Pressure dependencies of the thermal diffusion factors, αT, of nine helium–fluoroethane systems at 300 K: Prediction of the variation with temperature of the limiting diffusion coefficients of these systems from αT values at zero pressure

1996 ◽  
Vol 104 (1) ◽  
pp. 296-299 ◽  
Author(s):  
Peter J. Dunlop ◽  
C. M. Bignell
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Coefficients

QUANTITATIVE STUDY OF THERMAL DIFFUSION OF ELEMENTS ACROSS A ZnSe/GaAs INTERFACE USING SIMS

2001 ◽  
Vol 08 (01n02) ◽  
pp. 33-42 ◽  
Author(s):  
F. S. GARD ◽  
J. D. RILEY ◽  
R. LECKEY ◽  
B. F. USHER ◽  
K. PRINCE ◽  
...  
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Coefficients ◽  
Gaas Substrate ◽  
Comparison Study ◽  
Resolution Limit ◽  
Annealing Temperatures ◽  
Gaas Substrates ◽  
Gaas Matrix ◽  
Sims Analysis ◽  
Secondary Ion

ZnSe epilayers were grown on GaAs substrates, which had been treated with Se and Zn prior to the growth process. Thermal diffusion of elements across the interface was investigated, using secondary ion mass spectroscopy (SIMS). Ion-implanted standards have been used to calculate the "useful ion yield" for Zn and Se in the GaAs matrix and for Ga and As in the ZnSe matrix. Consequently, SIMS raw data were converted to quantified data. Diffusion of Ga atoms across the interface was observed for Zn-pretreated substrates. A comparison study showed that Se pretreatment of the GaAs substrate prevents thermal diffusion of Ga across the interface. This effect is believed to be due to the formation of GaAs x Se y layers at the interface, which acts as a barrier to diffusion. The Ga diffusion coefficients at annealing temperatures of 400°C, 500°C and 600°C were found to be 2.1×10-16 cm 2/s, 1.9×10-15 cm 2/s and 2.2×10-14 cm -2/s, respectively. The thermal diffusion of other elements across the interface was not observed within the resolution limit of SIMS analysis.

Soret Effect for a Ternary Mixture in Porous Cavity: Modeling With Variable Diffusion Coefficients and Viscosity

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
T. J. Jaber ◽  
Y. Yan ◽  
M. Z. Saghir
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Coefficients ◽  
Molecular Diffusion ◽  
Soret Effect ◽  
Left Wall ◽  
Porous Cavity ◽  
Buoyancy Convection ◽  
Variable Diffusion ◽  
Variable Diffusion Coefficients ◽  
The Right

A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion.

Sign in / Sign up

Export Citation Format

Share Document