Materials Data on Na7Al2Sb5 by Materials Project
Na7Al2Sb5 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five Sb+2.60- atoms to form distorted NaSb5 trigonal bipyramids that share corners with four equivalent AlSb4 tetrahedra, corners with two NaSb5 trigonal bipyramids, edges with two equivalent AlSb4 tetrahedra, and edges with four NaSb5 trigonal bipyramids. There are a spread of Na–Sb bond distances ranging from 3.24–3.41 Å. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Sb+2.60- atoms. There are a spread of Na–Sb bond distances ranging from 3.11–3.49 Å. In the third Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four Sb+2.60- atoms. There are a spread of Na–Sb bond distances ranging from 3.11–3.37 Å. In the fourth Na1+ site, Na1+ is bonded to five Sb+2.60- atoms to form NaSb5 trigonal bipyramids that share corners with four equivalent AlSb4 tetrahedra, corners with two NaSb5 trigonal bipyramids, edges with two equivalent AlSb4 tetrahedra, and edges with four NaSb5 trigonal bipyramids. There are a spread of Na–Sb bond distances ranging from 3.29–3.39 Å. In the fifth Na1+ site, Na1+ is bonded to five Sb+2.60- atoms to form distorted NaSb5 trigonal bipyramids that share corners with four equivalent AlSb4 tetrahedra, corners with two NaSb5 trigonal bipyramids, edges with two equivalent AlSb4 tetrahedra, and edges with four NaSb5 trigonal bipyramids. There are a spread of Na–Sb bond distances ranging from 3.32–3.41 Å. Al3+ is bonded to four Sb+2.60- atoms to form AlSb4 tetrahedra that share a cornercorner with one AlSb4 tetrahedra, corners with six NaSb5 trigonal bipyramids, an edgeedge with one AlSb4 tetrahedra, and edges with three NaSb5 trigonal bipyramids. There are a spread of Al–Sb bond distances ranging from 2.72–2.80 Å. There are three inequivalent Sb+2.60- sites. In the first Sb+2.60- site, Sb+2.60- is bonded in a 6-coordinate geometry to six Na1+, one Al3+, and one Sb+2.60- atom. The Sb–Sb bond length is 2.93 Å. In the second Sb+2.60- site, Sb+2.60- is bonded in a 9-coordinate geometry to seven Na1+ and two equivalent Al3+ atoms. In the third Sb+2.60- site, Sb+2.60- is bonded in a 9-coordinate geometry to seven Na1+ and two equivalent Al3+ atoms.