On Concentration-Dependent Solid State Diffusion

1991 ◽  
Vol 230 ◽  
Author(s):  
Yang-Tse Cheng
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
The Self ◽  
Solid State Diffusion ◽  
Equation Approach ◽  
Intrinsic Diffusion ◽  
Self Diffusion ◽  
State Diffusion ◽  
Master Equation Approach ◽  
Semi Empirical

AbstractUsing a master equation approach, we derive a general expression for the diffusion coefficient as a function of concentration-dependent jump rates. When this approach is applied to diffusion in a binary solid, Darken's equation for intrinsic diffusion coefficients is derived together with an expression for self diffusion coefficients which satisfies the semi-empirical Ugaste relationship. This analysis suggests that the Darken term and the self diffusion coefficients are in general related.

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.

CALCULATIONS OF SELF-DIFFUSION PROCESS AND COEFFICIENT IN ORDERED B2 AlCo

2013 ◽  
Vol 27 (19) ◽  
pp. 1341034
Author(s):  
ZHI-SHENG NONG ◽  
JING-CHUAN ZHU ◽  
YONG CAO ◽  
XIA-WEI YANG ◽  
ZHONG-HONG LAI ◽  
...  
Keyword(s):  
Diffusion Process ◽  
First Principles ◽  
Diffusion Coefficients ◽  
Density Functional ◽  
Nearest Neighbor ◽  
The Self ◽  
First Principles Calculations ◽  
Self Diffusion ◽  
Diffusion Mechanisms ◽  
Semi Empirical

The self-diffusion process in B2 type intermetallic compound AlCo has been investigated by the first-principles calculations within the frame work of density functional theory (DFT). The obtained mono-vacancy formation, migration and activation energies for four self-diffusion mechanisms, the next-nearest-neighbor (NNN) jump, [110] six-jump cycle (6JC), straight [100] 6JC and bent [100] 6JC diffusion show that the NNN jump mechanism of Co vacancy requires the lowest activation energy (Q = 6.835 eV ) in these diffusion mechanisms, which indicates that it is the main way of self-diffusion in AlCo . The electronic structure including the electron density difference on (-1 1 0) plane as well as atomic Mulliken populations were calculated, and the change of bonding behavior during the [110] 6JC process was discussed in detail. Finally, the self-diffusion coefficients of NNN jump and 6JC mechanisms for AlCo were also studied via the first-principles calculations and semi-empirical predictions, which indicates that the self-diffusion coefficients for NNN jump of Co vacancy show the highest value than the others.

Self-Diffusion of Sodium, Chloride and Iodide Ions in Acetonitrile-Water Mixtures

1987 ◽  
Vol 42 (9) ◽  
pp. 1014-1016 ◽  
Author(s):  
E. Hawlicka
Keyword(s):  
Diffusion Coefficient ◽  
Sodium Chloride ◽  
Diffusion Coefficients ◽  
Preferential Solvation ◽  
Solvent Composition ◽  
The Self ◽  
Sodium Ions ◽  
Iodide Ions ◽  
Self Diffusion ◽  
Self Diffusion Coefficient

The self-diffusion coefficient of sodium, chloride and iodide ions in acetonitrile-water mixtures at 25.0 ± 0.05 °C has been measured in dependence on the salt molarity in the range 1.0 ·10-4 1.0 ·10-2 mol/dm3. The ionic self-diffusion coefficients in infinitely diluted solutions have been computed. The influence of the solvent composition on the solvation of the ions is discussed. Preferential solvation of the ions by acetonitrile above 15m ol% of acetonitrile has been found. An effect of the sodium ions on the formation of acetonitrile globules is postulated.

scholarly journals Diffusion Coefficients at Infinite Dilution of Carbon Dioxide and Methane in Water, Ethanol, Cyclohexane, Toluene, Methanol, and Acetone: A PFG-NMR and MD Simulation Study

2021 ◽  
Author(s):  
Daniel Bellaire ◽  
Oliver Großmann ◽  
Kerstin Münnemann ◽  
Hans Hasse
Keyword(s):  
Carbon Dioxide ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Infinite Dilution ◽  
The Self ◽  
Resonance Spectroscopy ◽  
Self Diffusion ◽  
P Diffusion ◽  
Dynamics Simulations ◽  
Pfg Nmr

Diffusion coefficients at infinite dilution are important basic data for all processes involving mass transfer. They can be obtained from studying samplesin equilibrium using nuclear magnetic resonance spectroscopy with pulsed field gradients (PFG-NMR), a technique which is widely used in chemistry but isonly rarely applied in engineering studies. This advantageous technique was employed here to measure the self-diffusion coefficients of diluted solutions ofcarbon dioxide and methane in the pure solvents water, ethanol, cyclohexane, toluene, methanol, and acetone at 298.15 K. For the systems (carbon dioxide +water) and (carbon dioxide + ethanol), measurements were also carried out at 308.15 K, 318.15 K and 333.15 K. Except for (methane + water) and (methane +toluene), no literature data for the methane-containing systems were previously available. At the studied solute concentrations, there is practically no differencebetween the self-diffusion coefficient and the mutual diffusion coefficient. The experimental results are compared to experimental literature data as well as toresults from semi-empirical methods for the prediction of diffusion coefficients at infinite dilution. Furthermore, molecular dynamics simulations were carried outfor all systems to determine the diffusion coefficient at infinite dilution based on force fields that were taken from the literature, and the results are compared tothe experimental data and those from the classical prediction methods.

SELF-DIFFUSION OF RUBIDIUM AS INFLUENCED BY SOIL MOISTURE TENSION

1963 ◽  
Vol 43 (1) ◽  
pp. 44-51 ◽  
Author(s):  
A. S. Patil ◽  
K. M. King ◽  
M. H. Miller
Keyword(s):  
Diffusion Coefficient ◽  
Soil Moisture ◽  
Diffusion Coefficients ◽  
The Self ◽  
Self Diffusion ◽  
Steady State Method ◽  
Loam Soil ◽  
Time Periods ◽  
Self Diffusion Coefficient

A non steady-state method was used for the laboratory determination of the self-diffusion coefficient of rubidium in loam soil at soil moisture tensions of.16, 1.17, and 15 atmospheres. Soil volumes (half-cells) 1.0 centimeter long and 2.5 centimeters in diameter, containing rubidium labelled with Rb86, were placed in contact with similar but unlabelled half-cells. After varying time periods, the half-cells were separated and extracted with 1N NH4Ac, and the transfer of Rb86 determined.The diffusion followed the simple theory. The self-diffusion coefficients for rubidium at 25 °C. were as follows: 16 × 10−4 cm.2/hr. at 0.16 atm.; 4.9 × 10−4 cm.2/hr. at 1.17 atm.; 2.3 × 10−4 cm.2/hr. at 15 atm. In free solution, the self-diffusion coefficient is 7.2 × 10−2 cm.2/hr.

Self-Diffusion in Intrinsic and Extrinsic Silicon Using Isotopically Pure 30Silicon Layer

2001 ◽  
Vol 669 ◽  
Author(s):  
Yukio Nakabayashi ◽  
Hirman I. Osman ◽  
Toru Segawa ◽  
Kazunari Toyonaga ◽  
Satoru Matsumoto ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Intrinsic Diffusion Coefficient ◽  
Intrinsic Diffusion ◽  
Self Diffusion ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTSilicon self–diffusion coefficients were measured in intrinsic and extrinsic silicon from870 to 1070°C using isotopically pure 30Si layer. 30Si diffusion profiles are determined by secondary ion mass spectrometry. The temperature dependence of intrinsic diffusion coefficient in bulk Si isobtained. Comparing it in heavily As-doped or B-doped Si, it is found that Si self-diffusion is entirely mediated by interstitialcy mechanism at lower temperatures below 870°C.

Effect of moisture content and soil type on self diffusion of 86Rb in soils

1963 ◽  
Vol 60 (2) ◽  
pp. 239-244 ◽  
Author(s):  
I. J. Graham-Bryce
Keyword(s):  
Diffusion Coefficient ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Pore Space ◽  
Considerable Effect ◽  
The Self ◽  
Self Diffusion ◽  
Moisture Contents ◽  
Wide Range ◽  
Self Diffusion Coefficient

Self-diffusion coefficients (D) for Rb+ have been measured in a heteroionic Lower Greensand soil over a wide range of moisture contents at three different compactions. The moisture content is shown to have a considerable effect on the value of the self-diffusion coefficient, a rapid rise in the value of D taking place between 5 and 10% moisture content. It is shown that this effect is not simply due to the increased volume of water-filled pore space at higher moisture contents, and other possible factors which could influence the shape of the diffusion coefficient/moisture content curve are discussed. Diffusion coefficients for Rb+ in eight other soils at pF 2 are also reported, but no simple correlation with any of several soil properties measured could be found. A value of 1·0 × 10−7cm2/sec. would seem to be a reasonable generalization for the self-diffusion coefficient of Rb+ in moist calcium-dominated soils.

Simulation of the Properties of 1-Ethyl-3-Methyl-Imidazolium Chloride/Chloroaluminate Ionic Liquids: Concentration and Temperature Dependence

2012 ◽  
Vol 457-458 ◽  
pp. 249-252
Author(s):  
Guo Cai Tian ◽  
Ding Wang ◽  
Ya Dong Li
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Molar Fraction ◽  
Chemical Properties ◽  
The Self ◽  
Dynamics Simulation ◽  
Imidazolium Chloride ◽  
Self Diffusion ◽  
Conductivity Increase ◽  
Self Diffusion Coefficient

Influences of the molar fractions of AlCl3and temperature on room temperature molten salts 1-ethyl-3-methyl-imidazolium Chloride /Chloroaluminate [Emim]Cl/AlCl3are studied by molecular dynamics simulation. The physical and chemical properties such as density, diffusion coefficients, viscosity, conductivity of [Emim]Cl/AlCl3with different molar fraction of AlCl3are calculated. The density is obtained as 1.1744g/cm3for [Emim]Cl, which agree well with the experimental value (1.186g/cm3). It was shown that the density and conductivity increase, whereas the viscosity decreases with the increasing of molar fraction of AlCl3. The self-diffusion coefficients of [Emim]+, Cl-and AlCl3increases and the changes of self-diffusion coefficient of AlCl3is the biggest as to molar fraction increase. It is shown that the conductivity, the self-diffusion coefficient of particles all increase, and the changes of AlCl3is the biggest with the increasing of temperature, whereas the density and viscosity reduce.

scholarly journals Self-Diffusion Coefficients, Aggregation Numbers and the Range of Existence of Spherical Micelles of Oxyethylated Alkylphenols

2021 ◽  
Author(s):  
Victor P. Arkhipov ◽  
Natalia A. Kuzina ◽  
Andrei Filippov
Keyword(s):  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
The Self ◽  
Self Diffusion ◽  
Aggregation Numbers ◽  
Temperature Ranges ◽  
Spherical Micelles ◽  
Limiting Values

AbstractAggregation numbers were calculated based on measurements of the self-diffusion coefficients, the effective hydrodynamic radii of micelles and aggregates of oxyethylated alkylphenols in aqueous solutions. On the assumption that the radii of spherical micelles are equal to the lengths of fully extended neonol molecules, the limiting values of aggregation numbers corresponding to spherically shaped neonol micelles were calculated. The concentration and temperature ranges under which spherical micelles of neonols are formed were determined.

scholarly journals Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4030
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Surface Effect ◽  
Bulk Water ◽  
Self Diffusion ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Chain Lengths ◽  
Fluid Diffusion ◽  
Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

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