[Table of Contents]

Plasma and Fusion Research

Volume 6, 2405062 (2011)

Regular Articles

Interstitial Diffusion of C Interacting with Ambient H in Tungsten Crystals
Daiji KATO, Hirotomo IWAKIRI1), Kazunori MORISHITA2) and Takeo MUROGA
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
1)
University of the Ryukyus, Okinawa 903-0213, Japan
2)
Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
(Received 22 December 2010 / Accepted 12 April 2011 / Published 1 July 2011)

Abstract

Negative binding energies between interstitial C (octahedral) and H (tetrahedral) in a bulk crystal of W (bcc) were obtained with the first-principle calculations, which indicate repulsive interaction in the interstitial C-H pair. The electron cloud associated to the each interstitial atom was analyzed with Bader's method. This analysis gives negative fractional charges of −0.35 and −0.37 for the interstitial C and H, respectively, supporting the repulsive interaction between them. Interstitial diffusion of C was studied including influences of ambient H atoms in the mean field approximation and the ergodic assumption. The calculated diffusion coefficients are significantly increased by the repulsive interaction with the H atoms.

Keywords

diffusion coefficient, interstitial atom, hydrogen, carbon, tungsten, material-mixing, first-principle method

DOI: 10.1585/pfr.6.2405062

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This paper may be cited as follows:

Daiji KATO, Hirotomo IWAKIRI, Kazunori MORISHITA and Takeo MUROGA, Plasma Fusion Res. 6, 2405062 (2011).