H permeation in molybdenum: temperature dependence and compensation effect from first-principles simulation

We systematically carried out first-principles simulations to study H diffusion and permeation in molybdenum (Mo) and found that their activation energies are the temperature dependence and exhibit the compensation effect. The H migration is primarily via two nearest neighbor tetrahedral sites and i...

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Bibliographic Details
Published in:Journal of nuclear science and technology 2019-11, Vol.56 (11), p.1014-1028
Main Authors: Yang, Kun Jie, Liu, Yue-Lin, Shao, Peng, Zhang, Xu, Han, Quan-Fu, Ma, Yuming
Format: Article
Language:English
Subjects:
Activation energy
Compensation
Diffusivity
Energy
Energy of solution
First principles
first-principles simulations
Free energy
H diffusion/permeation
Heat of solution
Molybdenum
Penetration
Permeability
Temperature
temperature and compensation effect
Temperature dependence
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Summary:We systematically carried out first-principles simulations to study H diffusion and permeation in molybdenum (Mo) and found that their activation energies are the temperature dependence and exhibit the compensation effect. The H migration is primarily via two nearest neighbor tetrahedral sites and its migrating energy raises notably with increasing temperature, which is caused by vibration free energy alteration with the temperature. The H permeation activation energy is also dependent strongly on the temperature since it is the sum of solution energy and migrating energy of H. Our predicted H diffusivity/permeability with the temperature is in quantitative agreement with the experimental result in Mo. The impurity capturing effect can cause the alteration of H diffusivity/permeability with the temperature. Despite the diffusion/permeation activation energy and pre-factor depending strongly on the temperature, the diffusivity/permeability still follows the Arrhenius curve with rising temperature. This attributes to the compensation effect between activation energy and pre-factor, i.e. the increment of the pre-factor compensate directly the modification of diffusivity/permeability in the case of a variation in the activation energy with rising temperature.
ISSN:0022-3131
1881-1248
DOI:10.1080/00223131.2019.1637796