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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K3Nb2CuSe12 by Materials Project

K3Nb2CuSe12 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Se+1.33- atoms. There are a spread of K–Se bond distances ranging from 3.39–3.73 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine Se+1.33- atoms. There are a spread of K–Se bond distances ranging from 3.43–3.88 Å. In the third K1+ site, K1+ is bonded in a 9-coordinate geometry to nine Se+1.33- atoms. There are a spread of K–Se bond distances ranging from 3.35–4.01 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to seven Se+1.33- atoms to form distorted NbSe7 pentagonal bipyramids that share an edgeedge with one CuSe4 tetrahedra and a faceface with one NbSe7 pentagonal bipyramid. There are a spread of Nb–Se bond distances ranging from 2.45–2.97 Å. In the second Nb5+ site, Nb5+ is bonded to seven Se+1.33- atoms to form distorted NbSe7 pentagonal bipyramids that share an edgeedge with one CuSe4 tetrahedra and a faceface with one NbSe7 pentagonal bipyramid. There are a spread of Nb–Se bond distances ranging from 2.46–2.89 Å. Cu3+ is bonded to four Se+1.33- atoms to form CuSe4 tetrahedra that share edges with two NbSe7 pentagonal bipyramids. There are a spread of Cu–Se bond distances ranging from 2.39–2.55 Å. There are twelve inequivalent Se+1.33- sites. In the first Se+1.33- site, Se+1.33- is bonded in a 1-coordinate geometry to three K1+, one Nb5+, and one Se+1.33- atom. The Se–Se bond length is 2.78 Å. In the second Se+1.33- site, Se+1.33- is bonded in a 6-coordinate geometry to two K1+, one Nb5+, one Cu3+, and two Se+1.33- atoms. The Se–Se bond length is 2.55 Å. In the third Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to four K1+, one Nb5+, and one Cu3+ atom. In the fourth Se+1.33- site, Se+1.33- is bonded in a 1-coordinate geometry to two K1+, one Nb5+, and two Se+1.33- atoms. There are one shorter (2.42 Å) and one longer (3.35 Å) Se–Se bond lengths. In the fifth Se+1.33- site, Se+1.33- is bonded in a 6-coordinate geometry to one K1+ and five Se+1.33- atoms. There are a spread of Se–Se bond distances ranging from 2.44–3.52 Å. In the sixth Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to four K1+, one Nb5+, and one Cu3+ atom. In the seventh Se+1.33- site, Se+1.33- is bonded in a 3-coordinate geometry to two K1+, one Nb5+, and one Se+1.33- atom. The Se–Se bond length is 2.43 Å. In the eighth Se+1.33- site, Se+1.33- is bonded in a 3-coordinate geometry to two K1+, two Nb5+, and one Se+1.33- atom. In the ninth Se+1.33- site, Se+1.33- is bonded in a 1-coordinate geometry to one K1+, two Nb5+, and one Se+1.33- atom. In the tenth Se+1.33- site, Se+1.33- is bonded in a 1-coordinate geometry to two equivalent K1+, one Nb5+, and two Se+1.33- atoms. The Se–Se bond length is 2.45 Å. In the eleventh Se+1.33- site, Se+1.33- is bonded in a 2-coordinate geometry to one K1+, two Nb5+, and one Se+1.33- atom. In the twelfth Se+1.33- site, Se+1.33- is bonded in a 4-coordinate geometry to two K1+, one Nb5+, one Cu3+, and one Se+1.33- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNb(CuSe2)2 by Materials Project

KCu2NbSe4 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of K–Se bond distances ranging from 3.45–3.93 Å. Nb5+ is bonded to four Se2- atoms to form NbSe4 tetrahedra that share edges with four CuSe4 tetrahedra. There are a spread of Nb–Se bond distances ranging from 2.43–2.48 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with four equivalent CuSe4 tetrahedra and edges with two equivalent NbSe4 tetrahedra. There are three shorter (2.46 Å) and one longer (2.47 Å) Cu–Se bond lengths. In the second Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with six CuSe4 tetrahedra and edges with two equivalent NbSe4 tetrahedra. There are two shorter (2.45 Å) and two longer (2.46 Å) Cu–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one K1+, one Nb5+, and three Cu1+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent K1+, one Nb5+, and two Cu1+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to four equivalent K1+, one Nb5+, and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2NbCuSe4 by Materials Project

K2NbCuSe4 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. K1+ is bonded to eight equivalent Se2- atoms to form distorted KSe8 hexagonal bipyramids that share corners with four equivalent KSe8 hexagonal bipyramids, corners with two equivalent NbSe4 tetrahedra, corners with four equivalent CuSe4 tetrahedra, edges with six equivalent KSe8 hexagonal bipyramids, edges with two equivalent CuSe4 tetrahedra, edges with three equivalent NbSe4 tetrahedra, and faces with two equivalent KSe8 hexagonal bipyramids. There are a spread of K–Se bond distances ranging from 3.53–3.71 Å. Nb5+ is bonded to four equivalent Se2- atoms to form NbSe4 tetrahedra that share corners with four equivalent KSe8 hexagonal bipyramids, edges with six equivalent KSe8 hexagonal bipyramids, and edges with two equivalent CuSe4 tetrahedra. All Nb–Se bond lengths are 2.43 Å. Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with eight equivalent KSe8 hexagonal bipyramids, edges with four equivalent KSe8 hexagonal bipyramids, and edges with two equivalent NbSe4 tetrahedra. All Cu–Se bond lengths are 2.47 Å. Se2- is bonded in a 6-coordinate geometry to four equivalent K1+, one Nb5+, and one Cu1+ atom.

36 MATERIALS SCIENCE↗