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Inflexible stoichiometry in bulk pyrite FeS 2 as viewed by in situ and high‐resolution X‐ray diffraction
Author(s) -
McAuliffe Rebecca D.,
Shoemaker Daniel P.
Publication year - 2018
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520618010144
Subject(s) - pyrite , stoichiometry , diffraction , sulfur , pyrrhotite , x ray crystallography , chemistry , analytical chemistry (journal) , solubility , materials science , iron sulfide , mineralogy , metallurgy , optics , physics , environmental chemistry
Non‐stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS 2 , as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS 2−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 FeS 2 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 FeS 2 can be resolved, which portrays iron pyrite as prone to forming sulfur‐deficient compounds, but not intrinsic defects in the manner of NiS 2−δ .