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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na6FeSe4 by Materials Project

Na6FeSe4 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four Se2- atoms to form distorted NaSe4 tetrahedra that share corners with two equivalent FeSe4 tetrahedra, corners with eight equivalent NaSe4 tetrahedra, and an edgeedge with one FeSe4 tetrahedra. There are a spread of Na–Se bond distances ranging from 2.88–3.03 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.97–3.58 Å. Fe2+ is bonded to four Se2- atoms to form FeSe4 tetrahedra that share corners with six equivalent NaSe4 tetrahedra and edges with three equivalent NaSe4 tetrahedra. All Fe–Se bond lengths are 2.48 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to nine Na1+ and one Fe2+ atom. In the second Se2- site, Se2- is bonded in a 8-coordinate geometry to seven Na1+ and one Fe2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3FeSe3 by Materials Project

Na3FeSe3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form distorted NaSe6 octahedra that share corners with eight NaSe6 octahedra, corners with four equivalent FeSe4 tetrahedra, edges with five NaSe6 octahedra, and edges with two equivalent FeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–65°. There are a spread of Na–Se bond distances ranging from 3.00–3.56 Å. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form distorted NaSe6 octahedra that share corners with six equivalent NaSe6 octahedra, corners with three equivalent FeSe4 tetrahedra, edges with three equivalent NaSe6 octahedra, an edgeedge with one FeSe4 tetrahedra, faces with two equivalent NaSe6 octahedra, and a faceface with one FeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–65°. There are a spread of Na–Se bond distances ranging from 2.92–3.29 Å. In the third Na1+ site, Na1+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.93–3.54 Å. Fe3+ is bonded to four Se2- atoms to form FeSe4 tetrahedra that share corners with seven NaSe6 octahedra, edges with three NaSe6 octahedra, an edgeedge with one FeSe4 tetrahedra, and a faceface with one NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 13–54°. There are a spread of Fe–Se bond distances ranging from 2.37–2.40 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six Na1+ and one Fe3+ atom. In the second Se2- site, Se2- is bonded in a 8-coordinate geometry to six Na1+ and two equivalent Fe3+ atoms. In the third Se2- site, Se2- is bonded in a 7-coordinate geometry to six Na1+ and one Fe3+ atom.

36 MATERIALS SCIENCE↗