Journal Article

FZJ-2020-04517

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Atomic-scale Characterization of Commensurate and Incommensurate Vacancy Superstructures in Natural Pyrrhotites

Jin, L. (Corresponding author)FZJ* ; Koulialias, D. ; Schnedler, M.FZJ* ; Gehring, M.FZJ* ; Posfai, M. ; Ebert, P.FZJ* ; Charilaou, M. ; Schaueblin, R. E. ; Jia, C.-L.FZJ* ; Loeffler, J. F. ; Dunin-Borkowski, R.FZJ*

2021
GeoScienceWorld Alexandria, Va.

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Please use a persistent id in citations: http://hdl.handle.net/2128/26654  doi:10.2138/am-2020-7479ccby  doi:10.2138/am-2020-7479CCBY

Abstract: Pyrrhotites, characterized by the chemical formula Fe1–δS (0 < δ ≤ 1/8), represent an extended group of minerals that are derived from the NiAs-type FeS aristotype. They contain layered arrangements of ordered Fe vacancies, which are at the origin of the various magnetic signals registered from certain natural rocks and can act as efficient electrocatalysts in oxygen evolution reactions in ultrathin form. Despite extensive studies over the past century, the local structural details of pyrrhotite superstructures formed by different arrangements of Fe vacancies remain unclear, in particular at the atomic scale. Here, atomic-resolution high-angle annular dark-field imaging and nanobeam electron diffraction in the scanning transmission electron microscope are used to study natural pyrrhotite samples that contain commensurate 4C and incommensurate 4.91 ± 0.02C constituents. Local measurements of both the intensities and the picometer-scale shifts of individual Fe atomic columns are shown to be consistent with a model for the structure of 4C pyrrhotite, which was derived using X-ray diffraction by Tokonami et al. (1972). In 4.91 ± 0.02C pyrrhotite, 5C-like unequally sized nano-regions are found to join at anti-phase-like boundaries, leading to the incommensurability observed in the present pyrrhotite sample. This conclusion is supported by computer simulations. The local magnetic properties of each phase are inferred from the measurements. A discussion of perspectives for the quantitative counting of Fe vacancies at the atomic scale is presented.

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Contributing Institute(s):

1. Physik Nanoskaliger Systeme (ER-C-1)

Research Program(s):

1. 5351 - Platform for Correlative, In Situ and Operando Characterization (POF4-535) (POF4-535)
2. 3D MAGiC - Three-dimensional magnetization textures: Discovery and control on the nanoscale (856538) (856538)
3. ESTEEM3 - Enabling Science and Technology through European Electron Microscopy (823717) (823717)
4. DARPA, Phase 2 - Defense Advanced Research Projects Agency Manipulation of magnetic skyrmions for logicin- memory applications (Z1422.01.18) (Z1422.01.18)

Appears in the scientific report 2021

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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