Room-temperature precipitation from aqueous solutions yields the hitherto unknown metastable stoichiometric iron selenide (ms-FeSe) with tetragonal anti-PbO type structure. Samples with improved crystallinity are obtained by diffusion-controlled precipitation or hydrothermal recrystallization. The relations of ms-FeSe to superconducting η-FeSe 1-x and other neighbor phases of the iron-selenium system are established by high-temperature X-ray diffraction, DSC/TG/MS (differential scanning calorimetry/ thermogravimetry/mass spectroscopy), 57Fe Mössbauer spectroscopy, magnetization measurements, and transmission electron microscopy. Above 300 °C, ms-FeSe decomposes irreversibly to η-FeSe 1-x and Fe 7Se 8. The structural parameters of ms-FeSe (P4/nmm, a = 377.90(1) pm, c = 551.11(3) pm, Z = 2), obtained by Rietveld refinement, differ significantly from literature data for η-FeSe 1-x. The Mössbauer spectrum rules out interstitial iron atoms or additional phases. Magnetization data suggest canted antiferromagnetism below T N = 50 K. Stoichiometric non-superconducting ms-FeSe can be regarded as the true parent compound for the 11 iron-chalcogenide superconductors and may serve as starting point for new chemical modifications. © 2012 American Chemical Society.
CITATION STYLE
Nitsche, F., Goltz, T., Klauss, H. H., Isaeva, A., Müller, U., Schnelle, W., … Ruck, M. (2012). Room-temperature synthesis, hydrothermal recrystallization, and properties of metastable stoichiometric FeSe. Inorganic Chemistry, 51(13), 7370–7376. https://doi.org/10.1021/ic300798p
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