Inflexible stoichiometry in bulk pyrite FeS2 as viewed by in situ and high-resolution X-ray diffraction

Rebecca D. McAuliffe, Daniel P. Shoemaker

Research output: Contribution to journalArticlepeer-review


Non-stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS2, as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS2−δ with δ up to 0.25, the current consensus based on calculated formation energies of intrinsic defects has lent support to line-compound behavior. Here it is shown that pyrite stoichiometry is relatively inflexible in both reductive conditions and in autogenous sulfur partial pressure, which produces samples with precise stoichiometry of FeS2 even at different Fe/S ratios. By properly standardizing in situ gas-flow X-ray diffraction measurements, no significant changes in the lattice parameter of FeS2 can be resolved, which portrays iron pyrite as prone to forming sulfur-deficient compounds, but not intrinsic defects in the manner of NiS2−δ.

Original languageEnglish (US)
Pages (from-to)436-444
Number of pages9
JournalActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials
Issue number5
StatePublished - Oct 2018


  • high-resolution X-ray diffraction
  • in situ high-resolution X-ray diffraction
  • iron pyrite
  • stoichiometry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Metals and Alloys
  • Materials Chemistry


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