Volume 118, Number 4, May 2017
|Number of page(s)||7|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||19 July 2017|
Hydrogen trapping in MAX phase Ti3SiC2: Insight from chemical bonding by density functional theory
1 Key Laboratory of Nuclear Physics and Ion- beam Application (MOE), Institute of Modern Physics, Fudan University - Shanghai 200433, China
2 State Key Laboratory of Solid Lubrication, Lanzhou, Institute of Chemical Physics, Chinese Academy of Sciences - Lanzhou 730000, China
3 Department of Aeronautic and Astronautic, Fudan University - Shanghai 200433, China
4 Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics - Mianyang, 621900, China
5 School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology - Gardens Point Campus, QLD 4001, Brisbane, Australia
Received: 2 March 2017
Accepted: 12 June 2017
Understanding hydrogen (H) isotope trapping in materials is essential to optimize the material performance in a nuclear environment for the fabrication of nuclear devices. By using the density functional theory (DFT), herein we have systematically investigated the behaviour of hydrogen in the MAX phase Ti3SiC2 in the presence and absence of a vacancy (V). When a vacancy is generated in a favorable plane for hydrogen accumulating (Si plane), two distinct behavours of hydrogen in the Si plane have been identified by chemical bond analysis, i.e., the Ti-H and Si-H bonding, which synergistically results in VH2 complexes prevailing in the host matrix. Different from metals and other ceramics, the trapping mechanism of H in Ti3SiC2 essentially originates from the spatially inhomogeneous distribution of free-charge density and large discrepancy of electronegativity between the host atoms. Our theoretical results offer great insights into the rational design of new high-performance nuclear materials.
PACS: 71.55.Ak – Metals, semimetals, and alloys / 71.10.Ca – Electron gas, Fermi gas / 81.05.Bx – Metals, semimetals, and alloys
© EPLA, 2017
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