highly suitable candidate catalysts for oxygen evolution and reduction reactions (OER/ORR) as they offer numerous parameters for optimizing the electronic structure and catalytic sites. Herein, FeCoNiMoW HEA nanoparticles are synthesized using a solution‐based low‐temperature approach. Such FeCoNiMoW nanoparticles show high entropy properties, subtle lattice distortions, and modulated electronic structure, leading to superior OER performance with an overpotential of 233 mV at 10 mA cm−2 and 276 mV at 100 mA cm−2. Density functional theory calculations reveal the electronic structures of the FeCoNiMoW active sites with an optimized d‐band center position that enables suitable adsorption of OOH* intermediates and reduces the Gibbs free energy barrier in the OER process. Aqueous zinc–air batteries (ZABs) based on this HEA demonstrate a high open circuit potential of 1.59 V, a peak power density of 116.9 mW cm−2, a specific capacity of 857 mAh gZn−1, and excellent stability for over 660 h of continuous charge–discharge cycles. Flexible and solid ZABs are also assembled and tested, displaying excellent charge–discharge performance at different bending angles. This work shows the significance of 4d/5d metal‐modulated electronic structure and optimized adsorption ability to improve the performance of OER/ORR, ZABs, and beyond.},
author = {He, Ren and Yang, Linlin and Zhang, Yu and Jiang, Daochuan and Lee, Seungho and Horta, Sharona and Liang, Zhifu and Lu, Xuan and Ostovari Moghaddam, Ahmad and Li, Junshan and Ibáñez, Maria and Xu, Ying and Zhou, Yingtang and Cabot, Andreu},
issn = {1521-4095},
journal = {Advanced Materials},
keywords = {Mechanical Engineering, Mechanics of Materials, General Materials Science},
number = {46},
publisher = {Wiley},
title = {{A 3d‐4d‐5d high entropy alloy as a bifunctional oxygen catalyst for robust aqueous zinc–air batteries}},
doi = {10.1002/adma.202303719},
volume = {35},
year = {2023},
}
@article{12697,
abstract = {Models for same-material contact electrification in granular media often rely on a local charge-driving parameter whose spatial variations lead to a stochastic origin for charge exchange. Measuring the charge transfer from individual granular spheres after contacts with substrates of the same material, we find instead a “global” charging behavior, coherent over the sample’s whole surface. Cleaning and baking samples fully resets charging magnitude and direction, which indicates the underlying global parameter is not intrinsic to the material, but acquired from its history. Charging behavior is randomly and irreversibly affected by changes in relative humidity, hinting at a mechanism where adsorbates, in particular, water, are fundamental to the charge-transfer process.},
author = {Grosjean, Galien M and Waitukaitis, Scott R},
issn = {1079-7114},
journal = {Physical Review Letters},
keywords = {General Physics, Electrostatics, Triboelectricity, Soft Matter, Acoustic Levitation, Granular Materials},
number = {9},
publisher = {American Physical Society},
title = {{Single-collision statistics reveal a global mechanism driven by sample history for contact electrification in granular media}},
doi = {10.1103/physrevlett.130.098202},
volume = {130},
year = {2023},
}
@article{13197,
abstract = {Nominally identical materials exchange net electric charge during contact through a mechanism that is still debated. ‘Mosaic models’, in which surfaces are presumed to consist of a random patchwork of microscopic donor/acceptor sites, offer an appealing explanation for this phenomenon. However, recent experiments have shown that global differences persist even between same-material samples, which the standard mosaic framework does not account for. Here, we expand the mosaic framework by incorporating global differences in the densities of donor/acceptor sites. We develop
an analytical model, backed by numerical simulations, that smoothly connects the global and deterministic charge transfer of different materials to the local and stochastic mosaic picture normally associated with identical materials. Going further, we extend our model to explain the effect of contact asymmetries during sliding, providing a plausible explanation for reversal of charging sign that has been observed experimentally.},
author = {Grosjean, Galien M and Waitukaitis, Scott R},
issn = {2475-9953},
journal = {Physical Review Materials},
keywords = {Physics and Astronomy (miscellaneous), General Materials Science},
number = {6},
publisher = {American Physical Society},
title = {{Asymmetries in triboelectric charging: Generalizing mosaic models to different-material samples and sliding contacts}},
doi = {10.1103/physrevmaterials.7.065601},
volume = {7},
year = {2023},
}
@article{13251,
abstract = {A rotating organic cation and a dynamically disordered soft inorganic cage are the hallmark features of organic-inorganic lead-halide perovskites. Understanding the interplay between these two subsystems is a challenging problem, but it is this coupling that is widely conjectured to be responsible for the unique behavior of photocarriers in these materials. In this work, we use the fact that the polarizability of the organic cation strongly depends on the ambient electrostatic environment to put the molecule forward as a sensitive probe of the local crystal fields inside the lattice cell. We measure the average polarizability of the C/N–H bond stretching mode by means of infrared spectroscopy, which allows us to deduce the character of the motion of the cation molecule, find the magnitude of the local crystal field, and place an estimate on the strength of the hydrogen bond between the hydrogen and halide atoms. Our results pave the way for understanding electric fields in lead-halide perovskites using infrared bond spectroscopy.},
author = {Wei, Yujing and Volosniev, Artem and Lorenc, Dusan and Zhumekenov, Ayan A. and Bakr, Osman M. and Lemeshko, Mikhail and Alpichshev, Zhanybek},
issn = {1948-7185},
journal = {The Journal of Physical Chemistry Letters},
keywords = {General Materials Science, Physical and Theoretical Chemistry},
number = {27},
pages = {6309--6314},
publisher = {American Chemical Society},
title = {{Bond polarizability as a probe of local crystal fields in hybrid lead-halide perovskites}},
doi = {10.1021/acs.jpclett.3c01158},
volume = {14},
year = {2023},
}
@article{13346,
abstract = {The self-assembly of nanoparticles driven by small molecules or ions may produce colloidal superlattices with features and properties reminiscent of those of metals or semiconductors. However, to what extent the properties of such supramolecular crystals actually resemble those of atomic materials often remains unclear. Here, we present coarse-grained molecular simulations explicitly demonstrating how a behavior evocative of that of semiconductors may emerge in a colloidal superlattice. As a case study, we focus on gold nanoparticles bearing positively charged groups that self-assemble into FCC crystals via mediation by citrate counterions. In silico ohmic experiments show how the dynamically diverse behavior of the ions in different superlattice domains allows the opening of conductive ionic gates above certain levels of applied electric fields. The observed binary conductive/nonconductive behavior is reminiscent of that of conventional semiconductors, while, at a supramolecular level, crossing the “band gap” requires a sufficient electrostatic stimulus to break the intermolecular interactions and make ions diffuse throughout the superlattice’s cavities.},
author = {Lionello, Chiara and Perego, Claudio and Gardin, Andrea and Klajn, Rafal and Pavan, Giovanni M.},
issn = {1936-086X},
journal = {ACS Nano},
keywords = {General Physics and Astronomy, General Engineering, General Materials Science},
number = {1},
pages = {275--287},
publisher = {American Chemical Society},
title = {{Supramolecular semiconductivity through emerging ionic gates in ion–nanoparticle superlattices}},
doi = {10.1021/acsnano.2c07558},
volume = {17},
year = {2023},
}
@article{14831,
abstract = {Catalysis, the acceleration of product formation by a substance that is left unchanged, typically results from multiple elementary processes, including diffusion of the reactants toward the catalyst, chemical steps, and release of the products. While efforts to design catalysts are often focused on accelerating the chemical reaction on the catalyst, catalysis is a global property of the catalytic cycle that involves all processes. These are controlled by both intrinsic parameters such as the composition and shape of the catalyst and extrinsic parameters such as the concentration of the chemical species at play. We examine here the conditions that catalysis imposes on the different steps of a reaction cycle and the respective role of intrinsic and extrinsic parameters of the system on the emergence of catalysis by using an approach based on first-passage times. We illustrate this approach for various decompositions of a catalytic cycle into elementary steps, including non-Markovian decompositions, which are useful when the presence and nature of intermediate states are a priori unknown. Our examples cover different types of reactions and clarify the constraints on elementary steps and the impact of species concentrations on catalysis.},
author = {Sakref, Yann and Muñoz Basagoiti, Maitane and Zeravcic, Zorana and Rivoire, Olivier},
issn = {1520-5207},
journal = {The Journal of Physical Chemistry B},
keywords = {Materials Chemistry, Surfaces, Coatings and Films, Physical and Theoretical Chemistry},
number = {51},
pages = {10950--10959},
publisher = {American Chemical Society},
title = {{On kinetic constraints that catalysis imposes on elementary processes}},
doi = {10.1021/acs.jpcb.3c04627},
volume = {127},
year = {2023},
}
@article{12137,
abstract = {We investigate the local self-sustained process underlying spiral turbulence in counter-rotating Taylor–Couette flow using a periodic annular domain, shaped as a parallelogram, two of whose sides are aligned with the cylindrical helix described by the spiral pattern. The primary focus of the study is placed on the emergence of drifting–rotating waves (DRW) that capture, in a relatively small domain, the main features of coherent structures typically observed in developed turbulence. The transitional dynamics of the subcritical region, far below the first instability of the laminar circular Couette flow, is determined by the upper and lower branches of DRW solutions originated at saddle-node bifurcations. The mechanism whereby these solutions self-sustain, and the chaotic dynamics they induce, are conspicuously reminiscent of other subcritical shear flows. Remarkably, the flow properties of DRW persist even as the Reynolds number is increased beyond the linear stability threshold of the base flow. Simulations in a narrow parallelogram domain stretched in the azimuthal direction to revolve around the apparatus a full turn confirm that self-sustained vortices eventually concentrate into a localised pattern. The resulting statistical steady state satisfactorily reproduces qualitatively, and to a certain degree also quantitatively, the topology and properties of spiral turbulence as calculated in a large periodic domain of sufficient aspect ratio that is representative of the real system.},
author = {Wang, B. and Ayats López, Roger and Deguchi, K. and Mellibovsky, F. and Meseguer, A.},
issn = {1469-7645},
journal = {Journal of Fluid Mechanics},
keywords = {Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, Applied Mathematics},
publisher = {Cambridge University Press},
title = {{Self-sustainment of coherent structures in counter-rotating Taylor–Couette flow}},
doi = {10.1017/jfm.2022.828},
volume = {951},
year = {2022},
}
@article{12146,
abstract = {In this paper, we explore the stability and dynamical relevance of a wide variety of steady, time-periodic, quasiperiodic, and chaotic flows arising between orthogonally stretching parallel plates. We first explore the stability of all the steady flow solution families formerly identified by Ayats et al. [“Flows between orthogonally stretching parallel plates,” Phys. Fluids 33, 024103 (2021)], concluding that only the one that originates from the Stokesian approximation is actually stable. When both plates are shrinking at identical or nearly the same deceleration rates, this Stokesian flow exhibits a Hopf bifurcation that leads to stable time-periodic regimes. The resulting time-periodic orbits or flows are tracked for different Reynolds numbers and stretching rates while monitoring their Floquet exponents to identify secondary instabilities. It is found that these time-periodic flows also exhibit Neimark–Sacker bifurcations, generating stable quasiperiodic flows (tori) that may sometimes give rise to chaotic dynamics through a Ruelle–Takens–Newhouse scenario. However, chaotic dynamics is unusually observed, as the quasiperiodic flows generally become phase-locked through a resonance mechanism before a strange attractor may arise, thus restoring the time-periodicity of the flow. In this work, we have identified and tracked four different resonance regions, also known as Arnold tongues or horns. In particular, the 1 : 4 strong resonance region is explored in great detail, where the identified scenarios are in very good agreement with normal form theory. },
author = {Wang, B. and Ayats López, Roger and Meseguer, A. and Marques, F.},
issn = {1089-7666},
journal = {Physics of Fluids},
keywords = {Condensed Matter Physics, Fluid Flow and Transfer Processes, Mechanics of Materials, Computational Mechanics, Mechanical Engineering},
number = {11},
publisher = {AIP Publishing},
title = {{Phase-locking flows between orthogonally stretching parallel plates}},
doi = {10.1063/5.0124152},
volume = {34},
year = {2022},
}
@article{12213,
abstract = {Motivated by properties-controlling potential of the strain, we investigate strain dependence of structure, electronic, and magnetic properties of Sr2IrO4 using complementary theoretical tools: ab-initio calculations, analytical approaches (rigid octahedra picture, Slater-Koster integrals), and extended t−J model. We find that strain affects both Ir-Ir distance and Ir-O-Ir angle, and the rigid octahedra picture is not relevant. Second, we find fundamentally different behavior for compressive and tensile strain. One remarkable feature is the formation of two subsets of bond- and orbital-dependent carriers, a compass-like model, under compression. This originates from the strain-induced renormalization of the Ir-O-Ir superexchange and O on-site energy. We also show that under compressive (tensile) strain, Fermi surface becomes highly dispersive (relatively flat). Already at a tensile strain of 1.5%, we observe spectral weight redistribution, with the low-energy band acquiring almost purely singlet character. These results can be directly compared with future experiments.},
author = {Paerschke, Ekaterina and Chen, Wei-Chih and Ray, Rajyavardhan and Chen, Cheng-Chien},
issn = {2397-4648},
journal = {npj Quantum Materials},
keywords = {Condensed Matter Physics, Electronic, Optical and Magnetic Materials},
publisher = {Springer Nature},
title = {{Evolution of electronic and magnetic properties of Sr₂IrO₄ under strain}},
doi = {10.1038/s41535-022-00496-w},
volume = {7},
year = {2022},
}
@article{12227,
abstract = {Polydicyclopentadiene (pDCPD), a thermoset with excellent mechanical properties, has enormous potential as a lightweight, tough, and stable matrix material owing to its highly cross-linked macromolecular network. This work describes generating pDCPD-based foams and hierarchically porous carbons derived therefrom by combining ring-opening metathesis polymerization (ROMP) of DCPD, high internal phase emulsions (HIPEs) as structural templates, and subsequent carbonization. The structure and function of the carbon foams were characterized and discussed in detail using scanning electron, transmission electron, or atomic force microscopy (SEM, TEM, AFM), electron energy-loss spectroscopy (TEM-EELS), N2 sorption, and analyses of electrical conductivity as well as mechanical properties. The resulting materials exhibited uniform, shape-retaining shrinkage of only ∼1/3 after carbonization. No structural failure was observed even when the pDCPD precursor foams were heated to 1400 °C. Instead, the high porosity, void size, and 3D interconnectivity were fully preserved, and the void diameters could be adjusted between 87 and 2.5 μm. Moreover, foams have a carbon content >97%, an electronic conductivity of up to 2800 S·m–1, a Young’s modulus of up to 2.1 GPa, and a specific surface area of up to 1200 m2·g–1. Surprisingly, the pDCPD foams were carbonized into shapes other than monoliths, such as 10’s of micron thick membranes or foamy coatings adhered to a metal foil or grid substrate. The latter coatings even adhere upon bending. Finally, as a use case, carbonized foams were applied as porous cathodes for Li–O2 batteries where the foams show a favorable combination of porosity, active surface area, and pore size for outstanding capacity.},
author = {Kovačič, Sebastijan and Schafzahl, Bettina and Matsko, Nadejda B. and Gruber, Katharina and Schmuck, Martin and Koller, Stefan and Freunberger, Stefan Alexander and Slugovc, Christian},
issn = {2574-0962},
journal = {ACS Applied Energy Materials},
keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)},
number = {11},
pages = {14381--14390},
publisher = {American Chemical Society},
title = {{Carbon foams via ring-opening metathesis polymerization of emulsion templates: A facile method to make carbon current collectors for battery applications}},
doi = {10.1021/acsaem.2c02787},
volume = {5},
year = {2022},
}
@article{12236,
abstract = {High-entropy materials offer numerous advantages as catalysts, including a flexible composition to tune the catalytic activity and selectivity and a large variety of adsorption/reaction sites for multistep or multiple reactions. Herein, we report on the synthesis, properties, and electrocatalytic performance of an amorphous high-entropy boride based on abundant transition metals, CoFeNiMnZnB. This metal boride provides excellent performance toward the oxygen evolution reaction (OER), including a low overpotential of 261 mV at 10 mA cm–2, a reduced Tafel slope of 56.8 mV dec–1, and very high stability. The outstanding OER performance of CoFeNiMnZnB is attributed to the synergistic interactions between the different metals, the leaching of Zn ions, the generation of oxygen vacancies, and the in situ formation of an amorphous oxyhydroxide at the CoFeNiMnZnB surface during the OER.},
author = {Wang, Xiang and Zuo, Yong and Horta, Sharona and He, Ren and Yang, Linlin and Ostovari Moghaddam, Ahmad and Ibáñez, Maria and Qi, Xueqiang and Cabot, Andreu},
issn = {1944-8252},
journal = {ACS Applied Materials & Interfaces},
keywords = {General Materials Science},
number = {42},
pages = {48212--48219},
publisher = {American Chemical Society},
title = {{CoFeNiMnZnB as a high-entropy metal boride to boost the oxygen evolution reaction}},
doi = {10.1021/acsami.2c11627},
volume = {14},
year = {2022},
}
@article{13991,
abstract = {The prediction and realization of topological insulators have sparked great interest in experimental approaches to the classification of materials1,2,3. The phase transition between non-trivial and trivial topological states is important, not only for basic materials science but also for next-generation technology, such as dissipation-free electronics4. It is therefore crucial to develop advanced probes that are suitable for a wide range of samples and environments. Here we demonstrate that circularly polarized laser-field-driven high-harmonic generation is distinctly sensitive to the non-trivial and trivial topological phases in the prototypical three-dimensional topological insulator bismuth selenide5. The phase transition is chemically initiated by reducing the spin–orbit interaction strength through the substitution of bismuth with indium atoms6,7. We find strikingly different high-harmonic responses of trivial and non-trivial topological surface states that manifest themselves as a conversion efficiency and elliptical dichroism that depend both on the driving laser ellipticity and the crystal orientation. The origins of the anomalous high-harmonic response are corroborated by calculations using the semiconductor optical Bloch equations with pairs of surface and bulk bands. As a purely optical approach, this method offers sensitivity to the electronic structure of the material, including its nonlinear response, and is compatible with a wide range of samples and sample environments.},
author = {Heide, Christian and Kobayashi, Yuki and Baykusheva, Denitsa Rangelova and Jain, Deepti and Sobota, Jonathan A. and Hashimoto, Makoto and Kirchmann, Patrick S. and Oh, Seongshik and Heinz, Tony F. and Reis, David A. and Ghimire, Shambhu},
issn = {1749-4893},
journal = {Nature Photonics},
keywords = {Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials},
number = {9},
pages = {620--624},
publisher = {Springer Nature},
title = {{Probing topological phase transitions using high-harmonic generation}},
doi = {10.1038/s41566-022-01050-7},
volume = {16},
year = {2022},
}
@article{12278,
abstract = {Mercury telluride (HgTe) thin films with a critical thickness of 6.5 nm are predicted to possess a gapless Dirac-like band structure. We report a comprehensive study on gated and optically doped samples by magnetooptical spectroscopy in the THz range. The quasi-classical analysis of the cyclotron resonance allowed the mapping of the band dispersion of Dirac charge carriers in a broad range of electron and hole doping. A smooth transition through the charge neutrality point between Dirac holes and electrons was observed. An additional peak coming from a second type of holes with an almost density-independent mass of around 0.04m0 was detected in the hole-doping range and attributed to an asymmetric spin splitting of the Dirac cone. Spectroscopic evidence for disorder-induced band energy fluctuations could not be detected in present cyclotron resonance experiments.},
author = {Shuvaev, Alexey and Dziom, Uladzislau and Gospodarič, Jan and Novik, Elena G. and Dobretsova, Alena A. and Mikhailov, Nikolay N. and Kvon, Ze Don and Pimenov, Andrei},
issn = {2079-4991},
journal = {Nanomaterials},
keywords = {General Materials Science, General Chemical Engineering},
number = {14},
publisher = {MDPI},
title = {{Band structure near the Dirac Point in HgTe quantum wells with critical thickness}},
doi = {10.3390/nano12142492},
volume = {12},
year = {2022},
}