Tuesday, August 6, 2013

1308.0873 (Yi-Guo Xu et al.)

Vacancy trapping behaviors of hydrogen atoms in Ti3SiC2: a
first-principles study

Yi-Guo Xu, Xue-Dong Ou, Xi-Ming Rong
The behaviors of hydrogen (H) in MAX phase material Ti3SiC2 have been investigated using first-principles method. We show that a single H atom prefers to stay 1.01 {\AA} down of the Si vacancy with solution energy of about -4.07 eV, lowerthan that in bulk Ti3SiC2. Multi H atoms exhibit a repulsive interaction at the Si vacancy. And up to five H atoms can be trapped by a Si vacancy without H2 molecules formation. These results suggest the strong vacancy trapping characteristic of H atoms in Ti3SiC2. Meanwhile, the barrier for H diffusion from an interstitial site to a vacancy is 1.17 eV, which is much larger than that in metals, indicating that to some extent H atoms can not easily migrate or aggregate to form bubble in Ti3SiC.
View original: http://arxiv.org/abs/1308.0873

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