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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na6Si2Se7 by Materials Project

Na6Si2Se7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are two shorter (2.86 Å) and two longer (2.94 Å) Na–Se bond lengths. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with two equivalent NaSe6 octahedra, corners with two equivalent SiSe4 tetrahedra, edges with four equivalent NaSe6 octahedra, and edges with two equivalent SiSe4 tetrahedra. The corner-sharing octahedral tilt angles are 4°. There are a spread of Na–Se bond distances ranging from 2.90–3.29 Å. In the third Na1+ site, Na1+ is bonded to six Se2- atoms to form distorted NaSe6 octahedra that share corners with two NaSe6 octahedra, a cornercorner with one SiSe4 tetrahedra, edges with four NaSe6 octahedra, and edges with three equivalent SiSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 4–40°. There are a spread of Na–Se bond distances ranging from 2.99–3.54 Å. In the fourth 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 2.97–3.60 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with two NaSe6 octahedra, a cornercorner with one SiSe4 tetrahedra, and edges with four NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 19–59°. There are a spread of Si–Se bond distances ranging from 2.27–2.35 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted bent 120 degrees geometry to four Na1+ and two equivalent Si4+ atoms. In the second Se2- site, Se2- is bonded to five Na1+ and one Si4+ atom to form a mixture of distorted edge and corner-sharing SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 0–78°. In the third Se2- site, Se2- is bonded to five Na1+ and one Si4+ atom to form a mixture of edge and corner-sharing SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Na1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Si2Se5 by Materials Project

Na2Si2Se5 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first 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 3.11–3.54 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 3.03–3.58 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four Se2- atoms to form corner-sharing SiSe4 tetrahedra. There are a spread of Si–Se bond distances ranging from 2.23–2.32 Å. In the second Si4+ site, Si4+ is bonded to four Se2- atoms to form corner-sharing SiSe4 tetrahedra. There are a spread of Si–Se bond distances ranging from 2.23–2.32 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Na1+ and one Si4+ atom to form distorted corner-sharing SeNa3Si tetrahedra. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the third Se2- site, Se2- is bonded in a water-like geometry to two equivalent Si4+ atoms. In the fourth Se2- site, Se2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the fifth Se2- site, Se2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3SiSe4 by Materials Project

Na3SiSe4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se+1.75- atoms to form distorted NaSe6 octahedra that share a cornercorner with one NaSe6 octahedra, corners with four SiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with four NaSe6 octahedra, an edgeedge with one SiSe4 tetrahedra, and an edgeedge with one NaSe5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 12°. There are a spread of Na–Se bond distances ranging from 2.86–3.47 Å. In the second Na1+ site, Na1+ is bonded to six Se+1.75- atoms to form distorted NaSe6 octahedra that share corners with two equivalent NaSe6 octahedra, corners with four SiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with three NaSe6 octahedra, an edgeedge with one SiSe4 tetrahedra, and an edgeedge with one NaSe5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 13–39°. There are a spread of Na–Se bond distances ranging from 2.92–3.63 Å. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se+1.75- atoms. There are a spread of Na–Se bond distances ranging from 2.92–3.34 Å. In the fourth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six Se+1.75- atoms. There are a spread of Na–Se bond distances ranging from 2.93–3.36 Å. In the fifth Na1+ site, Na1+ is bonded to five Se+1.75- atoms to form NaSe5 trigonal bipyramids that share corners with four NaSe6 octahedra, corners with three SiSe4 tetrahedra, edges with five NaSe6 octahedra, and an edgeedge with one SiSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 3–91°. There are a spread of Na–Se bond distances ranging from 2.93–3.19 Å. In the sixth Na1+ site, Na1+ is bonded to six Se+1.75- atoms to form NaSe6 octahedra that share corners with three NaSe6 octahedra, corners with two equivalent SiSe4 tetrahedra, edges with five NaSe6 octahedra, edges with two SiSe4 tetrahedra, and edges with three equivalent NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 12–39°. There are a spread of Na–Se bond distances ranging from 3.05–3.24 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four Se+1.75- atoms to form SiSe4 tetrahedra that share corners with four NaSe6 octahedra, corners with two equivalent NaSe5 trigonal bipyramids, and edges with three NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 19–72°. There are a spread of Si–Se bond distances ranging from 2.26–2.37 Å. In the second Si4+ site, Si4+ is bonded to four Se+1.75- atoms to form SiSe4 tetrahedra that share corners with six NaSe6 octahedra, a cornercorner with one NaSe5 trigonal bipyramid, an edgeedge with one NaSe6 octahedra, and an edgeedge with one NaSe5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 4–78°. There are a spread of Si–Se bond distances ranging from 2.27–2.36 Å. There are eight inequivalent Se+1.75- sites. In the first Se+1.75- site, Se+1.75- is bonded to four Na1+ and one Si4+ atom to form distorted SeNa4Si trigonal bipyramids that share a cornercorner with one SeNa5Si octahedra, edges with three SeNa5Si octahedra, and an edgeedge with one SeNa4Si trigonal bipyramid. The corner-sharing octahedral tilt angles are 17°. In the second Se+1.75- site, Se+1.75- is bonded in a 1-coordinate geometry to three Na1+, one Si4+, and one Se+1.75- atom. The Se–Se bond length is 2.43 Å. In the third Se+1.75- site, Se+1.75- is bonded to five Na1+ and one Si4+ atom to form distorted SeNa5Si octahedra that share corners with two SeNa5Si octahedra, edges with six SeNa5Si octahedra, and an edgeedge with one SeNa4Si trigonal bipyramid. The corner-sharing octahedra tilt angles range from 11–24°. In the fourth Se+1.75- site, Se+1.75- is bonded in a 6-coordinate geometry to five Na1+ and one Si4+ atom. In the fifth Se+1.75- site, Se+1.75- is bonded in a 1-coordinate geometry to two Na1+, one Si4+, and one Se+1.75- atom. In the sixth Se+1.75- site, Se+1.75- is bonded to five Na1+ and one Si4+ atom to form distorted SeNa5Si octahedra that share corners with two SeNa5Si octahedra, a cornercorner with one SeNa4Si trigonal bipyramid, edges with six SeNa5Si octahedra, and an edgeedge with one SeNa4Si trigonal bipyramid. The corner-sharing octahedra tilt angles range from 7–11°. In the seventh Se+1.75- site, Se+1.75- is bonded to five Na1+ and one Si4+ atom to form distorted SeNa5Si octahedra that share corners with two SeNa5Si octahedra, edges with four SeNa5Si octahedra, and an edgeedge with one SeNa4Si trigonal bipyramid. The corner-sharing octahedra tilt angles range from 7–24°. In the eighth Se+1.75- site, Se+1.75- is bonded in a 6-coordinate geometry to five Na1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4SiSe4 by Materials Project

Na4SiSe4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are two shorter (2.87 Å) and two longer (3.15 Å) Na–Se bond lengths. In the second Na1+ site, Na1+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.98–3.10 Å. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.92–3.23 Å. Si4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are three shorter (2.30 Å) and one longer (2.31 Å) Si–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded to five Na1+ and one Si4+ atom to form a mixture of distorted edge and corner-sharing SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 0–52°. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to five Na1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗