Materials Data on Si12Ni31 by Materials Project

Ni31Si12 crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are eight inequivalent Ni+1.55+ sites. In the first Ni+1.55+ site, Ni+1.55+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.31–2.88 Å. In the second Ni+1.55+ site, Ni+1.55+ is bonded to five Si4- atoms to form a mixture of edge and corner-sharing NiSi5 trigonal bipyramids. There are three shorter (2.33 Å) and two longer (2.57 Å) Ni–Si bond lengths. In the third Ni+1.55+ site, Ni+1.55+ is bonded to four Si4- atoms to form distorted NiSi4 tetrahedra that share corners with twelve NiSi4 tetrahedra, a cornercorner with one NiSi5 trigonal bipyramid, edges with three equivalent NiSi4 tetrahedra, and a faceface with one NiSi4 tetrahedra. There are one shorter (2.38 Å) and three longer (2.43 Å) Ni–Si bond lengths. In the fourth Ni+1.55+ site, Ni+1.55+ is bonded to four Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. There are three shorter (2.43 Å) and one longer (2.49 Å) Ni–Si bond lengths. In the fifth Ni+1.55+ site, Ni+1.55+ is bonded to four Si4- atoms to form NiSi4 tetrahedra that share corners with nine NiSi4 tetrahedra, corners with three equivalent NiSi5 trigonal bipyramids, and edges with three equivalent NiSi4 tetrahedra. There are three shorter (2.31 Å) and one longer (2.53 Å) Ni–Si bond lengths. In the sixth Ni+1.55+ site, Ni+1.55+ is bonded in a distorted trigonal non-coplanar geometry to three Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.30–2.40 Å. In the seventh Ni+1.55+ site, Ni+1.55+ is bonded to four Si4- atoms to form NiSi4 tetrahedra that share corners with thirteen NiSi4 tetrahedra, a cornercorner with one NiSi5 trigonal bipyramid, and edges with five NiSi4 tetrahedra. There are a spread of Ni–Si bond distances ranging from 2.30–2.48 Å. In the eighth Ni+1.55+ site, Ni+1.55+ is bonded to four Si4- atoms to form distorted NiSi4 tetrahedra that share corners with thirteen NiSi4 tetrahedra, edges with four NiSi4 tetrahedra, and an edgeedge with one NiSi5 trigonal bipyramid. There are a spread of Ni–Si bond distances ranging from 2.24–2.40 Å. There are five inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 11-coordinate geometry to eleven Ni+1.55+ atoms. In the second Si4- site, Si4- is bonded in a distorted q6 geometry to ten Ni+1.55+ atoms. In the third Si4- site, Si4- is bonded in a 10-coordinate geometry to ten Ni+1.55+ atoms. In the fourth Si4- site, Si4- is bonded in a 10-coordinate geometry to ten Ni+1.55+ atoms. In the fifth Si4- site, Si4- is bonded in a 9-coordinate geometry to eleven Ni+1.55+ atoms.