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Behaviors of helium in Cr 2 AlC from first principles
Author(s) -
Wang Chunjie,
Zhang Weiguang,
Han Zhibin,
Shi Liqun
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15781
Subject(s) - helium , helium atom , hexahedron , atomic physics , materials science , atom (system on chip) , interstitial defect , molecular physics , chemistry , condensed matter physics , doping , physics , thermodynamics , optoelectronics , finite element method , computer science , embedded system
Abstract The properties of helium incorporation and transport in Cr 2 AlC have been investigated using first principles method. The results of calculation show that a single helium atom is preferred to reside at an interstitial position near the Al plane in perfect Cr 2 AlC crystal, attributing to the low predicted formation energy. Helium atoms are expected to aggregate in Al layers. The interaction between helium and lattice atoms is primarily elastic due to the closed‐shell electronic structure of helium. The Doping of helium leads to a weakening of the Cr–Al bonds. Furthermore, an interstitial helium atom is likely to migrate along an indirect migration pathway from the hexahedral interstitial position on Al plane ( I A lC ), passing by the nearest tetrahedral interstitial position near Al plane ( I A lCr ), and finally reach to another hexahedral interstitial position ( I A lC ) with an activation energy of 1.21 eV. The high activation energy suggests a relatively low migration for helium atoms in Cr 2 AlC as well as a slow growth rate of helium bubbles for the early stage of helium irradiation.