Self-diffusion of Ag+ and Na+ in molten Ca(NO3)2-KNO3

1972 ◽  
Vol 25 (8) ◽  
pp. 1613 ◽  
Author(s):  
BJ Welch ◽  
CA Angell
Keyword(s):  
Electrical Conductance ◽  
Ionic Species ◽  
Tracer Diffusion ◽  
Dilute Solution ◽  
Self Diffusion ◽  
Capillary Method ◽  
Arrhenius Temperature Dependence ◽  
Radio Tracer ◽  
Tracer Diffusion Coefficients ◽  
Arrhenius Temperature

In order to explore the behaviour of diffusing ionic species in a molten salt in which non-Arrhenius behaviour of other transport properties is established, the diffusivities in dilute solution of Ag+ and Na+ in 38.1 mol% Ca(NO3)2+ 61.9 mol% KNO3 have been measured. For both ions limited radio-tracer diffusion coefficients, determined using a diffusion-out-of-capillary method, are reported. D(Ag+) has also been measured by chronopotentiometry, by which means the range and reliability of the measurements were considerably extended. Chronopotentiometric and tracer data agree within expected errors of measurement. Both ionic diffusivities show a non-Arrhenius temperature dependence which is indistinguishable in magnitude from that of the electrical conductance of the solvent melt.

Fick’s Laws

2020 ◽  
pp. 141-161
Author(s):  
Brian Cantor
Keyword(s):  
Solid Material ◽  
Kirkendall Effect ◽  
Tracer Diffusion ◽  
Wide Range ◽  
German Science ◽  
Arrhenius Temperature Dependence ◽  
The Difference ◽  
Tracer Diffusion Coefficients ◽  
Medicine And Culture ◽  
Arrhenius Temperature

Atoms and molecules are not completely immobile within a solid material. They move by jumping into vacancies or interstitial sites in the crystal lattice. The laws describing their motion were discovered by Adolf Fick in the mid-19th century, modelled on analogous laws for the flow of heat (Fourier’s law) and electricity (Ohm’s law). According to Fick’s first law, the rate at which atoms move is proportional to the concentration gradient, with the diffusion coefficient defined as the constant of proportionality. Fick’s second law generalises the first law to a wide range of situations and is called the diffusion equation. This chapter examines a number of characteristic diffusion profiles; the difference between self, intrinsic, inter- and tracer diffusion coefficients; the Kirkendall effect and porosity formation when different components move at different speeds; and the Arrhenius temperature dependence of diffusion. Fick was a physiologist and derived his laws initially to describe the flow of blood through the heart. He made advances in anatomy, physiology and medicine, developing methods of monitoring blood pressure, muscular power, corneal pressure and glaucoma. He lived at the time of Bismarck’s post-Napoléonic unification of Germany and the associated flowering of German science, engineering, medicine and culture.

scholarly journals The analysis of intermolecular interactions in concentrated hyaluronan solutions suggest no evidence for chain–chain association

2000 ◽  
Vol 350 (1) ◽  
pp. 329-335 ◽  
Author(s):  
Phillip GRIBBON ◽  
Boon Chin HENG ◽  
Timothy E. HARDINGHAM
Keyword(s):  
Fluorescence Recovery After Photobleaching ◽  
Hydrodynamic Radius ◽  
Hydrophobic Interactions ◽  
Lateral Diffusion ◽  
Tracer Diffusion ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Chain Flexibility ◽  
Self Diffusion ◽  
Confocal Fluorescence

Confocal fluorescence recovery after photobleaching (confocal-FRAP) was used to examine the influence of electrolytes (NaCl, KCl, MgCl2, MnCl2 and CaCl2) on the network and hydrodynamic properties of fluoresceinamine-labelled hyaluronan (FA-HA) at concentrations up to 10mg/ml. Self and tracer lateral diffusion coefficients showed that in Ca2+ and Mn2+, FA-HA (830kDa) was more compact than in Mg2+, Na+ or K+. These results were correlated with changes in the hydrodynamic radius of HA, determined by multi-angle laser-light-scattering analysis in dilute solution, which was smaller in CaCl2 (36nm) than in NaCl (43nm). The permeability of more concentrated solutions of HA (< 10mg/ml) to FITC-dextran tracers (2000kDa) was higher in CaCl2. The properties of HA in urea (up to 6M) were investigated to test for hydrophobic interactions and also in ethanol/water (up to 62%, v/v). In both, there was reduced hydrodynamic size and increased permeability to FITC-dextran, suggesting increased chain flexibility, but it did not show the changes predicted if chain–chain association was disrupted by urea, or enhanced by ethanol. Oligosaccharides of HA (HA20–26) also had no effect on the self diffusion of high-molecular-mass FA-HA (830kDa) solutions, or on dextran tracer diffusion, showing that there were no chain–chain interactions open to competition by short-chain segments. The results suggest that the effects of electrolytes and solvent are determined primarily by their effect on HA chain flexibility, with no evidence for association between chain segments contributing significantly to the major properties.

Elastic After-Effect Due to Oxygen Relaxation in Yba2Cu3O7−δAbove Tc

1990 ◽  
Vol 209 ◽  
Author(s):  
J. R. Cost ◽  
P. E. Armstrong ◽  
R. B. Poeppel ◽  
J. T. Stanley
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Internal Friction ◽  
Relaxation Times ◽  
Tracer Diffusion ◽  
Induced Motion ◽  
Arrhenius Temperature Dependence ◽  
After Effect ◽  
Friction Measurements ◽  
Arrhenius Temperature

ABSTRACTIsothermal elastic after-effect measurements to obtain relaxation times for the stress-induced motion of oxygen in YBa2Cu3O7−δ have been made from 50°C to 110°C. These results extend our previous internal friction measurements of the same oxygen relaxation to lower temperatures. The combined results, which cover nine orders of magnitude in relaxation time, show a classical Arrhenius temperature dependence, activation energy Q−1.13±0.01 eV and attempt frequency τ0−1.6×10−13 s (log τ0−.12.79±0.13). The mechanism of the relaxation is considered to be stress-induced ordering of oxygen atoms on theCuO basal plane. Diffusivities obtained from these results are compared with those from tracer diffusion of oxygen.

Tracer diffusion coefficients of tritiated water and acetonitrile in water + acetonitrile mixtures

1980 ◽  
Vol 33 (8) ◽  
pp. 1667 ◽  
Author(s):  
AJ Easteal
Keyword(s):  
Diffusion Coefficients ◽  
Structural Model ◽  
Tritiated Water ◽  
Tracer Diffusion ◽  
Solution Viscosity ◽  
Composition Region ◽  
Self Diffusion ◽  
Composition Variation ◽  
Diaphragm Cell ◽  
Tracer Diffusion Coefficients

Tracer diffusion coefficients of tritiated water (HTO) and 14C-labelled acetonitrile have been measured at 298.15 K by the diaphragm cell method, for the whole range of compositions of water+ acetonitrile binary mixtures. The composition variation of (a) the deviation of D from additivity and (b) the product Dη, for each component, has been evaluated. The variation of Dη is discussed in terms of the Naberukhin- Rogov structural model for solutions of non-electrolytes in water. ��� The diffusion data have been used to test a semiempirical relationship, between solution viscosity and self-diffusion coefficients, due to Albright. For the composition region of 5-55 mole % acetonitrile Albright's equation gives calculated viscosities which agree well with observed values. The calculation fails to reproduce the observed variation of viscosity for the composition region of 60-95 mole % acetonitrile.

Prediction of Diffusion Coefficients in Liquid and Solids

2015 ◽  
Vol 364 ◽  
pp. 182-191 ◽  
Author(s):  
William Yi Wang ◽  
Bi Cheng Zhou ◽  
Jia Jia Han ◽  
Hua Zhi Fang ◽  
Shun Li Shang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
First Principles Calculations ◽  
Dominant Contribution ◽  
Creep Properties ◽  
Exchange Correlation ◽  
Self Diffusion ◽  
Tracer Diffusion Coefficients

Our activities in predicting diffusion coefficients in fcc, bcc, and hcp solid solutions using first-principles calculations and in liquid usingabinitiomolecular dynamics are reviewed. These include self-diffusion coefficients [1-4], tracer diffusion coefficients in dilute solutions [5-7], calculation of migration entropy [8], tracer diffusion coefficients in metallic and oxide liquid [9, 10], and effects of vacancy on diffusion of oxygen [11, 12]. The effects of exchange correlation functionals are examined in some cases along with charge transfer between solute and solvent elements. The dominant contribution of diffusion on the effects of Re addition on the creep properties of Ni-base superalloys is discussed [13].

Arsenic Diffusion in Intrinsic Gallium Arsenide

1998 ◽  
Vol 527 ◽  
Author(s):  
G. Bösker ◽  
N.A. Stolwijk ◽  
H. Mehrer ◽  
U. Södervall ◽  
J.V. Thordson ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Mass Spectroscopy ◽  
Diffusion Coefficients ◽  
Nitrogen Doping ◽  
Tracer Diffusion ◽  
Substantial Contribution ◽  
Ambient Conditions ◽  
Self Diffusion ◽  
Tracer Diffusion Coefficients ◽  
Secondary Ion

ABSTRACTSelf-diffusion on the As sublattice in intrinsic GaAs was investigated in a direct way by As tracer diffusion measurements using the radioisotopes 73As and 76As and in an indirect way by annealing of buried nitrogen doping layers in epitaxially grown GaAs/GaAs:N heterostructures. The latter experiments were analyzed by secondary ion mass spectroscopy and interpreted within the framework of the kick-out mechanism yielding the As diffusivities mediated by As interstitials IAs. Comparison of with tracer diffusion coefficients – including data reported in the literature–points to a substantial contribution of IAs to As diffusion in intrinsic GaAs under As-rich ambient conditions.

Point Defects and Diffusion in Ni3Ga

1998 ◽  
Vol 527 ◽  
Author(s):  
T. IKEDA ◽  
A. Almazouzi ◽  
A. Funao ◽  
H. Numakura ◽  
M. Koiwa ◽  
...  
Keyword(s):  
Point Defects ◽  
Positron Lifetime ◽  
Major Element ◽  
Tracer Diffusion ◽  
The Self ◽  
Self Diffusion ◽  
Order Of Magnitude ◽  
Constituent Elements ◽  
Tracer Diffusion Coefficients ◽  
And Diffusion

ABSTRACTThe properties of intrinsic point defects and the self-diffusion behaviour of the constituent elements in Ni3Ga have been studied by positron annihilation, tracer diffusion and interdiffusion experiments. Thermal vacancies have been detected by positron lifetime measurements for specimens quenched from high temperatures. The vacancy formation energy is in the range between 1.7 and 1.8 eV, and is not dependent strongly on the composition. The tracer diffusion coefficients of Ni and Ga are of the same order of magnitude, and the interdiffusion coefficient is about 10 times larger than the diffusion coefficient of Ni. The diffusion in Ni3Ga has been found to satisfy the Darken-Manning equation, as expected from the model of the self-diffusion in this type of materials, where both the species of atoms are assumed to migrate primarily in the sub-lattice of the major element via the ordinary vacancy mechanism.

scholarly journals Mixed alkali effect in sodium thiosulfate pentahydrate melt

1988 ◽  
Vol 66 (2) ◽  
pp. 242-245 ◽  
Author(s):  
Shakira S. Islam ◽  
Kochi Ismail
Keyword(s):  
Glass Transition ◽  
Sodium Thiosulfate ◽  
Electrical Conductance ◽  
Molar Conductance ◽  
Polarization Model ◽  
Density Data ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Arrhenius Temperature Dependence ◽  
Arrhenius Temperature

Density and electrical conductance measurements of 0.35[XNaNO3 + (1 − X)KNO3] + 0.65Na2S2O3•5H2O melt were made as functions of temperature and X. Molar volume, V, is found to be additive. The percent deviation of Vext (extrapolated V of the pure solute from the plot of V vs. total added alkali ion fraction) from Vcal (calculated V of the pure solute from its high temperature density data) increases monotonically as the amount of NaNO3 in the hydrate melt increases, thereby manifesting a "structure-forming" tendency of NaNO3. The non-Arrhenius temperature dependence of molar conductance, Λ is analyzed in terms of the Vogel–Tammann–Fulcher (VTF) equation. Mixed alkali effect (MAE) has been observed on Λ and T0 (ideal glass transition temperature). A competitive polarization model has been used to explain the MAE on Λ.

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