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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Hf(CoSi)2 by Materials Project

Hf(CoSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Hf4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Hf–Si bond lengths are 2.89 Å. Co2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CoSi4 tetrahedra. All Co–Si bond lengths are 2.24 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Hf4+, four equivalent Co2+, and one Si4- atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Co3Si4 by Materials Project

Hf2Co3Si4 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Hf4+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Hf–Si bond distances ranging from 2.74–3.04 Å. There are two inequivalent Co+2.67+ sites. In the first Co+2.67+ site, Co+2.67+ is bonded in a distorted pentagonal planar geometry to five Si4- atoms. There are a spread of Co–Si bond distances ranging from 2.32–2.41 Å. In the second Co+2.67+ site, Co+2.67+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Co–Si bond distances ranging from 2.29–2.48 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 12-coordinate geometry to four equivalent Hf4+ and five Co+2.67+ atoms. In the second Si4- site, Si4- is bonded in a 11-coordinate geometry to four equivalent Hf4+ and three Co+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf6Co16Si7 by Materials Project

Hf6Co16Si7 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to eight Co and four equivalent Si atoms. All Hf–Co bond lengths are 2.76 Å. All Hf–Si bond lengths are 2.88 Å. There are two inequivalent Co sites. In the first Co site, Co is bonded in a 7-coordinate geometry to three equivalent Hf, six Co, and four Si atoms. There are three shorter (2.51 Å) and three longer (2.71 Å) Co–Co bond lengths. There are one shorter (2.35 Å) and three longer (2.49 Å) Co–Si bond lengths. In the second Co site, Co is bonded in a 12-coordinate geometry to three equivalent Hf, six Co, and three equivalent Si atoms. All Co–Co bond lengths are 2.54 Å. All Co–Si bond lengths are 2.31 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a body-centered cubic geometry to eight equivalent Co atoms. In the second Si site, Si is bonded to four equivalent Hf and eight Co atoms to form a mixture of corner and face-sharing SiHf4Co8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf4Co4Si7 by Materials Project

Hf4Co4Si7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to seven Si+2.86- atoms to form HfSi7 pentagonal bipyramids that share corners with eight equivalent CoSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, edges with three equivalent HfSi7 pentagonal bipyramids, faces with four equivalent CoSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–52°. There are a spread of Hf–Si bond distances ranging from 2.75–2.85 Å. In the second Hf4+ site, Hf4+ is bonded to seven Si+2.86- atoms to form HfSi7 pentagonal bipyramids that share corners with eight equivalent CoSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, an edgeedge with one HfSi7 pentagonal bipyramid, faces with four equivalent CoSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–53°. There are a spread of Hf–Si bond distances ranging from 2.71–2.86 Å. Co1+ is bonded to six Si+2.86- atoms to form distorted CoSi6 octahedra that share corners with six equivalent CoSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, edges with three equivalent CoSi6 octahedra, faces with two equivalent CoSi6 octahedra, and faces with four HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 32–36°. There are a spread of Co–Si bond distances ranging from 2.36–2.39 Å. There are four inequivalent Si+2.86- sites. In the first Si+2.86- site, Si+2.86- is bonded in a 9-coordinate geometry to five Hf4+ and four equivalent Co1+ atoms. In the second Si+2.86- site, Si+2.86- is bonded in a 6-coordinate geometry to one Hf4+, four equivalent Co1+, and one Si+2.86- atom. The Si–Si bond length is 2.36 Å. In the third Si+2.86- site, Si+2.86- is bonded in a 10-coordinate geometry to eight Hf4+ and two equivalent Si+2.86- atoms. There are one shorter (2.52 Å) and one longer (2.53 Å) Si–Si bond lengths. In the fourth Si+2.86- site, Si+2.86- is bonded in a 12-coordinate geometry to four Hf4+ and four equivalent Co1+ atoms.

36 MATERIALS SCIENCE↗