Crystallographic Characterization of Nb₃Sn Coatings and N-Doped Niobium via EBSD and SIMS

Historically, niobium has been used as the superconducting material in SRF cavities. Due the high operational costs, other materials are currently being considered. Nb₃Sn coatings have been investigated over the past several decades, motivated by potentially higher operating temperatures. More recently niobium has been doped with nitrogen to improve the quality factor (Q). Currently, a need for better understanding still exists for both mechanisms. EBSD has been shown to be a viable technique to determine the crystallographic orientation and the size of the Nb₃Sn grains. The EBSD maps obtained show a bimodal distribution of grain sizes with smaller Nb₃Sn grains found present near the Nb₃Sn/Nb interface. In addition to the Nb₃Sn coatings, N-doped niobium coupons were analyzed by EBSD and found that the coupon had preferred surface orientation. The EBSD analysis was found to be vital as specific grains could be targeted in SIMS to better understand the diffusion of nitrogen with respect to crystal orientation.
Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany