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

Abstract

We report on atomic-scale analyses of the microstructure of an Nb 3Sn 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 3Sn on a Nb substrate is found and four types of orientation relationships (ORs) at the Nb 3Sn/Nb interface are identified by electron diffraction or high-resolution scanning transmission electron microscopy (HR-STEM) analyses. Thin Nb 3Sn grains are observed in regions with a low Sn flux and they have a specific OR: Nb 3Sn (1$$\bar{2}$$0) //Nb ($$\bar{1}$$11) and Nb 3Sn (002) //Nb (0$$\bar{1}$$1) The Nb 3Sn/Nb interface of thin grains has a large lattice mismatch, 12.3%, between Nb(0$$\bar{1}$$1) and Nb 3Sn (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 3Sn/Nb interface and remain in the grains due to the slow diffusion of Sn in bulk Nb 3Sn. 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 3Sn/Nb interface provides important information about the formation of imperfections in Nb 3Sn coatings, such as large thin-regions and Sn-deficient regions, which are critical to the performance of Nb 3Sn SRF cavities for accelerators.

Authors:
ORCiD logo [1];  [2];  [3];  [2];  [3];  [4];  [4];  [3]
  1. Northwestern Univ., Evanston, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. Northwestern Univ., Evanston, IL (United States)
  4. Cornell Univ., Ithaca, NY (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1511670
Report Number(s):
FERMILAB-PUB]-18-767-TD
Journal ID: ISSN 0953-2048; 1718533
Grant/Contract Number:  
AC02-07CH11359
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Superconductor Science and Technology
Additional Journal Information:
Journal Volume: 32; Journal Issue: 2; Journal ID: ISSN 0953-2048
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Lee, Jaeyel, Posen, Sam, Mao, Zugang, Trenikhina, Yulia, He, Kai, Hall, Daniel L., Liepe, Matthias, and Seidman, David N.. Atomic-scale analyses of Nb3Sn on Nb prepared by vapor diffusion for superconducting radiofrequency cavity applications: a correlative study. United States: N. p., 2018. Web. doi:10.1088/1361-6668/aaf268.
Lee, Jaeyel, Posen, Sam, Mao, Zugang, Trenikhina, Yulia, He, Kai, Hall, Daniel L., Liepe, Matthias, & Seidman, David N.. Atomic-scale analyses of Nb3Sn on Nb prepared by vapor diffusion for superconducting radiofrequency cavity applications: a correlative study. United States. doi:10.1088/1361-6668/aaf268.
Lee, Jaeyel, Posen, Sam, Mao, Zugang, Trenikhina, Yulia, He, Kai, Hall, Daniel L., Liepe, Matthias, and Seidman, David N.. Thu . "Atomic-scale analyses of Nb3Sn on Nb prepared by vapor diffusion for superconducting radiofrequency cavity applications: a correlative study". United States. doi:10.1088/1361-6668/aaf268. https://www.osti.gov/servlets/purl/1511670.
@article{osti_1511670,
title = {Atomic-scale analyses of Nb3Sn on Nb prepared by vapor diffusion for superconducting radiofrequency cavity applications: a correlative study},
author = {Lee, Jaeyel and Posen, Sam and Mao, Zugang and Trenikhina, Yulia and He, Kai and Hall, Daniel L. and Liepe, Matthias and Seidman, David N.},
abstractNote = {We report on atomic-scale analyses of the microstructure of an Nb3Sn 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 Nb3Sn on a Nb substrate is found and four types of orientation relationships (ORs) at the Nb3Sn/Nb interface are identified by electron diffraction or high-resolution scanning transmission electron microscopy (HR-STEM) analyses. Thin Nb3Sn grains are observed in regions with a low Sn flux and they have a specific OR: Nb3Sn (1$\bar{2}$0) //Nb ($\bar{1}$11) and Nb3Sn (002) //Nb (0$\bar{1}$1) The Nb3Sn/Nb interface of thin grains has a large lattice mismatch, 12.3%, between Nb(0$\bar{1}$1) and Nb3Sn (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 Nb3Sn/Nb interface and remain in the grains due to the slow diffusion of Sn in bulk Nb3Sn. 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 Nb3Sn/Nb interface provides important information about the formation of imperfections in Nb3Sn coatings, such as large thin-regions and Sn-deficient regions, which are critical to the performance of Nb3Sn SRF cavities for accelerators.},
doi = {10.1088/1361-6668/aaf268},
journal = {Superconductor Science and Technology},
issn = {0953-2048},
number = 2,
volume = 32,
place = {United States},
year = {2018},
month = {12}
}

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