Probing reduction and oxidation behavior of iron oxides and iron by reactive in-situ X-ray diffraction

The reduction of iron oxides and their re-oxidation will be analyzed by in-situ/operando, high temperature (HT) X-ray diffraction experiments under various atmospheres (air, 5% hydrogen in nitrogen, oxygen) and with different heating ramps (up to 900 °C).

The oxygen loss and incorporation will be monitored by determinations of lattice parameters and site occupation factors under reactive conditions. To probe for particle size effects, iron oxides will be synthesized following different synthetic routes (e.g. precipitation, solid-state) and temperature regimes, and crystallite sizes will be estimated using the Scherrer formula (and compared to electron micrographs where appropriate). The influence of dopants or impurities on the oxidation and reduction behavior (cyclability) of iron will be checked, with the dopant status to be determined by ICP-OES. Selected samples are to be investigated by thermal analyses using DSC/TGA (up to 1500 °C), and detected phase changes will be compared to findings from Mössbauer spectroscopy and XRD.

Scientific questions

  • How does the kinetics of oxidation/reduction and cyclability differ for different particle sizes and dopant contents?
  • To what extent do variations in conditions (atmosphere, temperature) cause an alteration of the phase composition?
  • Which time resolution will be possible during in situ thermal oxidation and reduction?
  • Is it possible to correlate findings from in-situ and ex-situ observations?
  • To what extent is it possible to mimic realistic thermochemical conditions in combustion chambers by analytical set-ups under reactive atmospheres?

Team

Technical University of Darmstadt

Contact

work +49 6151 16-22931

Work L2|05 317
Alarich-Weiss-Straße 12
64287 Darmstadt

Technical University of Darmstadt

Associated member

Contact

work +49 6151 16-22934

Work L2|05 111
Alarich-Weiss-Str- 12
64287 Darmstadt