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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Fe3S4 by Materials Project

Fe3S4 is Calaverite-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Fe3S4 sheets oriented in the (0, 0, 1) direction. there are three inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form distorted edge-sharing FeS6 pentagonal pyramids. All Fe–S bond lengths are 2.37 Å. In the second Fe+2.67+ site, Fe+2.67+ is bonded in a 6-coordinate geometry to six S2- atoms. There are three shorter (2.18 Å) and three longer (2.57 Å) Fe–S bond lengths. In the third Fe+2.67+ site, Fe+2.67+ is bonded in a 6-coordinate geometry to six S2- atoms. There are three shorter (2.16 Å) and three longer (2.58 Å) Fe–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Fe+2.67+ atoms. In the second S2- site, S2- is bonded to six Fe+2.67+ atoms to form a mixture of distorted edge, corner, and face-sharing SFe6 octahedra. The corner-sharing octahedral tilt angles are 44°. In the third S2- site, S2- is bonded to six Fe+2.67+ atoms to form a mixture of distorted edge, corner, and face-sharing SFe6 octahedra. The corner-sharing octahedral tilt angles are 44°. In the fourth S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3S4 by Materials Project

Fe3S4 crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Fe3S4 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are three shorter (2.25 Å) and three longer (2.38 Å) Fe–S bond lengths. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six equivalent S2- atoms to form a mixture of edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles are 49°. All Fe–S bond lengths are 2.27 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to six Fe+2.67+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3S4 by Materials Project

Fe3S4 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Fe3S4 sheets oriented in the (1, 0, 0) direction. there are three inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form a mixture of edge, corner, and face-sharing FeS6 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Fe–S bond distances ranging from 2.17–2.34 Å. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form a mixture of distorted edge, corner, and face-sharing FeS6 octahedra. The corner-sharing octahedra tilt angles range from 43–47°. There are a spread of Fe–S bond distances ranging from 2.20–2.42 Å. In the third Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form a mixture of edge, corner, and face-sharing FeS6 octahedra. The corner-sharing octahedra tilt angles range from 43–57°. There are a spread of Fe–S bond distances ranging from 2.21–2.35 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Fe+2.67+ atoms. In the second S2- site, S2- is bonded in a trigonal non-coplanar geometry to three Fe+2.67+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to six Fe+2.67+ atoms. In the fourth S2- site, S2- is bonded in a 6-coordinate geometry to six Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3S4 by Materials Project

Fe3S4 is Hausmannite structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to four equivalent S2- atoms to form corner-sharing FeS4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. All Fe–S bond lengths are 2.14 Å. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six equivalent S2- atoms to form FeS6 octahedra that share corners with six equivalent FeS4 tetrahedra and edges with six equivalent FeS6 octahedra. All Fe–S bond lengths are 2.34 Å. S2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3S4 by Materials Project

Fe3S4 is Hausmannite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with six equivalent FeS4 tetrahedra and edges with six FeS6 octahedra. There are four shorter (2.33 Å) and two longer (2.34 Å) Fe–S bond lengths. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six equivalent S2- atoms to form FeS6 octahedra that share corners with six equivalent FeS4 tetrahedra and edges with six equivalent FeS6 octahedra. All Fe–S bond lengths are 2.29 Å. In the third Fe+2.67+ site, Fe+2.67+ is bonded to four S2- atoms to form corner-sharing FeS4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–58°. There are one shorter (2.15 Å) and three longer (2.17 Å) Fe–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to four Fe+2.67+ atoms to form a mixture of distorted corner and edge-sharing SFe4 trigonal pyramids. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The low-temperature heat capacity and thermodynamic properties of greigite (Fe 3 S 4 )

Heat capacity measurements provide important insights into the energetic, thermodynamic, and magnetic properties of materials. Herein we report the heat capacity of greigite (Fe 3 S 4 ) from 1.8 to 300 K. Greigite is a magnetic spinel mineral and through a ferromagnetic magnon term, C fsw = B fsw T 3/2 , ferrimagnetic ordering is observed in the low-temperature heat capacity. Using a set of theoretical fits of the experimental data, we calculate the thermodynamic functions, including the standard entropy ($Δ_{0}^{T}$S m °). Greigite is important in iron sulfide formation and reaction pathways in environmental, ore-forming, and technological settings and previous work has measured enthalpies $ΔH_{r}°$ of formation and decomposition to neighboring phases. In this work, the stability of greigite relative to the elements is demonstrated with a negative Gibbs energy ($ΔG_{r}°$) of formation and the stability relative to decomposition products of pyrrhotite (FeS 1.092 ) and pyrite (FeS 2 ) is demonstrated with a positive Gibbs energy ($ΔG_{r}°$) of decomposition. Values of the standard thermodynamic functions C p,m °, $Δ_{0}^{T}$S m °, $Δ_{0}^{T}$H m °, and Φ m ° are tabulated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗