Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study
Voids in face-centered cubic (fcc) metals are commonly assumed to form via the aggregation of vacancies; however, the mechanisms of vacancy clustering and diffusion are not fully understood. In this study, we use computational modeling to provide a detailed insight into the structures and formation...
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| Format: | Article |
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MDPI AG
2023-04-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/13/9/1464 |
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| author | Vasileios Fotopoulos David Mora-Fonz Manuel Kleinbichler Rishi Bodlos Ernst Kozeschnik Lorenz Romaner Alexander L. Shluger |
| author_facet | Vasileios Fotopoulos David Mora-Fonz Manuel Kleinbichler Rishi Bodlos Ernst Kozeschnik Lorenz Romaner Alexander L. Shluger |
| author_sort | Vasileios Fotopoulos |
| collection | DOAJ |
| description | Voids in face-centered cubic (fcc) metals are commonly assumed to form via the aggregation of vacancies; however, the mechanisms of vacancy clustering and diffusion are not fully understood. In this study, we use computational modeling to provide a detailed insight into the structures and formation energies of primary vacancy clusters, mechanisms and barriers for their migration in bulk copper, and how these properties are affected at simple grain boundaries. The calculations were carried out using embedded atom method (EAM) potentials and density functional theory (DFT) and employed the site-occupation disorder code (SOD), the activation relaxation technique nouveau (ARTn) and the knowledge led master code (KLMC). We investigate stable structures and migration paths and barriers for clusters of up to six vacancies. The migration of vacancy clusters occurs via hops of individual constituent vacancies with di-vacancies having a significantly smaller migration barrier than mono-vacancies and other clusters. This barrier is further reduced when di-vacancies interact with grain boundaries. This interaction leads to the formation of self-interstitial atoms and introduces significant changes into the boundary structure. Tetra-, penta-, and hexa-vacancy clusters exhibit increasingly complex migration paths and higher barriers than smaller clusters. Finally, a direct comparison with the DFT results shows that EAM can accurately describe the vacancy-induced relaxation effects in the Cu bulk and in grain boundaries. Significant discrepancies between the two methods were found in structures with a higher number of low-coordinated atoms, such as penta-vacancies and di-vacancy absortion by grain boundary. These results will be useful for modeling the mechanisms of diffusion of complex defect structures and provide further insights into the structural evolution of metal films under thermal and mechanical stress. |
| first_indexed | 2024-03-11T04:10:40Z |
| format | Article |
| id | doaj.art-01d04daf0f1146a6a5ec0eb97a7e4321 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-11T04:10:40Z |
| publishDate | 2023-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-01d04daf0f1146a6a5ec0eb97a7e43212023-11-17T23:26:25ZengMDPI AGNanomaterials2079-49912023-04-01139146410.3390/nano13091464Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT StudyVasileios Fotopoulos0David Mora-Fonz1Manuel Kleinbichler2Rishi Bodlos3Ernst Kozeschnik4Lorenz Romaner5Alexander L. Shluger6Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UKDepartment of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UKKAI—Kompetenzzentrum Automobil- und Industrieelektronik GmbH, Europastrasse 8, 9524 Villach, AustriaMaterials Center Leoben Forschung GmbH (MCL), Roseggerstraße 12, 8700 Leoben, AustriaInstitute of Materials Science and Technology, TU Wien, Getreidemarkt 9, 1060 Vienna, AustriaMaterials Center Leoben Forschung GmbH (MCL), Roseggerstraße 12, 8700 Leoben, AustriaDepartment of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UKVoids in face-centered cubic (fcc) metals are commonly assumed to form via the aggregation of vacancies; however, the mechanisms of vacancy clustering and diffusion are not fully understood. In this study, we use computational modeling to provide a detailed insight into the structures and formation energies of primary vacancy clusters, mechanisms and barriers for their migration in bulk copper, and how these properties are affected at simple grain boundaries. The calculations were carried out using embedded atom method (EAM) potentials and density functional theory (DFT) and employed the site-occupation disorder code (SOD), the activation relaxation technique nouveau (ARTn) and the knowledge led master code (KLMC). We investigate stable structures and migration paths and barriers for clusters of up to six vacancies. The migration of vacancy clusters occurs via hops of individual constituent vacancies with di-vacancies having a significantly smaller migration barrier than mono-vacancies and other clusters. This barrier is further reduced when di-vacancies interact with grain boundaries. This interaction leads to the formation of self-interstitial atoms and introduces significant changes into the boundary structure. Tetra-, penta-, and hexa-vacancy clusters exhibit increasingly complex migration paths and higher barriers than smaller clusters. Finally, a direct comparison with the DFT results shows that EAM can accurately describe the vacancy-induced relaxation effects in the Cu bulk and in grain boundaries. Significant discrepancies between the two methods were found in structures with a higher number of low-coordinated atoms, such as penta-vacancies and di-vacancy absortion by grain boundary. These results will be useful for modeling the mechanisms of diffusion of complex defect structures and provide further insights into the structural evolution of metal films under thermal and mechanical stress.https://www.mdpi.com/2079-4991/13/9/1464vacanciesdiffusionmetalsdensity functional theoryembedded atom method |
| spellingShingle | Vasileios Fotopoulos David Mora-Fonz Manuel Kleinbichler Rishi Bodlos Ernst Kozeschnik Lorenz Romaner Alexander L. Shluger Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study Nanomaterials vacancies diffusion metals density functional theory embedded atom method |
| title | Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study |
| title_full | Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study |
| title_fullStr | Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study |
| title_full_unstemmed | Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study |
| title_short | Structure and Migration Mechanisms of Small Vacancy Clusters in Cu: A Combined EAM and DFT Study |
| title_sort | structure and migration mechanisms of small vacancy clusters in cu a combined eam and dft study |
| topic | vacancies diffusion metals density functional theory embedded atom method |
| url | https://www.mdpi.com/2079-4991/13/9/1464 |
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