Direct atomic-scale imaging of hydrogen and oxygen interstitials in pure niobium using atom-probe tomography and aberration-corrected scanning transmission electron microscopy

Yoon Jun Kim, Runzhe Tao, Robert F. Klie, David N. Seidman*

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Imaging the three-dimensional atomic-scale structure of complex interfaces has been the goal of many recent studies, due to its importance to technologically relevant areas. Combining atom-probe tomography and aberration-corrected scanning transmission electron microscopy (STEM), we present an atomic-scale study of ultrathin (∼5 nm) native oxide layers on niobium (Nb) and the formation of ordered niobium hydride phases near the oxide/Nb interface. Nb, an elemental type-II superconductor with the highest critical temperature (Tc = 9.2 K), is the preferred material for superconducting radio frequency (SRF) cavities in next-generation particle accelerators. Nb exhibits high solubilities for oxygen and hydrogen, especially within the RF-field penetration depth, which is believed to result in SRF quality factor losses. STEM imaging and electron energy-loss spectroscopy followed by ultraviolet laser-assisted local-electrode atom-probe tomography on the same needle-like sample reveals the NbO2, Nb2O 5, NbO, Nb stacking sequence; annular bright-field imaging is used to visualize directly hydrogen atoms in bulk β-NbH.

Original languageEnglish (US)
Pages (from-to)732-739
Number of pages8
JournalACS nano
Volume7
Issue number1
DOIs
StatePublished - Jan 22 2013

Keywords

  • Nb
  • Nb oxides
  • NbH
  • aberration-corrected STEM
  • annular bright-field images
  • atom-probe tomography

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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