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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na(La2Se3)4 by Materials Project

Na(La2Se3)4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Na1+ is bonded to eight Se2- atoms to form distorted NaSe8 hexagonal bipyramids that share corners with eight equivalent LaSe8 hexagonal bipyramids, edges with four equivalent LaSe8 hexagonal bipyramids, and faces with eight LaSe8 hexagonal bipyramids. There are four shorter (3.08 Å) and four longer (3.32 Å) Na–Se bond lengths. There are three inequivalent La+2.88+ sites. In the first La+2.88+ site, La+2.88+ is bonded to eight Se2- atoms to form distorted LaSe8 hexagonal bipyramids that share corners with two equivalent NaSe8 hexagonal bipyramids, corners with six LaSe8 hexagonal bipyramids, edges with four LaSe8 hexagonal bipyramids, a faceface with one NaSe8 hexagonal bipyramid, and faces with seven LaSe8 hexagonal bipyramids. There are a spread of La–Se bond distances ranging from 3.03–3.30 Å. In the second La+2.88+ site, La+2.88+ is bonded to eight Se2- atoms to form distorted LaSe8 hexagonal bipyramids that share corners with eight LaSe8 hexagonal bipyramids, edges with two equivalent NaSe8 hexagonal bipyramids, edges with two equivalent LaSe8 hexagonal bipyramids, and faces with eight LaSe8 hexagonal bipyramids. There are a spread of La–Se bond distances ranging from 3.04–3.23 Å. In the third La+2.88+ site, La+2.88+ is bonded to eight Se2- atoms to form distorted LaSe8 hexagonal bipyramids that share corners with eight LaSe8 hexagonal bipyramids, edges with four LaSe8 hexagonal bipyramids, faces with two equivalent NaSe8 hexagonal bipyramids, and faces with six LaSe8 hexagonal bipyramids. There are a spread of La–Se bond distances ranging from 3.05–3.28 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to six La+2.88+ atoms. In the second Se2- site, Se2- is bonded to one Na1+ and five La+2.88+ atoms to form a mixture of distorted corner, edge, and face-sharing SeNaLa5 octahedra. The corner-sharing octahedra tilt angles range from 20–50°. In the third Se2- site, Se2- is bonded to one Na1+ and five La+2.88+ atoms to form a mixture of distorted corner, edge, and face-sharing SeNaLa5 octahedra. The corner-sharing octahedra tilt angles range from 15–50°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaLaSe2 by Materials Project

NaLaSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Na1+ is bonded to six equivalent Se2- atoms to form NaSe6 octahedra that share corners with six equivalent LaSe6 octahedra, edges with six equivalent NaSe6 octahedra, and edges with six equivalent LaSe6 octahedra. The corner-sharing octahedral tilt angles are 3°. All Na–Se bond lengths are 3.14 Å. La3+ is bonded to six equivalent Se2- atoms to form LaSe6 octahedra that share corners with six equivalent NaSe6 octahedra, edges with six equivalent NaSe6 octahedra, and edges with six equivalent LaSe6 octahedra. The corner-sharing octahedral tilt angles are 3°. All La–Se bond lengths are 3.02 Å. Se2- is bonded to three equivalent Na1+ and three equivalent La3+ atoms to form a mixture of edge and corner-sharing SeNa3La3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaLaSe2 by Materials Project

NaLaSe2 is Caswellsilverite-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with six equivalent NaSe6 octahedra, edges with four equivalent NaSe6 octahedra, and edges with eight equivalent LaSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.96 Å) and four longer (3.09 Å) Na–Se bond lengths. La3+ is bonded to six Se2- atoms to form LaSe6 octahedra that share corners with six equivalent LaSe6 octahedra, edges with four equivalent LaSe6 octahedra, and edges with eight equivalent NaSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.96 Å) and four longer (3.09 Å) La–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Na1+ and four equivalent La3+ atoms to form a mixture of edge and corner-sharing SeNa2La4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second Se2- site, Se2- is bonded to four equivalent Na1+ and two equivalent La3+ atoms to form SeNa4La2 octahedra that share corners with six equivalent SeNa4La2 octahedra and edges with twelve SeNa2La4 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaLa2Se3 by Materials Project

NaLa2Se3 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Na1+ is bonded to six equivalent Se2- atoms to form NaSe6 octahedra that share corners with six equivalent LaSe6 octahedra, edges with six equivalent NaSe6 octahedra, and edges with six equivalent LaSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Na–Se bond lengths are 3.09 Å. La+2.50+ is bonded to six Se2- atoms to form LaSe6 octahedra that share corners with three equivalent NaSe6 octahedra, corners with three equivalent LaSe6 octahedra, edges with three equivalent NaSe6 octahedra, and edges with nine equivalent LaSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are three shorter (3.01 Å) and three longer (3.09 Å) La–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Na1+ and three equivalent La+2.50+ atoms to form a mixture of corner and edge-sharing SeNa3La3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second Se2- site, Se2- is bonded to six equivalent La+2.50+ atoms to form a mixture of corner and edge-sharing SeLa6 octahedra. The corner-sharing octahedral tilt angles are 2°.

36 MATERIALS SCIENCE↗