Analysis of Nb{sub 3}Sn surface layers for superconducting radio frequency cavity applications

Journal Article · Mon Feb 23 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4913617· OSTI ID:22412709

Becker, Chaoyue ^[1]; Posen, Sam; Hall, Daniel Leslie ^[2]; Groll, Nickolas; Proslier, Thomas ^[1]; Cook, Russell ^[3]; Schlepütz, Christian M. ^[4]; Liepe, Matthias ^[2]; Pellin, Michael ^[1]; Zasadzinski, John ^[5]

---

1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States)
3. Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
4. X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
5. Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

We present an analysis of Nb{sub 3}Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb{sub 3}Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T{sub c}) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb{sub 3}Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb{sub 3}Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T{sub c} regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb{sub 3}Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

• OSTI ID: 22412709
• Journal Information: Applied Physics Letters, Vol. 106, Issue 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COATINGS
CRITICAL TEMPERATURE
CROSS SECTIONS
DENSITY OF STATES
DIFFUSION
FILMS
GHZ RANGE
LAYERS
NIOBIUM BASE ALLOYS
POLYCRYSTALS
RADIOWAVE RADIATION
SUPERCOMPUTERS
SURFACES
TIN ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
TUNNEL EFFECT
X-RAY DIFFRACTION