Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the po...Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the polymeric membranes. Based on Hansen solubility parameters theory, the mixture of DMC and DMSO was selected among a dozen of solvents for the preparation of PVDF membranes by thermally induced phase separation. The addition of two protic ionic liquids(PILs), bis(2-ethyl hexyl) ammonium hydrogen phosphate [EHNH_2][H_2PO_4], and imidazolium hexanoate [Im][Hex] to PVDF membranes at concentrations(10% < wP IL< 50%) has been investigated by SEM, FTIR, DSC, TGA, EIS, and DMA. The inclusion of ionic liquids into the polymer matrix influences structural parameters(degree of crystallinity and electroactive phases), thermal stability, proton conductivity and mechanical properties of the membranes. The membranes become transparent regardless type of ionic liquid employed. A small amount of ionic liquids increases the degree of crystallinity and facilitates the production of polar β and γ crystals. The proton conductivity mechanism(Grotthuss) is dependent on the ionic liquid structure(due to its selforganization in water) and the content in the PVDF membrane, as well as the membrane water uptake.Different behavior has been observed for the two ionic liquids, which stresses the challenge on selecting an appropriate cation and anion combination. The obtained composite membranes exhibited excellent mechanical performance and reduced elastic modulus, with respect to the pure polymer matrix. These results indicate that PVDF/IL composite membranes have a high potential for PEMFC applications.展开更多
The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</s...The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</sub>-CaO binary diagrams, constituting the ternary system, were first studied by Differential Scanning Calorimetry (DSC) measurements and X-Ray Diffraction (XRD) characterization;a good agreement was obtained between the phase diagram models calculated with FactSage®software (FTsalt database) and present experimental data. As the CaF<sub>2</sub>-CaO liquidus could not be measured by DSC due to the high melting temperature, this diagram was calculated using FTsalt database combined with FToxid database of FactSage<sup>®</sup> software. The ternary phase diagram was obtained by calculations and exhibits an eutectic at the composition CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO (78.2-15.7-6.1 mol.%) melting at 637°C, and five peritectic points. Measurements of relevant vertical cross-sections for three CaCl<sub>2</sub>-CaF<sub>2</sub> compositions (50-50, 40-60 and 30-70 mol.%) up to 18 mol.% CaO are in agreement with the ternary phase diagram model. For each section, the liquidus temperature is constant up to around 11 mol.% CaO and then sharply increases. Moreover, an increase of CaF<sub>2</sub> content in CaCl<sub>2</sub>-CaF<sub>2</sub> melt leads to a decrease of the CaO solubility in isothermal condition.展开更多
Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor ph...Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor phase is of major importance concerning the control and characterization of the process. The liquid droplet size distribution has a high influence on the kinetic properties of the as-sprayed nanometer particles before impacting on a target substrate. An overview of existing models is provided dealing with the penetration of the liquid phase into the thermal flame and the resulting fragmentation and vaporization of this phase before impact. The physical characteristics of the flow as well as existing Lagrangian and Eulerian modeling strategies are briefly discussed while paying attention to the physical parameters characterized and measured by numerical simulation. The potential of the various models and also their limits are intended to be highlighted. Future coupled Eulerian-Lagrangian modeling strategies are also proposed for a global and more exhaustive representation of the injection, fragmentation and dispersion part of the two-phase gas-liquid flow before particle impact on the substrate.展开更多
A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by couplin...A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by coupling a collective atomic spin model with an ML-IAP.Together they represent a potential energy surface from which the mechanical forces on the atoms and the precession dynamics of the atomic spins are computed.Both the atomic spin model and the ML-IAP are parametrized on data from first-principles calculations.We demonstrate the efficacy of our data-driven framework across magneto-structural phase transitions by generating a magneto-elastic ML-IAP forα-iron.The combined potential energy surface yields excellent agreement with firstprinciples magneto-elastic calculations and quantitative predictions of diverse materials properties including bulk modulus,magnetization,and specific heat across the ferromagnetic–paramagnetic phase transition.展开更多
Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a...Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a promising tool,since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas.We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer.A polystyrene(CH)foil was irradiated by a laser of 133 J,1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser(153 J,11 ps).The ablation front interferograms were processed in combination with a set of reference images obtained ex situ using phase-stepping.We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above 1022 cm−3.These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.展开更多
基金“La region Centre Val de Loire” for financial support to the researchers involved in this study under “Lavoisier II” regional program。
文摘Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the polymeric membranes. Based on Hansen solubility parameters theory, the mixture of DMC and DMSO was selected among a dozen of solvents for the preparation of PVDF membranes by thermally induced phase separation. The addition of two protic ionic liquids(PILs), bis(2-ethyl hexyl) ammonium hydrogen phosphate [EHNH_2][H_2PO_4], and imidazolium hexanoate [Im][Hex] to PVDF membranes at concentrations(10% < wP IL< 50%) has been investigated by SEM, FTIR, DSC, TGA, EIS, and DMA. The inclusion of ionic liquids into the polymer matrix influences structural parameters(degree of crystallinity and electroactive phases), thermal stability, proton conductivity and mechanical properties of the membranes. The membranes become transparent regardless type of ionic liquid employed. A small amount of ionic liquids increases the degree of crystallinity and facilitates the production of polar β and γ crystals. The proton conductivity mechanism(Grotthuss) is dependent on the ionic liquid structure(due to its selforganization in water) and the content in the PVDF membrane, as well as the membrane water uptake.Different behavior has been observed for the two ionic liquids, which stresses the challenge on selecting an appropriate cation and anion combination. The obtained composite membranes exhibited excellent mechanical performance and reduced elastic modulus, with respect to the pure polymer matrix. These results indicate that PVDF/IL composite membranes have a high potential for PEMFC applications.
文摘The CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO phase diagram was investigated in the CaO low region (<40 mol.%). CaCl<sub>2</sub>-CaF<sub>2</sub> and CaCl<sub>2</sub>-CaO binary diagrams, constituting the ternary system, were first studied by Differential Scanning Calorimetry (DSC) measurements and X-Ray Diffraction (XRD) characterization;a good agreement was obtained between the phase diagram models calculated with FactSage®software (FTsalt database) and present experimental data. As the CaF<sub>2</sub>-CaO liquidus could not be measured by DSC due to the high melting temperature, this diagram was calculated using FTsalt database combined with FToxid database of FactSage<sup>®</sup> software. The ternary phase diagram was obtained by calculations and exhibits an eutectic at the composition CaCl<sub>2</sub>-CaF<sub>2</sub>-CaO (78.2-15.7-6.1 mol.%) melting at 637°C, and five peritectic points. Measurements of relevant vertical cross-sections for three CaCl<sub>2</sub>-CaF<sub>2</sub> compositions (50-50, 40-60 and 30-70 mol.%) up to 18 mol.% CaO are in agreement with the ternary phase diagram model. For each section, the liquidus temperature is constant up to around 11 mol.% CaO and then sharply increases. Moreover, an increase of CaF<sub>2</sub> content in CaCl<sub>2</sub>-CaF<sub>2</sub> melt leads to a decrease of the CaO solubility in isothermal condition.
文摘Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor phase is of major importance concerning the control and characterization of the process. The liquid droplet size distribution has a high influence on the kinetic properties of the as-sprayed nanometer particles before impacting on a target substrate. An overview of existing models is provided dealing with the penetration of the liquid phase into the thermal flame and the resulting fragmentation and vaporization of this phase before impact. The physical characteristics of the flow as well as existing Lagrangian and Eulerian modeling strategies are briefly discussed while paying attention to the physical parameters characterized and measured by numerical simulation. The potential of the various models and also their limits are intended to be highlighted. Future coupled Eulerian-Lagrangian modeling strategies are also proposed for a global and more exhaustive representation of the injection, fragmentation and dispersion part of the two-phase gas-liquid flow before particle impact on the substrate.
基金All authors thank Mark Wilson for his detailed review and edits.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology&Engineering Solutions of Sandia,LLC,a wholly owned subsidiary of Honeywell International Inc.,for the U.S.Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.This paper describes objective technical results and analysis.Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S.Department of Energy or the United States Government.A.C.acknowledges funding from the Center for Advanced Systems Understanding(CASUS)which is financed by the German Federal Ministry of Education and Research(BMBF)and by the Saxon State Ministry for Science,Art,and Tourism(SMWK)with tax funds on the basis of the budget approved by the Saxon State Parliament.
文摘A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by coupling a collective atomic spin model with an ML-IAP.Together they represent a potential energy surface from which the mechanical forces on the atoms and the precession dynamics of the atomic spins are computed.Both the atomic spin model and the ML-IAP are parametrized on data from first-principles calculations.We demonstrate the efficacy of our data-driven framework across magneto-structural phase transitions by generating a magneto-elastic ML-IAP forα-iron.The combined potential energy surface yields excellent agreement with firstprinciples magneto-elastic calculations and quantitative predictions of diverse materials properties including bulk modulus,magnetization,and specific heat across the ferromagnetic–paramagnetic phase transition.
基金supported by the National Nuclear Security Administration (DENA0003882)funding from the Conseil Règional Aquitaine (INTALAX)+1 种基金the Agence Nationale de la Recherche (ANR-10-IDEX-03-02, ANR-15CE30-0011)supported by Research Grant No. PID2019-108764RB-I00 from the Spanish Ministry of Science and Innovation
文摘Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a promising tool,since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas.We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer.A polystyrene(CH)foil was irradiated by a laser of 133 J,1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser(153 J,11 ps).The ablation front interferograms were processed in combination with a set of reference images obtained ex situ using phase-stepping.We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above 1022 cm−3.These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.
