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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on NbCu3Se4 by Materials Project

Cu3NbSe4 is Sulvanite structured and crystallizes in the cubic P-43m space group. The structure is three-dimensional. Nb5+ is bonded to four equivalent Se2- atoms to form NbSe4 tetrahedra that share edges with six equivalent CuSe4 tetrahedra. All Nb–Se bond lengths are 2.47 Å. Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with eight equivalent CuSe4 tetrahedra and edges with two equivalent NbSe4 tetrahedra. All Cu–Se bond lengths are 2.47 Å. Se2- is bonded to one Nb5+ and three equivalent Cu1+ atoms to form a mixture of distorted edge and corner-sharing SeNbCu3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb4CuSe8 by Materials Project

Nb4CuSe8 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Nb4CuSe8 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Nb+3.75+ sites. In the first Nb+3.75+ site, Nb+3.75+ is bonded to six Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with four equivalent CuSe6 octahedra and edges with six NbSe6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of Nb–Se bond distances ranging from 2.61–2.65 Å. In the second Nb+3.75+ site, Nb+3.75+ is bonded to six Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with two equivalent CuSe6 octahedra, edges with six NbSe6 pentagonal pyramids, and a faceface with one CuSe6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Nb–Se bond distances ranging from 2.60–2.66 Å. Cu1+ is bonded to six Se2- atoms to form CuSe6 octahedra that share corners with twelve NbSe6 pentagonal pyramids, edges with two equivalent CuSe6 octahedra, and faces with two equivalent NbSe6 pentagonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.58–2.61 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Nb+3.75+ and one Cu1+ atom to form distorted corner-sharing SeNb3Cu trigonal pyramids. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three Nb+3.75+ and two equivalent Cu1+ atoms. In the third Se2- site, Se2- is bonded in a distorted T-shaped geometry to three Nb+3.75+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Nb+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbCuSe2 by Materials Project

NbCuSe2 is Ilmenite-like structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Nb3+ is bonded to six Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with nine equivalent CuSe4 trigonal pyramids, edges with six equivalent NbSe6 pentagonal pyramids, and a faceface with one CuSe4 trigonal pyramid. There are three shorter (2.63 Å) and three longer (2.67 Å) Nb–Se bond lengths. Cu1+ is bonded to four Se2- atoms to form distorted CuSe4 trigonal pyramids that share corners with nine equivalent NbSe6 pentagonal pyramids, corners with six equivalent CuSe4 trigonal pyramids, and a faceface with one NbSe6 pentagonal pyramid. There are one shorter (2.35 Å) and three longer (2.44 Å) Cu–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent Nb3+ and three equivalent Cu1+ atoms. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three equivalent Nb3+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb6CuSe8 by Materials Project

Nb6CuSe8 crystallizes in the trigonal P-3 space group. The structure is three-dimensional. Nb+2.50+ is bonded to six Se2- atoms to form a mixture of distorted face, edge, and corner-sharing NbSe6 octahedra. The corner-sharing octahedra tilt angles range from 45–56°. There are a spread of Nb–Se bond distances ranging from 2.60–2.80 Å. Cu1+ is bonded in a distorted hexagonal planar geometry to six equivalent Se2- atoms. All Cu–Se bond lengths are 3.23 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to six equivalent Nb+2.50+ atoms to form distorted face-sharing SeNb6 pentagonal pyramids. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent Nb+2.50+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗