First-principles study on surface stability of tantalum carbides
| Autor: | Dinesh K. Shetty, Wen Li Yan, Feng Liu, Guang-Hong Lu, Michael Sygnatowicz |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Materials science Tantalum chemistry.chemical_element Cleavage (crystal) 02 engineering and technology Surfaces and Interfaces 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Surface energy Surfaces Coatings and Films Carbide Metal chemistry.chemical_compound Crystallography chemistry Covalent bond visual_art 0103 physical sciences Materials Chemistry visual_art.visual_art_medium 0210 nano-technology Tantalum carbide Metallic bonding |
| Zdroj: | Surface Science. 644:24-28 |
| ISSN: | 0039-6028 |
| DOI: | 10.1016/j.susc.2015.09.003 |
| Popis: | Using first-principles method, surface energies of crystal planes of different tantalum carbide phases have been calculated. Quantum size effects are shown to possibly play a considerable role in determining accurate surface energies of these metallic films, which have been neglected in previous works. The γ-TaC phase has a more stable (0 0 1) surface than the close-packed (1 1 1) surface. In the α-Ta 2 C phase, (0 0 1) surface with only Ta termination is more stable than that of mixed Ta-C termination because the metallic bonds between Ta atoms are weaker than the Ta-C covalent bonds. The same is true for the ζ-Ta 4 C 3 phase. The introduction of structural vacancies in the ζ-Ta 4 C 3 − x phase creates more direct Ta metallic bonds, making the Ta-terminated surfaces even more stable. This is consistent with the experimental observations of cleavage of the basal planes, lamellae bridging of cracks, and the high fracture toughness of ζ-Ta 4 C 3 − x . |
| Databáze: | OpenAIRE |
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