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Herve Jobic - One of the best experts on this subject based on the ideXlab platform.

  • proton transport in a highly conductive porous zirconium based metal organic framework molecular insight
    Angewandte Chemie, 2016
    Co-Authors: Daiane Damasceno Borges, Herve Jobic, Thomas Devic, Christian Serre, Farid Nouar, Sabine Devautourvinot, Jacques Ollivier, Rocio Semino, Francesco Paesani, G. Maurin
    Abstract:

    The water stable UiO-66(Zr)-(CO2H)2 MOF exhibits a superprotonic conductivity of 2.3×10(-3)  S cm(-1) at 90 °C and 95 % relative humidity. Quasi-Elastic Neutron Scattering measurements combined with aMS-EVB3 molecular dynamics simulations were able to probe individually the dynamics of both confined protons and water molecules and to further reveal that the proton transport is assisted by the formation of a hydrogen-bonded water network that spans from the tetrahedral to the octahedral cages of this MOF. This is the first joint experimental/modeling study that unambiguously elucidates the proton-conduction mechanism at the molecular level in a highly conductive MOF.

  • diffusion of h2 co2 and their mixtures in the porous zirconium based metal organic framework mil 140a zr combination of quasi Elastic Neutron Scattering measurements and molecular dynamics simulations
    Journal of Physical Chemistry C, 2015
    Co-Authors: M Prakash, Herve Jobic, Christian Serre, Naseem A Ramsahye, Farid Nouar, Daiane Damasceno Borges, G. Maurin
    Abstract:

    The diffusivity of H2 and CO2 in the small pore Zr based metal–organic framework (MOF) MIL-140A(Zr) has been evaluated using a combination of quasi-Elastic Neutron Scattering measurements and molecular dynamics simulations. These two techniques were used to determine the self-diffusivities of H2, and the corrected and transport diffusivities of CO2, as single components and binary mixture. H2 was shown to be the faster of the two gases to diffuse through the narrow triangular channel of MIL-140A(Zr), its self-diffusivity value being 1 order of magnitude higher than that of CO2, at the same temperature. In this case, although no specific interaction sites are present, the CO2 interacts more strongly with the pore wall than H2, partly a consequence of its greater kinetic radius, which renders it slower than H2. In the context of a binary mixture, H2 still diffuses faster between the two, although with a slightly lower self-diffusivity, while that of CO2 increases slightly. However, the difference in terms o...

  • diffusion of light hydrocarbons in the flexible mil 53 cr metal organic framework a combination of quasi Elastic Neutron Scattering experiments and molecular dynamics simulations
    Journal of Physical Chemistry C, 2014
    Co-Authors: Nilton Rosenbach, Herve Jobic, M M Koza, Thomas Devic, Christian Serre, Aziz Ghoufi, Naseem A Ramsahye, C J Mota, G. Maurin
    Abstract:

    The dynamics of light hydrocarbons, including ethane, propane, and n-butane, is explored in the highly flexible metal–organic framework MIL-53(Cr) by combining quasi-Elastic Neutron Scattering measurements and molecular dynamics simulations. The loading dependence of the self-diffusivity shows peculiarities, including (i) a relatively rapid decrease of Ds at low loading for ethane and propane and (ii) an unusual increase of Ds for n-butane at high loading, following a decreasing profile up to intermediate loading. These diffusion behaviors are analyzed in light of the structural flexibility of the solids upon alkane adsorption characterized by the Neutron measurements. A 1D-type diffusion is evidenced for all alkanes with a jump sequence mainly ruled by the hydroxyl groups present at the surface of the MOF pore wall. This global translational motion is associated with a rotational dynamics that differs according to the nature of the alkane: whereas n-butane follows uniaxial displacements, ethane shows ran...

  • probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi Elastic Neutron Scattering experiments
    Journal of Chemical Physics, 2013
    Co-Authors: Evangelia Pantatosaki, Herve Jobic, Daniil I Kolokolov, Shilpi Karmakar, Rajesh B Biniwale, George K Papadopoulos
    Abstract:

    The problem of simulating processes involving equilibria and dynamics of guest sorbates within zeolitic imidazolate frameworks (ZIF) by means of molecular dynamics (MD) computer experiments is of growing importance because of the promising role of ZIFs as molecular “traps” for clean energy applications. A key issue for validating such an atomistic modeling attempt is the possibility of comparing the MD results, with real experiments being able to capture analogous space and time scales to the ones pertained to the computer experiments. In the present study, this prerequisite is fulfilled through the quasi-Elastic Neutron Scattering technique (QENS) for measuring self-diffusivity, by elaborating the incoherent Scattering signal of hydrogen nuclei. QENS and MD experiments were performed in parallel to probe the hydrogen motion, for the first time in ZIF members. The predicted and measured dynamics behaviors show considerable concentration variation of the hydrogen self-diffusion coefficient in the two topologically different ZIF pore networks of this study, the ZIF-3 and ZIF-8. Modeling options such as the flexibility of the entire matrix versus a rigid framework version, the mobility of the imidazolate ligand, and the inclusion of quantum mechanical effects in the potential functions were examined in detail for the sorption thermodynamics and kinetics of hydrogen and also of deuterium, by employing MD combined with Widom averaging towards studying phase equilibria. The latter methodology ensures a rigorous and efficient way for post-processing the dynamics trajectory, thereby avoiding stochastic moves via Monte Carlo simulation, over the large number of configurational degrees of freedom a nonrigid framework encompasses.

  • self and transport diffusivity of co2 in the metal organic framework mil 47 v explored by quasi Elastic Neutron Scattering experiments and molecular dynamics simulations
    ACS Nano, 2010
    Co-Authors: Fabrice Salles, Herve Jobic, Thomas Devic, Philip L Llewellyn, Christian Serre, Gerard Ferey, G. Maurin
    Abstract:

    Quasi-Elastic Neutron Scattering measurements are combined with molecular dynamics simulations to determine the self-diffusivity, corrected diffusivity, and transport diffusivity of CO2 in the metal−organic framework MIL-47(V) (MIL = Materials Institut Lavoisier) over a wide range of loading. The force field used for describing the host/guest interactions is first validated on the thermodynamics of the MIL-47(V)/CO2 system, prior to being transferred to the investigations of the dynamics. A decreasing profile is then deduced for Ds and Do whereas Dt presents a non monotonous evolution with a slight decrease at low loading followed by a sharp increase at higher loading. Such decrease of Dt which has never been evidenced in any microporous systems comes from the atypical evolution of the thermodynamic correction factor that reaches values below 1 at low loading. This implies that, due to intermolecular interactions, the CO2 molecules in MIL-47(V) do not behave like an ideal gas. Further, molecular simulatio...

G. Maurin - One of the best experts on this subject based on the ideXlab platform.

  • proton transport in a highly conductive porous zirconium based metal organic framework molecular insight
    Angewandte Chemie, 2016
    Co-Authors: Daiane Damasceno Borges, Herve Jobic, Thomas Devic, Christian Serre, Farid Nouar, Sabine Devautourvinot, Jacques Ollivier, Rocio Semino, Francesco Paesani, G. Maurin
    Abstract:

    The water stable UiO-66(Zr)-(CO2H)2 MOF exhibits a superprotonic conductivity of 2.3×10(-3)  S cm(-1) at 90 °C and 95 % relative humidity. Quasi-Elastic Neutron Scattering measurements combined with aMS-EVB3 molecular dynamics simulations were able to probe individually the dynamics of both confined protons and water molecules and to further reveal that the proton transport is assisted by the formation of a hydrogen-bonded water network that spans from the tetrahedral to the octahedral cages of this MOF. This is the first joint experimental/modeling study that unambiguously elucidates the proton-conduction mechanism at the molecular level in a highly conductive MOF.

  • diffusion of h2 co2 and their mixtures in the porous zirconium based metal organic framework mil 140a zr combination of quasi Elastic Neutron Scattering measurements and molecular dynamics simulations
    Journal of Physical Chemistry C, 2015
    Co-Authors: M Prakash, Herve Jobic, Christian Serre, Naseem A Ramsahye, Farid Nouar, Daiane Damasceno Borges, G. Maurin
    Abstract:

    The diffusivity of H2 and CO2 in the small pore Zr based metal–organic framework (MOF) MIL-140A(Zr) has been evaluated using a combination of quasi-Elastic Neutron Scattering measurements and molecular dynamics simulations. These two techniques were used to determine the self-diffusivities of H2, and the corrected and transport diffusivities of CO2, as single components and binary mixture. H2 was shown to be the faster of the two gases to diffuse through the narrow triangular channel of MIL-140A(Zr), its self-diffusivity value being 1 order of magnitude higher than that of CO2, at the same temperature. In this case, although no specific interaction sites are present, the CO2 interacts more strongly with the pore wall than H2, partly a consequence of its greater kinetic radius, which renders it slower than H2. In the context of a binary mixture, H2 still diffuses faster between the two, although with a slightly lower self-diffusivity, while that of CO2 increases slightly. However, the difference in terms o...

  • diffusion of light hydrocarbons in the flexible mil 53 cr metal organic framework a combination of quasi Elastic Neutron Scattering experiments and molecular dynamics simulations
    Journal of Physical Chemistry C, 2014
    Co-Authors: Nilton Rosenbach, Herve Jobic, M M Koza, Thomas Devic, Christian Serre, Aziz Ghoufi, Naseem A Ramsahye, C J Mota, G. Maurin
    Abstract:

    The dynamics of light hydrocarbons, including ethane, propane, and n-butane, is explored in the highly flexible metal–organic framework MIL-53(Cr) by combining quasi-Elastic Neutron Scattering measurements and molecular dynamics simulations. The loading dependence of the self-diffusivity shows peculiarities, including (i) a relatively rapid decrease of Ds at low loading for ethane and propane and (ii) an unusual increase of Ds for n-butane at high loading, following a decreasing profile up to intermediate loading. These diffusion behaviors are analyzed in light of the structural flexibility of the solids upon alkane adsorption characterized by the Neutron measurements. A 1D-type diffusion is evidenced for all alkanes with a jump sequence mainly ruled by the hydroxyl groups present at the surface of the MOF pore wall. This global translational motion is associated with a rotational dynamics that differs according to the nature of the alkane: whereas n-butane follows uniaxial displacements, ethane shows ran...

  • self and transport diffusivity of co2 in the metal organic framework mil 47 v explored by quasi Elastic Neutron Scattering experiments and molecular dynamics simulations
    ACS Nano, 2010
    Co-Authors: Fabrice Salles, Herve Jobic, Thomas Devic, Philip L Llewellyn, Christian Serre, Gerard Ferey, G. Maurin
    Abstract:

    Quasi-Elastic Neutron Scattering measurements are combined with molecular dynamics simulations to determine the self-diffusivity, corrected diffusivity, and transport diffusivity of CO2 in the metal−organic framework MIL-47(V) (MIL = Materials Institut Lavoisier) over a wide range of loading. The force field used for describing the host/guest interactions is first validated on the thermodynamics of the MIL-47(V)/CO2 system, prior to being transferred to the investigations of the dynamics. A decreasing profile is then deduced for Ds and Do whereas Dt presents a non monotonous evolution with a slight decrease at low loading followed by a sharp increase at higher loading. Such decrease of Dt which has never been evidenced in any microporous systems comes from the atypical evolution of the thermodynamic correction factor that reaches values below 1 at low loading. This implies that, due to intermolecular interactions, the CO2 molecules in MIL-47(V) do not behave like an ideal gas. Further, molecular simulatio...

  • Diffusion of CO2 in NaY and NaX Faujasite systems: Quasi-Elastic Neutron Scattering experiments and molecular dynamics simulations
    The European Physical Journal. Special Topics, 2007
    Co-Authors: D. Plant, H. Jobic, P. Llewellyn, G. Maurin
    Abstract:

    The diffusion of carbon dioxide in both NaX and NaY Faujasite systems is investigated by combining Quasi-Elastic Neutron Scattering (QENS) and Molecular Dynamics (MD) simulations. The transport diffusivity evaluated experimentally increases with the loading whereas the simulated self diffusivity decreases. This general behaviour is in good agreement with those previously reported in the literature for different gases in similar zeolites systems. It was also shown that the corrected diffusivity exhibits a significant concentration dependence. At low loading, the activation energies for diffusion derived from QENS and MD simulations are in agreement. They increase from NaY to NaX due to a stronger interaction between the CO2 molecules and the extra-framework cations. The extrapolation of the transport and self diffusivities to zero coverage allowed us to emphasize a good agreement between experiment and simulation.

J Albers - One of the best experts on this subject based on the ideXlab platform.

M. R. Chaves - One of the best experts on this subject based on the ideXlab platform.

  • on the transition to the x phase in highly brominated betaine calcium chloride dihydrate bccd
    Ferroelectrics, 2000
    Co-Authors: L. G. Vieira, M. R. Chaves, A. Almeida, M. Quilichini, J L Ribeiro, Olivier Hernandez, A Klopperpieper
    Abstract:

    Abstract We report dielectric and optical birefringence measurements in 38 % brominated BCCD, which confirm the transition to the X-phase, at ambient pressure, around Tc =80 K. These results are compared with Elastic Neutron Scattering data. A coexistence of the parent Pnma phase with the X-phase is observed in a large range of temperature centered at about Tc . It is found that the mosaic spread of the crystal varies strongly and irreversibly when a temperature cycle Pnma - X-phase - Pnma is performed. A 30% brominated BCCD has also been investigated by Elastic Neutron Scattering. For this compound, an intermediate incommensurate phase occuring between T1 ≈ 111 K and Tc ≈50 K is observed.

  • Elastic Neutron Scattering and dielectric behaviour of 4% brominated betaine calcium chloride dihydrate (BCCD)
    EDP Sciences, 1999
    Co-Authors: L. G. Vieira, M. R. Chaves, A. Almeida, M. Quilichini, J L Ribeiro, O. Hernandez, A Klopperpieper
    Abstract:

    We report a combined experimental study by means of Elastic Neutron Scattering and dielectric measurements of a partially deuterated and x=4% brominated BCCD (Betaine Calcium Chloride Dihydrate) crystal. The lowest-temperature phase is one-dimensional modulated and characterized by the coexistence of different commensurate domains (with δ = 1/4, 4/17, 2/9 and 1/5 on cooling), but with a clear predominance of the five-fold phase. A huge global thermal hysteresis of the wave-vector of the modulation, attaining values of about 9 K in the incommensurate phase and up to 15 K in the "harmless" low temperature part of the phase diagram, is observed up to Ti. The role of lattice defects on this phenomenon is discussed. Similarly to the behaviour of the pure compound, the structural modulation evolves on cooling towards a soliton regime (growth of third and fifth-order satellite peaks), probably with respect to a non-stabilized non-modulated ferroelectric phase. The critical temperatures deduced from dielectric constant and pyroelectric current measurements are in very good agreement with those obtained from Neutron Scattering. The dielectric anomaly observed in €''b(T) at T≈85 K, and known as the "Ts-anomaly" , could not be related with any special feature detected in the Neutron data, and in particular no correlation between this anomaly and the appearance of the soliton regime can be established

  • effect of electric fields on modulated structure of deuterated betaine calcium chloride dihydrate
    Physical Review B, 1993
    Co-Authors: M. R. Chaves, A Klopperpieper, J Albers, A. Almeida, J. C. Toledano, J M Kiat, W Schwarz, J Schneck, J L Ribeiro, Horst E. MÜser
    Abstract:

    The modulation wave vector q=δ(T)c * of deuterated betaine calcium chloride dihydrate (D-BCCD) was measured as a function of the temperature for certain dc electric fields, using Elastic Neutron Scattering. The results obtained are compared with the behavior of the dielectric constant of electric-field-biased D-BCCD. The temperature range of stability of the polar phases with δ= 2/7, 4/15, 2/9, 2/11 increases with a dc electric field along b. The results are discussed qualitatively, in terms of Landau theory

  • effect of hydrostatic pressure on the modulated structure of deuterated betaine calcium chloride dihydrate
    Physical Review B, 1993
    Co-Authors: M. R. Chaves, Horst E. MÜser, A Klopperpieper, A. Almeida, J M Kiat, W Schwarz, J Schneck, J Albers
    Abstract:

    In this work we present a study of Elastic Neutron Scattering in deuterated betaine calcium chloride dihydrate under hydrostatic pressure. This study provides clear evidence for the existence of a large number of high-order commensurate phases induced by pressure. Structural branching processes as predicted by the analysis of axial next-nearest-neighbor Ising models have been observed.

  • Elastic Neutron Scattering study of the devil s staircase behavior in deuterated betaine calcium chloride dihydrate
    Physical Review B, 1992
    Co-Authors: A. Almeida, M. R. Chaves, Horst E. MÜser, A Klopperpieper, J. C. Toledano, J M Kiat, W Schwarz, J Schneck, J L Ribeiro, J Albers
    Abstract:

    An Elastic-Neutron-Scattering study of partially deuterated dihydrate betaine calcium chloride (D-BCCD) is reported. We obtain direct diffraction evidence for the occurrence of a commensurate phase with wave vector q=δc*=(2/9)c* and for the absence of modulation of the lowest-temperature phase. The existence of another incommensurate phase adjacent to the δ=2/9 commensurate phase is pointed out and some indications of the existence of the δ=2/9 commensurate phase are described

J M Kiat - One of the best experts on this subject based on the ideXlab platform.