Würzburg 2018 – scientific programme
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 10: New Accelerator Concepts and Radiofrequency
AKBP 10.6: Talk
Thursday, March 22, 2018, 17:45–18:00, NW-Bau - HS2
Structural investigations of nitrogen-doped niobium for superconducting RF-cavities — •Márton Major1, Matthias Mahr1, Stefan Flege1, Lambert Alff1, Jens Conrad1, Ruben Grewe1, Michaela Arnold1, Norbert Pietralla1, and Florian Hug2 — 1Technische Universität Darmstadt, Darmstadt, Germany — 2Johannes Gutenberg Universität Mainz, Mainz, Germany
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic δ-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the α-Nb phase results in higher quality factors [Grassellino et al., Proc. SRF2015, MOBA06, 48].
Nb samples were N-doped at the refurbished UHV furnace at IKP Darmstadt. Reference samples were annealed in 1 bar nitrogen atmosphere at different temperatures. In this contribution the results on the structural investigations (x-ray diffraction and pole figure, secondary ion mass spectroscopy, scanning electron microscopy) at the Materials Research Department of TU Darmstadt will be presented.
Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H15RDRBA.