Influence of Diffusion Time on the Diffusion Coefficients of Gases in Polymers Determined by Pulsed Gradient Spin Echo NMR

2018 ◽  
Vol 51 (21) ◽  
pp. 8681-8688 ◽  
Author(s):  
Leoncio Garrido ◽  
Julio Guzmán
Keyword(s):  
Diffusion Coefficients ◽  
Spin Echo ◽  
Diffusion Time

Self-Diffusion in Molten Lithium Nitrate

1992 ◽  
Vol 47 (10) ◽  
pp. 1047-1050 ◽  
Author(s):  
C. Herdlicka ◽  
J. Richter ◽  
M. D. Zeidler
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Spin Echo ◽  
The Self ◽  
Lithium Nitrate ◽  
Equimolar Ratio ◽  
Self Diffusion ◽  
Field Gradients ◽  
Molten Lithium ◽  
Self Diffusion Coefficient

AbstractSelf-diffusion coefficients of 7Li+ ions have been measured in molten LiNO3 with several compositions of 6Li+ and 7Li+ over a temperature range from 537 to 615 K. The NMR spin-echo method with pulsed field gradients was applied. It was found that the self-diffusion coefficient depends on the isotopic composition and shows a maximum at equimolar ratio. At temperatures above 600 K this behaviour disappears.

PGSE-NMR & Sans from TPB Based Microemulsions

1989 ◽  
Vol 177 ◽  
Author(s):  
Paul M. Lindemuth ◽  
Boualem Hammouda ◽  
Joseph R. Duke ◽  
Frank D. Blum ◽  
Raymond L. Venable
Keyword(s):  
Diffusion Coefficients ◽  
Small Angle Neutron Scattering ◽  
Spin Echo ◽  
Water Concentration ◽  
Conductivity Measurements ◽  
Self Diffusion ◽  
Nmr Data ◽  
Pgse Nmr ◽  
Isotropic Region ◽  
Complete Inversion

ABSTRACTSelf-diffusion coefficients from pulsed-gradient spin-echo NMR are reported for four components of the tetradecylpyridinium bromide - 85% heptane/15% pentanol - water pseudoternary system. Measurements were taken throughout the inverted microemulsion region and also in a small isotropic region beyond the domain of lamellar liquid crystals. Observations of the self-diffusion coefficients for water relative to those of the surfactant, oil and alchohol show several distinct structural transitions within the water-in-oil region of the phase diagram. The smaller isotropic region exhibits a complete inversion of phase relative to the water-in-oil region. Conductivity measurements were used to further clarify the NMR data. Subsequent small angle neutron scattering (SANS) measurements on the same system show the transition from the single particle (heavy water + Stern layer droplet) scattering regime at low water concentration to the mixed single/interdroplet scattering regime when the intermicellar distance becomes comparable to the size of the micelles.

Molecular Dynamics Simulation of Molten Alkali Nitrates

2001 ◽  
Vol 56 (5) ◽  
pp. 337-341 ◽  
Author(s):  
G. Vöhringer ◽  
J. Richter
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Short Range ◽  
Spin Echo ◽  
Isotope Effects ◽  
Pair Potential ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Transport Effects

Abstract Molecular dynamics (MD) simulations have been performed for several pure alkali nitrate melts. Special attention was paid to the examination of the interaction potential: macroscopic quantities like pressure were calculated and compared with real values. To improve the results the commonly used potential for alkali nitrates (Coulomb pair potential and Born-type repulsion) has been extended by a short-range-attraction term to meet the real behaviour of the liquid. With these improved potentials, simulations of pure LiNO3, NaNO3, KNO3, and RbNO3 have been performed with special regard to the influence of size and mass of the cations on the transport effects to show analogies to isotope effects. The calculated self diffusion coefficients (SDC) have been compared to results obtained with the NMR spin echo method.

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