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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nb3FeSe6 by Materials Project

Nb3FeSe6 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 six equivalent FeSe6 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. In the second Nb3+ site, Nb3+ is bonded to six equivalent Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent FeSe6 octahedra, edges with six NbSe6 pentagonal pyramids, and a faceface with one FeSe6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.63 Å) and three longer (2.64 Å) Nb–Se bond lengths. Fe3+ is bonded to six equivalent Se2- atoms to form FeSe6 octahedra that share corners with twelve NbSe6 pentagonal pyramids and faces with two equivalent NbSe6 pentagonal pyramids. All Fe–Se bond lengths are 2.52 Å. Se2- is bonded in a distorted rectangular see-saw-like geometry to three Nb3+ and one Fe3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb4FeSe8 by Materials Project

Nb4FeSe8 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 distorted NbSe6 pentagonal pyramids that share edges with six equivalent NbSe6 pentagonal pyramids and faces with two equivalent FeSe6 octahedra. All Nb–Se bond lengths are 2.64 Å. In the second Nb+3.50+ site, Nb+3.50+ is bonded to six Se2- atoms to form distorted NbSe6 pentagonal pyramids that share corners with four equivalent FeSe6 octahedra and edges with six NbSe6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 48°. There are two shorter (2.59 Å) and four longer (2.64 Å) Nb–Se bond lengths. Fe2+ is bonded to six equivalent Se2- atoms to form FeSe6 octahedra that share corners with twelve equivalent NbSe6 pentagonal pyramids and faces with two equivalent NbSe6 pentagonal pyramids. All Fe–Se bond lengths are 2.57 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+3.50+ atoms. In the second Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Nb+3.50+ and one Fe2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbFeSe5 by Materials Project

NbFeSe5 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one NbFeSe5 sheet oriented in the (1, 0, 0) direction. Nb2+ is bonded in a 8-coordinate geometry to eight Se+0.80- atoms. There are a spread of Nb–Se bond distances ranging from 2.65–2.78 Å. Fe2+ is bonded to six Se+0.80- atoms to form edge-sharing FeSe6 octahedra. There are a spread of Fe–Se bond distances ranging from 2.41–2.61 Å. There are five inequivalent Se+0.80- sites. In the first Se+0.80- site, Se+0.80- is bonded in a 2-coordinate geometry to two equivalent Nb2+ atoms. In the second Se+0.80- site, Se+0.80- is bonded in a 2-coordinate geometry to two equivalent Nb2+ atoms. In the third Se+0.80- site, Se+0.80- is bonded to three equivalent Nb2+ and one Fe2+ atom to form a mixture of distorted corner and edge-sharing SeNb3Fe tetrahedra. In the fourth Se+0.80- site, Se+0.80- is bonded in a 3-coordinate geometry to three equivalent Fe2+ atoms. In the fifth Se+0.80- site, Se+0.80- is bonded in a 3-coordinate geometry to one Nb2+ and two equivalent Fe2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3FeSe10 by Materials Project

FeNb3Se10 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one FeNb3Se10 sheet oriented in the (1, 0, 0) direction. there are three inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded in a 8-coordinate geometry to eight Se+1.40- atoms. There are a spread of Nb–Se bond distances ranging from 2.66–2.85 Å. In the second Nb4+ site, Nb4+ is bonded in a 8-coordinate geometry to eight Se+1.40- atoms. There are a spread of Nb–Se bond distances ranging from 2.65–2.77 Å. In the third Nb4+ site, Nb4+ is bonded to six Se+1.40- atoms to form distorted NbSe6 octahedra that share edges with two equivalent NbSe6 octahedra and edges with two equivalent FeSe6 octahedra. There are a spread of Nb–Se bond distances ranging from 2.43–2.82 Å. Fe2+ is bonded to six Se+1.40- atoms to form FeSe6 octahedra that share edges with two equivalent NbSe6 octahedra and edges with two equivalent FeSe6 octahedra. There are a spread of Fe–Se bond distances ranging from 2.41–2.48 Å. There are ten inequivalent Se+1.40- sites. In the first Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two equivalent Nb4+ atoms. In the second Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two equivalent Nb4+ atoms. In the third Se+1.40- site, Se+1.40- is bonded to four Nb4+ atoms to form distorted corner-sharing SeNb4 tetrahedra. In the fourth Se+1.40- site, Se+1.40- is bonded in a 4-coordinate geometry to three Nb4+ and one Fe2+ atom. In the fifth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two equivalent Nb4+ atoms. In the sixth Se+1.40- site, Se+1.40- is bonded in a 2-coordinate geometry to two equivalent Nb4+ atoms. In the seventh Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to three Nb4+ atoms. In the eighth Se+1.40- site, Se+1.40- is bonded in a distorted trigonal non-coplanar geometry to one Nb4+ and two equivalent Fe2+ atoms. In the ninth Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to two equivalent Nb4+ and one Fe2+ atom. In the tenth Se+1.40- site, Se+1.40- is bonded in a 3-coordinate geometry to one Nb4+ and two equivalent Fe2+ atoms.

36 MATERIALS SCIENCE↗