Effects of Ni doping on various properties of NbH phases: A first-principles investigation
Abstract Changes in the stability, hydrogen diffusion, and mechanical properties of the NbH phases from Ni-doping was studied by using first-principles methods. The calculation results reveal that the single H atom adsorption is energetically favorable at the tetrahedral interstitial site (TIS) and...
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| Auteurs principaux: | , , , , , , |
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| Format: | article |
| Langue: | EN |
| Publié: |
Nature Portfolio
2017
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| Accès en ligne: | https://doaj.org/article/4a1df6a36d30498595fd2d30bbec5f11 |
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| Résumé: | Abstract Changes in the stability, hydrogen diffusion, and mechanical properties of the NbH phases from Ni-doping was studied by using first-principles methods. The calculation results reveal that the single H atom adsorption is energetically favorable at the tetrahedral interstitial site (TIS) and octahedral interstitial site (OIS). The preferred path of H diffusion is TIS-to-TIS, followed by TIS-to-OIS in both Nb16H and Nb15NiH. Ni-doping in the Nb15NiH alloy lowers the energy barrier of H diffusion, enhances the H-diffusion coefficient (D) and mechanical properties of the Nb16H phase. The value of D increases with increasing temperature, and this trend due to Ni doping clearly becomes weaker at higher temperatures. At the typical operating temperature of 400 K, the D value of Nb15NiH (TIS) is about 1.90 × 10−8 m2/s, which is about 80 times higher than that of Nb16H (TIS) (2.15 × 10−10 m2/s). Our calculations indicated that Ni-doping can greatly improve the diffusion of H in Nb. |
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