Volume 81, Number 5, March 2008
Article Number 56002
Number of page(s) 4
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 19 February 2008
EPL, 81 (2008) 56002
DOI: 10.1209/0295-5075/81/56002

Gravity-induced diffusion of isotope atoms in monoatomic solid Se

T. Mashimo1, 2, M. Ono2, X. S. Huang1, Y. Iguchi1, S. Okayasu2, K. Kobayashi3 and E. Nakamura3

1  Shock Wave and Condensed Matter Research Center, Kumamoto University - Kurokami-cho, Kumamoto 860-8555, Japan
2  Advanced Science Research Center, Japan Atomic Energy Agency - Tokai-mura, Nakagun, Ibaraki 319-1195, Japan
3  Institute for Study of the Earth's Interior, Okayama University - Misasa-cho, Tottri 682-0193, Japan

received 9 October 2007; accepted in final form 9 January 2008; published March 2008
published online 19 February 2008

A strong gravitational field resulted in the gravity-induced diffusion (sedimentation) of isotope atoms in monoatomic solid Se. The layer crystalline morphology consisting of three zones of the fine-grained crystals, the long crystals and feather-shaped crystals grown parallel to gravity direction appeared in the specimen ultracentrifuged at (0.8-1)$\times$106 G and at 190 °C. Change in the concentration ratio 82Se/76Se of > 0.8% was observed in the grown crystalline region. These results show an evidence for the sedimentation of substitutional atoms in solids via self-diffusion, and suggest the possibility of application to the control of impurity and crystalline states as well as to isotope separation.

PACS - Defects, impurities, and diffusion.
47.57.ef - Sedimentation and migration.
66.30.Fq - Self diffusion in metals, semimetals, and alloys .

© EPLA 2008