0000000000594169
AUTHOR
François Henn
Modelling of the cation motions in complex system: case of Na-mordenites
Abstract Semi-empirical inter-atomic potentials and Monte Carlo algorithms are proposed to predict the evolution of the interaction energy between sodium ions and a mordenite type aluminosilicate network as a function of Si/Al ratio. This result is favourably compared with the activation energy barriers for Na + `jumps' responsible for the polarization change, measured by thermally stimulated current (TSC) spectroscopy, for Na-mordenites characterized by Si/Al ratios ranged from 5.5 to 12. Finally, we propose a possible mechanism for the cation motions, which involves activation barriers within the same order of magnitude than those measured by TSC.
Voltage-activated transport of ions through single-walled carbon nanotubes
International audience; Ionic transport through single-walled carbon nanotubes (SWCNTs) is promising for many applications but remains both experimentally challenging and highly debated. Here we report ionic current measurements through microfluidic devices containing one or several SWCNTs of diameter of 1.2 to 2 nm unexpectedly showing a linear or a voltage-activated I-V dependence. Transition from an activated to a linear behavior, and stochastic fluctuations between different current levels were notably observed. For linear devices, the high conductance confirmed with different chloride salts indicates that the nanotube/water interface exhibits both a high surface charge density and flow…
Cations mobility and water adsorption in zeolites
As already pointed out [1], dielectric relaxation spectroscopy can be a convenient tool for probing ion dynamic in solids which depends on i) the structure in which ions are embedded and ii) the nature of the interaction ion/network. Consequently, the results obtained from this technique can be used as a data base for theoretical studies which goal is to calculate the ion binding energy and to simulate ionic displacements. Inversely, theoretical calculations are essential for confirming the experimental data and more particularly the method which is used for analysing the dielectric experimental response.