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

TL;DR

This study uses first-principles calculations to analyze how hydrogen atoms interact with vacancies in Ti3SiC2, revealing strong vacancy trapping and limited mobility of hydrogen in this material.

Contribution

It provides new insights into hydrogen trapping mechanisms and diffusion barriers in Ti3SiC2, a MAX phase material, through first-principles computational analysis.

Findings

Hydrogen prefers Si vacancies with a solution energy of -4.07 eV.

Up to five H atoms can be trapped by a single Si vacancy.

The diffusion barrier for H from interstitial sites to vacancies is 1.17 eV.

Abstract

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.