Materials Data on Ta8CoSe8 by Materials Project

Abstract

CoTa8Se8 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are eight inequivalent Ta sites. In the first Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Co and three Se atoms. Both Ta–Co bond lengths are 2.48 Å. There are one shorter (2.62 Å) and two longer (2.72 Å) Ta–Se bond lengths. In the second Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Co and three Se atoms. Both Ta–Co bond lengths are 2.53 Å. There are one shorter (2.59 Å) and two longer (2.68 Å) Ta–Se bond lengths. In the third Ta site, Ta is bonded to two equivalent Co and three Se atoms to form distorted TaCo2Se3 trigonal bipyramids that share corners with two equivalent TaSe6 octahedra, edges with two equivalent TaCo2Se3 trigonal bipyramids, and a faceface with one TaSe6 octahedra. The corner-sharing octahedral tilt angles are 49°. Both Ta–Co bond lengths are 2.48 Å. There are one shorter (2.63 Å) and two longer (2.69 Å) Ta–Se bond lengths. In the fourth Ta site, Ta is bonded in a 5-coordinate geometry to one Co and four Se atoms. The Ta–Co bond length is 2.86 Å. There are a spread of Ta–Se bond distances ranging from 2.64–2.74 Å. In the fifth Ta site, Ta is bonded in a 4-coordinate geometry to one Co and five Se atoms. The Ta–Co bond length is 2.95 Å. There are a spread of Ta–Se bond distances ranging from 2.59–3.10 Å. In the sixth Ta site, Ta is bonded in a 4-coordinate geometry to one Co and four Se atoms. The Ta–Co bond length is 2.94 Å. There are a spread of Ta–Se bond distances ranging from 2.64–2.81 Å. In the seventh Ta site, Ta is bonded to five Se atoms to form distorted TaSe5 trigonal bipyramids that share edges with two equivalent TaSe6 octahedra and edges with two equivalent TaSe5 trigonal bipyramids. There are a spread of Ta–Se bond distances ranging from 2.59–2.64 Å. In the eighth Ta site, Ta is bonded to six Se atoms to form distorted TaSe6 octahedra that share corners with two equivalent TaCo2Se3 trigonal bipyramids, edges with two equivalent TaSe6 octahedra, edges with two equivalent TaSe5 trigonal bipyramids, and a faceface with one TaCo2Se3 trigonal bipyramid. There are a spread of Ta–Se bond distances ranging from 2.60–2.80 Å. Co is bonded in a 9-coordinate geometry to nine Ta atoms. There are eight inequivalent Se sites. In the first Se site, Se is bonded in a pentagonal planar geometry to five Ta atoms. In the second Se site, Se is bonded in a distorted pentagonal planar geometry to five Ta atoms. In the third Se site, Se is bonded in a distorted T-shaped geometry to three Ta atoms. In the fourth Se site, Se is bonded in a 3-coordinate geometry to three Ta atoms. In the fifth Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms. In the sixth Se site, Se is bonded in a 5-coordinate geometry to five Ta atoms. In the seventh Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms. In the eighth Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms.