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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nb4CrSe8 by Materials Project

Nb4CrSe8 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Nb+3.50+ sites. In the first Nb+3.50+ site, Nb+3.50+ is bonded to six equivalent Se2- atoms to form NbSe6 octahedra that share edges with six equivalent NbSe6 octahedra and faces with two equivalent CrSe6 pentagonal pyramids. All Nb–Se bond lengths are 2.65 Å. In the second Nb+3.50+ site, Nb+3.50+ is bonded to six Se2- atoms to form NbSe6 octahedra that share corners with four equivalent CrSe6 pentagonal pyramids and edges with six NbSe6 octahedra. There are two shorter (2.62 Å) and four longer (2.64 Å) Nb–Se bond lengths. Cr2+ is bonded to six equivalent Se2- atoms to form distorted CrSe6 pentagonal pyramids that share corners with twelve equivalent NbSe6 octahedra and faces with two equivalent NbSe6 octahedra. The corner-sharing octahedral tilt angles are 45°. All Cr–Se bond lengths are 2.68 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Nb+3.50+ and one Cr2+ atom to form a mixture of distorted corner and edge-sharing SeNb3Cr trigonal pyramids. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbCrSe5 by Materials Project

NbCrSe5 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one NbCrSe5 sheet oriented in the (1, 0, 0) direction. Nb5+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Nb–Se bond distances ranging from 2.67–2.77 Å. Cr5+ is bonded to six Se2- atoms to form edge-sharing CrSe6 octahedra. There are a spread of Cr–Se bond distances ranging from 2.47–2.56 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to three equivalent Nb5+ and one Cr5+ atom. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Cr5+ atoms. In the third Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ atoms. In the fourth Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ atoms. In the fifth Se2- site, Se2- is bonded in a 3-coordinate geometry to one Nb5+ and two equivalent Cr5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb2CrSe4 by Materials Project

Nb2CrSe4 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Nb+2.50+ sites. In the first Nb+2.50+ site, Nb+2.50+ is bonded in a 7-coordinate geometry to one Cr3+ and six Se2- atoms. The Nb–Cr bond length is 2.43 Å. There are two shorter (2.59 Å) and four longer (2.79 Å) Nb–Se bond lengths. In the second Nb+2.50+ site, Nb+2.50+ is bonded to six equivalent Se2- atoms to form distorted NbSe6 pentagonal pyramids that share faces with two equivalent CrSe6 octahedra. All Nb–Se bond lengths are 2.62 Å. There are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six equivalent Se2- atoms to form CrSe6 octahedra that share faces with two equivalent NbSe6 pentagonal pyramids. All Cr–Se bond lengths are 2.56 Å. In the second Cr3+ site, Cr3+ is bonded in a 9-coordinate geometry to three equivalent Nb+2.50+ and six equivalent Se2- atoms. All Cr–Se bond lengths are 2.64 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to three Nb+2.50+ and two Cr3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb2CrSe4 by Materials Project

Nb2CrSe4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Nb+2.50+ is bonded to six Se2- atoms to form distorted NbSe6 octahedra that share corners with six equivalent CrSe6 octahedra, edges with six equivalent NbSe6 octahedra, and a faceface with one CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Nb–Se bond distances ranging from 2.58–2.87 Å. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with twelve equivalent NbSe6 octahedra, edges with two equivalent CrSe6 octahedra, and faces with two equivalent NbSe6 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are two shorter (2.57 Å) and four longer (2.62 Å) Cr–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to three equivalent Nb+2.50+ and one Cr3+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three equivalent Nb+2.50+ and two equivalent Cr3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3CrSe6 by Materials Project

Nb3CrSe6 is Ilmenite-like structured and crystallizes in the hexagonal P6_322 space group. The structure is three-dimensional. there are two inequivalent Nb3+ sites. In the first Nb3+ site, Nb3+ is bonded to six equivalent Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent CrSe6 octahedra, edges with six NbSe6 pentagonal pyramids, and a faceface with one CrSe6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.62 Å) and three longer (2.65 Å) Nb–Se bond lengths. In the second Nb3+ site, Nb3+ is bonded to six equivalent Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent CrSe6 octahedra and edges with six equivalent NbSe6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 47°. All Nb–Se bond lengths are 2.62 Å. Cr3+ is bonded to six equivalent Se2- atoms to form CrSe6 octahedra that share corners with twelve NbSe6 pentagonal pyramids and faces with two equivalent NbSe6 pentagonal pyramids. All Cr–Se bond lengths are 2.54 Å. Se2- is bonded in a distorted rectangular see-saw-like geometry to three Nb3+ and one Cr3+ atom.

36 MATERIALS SCIENCE↗