Materials Data on HfAlFe by Materials Project

Hf(Fe0.5Al0.5)2 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 Fe, and seven Al atoms. There are two shorter (3.09 Å) and one longer (3.10 Å) Hf–Hf bond lengths. There are a spread of Hf–Fe bond distances ranging from 2.85–3.02 Å. There are a spread of Hf–Al bond distances ranging from 2.94–3.02 Å. In the second Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Fe, and five Al atoms. The Hf–Hf bond length is 2.92 Å. There are a spread of Hf–Fe bond distances ranging from 2.87–3.01 Å. There are one shorter (2.86 Å) and four longer (3.02 Å) Hf–Al bond lengths. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to six Hf and six Al atoms to form FeHf6Al6 cuboctahedra that share corners with four equivalent AlHf6Al2Fe4 cuboctahedra, corners with fourteen FeHf6Al6 cuboctahedra, edges with six FeHf6Al6 cuboctahedra, faces with four equivalent FeHf6Al2Fe4 cuboctahedra, and faces with fourteen AlHf6Al2Fe4 cuboctahedra. There are a spread of Fe–Al bond distances ranging from 2.47–2.58 Å. In the second Fe site, Fe is bonded to six Hf, four Fe, and two equivalent Al atoms to form distorted FeHf6Al2Fe4 cuboctahedra that share corners with eight FeHf6Al6 cuboctahedra, corners with ten AlHf6Al2Fe4 cuboctahedra, edges with two equivalent FeHf6Al2Fe4 cuboctahedra, edges with four equivalent AlHf6Al4Fe2 cuboctahedra, faces with eight AlHf6Al2Fe4 cuboctahedra, and faces with ten FeHf6Al6 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.43–2.65 Å. Both Fe–Al bond lengths are 2.49 Å. In the third Fe site, Fe is bonded to six Hf, four equivalent Fe, and two equivalent Al atoms to form distorted FeHf6Al2Fe4 cuboctahedra that share corners with six FeHf6Al6 cuboctahedra, corners with twelve AlHf6Al2Fe4 cuboctahedra, edges with six FeHf6Al6 cuboctahedra, faces with eight equivalent FeHf6Al2Fe4 cuboctahedra, and faces with ten AlHf6Al2Fe4 cuboctahedra. Both Fe–Al bond lengths are 2.50 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Hf, four Fe, and two equivalent Al atoms to form distorted AlHf6Al2Fe4 cuboctahedra that share corners with four equivalent AlHf6Al4Fe2 cuboctahedra, corners with eight FeHf6Al6 cuboctahedra, edges with six equivalent AlHf6Al2Fe4 cuboctahedra, faces with eight AlHf6Al2Fe4 cuboctahedra, and faces with twelve FeHf6Al6 cuboctahedra. Both Al–Al bond lengths are 2.63 Å. In the second Al site, Al is bonded to six Hf, two equivalent Fe, and four Al atoms to form distorted AlHf6Al4Fe2 cuboctahedra that share corners with eight AlHf6Al2Fe4 cuboctahedra, corners with ten FeHf6Al2Fe4 cuboctahedra, edges with two equivalent AlHf6Al4Fe2 cuboctahedra, edges with four equivalent FeHf6Al2Fe4 cuboctahedra, faces with eight FeHf6Al6 cuboctahedra, and faces with ten AlHf6Al2Fe4 cuboctahedra. There are one shorter (2.49 Å) and one longer (2.59 Å) Al–Al bond lengths.