Materials Data on HfAlCu by Materials Project

Abstract

HfCuAl 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 Cu, and seven Al atoms. There are one shorter (3.12 Å) and two longer (3.18 Å) Hf–Hf bond lengths. There are three shorter (2.91 Å) and two longer (3.09 Å) Hf–Cu bond lengths. There are a spread of Hf–Al bond distances ranging from 3.02–3.08 Å. In the second Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Cu, and five Al atoms. The Hf–Hf bond length is 3.02 Å. There are a spread of Hf–Cu bond distances ranging from 2.98–3.05 Å. There are a spread of Hf–Al bond distances ranging from 2.97–3.06 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded to six Hf and six Al atoms to form CuHf6Al6 cuboctahedra that share corners with four equivalent AlHf6Al2Cu4 cuboctahedra, corners with fourteen CuHf6Al6 cuboctahedra, edges with six CuHf6Al6 cuboctahedra, faces with four equivalent CuHf6Al2Cu4 cuboctahedra, and faces with fourteen AlHf6Al2Cu4 cuboctahedra. There are a spread of Cu–Al bond distances ranging from 2.51–2.64 Å. In the second Cu site, Cu is bonded to six Hf, four Cu, and two equivalent Al atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with eight CuHf6Al6 cuboctahedra, corners with ten AlHf6Al2Cu4 cuboctahedra, edges with two equivalent CuHf6Al2Cu4 cuboctahedra, edges with four equivalent AlHf6Al4Cu2 cuboctahedra, faces with eight AlHf6Al2Cu4 cuboctahedra, and faces with ten CuHf6Al6 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.49–2.72 Å. Both Cu–Al bond lengths are 2.51 Å. In the third Cu site, Cu is bonded to six Hf, four equivalent Cu, and two equivalent Al atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with six CuHf6Al6 cuboctahedra, corners with twelve AlHf6Al2Cu4 cuboctahedra, edges with six CuHf6Al6 cuboctahedra, faces with eight equivalent CuHf6Al2Cu4 cuboctahedra, and faces with ten AlHf6Al2Cu4 cuboctahedra. Both Cu–Al bond lengths are 2.52 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Hf, four Cu, and two equivalent Al atoms to form distorted AlHf6Al2Cu4 cuboctahedra that share corners with four equivalent AlHf6Al4Cu2 cuboctahedra, corners with eight CuHf6Al6 cuboctahedra, edges with six equivalent AlHf6Al2Cu4 cuboctahedra, faces with eight AlHf6Al2Cu4 cuboctahedra, and faces with twelve CuHf6Al6 cuboctahedra. Both Al–Al bond lengths are 2.70 Å. In the second Al site, Al is bonded to six Hf, two equivalent Cu, and four Al atoms to form distorted AlHf6Al4Cu2 cuboctahedra that share corners with eight AlHf6Al2Cu4 cuboctahedra, corners with ten CuHf6Al2Cu4 cuboctahedra, edges with two equivalent AlHf6Al4Cu2 cuboctahedra, edges with four equivalent CuHf6Al2Cu4 cuboctahedra, faces with eight CuHf6Al6 cuboctahedra, and faces with ten AlHf6Al2Cu4 cuboctahedra. There are one shorter (2.55 Å) and one longer (2.69 Å) Al–Al bond lengths.