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Science 15 February 2002:
Vol. 295. no. 5558, pp. 1264 - 1266
DOI: 10.1126/science.1067746
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Reports

Protonic Diffusion in High-Pressure Ice VII

Eriko Katoh, H. Yamawaki, H. Fujihisa, M. Sakashita, K. Aoki*

Near ambient pressures, molecular diffusion dominates protonic diffusion in ice. Theoretical studies have predicted that protonic diffusion will dominate at high pressures in ice. We measured the protonic diffusion coefficient for the highest temperature molecular phase of ice VII at 400 kelvin over its entire stable pressure region. The values ranged from 10-17 to 10-15 square meters per second at pressures of 10 to 63 gigapascals. The diffusion coefficients extrapolated to high temperatures close to the ice VII melting curve were less by a factor of 102 to 103 than a superionic criterion of ~10-8 square meters per second, at which protons would diffuse freely.

National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, Tsukuba 305-8565, Ibaraki, Japan.
*   To whom correspondence should be addressed. E-mail: k-aoki{at}aist.go.jp

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Melting of ice under pressure.
E. Schwegler, M. Sharma, F. Gygi, and G. Galli (2008)
PNAS 105, 14779-14783
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