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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ta11(NiSe4)2 by Materials Project

Ta11Ni2Se8 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are six inequivalent Ta sites. In the first Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Ni and three Se atoms. Both Ta–Ni bond lengths are 2.54 Å. There are one shorter (2.56 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 one Ni and four Se atoms. The Ta–Ni bond length is 2.82 Å. There are two shorter (2.63 Å) and two longer (2.68 Å) Ta–Se bond lengths. In the third Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Ni and three Se atoms. Both Ta–Ni bond lengths are 2.56 Å. There are one shorter (2.68 Å) and two longer (2.72 Å) Ta–Se bond lengths. In the fourth Ta site, Ta is bonded in a 5-coordinate geometry to one Ni and four Se atoms. The Ta–Ni bond length is 2.84 Å. There are a spread of Ta–Se bond distances ranging from 2.62–2.81 Å. In the fifth Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Ni and three Se atoms. Both Ta–Ni bond lengths are 2.50 Å. There are one shorter (2.62 Å) and two longer (2.74 Å) Ta–Se bond lengths. In the sixth Ta site, Ta is bonded in a distorted square co-planar geometry to two equivalent Ni and two equivalent Se atoms. Both Ta–Ni bond lengths are 2.78 Å. Both Ta–Se bond lengths are 2.73 Å. Ni is bonded in a 9-coordinate geometry to nine Ta atoms. There are four inequivalent Se sites. In the first Se site, Se is bonded in a distorted T-shaped geometry to three Ta atoms. In the second Se site, Se is bonded in a 6-coordinate geometry to six Ta atoms. In the third Se site, Se is bonded in a 5-coordinate geometry to five Ta atoms. In the fourth Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2NiSe5 by Materials Project

Ta2NiSe5 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two Ta2NiSe5 sheets oriented in the (0, 1, 0) direction. Ta4+ is bonded to six Se2- atoms to form TaSe6 octahedra that share a cornercorner with one TaSe6 octahedra, edges with four equivalent TaSe6 octahedra, and edges with two equivalent NiSe4 tetrahedra. The corner-sharing octahedral tilt angles are 63°. There are a spread of Ta–Se bond distances ranging from 2.55–2.70 Å. Ni2+ is bonded to four Se2- atoms to form NiSe4 tetrahedra that share corners with two equivalent NiSe4 tetrahedra and edges with four equivalent TaSe6 octahedra. There are two shorter (2.36 Å) and two longer (2.39 Å) Ni–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted T-shaped geometry to two equivalent Ta4+ and one Ni2+ atom. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent Ta4+ and two equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2NiSe7 by Materials Project

Ta2NiSe7 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Ta2NiSe7 sheets oriented in the (1, 0, 0) direction. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Ta–Se bond distances ranging from 2.62–2.77 Å. In the second Ta5+ site, Ta5+ is bonded to six Se2- atoms to form TaSe6 octahedra that share edges with two equivalent NiSe6 octahedra and edges with four equivalent TaSe6 octahedra. There are a spread of Ta–Se bond distances ranging from 2.50–2.76 Å. Ni4+ is bonded to six Se2- atoms to form distorted NiSe6 octahedra that share edges with two equivalent TaSe6 octahedra and edges with two equivalent NiSe6 octahedra. There are a spread of Ni–Se bond distances ranging from 2.42–2.72 Å. There are seven inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta5+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Ta5+ and one Ni4+ atom. In the third Se2- site, Se2- is bonded in a distorted T-shaped geometry to one Ta5+ and two equivalent Ni4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to two equivalent Ta5+ and one Ni4+ atom. In the fifth Se2- site, Se2- is bonded in a distorted L-shaped geometry to two equivalent Ta5+ atoms. In the sixth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ta5+ atoms. In the seventh Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one Ta5+ and two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Ni3Se8 by Materials Project

Ta2Ni3Se8 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Ta5+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share corners with two equivalent NiSe5 square pyramids, edges with two equivalent TaSe6 pentagonal pyramids, and edges with two equivalent NiSe5 square pyramids. There are a spread of Ta–Se bond distances ranging from 2.54–2.62 Å. There are two inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded in a square co-planar geometry to four Se2- atoms. All Ni–Se bond lengths are 2.35 Å. In the second Ni2+ site, Ni2+ is bonded to five Se2- atoms to form NiSe5 square pyramids that share corners with two equivalent TaSe6 pentagonal pyramids, edges with two equivalent TaSe6 pentagonal pyramids, and edges with two equivalent NiSe5 square pyramids. There are four shorter (2.38 Å) and one longer (2.49 Å) Ni–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Ta5+ and one Ni2+ atom. In the second Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ta5+ and two Ni2+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to one Ta5+ and two equivalent Ni2+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to one Ta5+ and two equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta8NiSe8 by Materials Project

NiTa8Se8 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 one Ni and four Se atoms. The Ta–Ni bond length is 2.86 Å. There are a spread of Ta–Se bond distances ranging from 2.64–2.73 Å. In the second Ta site, Ta is bonded in a 4-coordinate geometry to one Ni and four Se atoms. The Ta–Ni bond length is 2.91 Å. There are a spread of Ta–Se bond distances ranging from 2.64–2.83 Å. In the third Ta site, Ta is bonded to six Se atoms to form distorted TaSe6 octahedra that share corners with two equivalent TaNi2Se3 trigonal bipyramids, edges with two equivalent TaSe6 octahedra, edges with two equivalent TaSe5 trigonal bipyramids, and a faceface with one TaNi2Se3 trigonal bipyramid. There are a spread of Ta–Se bond distances ranging from 2.61–2.79 Å. In the fourth Ta site, Ta is bonded in a 4-coordinate geometry to one Ni and five Se atoms. The Ta–Ni bond length is 2.92 Å. There are a spread of Ta–Se bond distances ranging from 2.60–3.14 Å. In the fifth Ta site, Ta is bonded to two equivalent Ni and three Se atoms to form distorted TaNi2Se3 trigonal bipyramids that share corners with two equivalent TaSe6 octahedra, corners with two equivalent TaNi2Se3 trigonal bipyramids, edges with three TaNi2Se3 trigonal bipyramids, and a faceface with one TaSe6 octahedra. The corner-sharing octahedral tilt angles are 49°. Both Ta–Ni bond lengths are 2.51 Å. There are one shorter (2.61 Å) and two longer (2.68 Å) Ta–Se bond lengths. In the sixth Ta site, Ta is bonded in a 5-coordinate geometry to two equivalent Ni and three Se atoms. Both Ta–Ni bond lengths are 2.54 Å. There are one shorter (2.58 Å) and two longer (2.68 Å) Ta–Se bond lengths. 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 2.60–2.64 Å. In the eighth Ta site, Ta is bonded to two equivalent Ni and three Se atoms to form a mixture of distorted corner and edge-sharing TaNi2Se3 trigonal bipyramids. Both Ta–Ni bond lengths are 2.51 Å. There are one shorter (2.61 Å) and two longer (2.70 Å) Ta–Se bond lengths. Ni 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 4-coordinate geometry to four Ta atoms. In the second Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms. In the third Se site, Se is bonded in a 4-coordinate geometry to four Ta atoms. In the fourth Se site, Se is bonded in a distorted pentagonal planar geometry to five Ta atoms. In the fifth Se site, Se is bonded in a pentagonal planar geometry to five Ta atoms. In the sixth Se site, Se is bonded in a 3-coordinate geometry to three Ta atoms. In the seventh Se site, Se is bonded in a 5-coordinate geometry to five Ta atoms. In the eighth Se site, Se is bonded in a distorted T-shaped geometry to three Ta atoms.

36 MATERIALS SCIENCE↗