|THP007||In-Situ EXAFS Investigations of Nb-Treatments in N2 at Elevated Temperatures||842|
|THP005||use link to see paper's listing under its alternate paper code|
Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H15PXRB1.
Smooth polycrystalline Nb metal foils were exposed to dilute N2 and Kr atmospheres at elevated temperatures of up to 900°C. Transmission mode X-ray absorption spectroscopy (EXAFS) experiments were used to study the resulting changes of the atomic short range order structure in-situ. EXAFS data were collected prior to any heat treatment as well as during the different process steps at elevated temperatures with a time resolution of about 1 s, and the samples were also studied after cooling to room temperature. In general, only very small changes of the Nb-EXAFS data could be detected after the processing in N2-atmospheres, and no evidence for bulk formation of Nb-nitrides was found. In contrast, the quantitative EXAFS data evaluation revealed slightly distorted Nb-Nb coordinations, suggesting that N-atoms are increasingly incorporated on octahedral interstitial sites in the host lattice with increasing N2-exposure. For the treatments in Kr-atmospheres, simultaneous measurements are feasible at both the K-edge of the Nb host and the Kr dopant. Those studies gave clear evidence for a Kr uptake during the heat treatment, and will be discussed in more detail at the conference.
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP007|
|About •||paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019|
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