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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on HfReSi2 by Materials Project

HfReSi2 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Hf–Si bond distances ranging from 2.74–2.94 Å. In the second Hf4+ site, Hf4+ is bonded to seven Si4- atoms to form HfSi7 pentagonal bipyramids that share corners with two equivalent ReSi6 octahedra, corners with two equivalent HfSi7 pentagonal bipyramids, edges with three equivalent HfSi7 pentagonal bipyramids, and faces with two equivalent ReSi6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Hf–Si bond distances ranging from 2.78–2.89 Å. There are two inequivalent Re4+ sites. In the first Re4+ site, Re4+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Re–Si bond distances ranging from 2.42–2.67 Å. In the second Re4+ site, Re4+ is bonded to six Si4- atoms to form distorted ReSi6 octahedra that share corners with two equivalent HfSi7 pentagonal bipyramids, edges with two equivalent ReSi6 octahedra, and faces with two equivalent HfSi7 pentagonal bipyramids. There are two shorter (2.53 Å) and four longer (2.55 Å) Re–Si bond lengths. There are five inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to six Hf4+, two equivalent Re4+, and one Si4- atom. The Si–Si bond length is 2.40 Å. In the second Si4- site, Si4- is bonded in a 7-coordinate geometry to four equivalent Hf4+, two equivalent Re4+, and one Si4- atom. The Si–Si bond length is 2.41 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to five Hf4+ and four Re4+ atoms. In the fourth Si4- site, Si4- is bonded in a 2-coordinate geometry to two equivalent Hf4+ and four Re4+ atoms. In the fifth Si4- site, Si4- is bonded in a 7-coordinate geometry to three Hf4+, three Re4+, and one Si4- atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfReSi by Materials Project

HfReSi crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to six equivalent Re and five Si atoms. There are two shorter (2.91 Å) and four longer (3.00 Å) Hf–Re bond lengths. There are four shorter (2.72 Å) and one longer (2.82 Å) Hf–Si bond lengths. Re is bonded in a 10-coordinate geometry to six equivalent Hf and four Si atoms. There are two shorter (2.47 Å) and two longer (2.63 Å) Re–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Re atoms. In the second Si site, Si is bonded in a 6-coordinate geometry to six equivalent Hf and three equivalent Re atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf9Re4Si by Materials Project

Hf9Re4Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 1-coordinate geometry to four Re and one Si atom. There are a spread of Hf–Re bond distances ranging from 2.88–3.07 Å. The Hf–Si bond length is 2.70 Å. In the second Hf site, Hf is bonded in a distorted T-shaped geometry to two equivalent Re and one Si atom. Both Hf–Re bond lengths are 2.89 Å. The Hf–Si bond length is 3.06 Å. There are two inequivalent Re sites. In the first Re site, Re is bonded in a 12-coordinate geometry to eight Hf and four Re atoms. There are two shorter (2.71 Å) and two longer (2.80 Å) Re–Re bond lengths. In the second Re site, Re is bonded to six equivalent Hf and six equivalent Re atoms to form face-sharing ReHf6Re6 cuboctahedra. Si is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗