Materials Data on Sc6Si11Ni18 by Materials Project

Abstract

Sc6Ni18Si11 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are four inequivalent Sc2+ sites. In the first Sc2+ site, Sc2+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent Si4- atoms. All Sc–Si bond lengths are 2.89 Å. In the second Sc2+ site, Sc2+ is bonded in a 4-coordinate geometry to seven Si4- atoms. There are a spread of Sc–Si bond distances ranging from 2.79–3.26 Å. In the third Sc2+ site, Sc2+ is bonded to six Si4- atoms to form distorted ScSi6 pentagonal pyramids that share an edgeedge with one ScSi6 pentagonal pyramid, edges with four equivalent NiSi4 tetrahedra, and faces with two equivalent NiSi4 tetrahedra. There are a spread of Sc–Si bond distances ranging from 2.66–2.98 Å. In the fourth Sc2+ site, Sc2+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Sc–Si bond distances ranging from 2.77–2.95 Å. There are eight inequivalent Ni+1.78+ sites. In the first Ni+1.78+ site, Ni+1.78+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.36–2.61 Å. In the second Ni+1.78+ site, Ni+1.78+ is bonded in a 4-coordinate geometry to four Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.24–2.37 Å. In the third Ni+1.78+ site, Ni+1.78+ is bonded in a trigonal non-coplanar geometry to three Si4- atoms. There are one shorter (2.18 Å) and two longer (2.38 Å) Ni–Si bond lengths. In the fourth Ni+1.78+ site, Ni+1.78+ is bonded to four Si4- atoms to form NiSi4 tetrahedra that share corners with four equivalent NiSi4 tetrahedra, an edgeedge with one NiSi4 tetrahedra, and faces with two equivalent ScSi6 pentagonal pyramids. There are two shorter (2.36 Å) and two longer (2.41 Å) Ni–Si bond lengths. In the fifth Ni+1.78+ site, Ni+1.78+ is bonded to four Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. There are a spread of Ni–Si bond distances ranging from 2.35–2.55 Å. In the sixth Ni+1.78+ site, Ni+1.78+ is bonded to four Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. There are a spread of Ni–Si bond distances ranging from 2.29–2.56 Å. In the seventh Ni+1.78+ site, Ni+1.78+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Ni–Si bond distances ranging from 2.29–2.48 Å. In the eighth Ni+1.78+ site, Ni+1.78+ is bonded to four Si4- atoms to form distorted NiSi4 tetrahedra that share corners with seven NiSi4 tetrahedra, an edgeedge with one ScSi6 pentagonal pyramid, and an edgeedge with one NiSi4 tetrahedra. There are a spread of Ni–Si bond distances ranging from 2.33–2.52 Å. There are seven inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a cuboctahedral geometry to four equivalent Sc2+ and eight Ni+1.78+ atoms. In the second Si4- site, Si4- is bonded in a body-centered cubic geometry to eight Ni+1.78+ atoms. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to three Sc2+ and six Ni+1.78+ atoms. In the fourth Si4- site, Si4- is bonded in a 10-coordinate geometry to two equivalent Sc2+ and eight Ni+1.78+ atoms. In the fifth Si4- site, Si4- is bonded in a 12-coordinate geometry to four Sc2+, seven Ni+1.78+, and one Si4- atom. The Si–Si bond length is 2.61 Å. In the sixth Si4- site, Si4- is bonded in a 10-coordinate geometry to two equivalent Sc2+ and eight Ni+1.78+ atoms. In the seventh Si4- site, Si4- is bonded in a 12-coordinate geometry to four Sc2+, six Ni+1.78+, and two equivalent Si4- atoms.