First Direct Observation of Nanometer size Hydride Precipitations on Superconducting Niobium

Zu Hawn Sung; Arely Cano; Akshay Murthy; Evguenia Karapetrova; Jaeyel Lee; Martina Martinello; Anna Grassellino; Alexander Romanenko

arXiv · 2305.01022

First Direct Observation of Nanometer size Hydride Precipitations on Superconducting Niobium

Zu Hawn Sung·Arely Cano·Akshay Murthy·Evguenia Karapetrova·Jaeyel Lee·Martina Martinello·Anna Grassellino·Alexander Romanenko

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Abstract

Superconducting niobium serves as a key enabling material for superconducting radio frequency (SRF) technology as well as quantum computing devices. At room temperature, hydrogen commonly occupies tetragonal sites in the Nb lattice as metal (M)-gas (H) phase. When the temperature is decreased, however, solid solution of Nb-H starts to be precipitated. In this study, we show the first identified topographical features associated with nanometer-size hydride phase (Nb1-xHx) precipitates on metallic superconducting niobium using cryogenic-atomic force microscopy (AFM). Further, high energy grazing incidence X-ray diffraction reveals information regarding the structure and stoichiometry that these precipitates exhibit. Finally, through time-of-flight secondary ion mass spectroscopy (ToF-SIMS), we are able to locate atomic hydrogen sources near the top surface. This systematic study further explains localized degradation of RF superconductivity by the proximity effect due to hydrogen clusters.

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Zu Hawn Sung, Arely Cano, Akshay Murthy, Evguenia Karapetrova, Jaeyel Lee, Martina Martinello, Anna Grassellino, Alexander Romanenko. 2023-05-01. First Direct Observation of Nanometer size Hydride Precipitations on Superconducting Niobium. https://arxiv.org/abs/2305.01022

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