Diatomic substitutionals in superconducting Nb(1−x)B2
| Autor: | T.M. Lillo, Randall A. LaViolette, H. H. Farrell |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Superconductivity
Materials science Condensed matter physics Phonon Binding energy Fermi level Energy Engineering and Power Technology Electronic structure Condensed Matter Physics Diatomic molecule Electronic Optical and Magnetic Materials Condensed Matter::Materials Science symbols.namesake Vacancy defect Physics::Atomic and Molecular Clusters symbols Condensed Matter::Strongly Correlated Electrons Density functional theory Electrical and Electronic Engineering |
| Zdroj: | Physica C: Superconductivity. 449:1-8 |
| ISSN: | 0921-4534 |
| Popis: | Using first-principles, density functional theory calculations, we have shown that the increase in superconducting critical temperature to above 9 K experimentally observed for B-rich, off-stoichiometry NbB 2 material is associated with the formation of B-dimers on Nb sites rather than with the formation of Nb vacancies, as previously proposed. Our calculations show that certain of these B-dimer configurations have lower binding energies than do the vacancy structures. This result is pressure independent in the range between 0 and 10 GPa, and above. Further, the dimer-containing materials have a higher electronic density of states at the Fermi level than do the vacancy structures. Finally, the presence of B-dimers results in the splitting off of phonon normal modes. These last two factors are relevant to the improved superconducting properties. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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