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First-principles investigation of oxygen interaction with hydrogen/helium/vacancy irradiation defects in Ti3AlC2.
- Source :
- Physical Chemistry Chemical Physics (PCCP); 3/7/2021, Vol. 23 Issue 9, p5340-5351, 12p
- Publication Year :
- 2021
-
Abstract
- First-principles calculations have been performed to investigate the interaction between solute impurity O and H/He/vacancy irradiation defects in Ti<subscript>3</subscript>AlC<subscript>2</subscript>. The formation energy and occupation of O atoms within different defects as well as the trapping progress of O/H clusters are discussed. It is found that the O atom preferentially occupies the hexahedral interstitial site (I<subscript>hex</subscript>-1) in bulk Ti<subscript>3</subscript>AlC<subscript>2</subscript>, whereas it prefers to occupy the neighbouring tetrahedral interstitial site (I<subscript>tetr</subscript>-2) within pre-exisiting Al monovacancy (V<subscript>Al</subscript>), Al divacancy (2V<subscript>Al–Al</subscript>) and the 2V<subscript>Al–C</subscript> divacancy composed of Al and C vacancies. The appearance of C vacancy could greatly reduce the oxygen formation energy and make an O atom more inclined to occupy the center of C vacancy. Vacancy could capture more O atoms than H/He atoms, where V<subscript>Al</subscript> and 2V<subscript>Al–Al</subscript> could hold up to fifteen and eighteen O atoms, respectively. Meanwhile, the O could also promote the formation of Al vacancy. On the other hand, O atoms tend to occupy the interstitial sites near the Al atomic layer and have attraction to Al atoms, which is likely to enable the O atoms to combine with the Al atoms to form a Al<subscript>2</subscript>O<subscript>3</subscript> protective layer, thus effectively inhibiting further oxidation inside the Ti<subscript>3</subscript>AlC<subscript>2</subscript>. In addition, the H–O exhibits repulsion interaction, but strong attraction occurs in the He–O interaction. Therefore, the O atom has an inhibitory effect on the formation of the H cluster, while it could bind more He atoms to form a large number of He bubbles. Besides, the O impurity greatly reduces the trapping ability of vacancy to H atoms, and O and He have a synergistic interaction for inhibiting the aggregation of H clusters. The present results are expected to provide a new insight into the behaviour of Ti<subscript>3</subscript>AlC<subscript>2</subscript> under irradiation and oxidation conditions so that structural materials could be better designed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14639076
- Volume :
- 23
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- Physical Chemistry Chemical Physics (PCCP)
- Publication Type :
- Academic Journal
- Accession number :
- 149253029
- Full Text :
- https://doi.org/10.1039/d0cp06462a