scholarly journals The Pressure Dependence of Self Diffusion in Supercooled Light and Heavy Water

1988 ◽  
Vol 92 (10) ◽  
pp. 1111-1117 ◽  
Author(s):  
F. X. Prielmeier ◽  
E. W. Lang ◽  
R. J. Speedy ◽  
H.-D. Lüdemann
Keyword(s):  
Heavy Water ◽  
Pressure Dependence ◽  
Self Diffusion

Doping Effect in Nickel Oxide

2009 ◽  
Vol 289-292 ◽  
pp. 775-782 ◽  
Author(s):  
Zbigniew Jurasz ◽  
Krzysztof Adamaszek ◽  
Romuald Janik ◽  
Zbigniew Grzesik ◽  
Stanisław Mrowec
Keyword(s):  
Activation Energy ◽  
Nickel Oxide ◽  
High Temperatures ◽  
Oxygen Pressure ◽  
Pressure Dependence ◽  
Oxidation Rate ◽  
Doping Effect ◽  
Self Diffusion ◽  
Electron Holes ◽  
Influence Of Impurities

Detailed investigations of nonstoichiometry as well as chemical and self-diffusion in nickel oxide have shown that doubly ionised cation vacancies and electron holes are the predominant defects in this material. The present work is an attempt to demonstrate that aliovalent impurities (Cr, Al, Na and Li) may considerably influence the concentration of these defects and, consequently, the oxidation rate of nickel at high temperatures. It has been shown that small amounts of tri-valent impurities (Cr, Al) bring about an increase of the oxidation rate, while mono-valent ones (Li, Na) decrease the rate of oxidation. These phenomena may satisfactorily be explained in terms of a doping effect. All experiments have been carried out as a function of temperature (1373-1673 K) and oxygen pressure (1-105 Pa) and consequently, it was possible to determine the influence of impurities not only on the oxidation rate but also on the activation energy of reaction and its pressure dependence. The results of these investigations could again be elucidated in terms of doping effect.

Pressure Dependence of Self Diffusion in Some Neat Alkanes and Binary Mixtures

1990 ◽  
Vol 94 (3) ◽  
pp. 336-342 ◽  
Author(s):  
T. Vardag ◽  
F. Bachl ◽  
S. Wappmann ◽  
H.-D. Lüdemann
Keyword(s):  
Binary Mixtures ◽  
Pressure Dependence ◽  
Self Diffusion

Pressure dependence of self-diffusion in bcc thallium

1998 ◽  
Vol 77 (3) ◽  
pp. 653-660
Author(s):  
P. Knorr ◽  
Chr. Herzig
Keyword(s):  
Pressure Dependence ◽  
Self Diffusion

scholarly journals Pressure Dependence of Self-Diffusion in Fluid NH3 and ND3.

1998 ◽  
Vol 7 ◽  
pp. 1432-1434 ◽  
Author(s):  
T. Groß ◽  
J. Buchhauser ◽  
W. E. Price ◽  
I. N. Tarassov ◽  
H. -D. Lüdemann
Keyword(s):  
Pressure Dependence ◽  
Self Diffusion

p, T-Dependence of Self Diffusion in Mixtures of Hexane/Ethanol and Hexane/Dimethylether

1995 ◽  
Vol 50 (2-3) ◽  
pp. 149-154 ◽  
Author(s):  
A. Heinrich-Schramm ◽  
W. E. Price ◽  
H.-D. Lüdemann
Keyword(s):  
Hydrogen Bonding ◽  
Qualitative Analysis ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
The Self ◽  
Slight Effect ◽  
Self Diffusion ◽  
Dipole Interactions ◽  
Significant Difference

Abstract Self-diffusion in ethanol/hexane and dimethylether/hexane mixtures of various compositions has been measured at 215-350 K and up to 200 MPa. Qualitative analysis of the results indicates that, as expected, hydrogen bonding retards the self-diffusion of ethanol in the mixture, especially at the low temperatures. Dimethylether shows a slight effect of dipole-dipole interactions on the self-diffu­sion, as seen by a higher ΔE* value than for the alkane. However there is no significant difference in the pressure dependence for both mixtures. This is shown by considering the ratio of the two diffusion coefficients, which suggests that, contrary to what is observed for pure alcohols, pressure has little effect upon the hydrogen bonding of ethanol in the mixture. In additon, there is surprisingly little concentration dependence on the ratios for either mixture.

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