科研之友
微信
新浪微博
Facebook
分享链接
摘要
The He-3 (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 beta-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 beta-ErH2-xHex and beta-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 beta-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 beta-MH2-xHex systems depend mainly on the crystal structure of metal hydrides.
