Materials Data on Na5Ni9As7 by Materials Project

Abstract

Na5Ni9As7 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five As3- atoms to form distorted NaAs5 square pyramids that share corners with four NaAs6 pentagonal pyramids, corners with four equivalent NaAs5 square pyramids, corners with eight NiAs4 tetrahedra, an edgeedge with one NaAs6 pentagonal pyramid, edges with four equivalent NaAs5 square pyramids, and edges with seven NiAs4 tetrahedra. There are a spread of Na–As bond distances ranging from 2.68–2.78 Å. In the second Na1+ site, Na1+ is bonded to six equivalent As3- atoms to form distorted NaAs6 pentagonal pyramids that share corners with six equivalent NaAs5 square pyramids, corners with twelve NiAs4 tetrahedra, edges with twelve NiAs4 tetrahedra, and faces with two equivalent NaAs6 pentagonal pyramids. All Na–As bond lengths are 2.97 Å. In the third Na1+ site, Na1+ is bonded to six equivalent As3- atoms to form distorted NaAs6 pentagonal pyramids that share corners with six equivalent NaAs5 square pyramids, corners with twelve NiAs4 tetrahedra, edges with three equivalent NaAs5 square pyramids, edges with nine NiAs4 tetrahedra, and faces with two equivalent NaAs6 pentagonal pyramids. All Na–As bond lengths are 3.02 Å. There are three inequivalent Ni+1.78+ sites. In the first Ni+1.78+ site, Ni+1.78+ is bonded to four As3- atoms to form NiAs4 tetrahedra that share corners with four NaAs6 pentagonal pyramids, corners with two equivalent NaAs5 square pyramids, corners with ten NiAs4 tetrahedra, an edgeedge with one NaAs6 pentagonal pyramid, edges with four equivalent NaAs5 square pyramids, and edges with three NiAs4 tetrahedra. There are a spread of Ni–As bond distances ranging from 2.38–2.52 Å. In the second Ni+1.78+ site, Ni+1.78+ is bonded to four As3- atoms to form NiAs4 tetrahedra that share corners with two equivalent NaAs6 pentagonal pyramids, corners with two equivalent NaAs5 square pyramids, corners with twelve NiAs4 tetrahedra, edges with three NaAs6 pentagonal pyramids, edges with two equivalent NaAs5 square pyramids, and edges with three NiAs4 tetrahedra. There are a spread of Ni–As bond distances ranging from 2.32–2.59 Å. In the third Ni+1.78+ site, Ni+1.78+ is bonded to four As3- atoms to form NiAs4 tetrahedra that share corners with two equivalent NaAs6 pentagonal pyramids, corners with four equivalent NaAs5 square pyramids, corners with ten NiAs4 tetrahedra, edges with three NaAs6 pentagonal pyramids, an edgeedge with one NaAs5 square pyramid, and edges with four NiAs4 tetrahedra. There are a spread of Ni–As bond distances ranging from 2.34–2.47 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to three Na1+ and six Ni+1.78+ atoms. In the second As3- site, As3- is bonded in a 9-coordinate geometry to four Na1+ and five Ni+1.78+ atoms. In the third As3- site, As3- is bonded in a 9-coordinate geometry to six equivalent Na1+ and three equivalent Ni+1.78+ atoms.