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Science 9 November 2007:
Vol. 318. no. 5852, pp. 956 - 959
DOI: 10.1126/science.1145386
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Reports

Observation of the One-Dimensional Diffusion of Nanometer-Sized Dislocation Loops

K. Arakawa,1* K. Ono,2 M. Isshiki,3 K. Mimura,3 M. Uchikoshi,3 H. Mori1

Dislocations are ubiquitous linear defects and are responsible for many of the properties of crystalline materials. Studies on the glide process of dislocations in bulk materials have mostly focused on the response of dislocations with macroscopic lengths to external loading or unloading. Using in situ transmission electron microscopy, we show that nanometer-sized loops with a Burgers vector of 1/2<111> in {alpha}-Fe can undergo one-dimensional diffusion even in the absence of stresses that are effective in driving the loops. The loop size dependence of the loop diffusivity obtained is explained by the stochastic thermal fluctuation in the numbers of double kinks.

1 Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
2 Department of Material Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
3 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.

* To whom correspondence should be addressed. E-mail: arakawak{at}uhvem.osaka-u.ac.jp

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Science. ISSN 0036-8075 (print), 1095-9203 (online)