https://doi.org/10.1140/epjb/e2014-50570-9
Regular Article
Ab initio calculations of mechanical properties in β-MH2−xHex (M = Er, Sc)
1
School of Physical Electronics, University of Electronic Science
and Technology of China, Chengdu
610054, P.R.
China
2
Department of Physics and Engineering Technology, Sichuan
University of Arts and Science, Dazhou
635000, P.R.
China
3
Institute of Nuclear Physics and Chemistry, China Academy of
Engineering Physics, Mianyang
621900, P.R.
China
4
Department of Nuclear Engineering and Radiological Sciences,
University of Michigan, Ann
Arbor, MI
48109,
USA
a
e-mail: yanglildk@uestc.edu.cn
Received: 22 August 2014
Received in final form: 16 October 2014
Published online: 8 December 2014
The 3He (helium) accumulation due to tritium decays in rare-earth metal tritides can influence their mechanical properties and stabilities, limiting their applications as neutron generators. Ab initio calculations based on density functional theory have been performed to investigate the elastic constants, bulk modulus, shear modulus and Young’s modulus of the β-MH2−xHex (M = Er, Sc) systems, with the variety of the x (the ratio of He to M atoms), ranging from 0 to 0.1875. The changes in the mechanical properties of β-ErH2−xHex and β-ScH2−xHex exhibit two regimes, which is in agreement with the experimental observations. It appears that the different He concentrations cause the different interactions between metal atoms and their neighbors in β-MH2−xHex, a key factor which gives rise to the observed two regimes. When x is about 0.13, the mechanical properties of metal hydrides degrade significantly. Furthermore, the degradation mechanisms of the mechanical properties in the β-MH2−xHex systems depend mainly on the crystal structure of metal hydrides.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2014