Evolution in the structure of akaganeite and hematite during hydrothermal growth: An in situ synchrotron X-ray diffraction analysis

Kristina M. Peterson, Peter J. Heaney, Jeffrey E. Post

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Synchrotron X-ray diffraction was used to monitor the hydrothermal precipitation of akaganeite (β-FeOOH) and its transformation to hematite (Fe2O3) in situ. Akaganeite was the first phase to form and hematite was the final phase in our experiments with temperatures between 150 and 200 °C. Akaganeite was the only phase that formed at 100 °C. Rietveld analyses revealed that the akaganeite unit-cell volume contracted until the onset of dissolution, and subsequently expanded. This reversal at the onset of dissolution was associated with a substantial and rapid increase in occupancy of the Cl site, perhaps by OH- or Fe3+. Rietveld analyses supported the incipient formation of an OH-rich, Fe-deficient hematite phase in experiments between 150 and 200 °C. The inferred H concentrations of the first crystals were consistent with hydrohematite. With continued crystal growth, the Fe occupancies increased. Contraction in both a- and c-axes signaled the loss of hydroxyl groups and formation of a nearly stoichiometric hematite.

Original languageEnglish (US)
Pages (from-to)287-297
Number of pages11
JournalPowder Diffraction
Volume33
Issue number4
DOIs
StatePublished - Dec 1 2018

All Science Journal Classification (ASJC) codes

  • Radiation
  • Materials Science(all)
  • Instrumentation
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Evolution in the structure of akaganeite and hematite during hydrothermal growth: An in situ synchrotron X-ray diffraction analysis'. Together they form a unique fingerprint.

Cite this