Evidence from EXAFS for Different Ta/Ti Site Occupancy in High Critical Current Density Nb3Sn Superconductor Wires
| Autor: | David C. Larbalestier, A.K. Ghosh, Steve M. Heald, Zu-Hawn Sung, Peter J. Lee, Chiara Tarantini, Michael D. Brown |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Superconductivity
Multidisciplinary Large Hadron Collider Materials science Condensed matter physics Extended X-ray absorption fine structure Dopant Condensed Matter - Superconductivity lcsh:R FOS: Physical sciences lcsh:Medicine 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Future Circular Collider Article Superconductivity (cond-mat.supr-con) Lattice (order) 0103 physical sciences lcsh:Q 010306 general physics 0210 nano-technology lcsh:Science Critical field Stoichiometry |
| Zdroj: | Scientific Reports Scientific Reports, Vol 8, Iss 1, Pp 1-9 (2018) |
| ISSN: | 2045-2322 |
| Popis: | To meet critical current density, J$_c$, targets for the Future Circular Collider (FCC), the planned replacement for the Large Hadron Collider (LHC), the high field performance of Nb$_3$Sn must be improved, but champion J$_c$ values have remained static for the last 10 years. Making the A15 phase stoichiometric and enhancing the upper critical field H$_{c2}$ by Ti or Ta dopants are the standard strategies for enhancing high field performance but detailed recent studies show that even the best modern wires have broad composition ranges. To assess whether further improvement might be possible, we employed EXAFS to determine the lattice site location of dopants in modern high-performance Nb$_3$Sn strands with J$_c$ values amongst the best so far achieved. Although Ti and Ta primarily occupy the Nb sites in the A15 structure, we also find significant Ta occupancy on the Sn site. These findings indicate that the best performing Ti-doped stand is strongly sub-stoichiometric in Sn and that antisite disorder likely explains its high average H$_{c2}$ behavior. These new results suggest an important role for dopant and antisite disorder in minimizing superconducting property distributions and maximizing high field J$_c$ properties. 14 pages, 6 figures |
| Databáze: | OpenAIRE |
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