On energetics of allotrope transformations in transition-metal diborides via plane-by-plane shearing
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arXiv
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2023
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| _version_ | 1866909206364291072 |
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| author | Leiner, Thomas Koutná, Nikola Janovec, Jozef Zelený, Martin Mayrhofer, Paul H. Holec, David |
| author_facet | Leiner, Thomas Koutná, Nikola Janovec, Jozef Zelený, Martin Mayrhofer, Paul H. Holec, David |
| contents | Transition metal diborides crystallise in the $α$, $γ$, or $ω$ type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the $α$, $γ$, and $ω$ structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB$_2$ and MoB$_2$ possess the overall lowest sliding barriers among the investigated TMB$_2$s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2301_12840 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | On energetics of allotrope transformations in transition-metal diborides via plane-by-plane shearing Leiner, Thomas Koutná, Nikola Janovec, Jozef Zelený, Martin Mayrhofer, Paul H. Holec, David Materials Science Transition metal diborides crystallise in the $α$, $γ$, or $ω$ type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the $α$, $γ$, and $ω$ structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB$_2$ and MoB$_2$ possess the overall lowest sliding barriers among the investigated TMB$_2$s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants. |
| title | On energetics of allotrope transformations in transition-metal diborides via plane-by-plane shearing |
| topic | Materials Science |
| url | https://arxiv.org/abs/2301.12840 |