Sedimentation of Substitutional Solute Atoms in Condensed Matter: New Type of Diffusion

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 °C, 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.

• Periodical: Defect and Diffusion Forum (Volumes 237-240)
• Pages: 30-37
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.237-240.30
• Online since: April 2005
• Authors: Tsutomu Mashimo
• Keywords: Diffusion, Sedimentation of Atoms, Ultracentrifuge, Ultra-Strong Gravitational Field

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