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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on HfAlCo2 by Materials Project

Co2HfAl is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to eight equivalent Co atoms. All Hf–Co bond lengths are 2.61 Å. Co is bonded in a body-centered cubic geometry to four equivalent Hf and four equivalent Al atoms. All Co–Al bond lengths are 2.61 Å. Al is bonded in a distorted body-centered cubic geometry to eight equivalent Co atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfAlCo by Materials Project

HfCoAl crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 12-coordinate geometry to three equivalent Hf, five Co, and seven Al atoms. There are one shorter (3.10 Å) and two longer (3.11 Å) Hf–Hf bond lengths. There are three shorter (2.77 Å) and two longer (3.07 Å) Hf–Co bond lengths. There are a spread of Hf–Al bond distances ranging from 2.97–3.06 Å. In the second Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Co, and five Al atoms. The Hf–Hf bond length is 2.82 Å. There are a spread of Hf–Co bond distances ranging from 2.89–2.99 Å. There are a spread of Hf–Al bond distances ranging from 2.89–3.04 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to six Hf and six Al atoms to form distorted CoHf6Al6 cuboctahedra that share corners with four equivalent AlHf6Al2Co4 cuboctahedra, corners with six CoHf6Al6 cuboctahedra, edges with six CoHf6Al6 cuboctahedra, and faces with fourteen AlHf6Al2Co4 cuboctahedra. There are a spread of Co–Al bond distances ranging from 2.48–2.61 Å. In the second Co site, Co is bonded in a 12-coordinate geometry to six Hf, four Co, and two equivalent Al atoms. There are a spread of Co–Co bond distances ranging from 2.46–2.68 Å. Both Co–Al bond lengths are 2.43 Å. In the third Co site, Co is bonded to six Hf, four equivalent Co, and two equivalent Al atoms to form distorted CoHf6Al2Co4 cuboctahedra that share corners with six CoHf6Al6 cuboctahedra, corners with twelve AlHf6Al2Co4 cuboctahedra, edges with six CoHf6Al6 cuboctahedra, and faces with ten AlHf6Al2Co4 cuboctahedra. Both Co–Al bond lengths are 2.45 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Hf, four Co, and two equivalent Al atoms to form distorted AlHf6Al2Co4 cuboctahedra that share corners with four CoHf6Al6 cuboctahedra, corners with four equivalent AlHf6Al4Co2 cuboctahedra, edges with six equivalent AlHf6Al2Co4 cuboctahedra, faces with six CoHf6Al6 cuboctahedra, and faces with eight AlHf6Al2Co4 cuboctahedra. Both Al–Al bond lengths are 2.65 Å. In the second Al site, Al is bonded to six Hf, two equivalent Co, and four Al atoms to form distorted AlHf6Al4Co2 cuboctahedra that share corners with four equivalent CoHf6Al2Co4 cuboctahedra, corners with eight AlHf6Al2Co4 cuboctahedra, edges with two equivalent AlHf6Al4Co2 cuboctahedra, faces with six CoHf6Al6 cuboctahedra, and faces with ten AlHf6Al2Co4 cuboctahedra. There are one shorter (2.52 Å) and one longer (2.64 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf6Al16Co7 by Materials Project

Hf6Co7Al16 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a 4-coordinate geometry to four equivalent Co and eight Al atoms. All Hf–Co bond lengths are 3.08 Å. There are four shorter (2.81 Å) and four longer (3.04 Å) Hf–Al bond lengths. There are two inequivalent Co sites. In the first Co site, Co is bonded to four equivalent Hf and eight Al atoms to form a mixture of distorted face and corner-sharing CoHf4Al8 cuboctahedra. There are four shorter (2.45 Å) and four longer (2.65 Å) Co–Al bond lengths. In the second Co site, Co is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Co–Al bond lengths are 2.46 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 3-coordinate geometry to three equivalent Hf, three equivalent Co, and three equivalent Al atoms. All Al–Al bond lengths are 2.72 Å. In the second Al site, Al is bonded in a 4-coordinate geometry to three equivalent Hf, four Co, and six Al atoms. All Al–Al bond lengths are 2.84 Å.

36 MATERIALS SCIENCE↗