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DOE OSTI2020

Materials Data on Nb2Cr4Si5 by Materials Project

Nb2Cr4Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Nb2+ is bonded to seven Si+2.40- atoms to form a mixture of corner, edge, and face-sharing NbSi7 pentagonal bipyramids. There are a spread of Nb–Si bond distances ranging from 2.57–2.75 Å. There are two inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded in a 8-coordinate geometry to two equivalent Cr2+ and six Si+2.40- atoms. Both Cr–Cr bond lengths are 2.43 Å. There are a spread of Cr–Si bond distances ranging from 2.42–2.53 Å. In the second Cr2+ site, Cr2+ is bonded in a 7-coordinate geometry to seven Si+2.40- atoms. There are a spread of Cr–Si bond distances ranging from 2.35–2.74 Å. There are three inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to four equivalent Nb2+, four equivalent Cr2+, and two equivalent Si+2.40- atoms. Both Si–Si bond lengths are 2.43 Å. In the second Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to one Nb2+, six Cr2+, and three equivalent Si+2.40- atoms. There are one shorter (2.35 Å) and two longer (2.69 Å) Si–Si bond lengths. In the third Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to four equivalent Nb2+ and five Cr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb4Cr2Si5 by Materials Project

Nb4Cr2Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. there are two inequivalent Nb2+ sites. In the first Nb2+ site, Nb2+ is bonded to seven Si+2.40- atoms to form a mixture of distorted edge, face, and corner-sharing NbSi7 pentagonal bipyramids. There are a spread of Nb–Si bond distances ranging from 2.53–2.79 Å. In the second Nb2+ site, Nb2+ is bonded to seven Si+2.40- atoms to form a mixture of edge, face, and corner-sharing NbSi7 pentagonal bipyramids. There are a spread of Nb–Si bond distances ranging from 2.67–2.85 Å. Cr2+ is bonded in a 8-coordinate geometry to two equivalent Cr2+ and six Si+2.40- atoms. Both Cr–Cr bond lengths are 2.48 Å. There are a spread of Cr–Si bond distances ranging from 2.44–2.66 Å. There are three inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to eight Nb2+ and two equivalent Si+2.40- atoms. Both Si–Si bond lengths are 2.48 Å. In the second Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to five Nb2+, two equivalent Cr2+, and three equivalent Si+2.40- atoms. There are one shorter (2.64 Å) and two longer (2.80 Å) Si–Si bond lengths. In the third Si+2.40- site, Si+2.40- is bonded in a 11-coordinate geometry to five Nb2+, four equivalent Cr2+, and two equivalent Si+2.40- atoms. Both Si–Si bond lengths are 2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbCrSi by Materials Project

CrNbSi crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Nb2+ is bonded to five Si4- atoms to form distorted NbSi5 square pyramids that share corners with ten equivalent NbSi5 square pyramids, corners with six equivalent CrSi4 tetrahedra, edges with six equivalent NbSi5 square pyramids, and edges with six equivalent CrSi4 tetrahedra. There are four shorter (2.62 Å) and one longer (2.69 Å) Nb–Si bond lengths. Cr2+ is bonded to four Si4- atoms to form distorted CrSi4 tetrahedra that share corners with six equivalent NbSi5 square pyramids, corners with ten equivalent CrSi4 tetrahedra, edges with six equivalent NbSi5 square pyramids, and edges with two equivalent CrSi4 tetrahedra. There are two shorter (2.37 Å) and two longer (2.53 Å) Cr–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to three equivalent Nb2+ and six equivalent Cr2+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to six equivalent Nb2+ and three equivalent Cr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbCr4Si by Materials Project

NbCr4Si 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 Cr, and one Si atom. All Nb–Nb bond lengths are 3.00 Å. There are six shorter (2.85 Å) and six longer (2.86 Å) Nb–Cr bond lengths. The Nb–Si bond length is 2.79 Å. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six equivalent Nb and six equivalent Cr atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent CrNb3Cr6Si3 cuboctahedra, edges with six equivalent CrNb6Cr6 cuboctahedra, and faces with twenty CrCr6Si6 cuboctahedra. All Cr–Cr bond lengths are 2.47 Å. In the second Cr site, Cr is bonded to six equivalent Cr and six equivalent Si atoms to form CrCr6Si6 cuboctahedra that share corners with twelve equivalent CrNb3Cr6Si3 cuboctahedra, edges with six equivalent CrCr6Si6 cuboctahedra, and faces with twenty CrNb6Cr6 cuboctahedra. All Cr–Cr bond lengths are 2.33 Å. All Cr–Si bond lengths are 2.86 Å. In the third Cr site, Cr is bonded to three equivalent Nb, six Cr, and three equivalent Si atoms to form CrNb3Cr6Si3 cuboctahedra that share corners with eighteen CrNb6Cr6 cuboctahedra, edges with six equivalent CrNb3Cr6Si3 cuboctahedra, and faces with eighteen CrNb6Cr6 cuboctahedra. There are two shorter (2.37 Å) and two longer (2.51 Å) Cr–Cr bond lengths. There are one shorter (2.71 Å) and two longer (2.76 Å) Cr–Si bond lengths. Si is bonded in a 10-coordinate geometry to one Nb and twelve Cr atoms.

36 MATERIALS SCIENCE↗