Materials Data on Na(La2Se3)4 by Materials Project

Abstract

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°.