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(72) Production(s) de l'année 2024
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Structural and mechanical properties of bio-inspired polymer networks ![hal link](plugins/aigle//images/ext_link.jpg)
Auteur(s):
Conférence invité: Network dynamics: Synthesis, structure and mechanical properties (Les Houches School of Physics, FR, 2024-02-26)
Ref HAL: hal-04661726_v1
Exporter : BibTex | endNote
Résumé: We use molecular dynamics simulations to study the structural and mechanical properties of bead-spring polymer networks. In this study we deal with systems which are biologically-relevant as they result from the action of enzymes, i.e. biological catalysts. The latter convert repulsive monomers into attractive ones and hence, starting from a polymer solution, trigger the formation of a physically-crosslinked polymer network. This gel has a remarkably regular mesostructure in the form of a cluster phase. We simulate uniaxial tension of these networks. The evolution of their structural and mechanical properties during deformation is monitored by computing quantities such as the anisotropic pair correlation functions, Poisson's ratio, elastic moduli and stress-strain curves, and the effects of temperature and system composition (i.e. fraction of attractive monomers) are investigated.
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NEAR-FIELD RADIATIVE HEAT TRANSFER BETWEEN GRAPHENE-BASED NANOSTRUCTURES:
LATERALLY SHIFTED GRATINGS AND NANOPARTICLE-GRATING CONFIGURATIONS
Auteur(s):
Conférence invité: 32nd International Materials Research Congress Sociedad Mexicana de Materiales (cancun, MX, 2024-08-18)
Résumé: We examine the near-field radiative heat transfer between graphene-based nanostructures including parallel and laterally shifted graphene gratings and between nanoparticles and graphene gratings. We use the scattering matrix formalism together with a Local Basis Function Fourier-based method to calculate the graphene grating electromagnetic scattering. We study how the lateral shift can effectively modulate the heat transfer for different filling factor and chemical potential, and the role played by different electromagnetic modes in these structures on the radiative energy transfer. This studies has the potential to unveil new avenues for harnessing the lateral shift effect on radiative heat transfer in graphene-based nanodevices.
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Casimir-Lifshitz force for graphene-covered gratings ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s):
(Article) Publié:
Physical Review B, vol. 110 p.045446 (2024)
DOI: 10.1103/PhysRevB.110.045446
Résumé: We study the Casimir-Lifshitz force (CLF) between a gold plate and a graphene-covered dielectric grating. Using a scattering matrix (S-matrix) approach derived from the Fourier modal method (FMM), we find a significant enhancement in the CLF as compared to a mere dielectric slab coated with graphene, over a wide range of temperatures. Additionally, we demonstrate that the CLF depends strongly on the chemical potential of graphene, with maximal effects observed at lower filling fractions. Finally, we analyze the Casimir force gradient between a gold sphere and a graphene-coated dielectric grating, highlighting potential avenues for experimental measurements.
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Al‐Rich AlGaN Channel High Electron Mobility Transistors on Silicon: A Relevant Approach for High Temperature Stability of Electron Mobility ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s):
(Article) Publié:
Advanced Electronic Materials, vol. p. (2024)
Texte intégral en Openaccess : ![openaccess](plugins/aigle//images/logo-openaccess.png)
Ref HAL: hal-04665123_v1
DOI: 10.1002/aelm.202400069
Exporter : BibTex | endNote
Résumé: Abstract Ultrawide bandgap (UWBG) semiconductors offer new possibilities to develop power electronics. High voltage operation for the off‐state as well as high temperature stability of the devices in on‐state are required. More than AlGaN/GaN heterostructures, AlGaN/AlGaN heterostructures are promising candidates to meet these criteria. Furthermore, the possibility to choose the Al molar fraction of AlGaN paves the way to more tunable heterostructures. In this study, the electronic transport properties of AlGaN channel heterostructures grown on silicon substrates with various aluminum contents, focusing on the temperature dependence of the electron mobility, is investigated. Experimental results from Hall effect measurements are confronted with carrier scattering models and deep level transient spectroscopy analysis to quantify limiting effects. These results demonstrated the significant potential of Al‐rich AlGaN channel heterostructures grown on silicon substrates for high power and high temperature applications.
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Favorable and unfavorable many-body interactions for near-field radiative heat transfer in nanoparticle networks ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s):
(Article) Publié:
Journal Of Quantitative Spectroscopy And Radiative Transfer, vol. 327 p.109129 (2024)
DOI: 10.1016/j.jqsrt.2024.109129
Résumé: Near-field radiative heat transfer (NFRHT) in point-dipole nanoparticle networks is complicated due to the multiple scattering of thermally excited electromagnetic wave (namely, many-body interaction, MBI). The MBI regime is analyzed using the many-body radiative heat transfer theory at the particle scale for networks of a few nanoparticles. Effect of MBI on radiative heat diffusion in networks of a large number of nanoparticles is analyzed using the normal-diffusion radiative heat transfer theory at the continuum scale. An influencing factor is defined to numerically figure out the border of the different many-body interaction regimes. The whole space near the two nanoparticles can be divided into four zones, non-MBI zone, enhancement zone, inhibition zone and forbidden zone, respectively. Enhancement zone is relatively smaller than the inhibition zone, so many particles can lie in the inhibiting zone that the inhibition effect of many-body interaction on NFRHT in nanoparticle networks is common in literature. Analysis on the radiative thermal energy confirms that multiple scattering caused by the inserted scatterer accounts for the enhancement and inhibition of NFRHT. By arranging the nanoparticle network in aspect of structures and optical properties, the MBI can be used to modulate radiative heat diffusion characterized by the radiative effective thermal conductivity over a wide range, from inhibition (over 55% reduction) to amplification (30 times of magnitude). To achieve a notable MBI, it is necessary to introduce particles that have resonances well-matched with those of the particles of interest, irrespective of their match with the Planckian window. This work may help for the understanding of the thermal radiation in nanoparticle networks.
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Irreversible Monte Carlo Algorithms for Hard Disk Glasses: From Event-Chain to Collective Swaps ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Ghimenti Federico, Berthier L., van Wijland Frédéric
(Article) Publié:
Physical Review Letters, vol. 133 p.028202 (2024)
Texte intégral en Openaccess : ![arxiv](plugins/aigle//images/logo-arxiv.png)
Ref HAL: hal-04652024_v1
Ref Arxiv: 2402.06585
DOI: 10.1103/PhysRevLett.133.028202
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Equilibrium sampling of the configuration space in disordered systems requires algorithms that bypass the glassy slowing down of the physical dynamics. Irreversible Monte Carlo algorithms breaking detailed balance successfully accelerate sampling in some systems. We first implement an irreversible event-chain Monte Carlo algorithm in a model of continuously polydisperse hard disks. The effect of collective translational moves marginally affects the dynamics and results in a modest speedup that decreases with density. We then propose an irreversible algorithm performing collective particle swaps which outperforms all known Monte Carlo algorithms. We show that these collective swaps can also be used to prepare very dense jammed packings of disks.
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A multiscale approach to enhance the thermoelectric properties of α-SrSi2 through micro-/nano-structuring and Ba substitution ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Ghannam Rana, Coulomb Loic, Moll Adrien, Bérardan David
(Article) Publié:
Journal Of Alloys And Compounds, vol. 1002 p.175422 (2024)
Texte intégral en Openaccess : ![openaccess](plugins/aigle//images/logo-openaccess.png)
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