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.