DOI: 10.17188/1274330
title: Materials Data on Ni6Se5 by Materials Project

description: Ni6Se5 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are twelve inequivalent Ni+1.67+ sites. In the first Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form distorted NiSe5 trigonal bipyramids that share corners with four NiSe4 tetrahedra, corners with ten NiSe5 trigonal bipyramids, edges with four NiSe5 trigonal bipyramids, and a faceface with one NiSe5 trigonal bipyramid. There are a spread of Ni–Se bond distances ranging from 2.39–2.49 Å. In the second Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form distorted NiSe5 trigonal bipyramids that share corners with four NiSe4 tetrahedra, corners with ten NiSe5 trigonal bipyramids, and edges with five NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.34–2.57 Å. In the third Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form distorted NiSe5 trigonal bipyramids that share corners with four NiSe4 tetrahedra, corners with eight NiSe5 trigonal bipyramids, and edges with six NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.34–2.50 Å. In the fourth Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form distorted NiSe5 trigonal bipyramids that share corners with two equivalent NiSe4 tetrahedra, corners with six NiSe5 trigonal bipyramids, edges with two NiSe4 tetrahedra, edges with four NiSe5 trigonal bipyramids, and a faceface with one NiSe5 trigonal bipyramid. There are a spread of Ni–Se bond distances ranging from 2.37–2.68 Å. In the fifth Ni+1.67+ site, Ni+1.67+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Ni–Se bond distances ranging from 2.38–2.80 Å. In the sixth Ni+1.67+ site, Ni+1.67+ is bonded to four Se2- atoms to form NiSe4 tetrahedra that share corners with two NiSe5 square pyramids, corners with two equivalent NiSe4 tetrahedra, corners with six NiSe5 trigonal bipyramids, an edgeedge with one NiSe4 tetrahedra, and edges with two NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.31–2.37 Å. In the seventh Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form NiSe5 square pyramids that share corners with two equivalent NiSe5 square pyramids, corners with three NiSe4 tetrahedra, corners with four equivalent NiSe5 trigonal bipyramids, edges with three equivalent NiSe5 square pyramids, and edges with two NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.32–2.49 Å. In the eighth Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form NiSe5 trigonal bipyramids that share corners with eight NiSe5 square pyramids, corners with two equivalent NiSe4 tetrahedra, corners with two equivalent NiSe5 trigonal bipyramids, edges with two NiSe5 square pyramids, and edges with two equivalent NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.40–2.53 Å. In the ninth Ni+1.67+ site, Ni+1.67+ is bonded to four Se2- atoms to form NiSe4 tetrahedra that share corners with three NiSe5 square pyramids, corners with nine NiSe5 trigonal bipyramids, and edges with two NiSe4 tetrahedra. There are three shorter (2.32 Å) and one longer (2.35 Å) Ni–Se bond lengths. In the tenth Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form NiSe5 trigonal bipyramids that share corners with seven NiSe4 tetrahedra, corners with four NiSe5 trigonal bipyramids, edges with two NiSe5 square pyramids, an edgeedge with one NiSe4 tetrahedra, and an edgeedge with one NiSe5 trigonal bipyramid. There are a spread of Ni–Se bond distances ranging from 2.38–2.46 Å. In the eleventh Ni+1.67+ site, Ni+1.67+ is bonded to five Se2- atoms to form distorted NiSe5 square pyramids that share corners with two equivalent NiSe5 square pyramids, corners with four NiSe4 tetrahedra, corners with four equivalent NiSe5 trigonal bipyramids, edges with three equivalent NiSe5 square pyramids, and edges with two NiSe5 trigonal bipyramids. There are a spread of Ni–Se bond distances ranging from 2.32–2.63 Å. In the twelfth Ni+1.67+ site, Ni+1.67+ is bonded to four Se2- atoms to form NiSe4 tetrahedra that share corners with two NiSe5 square pyramids, corners with two equivalent NiSe4 tetrahedra, corners with eight NiSe5 trigonal bipyramids, an edgeedge with one NiSe4 tetrahedra, and an edgeedge with one NiSe5 trigonal bipyramid. There are a spread of Ni–Se bond distances ranging from 2.28–2.35 Å. There are ten inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to five Ni+1.67+ atoms. In the second Se2- site, Se2- is bonded in a distorted pentagonal planar geometry to five Ni+1.67+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to six Ni+1.67+ atoms. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to six Ni+1.67+ atoms. In the fifth Se2- site, Se2- is bonded in a distorted hexagonal planar geometry to six Ni+1.67+ atoms. In the sixth Se2- site, Se2- is bonded in a 6-coordinate geometry to six Ni+1.67+ atoms. In the seventh Se2- site, Se2- is bonded in a 6-coordinate geometry to six Ni+1.67+ atoms. In the eighth Se2- site, Se2- is bonded in a 6-coordinate geometry to six Ni+1.67+ atoms. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to five Ni+1.67+ atoms. In the tenth Se2- site, Se2- is bonded in a distorted hexagonal planar geometry to six Ni+1.67+ atoms.