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DOE OSTI2020

Materials Data on Nb4FeSi by Materials Project

Nb4FeSi is Khatyrkite-derived structured and crystallizes in the tetragonal P4/mcc space group. The structure is three-dimensional. Nb is bonded in a 4-coordinate geometry to two equivalent Fe and two equivalent Si atoms. Both Nb–Fe bond lengths are 2.60 Å. Both Nb–Si bond lengths are 2.71 Å. Fe is bonded in a 10-coordinate geometry to eight equivalent Nb and two equivalent Fe atoms. Both Fe–Fe bond lengths are 2.55 Å. Si is bonded in a 10-coordinate geometry to eight equivalent Nb and two equivalent Si atoms. Both Si–Si bond lengths are 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb6Fe16Si7 by Materials Project

Fe16Nb6Si7 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Nb is bonded in a 12-coordinate geometry to eight Fe and four equivalent Si atoms. There are four shorter (2.75 Å) and four longer (2.78 Å) Nb–Fe bond lengths. All Nb–Si bond lengths are 2.86 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to three equivalent Nb, six Fe, and three equivalent Si atoms. There are three shorter (2.42 Å) and three longer (2.47 Å) Fe–Fe bond lengths. All Fe–Si bond lengths are 2.30 Å. In the second Fe site, Fe is bonded in a 1-coordinate geometry to three equivalent Nb, six Fe, and four Si atoms. All Fe–Fe bond lengths are 2.70 Å. There are one shorter (2.34 Å) and three longer (2.47 Å) Fe–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Nb and eight Fe atoms to form a mixture of face and corner-sharing SiNb4Fe8 cuboctahedra. In the second Si site, Si is bonded in a body-centered cubic geometry to eight equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb4Fe4Si7 by Materials Project

Nb4Fe4Si7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Nb2+ sites. In the first Nb2+ site, Nb2+ is bonded to seven Si+2.86- atoms to form NbSi7 pentagonal bipyramids that share corners with eight equivalent FeSi6 octahedra, corners with eight NbSi7 pentagonal bipyramids, edges with three equivalent NbSi7 pentagonal bipyramids, faces with four equivalent FeSi6 octahedra, and faces with six NbSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 43–51°. There are a spread of Nb–Si bond distances ranging from 2.67–2.83 Å. In the second Nb2+ site, Nb2+ is bonded to seven Si+2.86- atoms to form NbSi7 pentagonal bipyramids that share corners with eight equivalent FeSi6 octahedra, corners with eight NbSi7 pentagonal bipyramids, an edgeedge with one NbSi7 pentagonal bipyramid, faces with four equivalent FeSi6 octahedra, and faces with six NbSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 42–53°. There are a spread of Nb–Si bond distances ranging from 2.65–2.83 Å. Fe3+ is bonded to six Si+2.86- atoms to form distorted FeSi6 octahedra that share corners with six equivalent FeSi6 octahedra, corners with eight NbSi7 pentagonal bipyramids, edges with three equivalent FeSi6 octahedra, faces with two equivalent FeSi6 octahedra, and faces with four NbSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 33–37°. There are two shorter (2.31 Å) and four longer (2.36 Å) Fe–Si bond lengths. There are four inequivalent Si+2.86- sites. In the first Si+2.86- site, Si+2.86- is bonded in a 6-coordinate geometry to one Nb2+, four equivalent Fe3+, and one Si+2.86- atom. The Si–Si bond length is 2.38 Å. In the second Si+2.86- site, Si+2.86- is bonded in a 10-coordinate geometry to eight Nb2+ and two equivalent Si+2.86- atoms. Both Si–Si bond lengths are 2.50 Å. In the third Si+2.86- site, Si+2.86- is bonded in a 9-coordinate geometry to five Nb2+ and four equivalent Fe3+ atoms. In the fourth Si+2.86- site, Si+2.86- is bonded in a 12-coordinate geometry to four Nb2+ and four equivalent Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3Fe8Si by Materials Project

Nb3Fe8Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are three inequivalent Nb sites. In the first Nb site, Nb is bonded in a 9-coordinate geometry to one Nb, twelve Fe, and three equivalent Si atoms. The Nb–Nb bond length is 2.93 Å. There are a spread of Nb–Fe bond distances ranging from 2.74–2.82 Å. All Nb–Si bond lengths are 2.88 Å. In the second Nb site, Nb is bonded in a 12-coordinate geometry to four Nb and twelve Fe atoms. All Nb–Nb bond lengths are 3.01 Å. There are a spread of Nb–Fe bond distances ranging from 2.79–2.83 Å. In the third Nb site, Nb is bonded in a 10-coordinate geometry to three equivalent Nb, twelve Fe, and one Si atom. There are a spread of Nb–Fe bond distances ranging from 2.72–2.95 Å. The Nb–Si bond length is 2.83 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded to three equivalent Nb, six Fe, and three equivalent Si atoms to form FeNb3Fe6Si3 cuboctahedra that share corners with twelve FeNb4Fe6Si2 cuboctahedra, edges with six equivalent FeNb3Fe6Si3 cuboctahedra, and faces with twenty FeNb6Fe6 cuboctahedra. There are three shorter (2.38 Å) and three longer (2.39 Å) Fe–Fe bond lengths. All Fe–Si bond lengths are 2.79 Å. In the second Fe site, Fe is bonded to six Nb and six Fe atoms to form FeNb6Fe6 cuboctahedra that share corners with twelve FeNb4Fe6Si2 cuboctahedra, edges with six equivalent FeNb6Fe6 cuboctahedra, and faces with twenty FeNb3Fe6Si3 cuboctahedra. There are three shorter (2.36 Å) and three longer (2.45 Å) Fe–Fe bond lengths. In the third Fe site, Fe is bonded to four Nb, six Fe, and two equivalent Si atoms to form FeNb4Fe6Si2 cuboctahedra that share corners with eighteen FeNb3Fe6Si3 cuboctahedra, edges with six FeNb5Fe6Si cuboctahedra, and faces with eighteen FeNb3Fe6Si3 cuboctahedra. There are two shorter (2.37 Å) and two longer (2.42 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.85 Å. In the fourth Fe site, Fe is bonded to five Nb, six Fe, and one Si atom to form FeNb5Fe6Si cuboctahedra that share corners with eighteen FeNb3Fe6Si3 cuboctahedra, edges with six FeNb5Fe6Si cuboctahedra, and faces with eighteen FeNb3Fe6Si3 cuboctahedra. There are two shorter (2.35 Å) and two longer (2.44 Å) Fe–Fe bond lengths. The Fe–Si bond length is 2.69 Å. Si is bonded in a 1-coordinate geometry to four Nb and twelve Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbFe4Si by Materials Project

NbFe4Si crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Nb is bonded in a 1-coordinate geometry to three equivalent Nb, twelve Fe, and one Si atom. All Nb–Nb bond lengths are 3.03 Å. There are a spread of Nb–Fe bond distances ranging from 2.73–2.89 Å. The Nb–Si bond length is 2.72 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Nb and six equivalent Fe atoms to form FeNb6Fe6 cuboctahedra that share corners with twelve equivalent FeNb3Fe6Si3 cuboctahedra, edges with six equivalent FeNb6Fe6 cuboctahedra, and faces with twenty FeFe6Si6 cuboctahedra. All Fe–Fe bond lengths are 2.40 Å. In the second Fe site, Fe is bonded to six equivalent Fe and six equivalent Si atoms to form FeFe6Si6 cuboctahedra that share corners with twelve equivalent FeNb3Fe6Si3 cuboctahedra, edges with six equivalent FeFe6Si6 cuboctahedra, and faces with twenty FeNb6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.31 Å. All Fe–Si bond lengths are 2.80 Å. In the third Fe site, Fe is bonded to three equivalent Nb, six Fe, and three equivalent Si atoms to form FeNb3Fe6Si3 cuboctahedra that share corners with eighteen FeNb6Fe6 cuboctahedra, edges with six equivalent FeNb3Fe6Si3 cuboctahedra, and faces with eighteen FeNb6Fe6 cuboctahedra. There are two shorter (2.35 Å) and two longer (2.44 Å) Fe–Fe bond lengths. There are one shorter (2.64 Å) and two longer (2.78 Å) Fe–Si bond lengths. Si is bonded in a 1-coordinate geometry to one Nb and twelve Fe atoms.

36 MATERIALS SCIENCE↗