Atomic-scale analyses of Nb 3 Sn on Nb prepared by vapor diffusion for superconducting radiofrequency cavity applications: A correlative study

Jaeyel Lee*, Sam Posen, Zugang Mao, Yulia Trenikhina, Kai He, Daniel L. Hall, Matthias Liepe, David N. Seidman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

We report on atomic-scale analyses of the microstructure of an Nb 3 Sn coating on Nb, prepared by a vapor diffusion process for superconducting radiofrequency (SRF) cavity applications using transmission electron microscopy, electron backscatter diffraction and first-principles calculations. Epitaxial growth of Nb 3 Sn on a Nb substrate is found and four types of orientation relationships (ORs) at the Nb 3 Sn/Nb interface are identified by electron diffraction or high-resolution scanning transmission electron microscopy (HR-STEM) analyses. Thin Nb 3 Sn grains are observed in regions with a low Sn flux and they have a specific OR: Nb 3 Sn //Nb and Nb 3 Sn //Nb The Nb 3 Sn/Nb interface of thin grains has a large lattice mismatch, 12.3%, between Nb and Nb 3 Sn (002) and a high density of misfit dislocations as observed by HR-STEM. Based on our microstructural analyses of the thin grains, we conclude that the thin regions are probably a result of a slow interfacial migration with this particular OR. The Sn-deficient regions are seen to form initially at the Nb 3 Sn/Nb interface and remain in the grains due to the slow diffusion of Sn in bulk Nb 3 Sn. The formation of Sn-deficient regions and the effects of interfacial energies on the formation of Sn-deficient regions at different interfaces are estimated by first-principles calculations. The finding of ORs at the Nb 3 Sn/Nb interface provides important information about the formation of imperfections in Nb 3 Sn coatings, such as large thin-regions and Sn-deficient regions, which are critical to the performance of Nb 3 Sn SRF cavities for accelerators.

Original languageEnglish (US)
Article number024001
JournalSuperconductor Science and Technology
Volume32
Issue number2
DOIs
StatePublished - Feb 2019

Funding

We are grateful to Drs Amir R Farkoosh, Xuefeng Zhou, and Sung-Il Baik, and Mr Qingqiang Ren for valuable discussions. We also thank Professors James P Sethna, Thomas Arias and David A Müller for valuable discussions and suggestions. This research is supported by the United States Department of Energy, Offices of High Energy. Fermilab is operated by the Fermi Research Alliance LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University's NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Cornell's Nb3Sn coating program is supported by United States Department of Energy grant DE-SC0008431. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University. We are grateful to Drs Amir R Farkoosh, Xuefeng Zhou, and Sung-Il Baik, and Mr Qingqiang Ren for valuable discussions. We also thank Professors James P Sethna, Thomas Arias and David A Müller for valuable discussions and suggestions. This research is supported by the United States Department of Energy, Offices of High Energy. Fermilab is operated by the Fermi Research Alliance LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Cornell’s Nb3Sn coating program is supported by United States Department of Energy grant DE-SC0008431. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University.

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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