Transformation dynamics of Ni clusters into NiO rings under electron beam irradiation

Daniel Knez*, Philipp Thaler, Alexander Volk, Gerald Kothleitner, Wolfgang E. Ernst, Ferdinand Hofer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report the transformation of nickel clusters into NiO rings by an electron beam induced nanoscale Kirkendall effect. High-purity nickel clusters consisting of a few thousand atoms have been used as precursors and were synthesized with the superfluid helium droplet technique. Aberration-corrected, analytical scanning transmission electron microscopy was applied to oxidise and simultaneously analyse the nanostructures. The transient dynamics of the oxidation could be documented by time lapse series using high-angle annular dark-field imaging and electron energy-loss spectroscopy. A two-step Cabrera-Mott oxidation mechanism was identified. It was found that water adsorbed adjacent to the clusters acts as oxygen source for the electron beam induced oxidation. The size-dependent oxidation rate was estimated by quantitative EELS measurements combined with molecular dynamics simulations. Our findings could serve to better control sample changes during examination in an electron microscope, and might provide a methodology to generate other metal oxide nanostructures.

Original languageEnglish
Pages (from-to)105-111
Number of pages7
Publication statusPublished - 1 May 2017


  • Cabrera-Mott oxidation
  • Electron beam induced oxidation
  • Kirkendall effect
  • Ni clusters
  • NiO rings
  • Sample damage

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

Fields of Expertise

  • Advanced Materials Science


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