Diffusion Studies. I. Diffusion Coefficients in Liquids by a Radiometric Porous-Frit Method1

1965 ◽  
Vol 69 (1) ◽  
pp. 303-309 ◽  
Author(s):  
Arthur E. Marcinkowsky ◽  
Frederick Nelson ◽  
Kurt A. Kraus
Keyword(s):  
Diffusion Coefficients ◽  
Diffusion Studies

Non-Stoichiometry and Cation Tracer Diffusion Studies in the Magnetite-UlvÖSpinel Solution, (Fe,Ti)3-δO4

1994 ◽  
Vol 369 ◽  
Author(s):  
Sanjeev Aggarwal ◽  
Rudiger Dieckmann
Keyword(s):  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Oxygen Activity ◽  
Spinel Solid Solution ◽  
Low Oxygen ◽  
Cation Diffusion ◽  
Deviation From Stoichiometry ◽  
Diffusion Studies ◽  
Tracer Diffusion Coefficients ◽  
Point Defect Structure

AbstractCation diffusion in the spinel solid solution (Fe1-xTix)3-δO4 (0≤ x ≤ 0.3) was investigated at 1200 ºC as a function of oxygen activity, aO2 and cationic composition, x. At different cationic compositions, cation tracer diffusion coefficients, D*Me of Me = Fe and Ti were measured as a function of oxygen activity. Plots of log DMe vs. loga0 show V-shaped curves, indicating that different types of point defects prevail at high anc low oxygen activities. Thermogravimetric experiments were conducted, using a high resolution microbalance, to determine the deviation from stoichiometry in (Fe1-xTix)3-δO4 at 1200 °C. δversus log aO2 curves are S-shaped. An analysis of the oxygen activity dependences of thecation diffusion coefficients and the deviation from stoichiometry with regardto the point defect structure suggests that at high oxygen activities cation vacancies are the predominant defects governing the deviation from stoichiometry and the diffusion ofcations. At low oxygen activities, and at small values of x, cation interstitials determine the deviation from stoichiometry, while they dominate for 0 ≤ x ≤ 0.3 inthe cation diffusion.

Oxygen diffusion studies. I. A preliminary ion microprobe investigation of oxygen diffusion in some rock-forming minerals

1982 ◽  
Vol 45 (337) ◽  
pp. 179-192 ◽  
Author(s):  
R. Freer ◽  
P. F. Dennis
Keyword(s):  
Diffusion Coefficients ◽  
Oxygen Diffusion ◽  
Isotope Exchange ◽  
Water Pressure ◽  
Ion Microprobe ◽  
Oxygen Isotope Exchange ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Diffusion Rates ◽  
Grossular Garnet

AbstractThe self diffusion of oxygen has been studied in prepared natural crystals of albite, grossular garnet, quartz, and ruffle by isotope exchange with hydrothermal water enriched in 18O, and subsequent analysis by ion microprobe. Measured oxygen diffusion coefficients (D) in quartz (‖c) may be described by D = 1.08 × 10−11 exp(−31.5 kcal/RT) cm2s−1 at 600−750°C and 1 kbar water pressure. For grossular, D = 2.5 × 10−16 cm2s−1 at 1050°C and 8 kbar, and D = 4.8 × 10−17 cm2s−1 at 850 °C and 2 kbar. All ruffle crystals exhibited variable amounts of corrosion, and an approximate diffusion coefficient of D(‖c) = 3.16 × 10−15 cm2s−1 cm2s−1 was obtained at 1050 °C and 1 kbar. Oxygen diffusion coefficients in albite, perpendicular to (001) faces, have been determined as a function of pressure at 600 °C Between 0.5 and 8.0 kbar pressure no systematic variation in the results was observed and most of the data may be described by D = 4.1 (±0.5) × 10−15 cm2s−1. Slow oxygen diffusion rates in quartz and garnet suggest that these minerals should have high ‘closure temperatures’ for oxygen exchange, and may provide reliable oxygen isotope exchange geothermometers.

The Deresination of Guayule: A Physical Model. Part II: A Two-Component Analog for Deresination

1984 ◽  
Vol 57 (2) ◽  
pp. 370-378
Author(s):  
S. Budiman ◽  
D. McIntyre
Keyword(s):  
Diffusion Coefficients ◽  
Abietic Acid ◽  
Additive Model ◽  
Molecular Size ◽  
Design Parameters ◽  
Model Compounds ◽  
Diffusion Behavior ◽  
Diffusion Studies ◽  
Two Component ◽  
Physical Geometry

Abstract Based on GPC, the worm resin can be separated into two distinct groups, large and small. To obtain the overall diffusion coefficients for the two groups that could be useful as commercial design parameters, the worms were converted into wet worm crepe. Diffusion studies with model compounds, abietic acid, and trilinolein, reveal that: (a) their diffusion coefficients for desorption into acetone are inversely proportional to their respective molecular size, (b) the diffusion behavior of the two model compounds in a mixture can be fitted to a simple additive model, and (c) their diffusion coefficients are quite similar to those of the two groups of resin constituents (large and small). It is, therefore, possible to model and optimize a commercial deresination process for guayule worms on the basis of the diffusion behavior of two model compounds linolein and abietic acid and the physical geometry.

Evidence for K+ and Cl− Binding Inside Muscle from Diffusion Studies

1973 ◽  
Vol 51 (5) ◽  
pp. 390-400 ◽  
Author(s):  
J. P. Caillé ◽  
J. A. M. Hinke
Keyword(s):  
Diffusion Coefficients ◽  
Binding Capacity ◽  
Dry Weight ◽  
Longitudinal Axis ◽  
Single Muscle ◽  
Glass Capillary ◽  
Diffusion Data ◽  
Diffusion Studies ◽  
The Mean ◽  
Polyelectrolyte Solutions

Intrafiber diffusion of 42K+, 36Cl−, and 14C-sorbitol was measured along the longitudinal axis of a single muscle fiber which had been placed inside the lumen of a glass capillary at least 24 h beforehand. The mean diffusion coefficients (× 10−5 cm2/s) in myoplasm at 10 °C and at pH 7.5 were 0.728 ± 0.008, 0.683 ± 0.006, and 0.216 ± 0.005 for K+, Cl−, and sorbitol, respectively. The K+ coefficient decreased, the Cl− coefficient increased, and the sorbitol coefficient remained unchanged as the pH of the muscle-capillary preparation was increased. By applying Wang's theory to explain diffusion in polyelectrolyte solutions (1954), we have estimated the diffusible volume (1 − ϕ) and the binding fractions (ƒK and ƒCl) of K+ and Cl− in myoplasm. From pH 5.2 to 10, ƒK varied from 0 to 0.13 and ƒCl varied from 0.13 to 0. Analysis of this K+ diffusion data along with the Na+ diffusion data from an earlier study (Can. J. Physiol. Pharmacol. 50, 228–237, 1972) leads to the prediction that myoplasm at physiological pH has a minimum binding capacity for Na+ and K+ of about 70 mmol/kg dry weight and a selectivity of 3.3 for Na+ over K+. Estimations of the diffusible volume ranged from 0.7 to 0.8, indicating that probably all the intrafiber water (74–78% by weight) is being utilized in the diffusion process.

Self-Diffusion in Isotopically Controlled Heterostructures of Elemental and Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
H. Bracht ◽  
E. E. Haller ◽  
K. Eberl ◽  
M. Cardona ◽  
R. Clark-Phelps
Keyword(s):  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Activation Enthalpy ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Exponential Factors ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTWe report self-diffusion studies of silicon between 855 and 1388°C in highly enriched epitaxial 28Si layers. Diffusion profiles of 30Si and 29Si are determined with high resolution secondary ion mass spectrometry (SIMS). The temperature dependence of the Si self-diffusion coefficients is accurately described with an activation enthalpy of 4.76 eV and a pre-exponential factor of 560 cm2s-1. The single activation enthalpy indicates that Si self-interstitials dominate self-diffusion over the whole temperature range investigated. Self- and interdiffusion in buried Al71GaAs/Al69GaAs/71GaAs isotope heterostructures with different Al composition is measured between 800 and 1160°C. Ga self-diffusion in AlGaAs and interdiffusion of Al and Ga at the AlGaAs/GaAs interface show that Ga diffusion decreases with increasing Al composition and that the interdiffusion coefficient depends linearly on Al concentration. Furthermore Al is found to diffuse more rapidly into GaAs than Ga diffuses in GaAs. The temperature dependence of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs is described by a single activation enthalpy in the range of 3.6±0.1 eV, but by different pre-exponential factors. Differences found for Ga and Al diffusion in GaAs and for Ga diffusion in AlGaAs with different Al concentrations are discussed.

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