SRF2021 - List of Authors (Johnson-McDaniel, D.)

Paper	Title	Page
THPTEV004	Surface Oxides on Nb and Nb₃Sn Surfaces: Toward a Deeper Understanding	836
	Z. Sun, M. Liepe, T.E. Oseroff, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, Z. Baraissov, D.A. Muller, N. Sitaraman Cornell University, Ithaca, New York, USA C. Dukes University of Virginia, Charlottesville, Virginia, USA D. Johnson-McDaniel, M. Salim CCMR, Ithaca, New York, USA
	Surface oxides on Nb and Nb₃Sn SRF cavities, as a thin ’dirty’ layer, could be critical to their performance as suggested by recent theory. Although these oxides have been studied in the past, we intend here to provide a deeper understanding based on a systematic study on coupon samples that have been processed under the different conditions currently used in SRF cavity treatments. Our aim is to obtain a more complete picture of the oxide evolution. This then might help to explain the observed cavity performance variation, and might allow designing a process to achieve a designed, optimized surface with controlled oxides types and thickness. We find that the surface oxides are in amorphous phase that exhibits normal conducting behaviors, while the pentoxide further degrades with time. Also, we observed a thin hydroxide layer on the outermost surface and possibly Nb(OH)x motifs in the bulk. Moreover, distinctive oxide structures were found in Nb₃Sn samples from vapor diffusion, electroplating, and sputtering. The semiconducting SnOx appeared through the oxide depth in vapor diffused Nb₃Sn, while a ~1 nm SnOx layer merely exists at the outermost surface of electroplated Nb₃Sn.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV004
About •	Received ※ 09 July 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 04 November 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Surface Oxides on Nb and Nb₃Sn Surfaces: Toward a Deeper Understanding

836

Z. Sun, M. Liepe, T.E. Oseroff, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, Z. Baraissov, D.A. Muller, N. Sitaraman
Cornell University, Ithaca, New York, USA
C. Dukes
University of Virginia, Charlottesville, Virginia, USA
D. Johnson-McDaniel, M. Salim
CCMR, Ithaca, New York, USA

Surface oxides on Nb and Nb₃Sn SRF cavities, as a thin ’dirty’ layer, could be critical to their performance as suggested by recent theory. Although these oxides have been studied in the past, we intend here to provide a deeper understanding based on a systematic study on coupon samples that have been processed under the different conditions currently used in SRF cavity treatments. Our aim is to obtain a more complete picture of the oxide evolution. This then might help to explain the observed cavity performance variation, and might allow designing a process to achieve a designed, optimized surface with controlled oxides types and thickness. We find that the surface oxides are in amorphous phase that exhibits normal conducting behaviors, while the pentoxide further degrades with time. Also, we observed a thin hydroxide layer on the outermost surface and possibly Nb(OH)x motifs in the bulk. Moreover, distinctive oxide structures were found in Nb₃Sn samples from vapor diffusion, electroplating, and sputtering. The semiconducting SnOx appeared through the oxide depth in vapor diffused Nb₃Sn, while a ~1 nm SnOx layer merely exists at the outermost surface of electroplated Nb₃Sn.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV004

About •

Received ※ 09 July 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 04 November 2021

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)