Sedimentation of Substitutional Solute Atoms in Condensed Matter: New Type of Diffusion |
| Journal |
Defect and Diffusion Forum (Volumes 237 - 240) |
| Volume |
Diffusion in Materials - DIMAT2004 |
| Edited by |
M. Danielewski, R. Filipek, R. Kozubski, W. Kucza, P. Zieba, Z. Zurek |
| Pages |
30-37 |
| DOI |
10.4028/www.scientific.net/DDF.237-240.30 |
| Authors |
Tsutomu Mashimo
|
| Keywords |
Diffusion, Sedimentation of Atoms, Ultracentrifuge, Ultra-Strong Gravitational Field |
| Abstract |
Ultra-strong gravitational field (Mega-gravity field) causes the sedimentation of even atoms (diffusion), and is expected to create a nonequilibrium crystal-chemical state in multi-component condensed matter. However, the materials science research under mega-gravity field has now remained as an unexploited field, while the sedimentation of molecules or polymer had been used in biochemistory. We presented a self-consistent diffusion equation for sedimentation of atoms in condensed matter. Next, we developed an ultracentrifuge apparatus to
generate strong acceleration field of over 1 million (1x106) g at temperature range up to 〜300 ℃, and, recently, succeeded in realization of the sedimentation of substitutional solute atoms in some alloys of Bi-Sb, In-Pb, Bi-Pb systems, etc. The diffusion coefficients in sedimentation on Bi-Sb alloy were estimated to be much greater than those at normal conditions by a factor of >20. It is suggested that the sedimentation of substitutional atoms in solids or liquids can be explained in a
new type of diffusion, where the diffusion mechanism for substitutional solute atoms was yet unknown. In this article, the recent progress in the investigation of sedimentation of atoms under mega-gravity field is reviewed, and the diffusion mechanism is discussed. The application of the mega-gravity field is also discussed. |
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