DOI: 10.17188/1652792
title: Materials Data on HfAlCr by Materials Project

description: HfCrAl is Hexagonal Laves-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are five inequivalent Hf sites. In the first Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, five Cr, and seven Al atoms. There are a spread of Hf–Hf bond distances ranging from 3.15–3.24 Å. There are a spread of Hf–Cr bond distances ranging from 2.95–3.04 Å. There are a spread of Hf–Al bond distances ranging from 2.99–3.07 Å. In the second Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Cr, and five Al atoms. There are one shorter (3.03 Å) and two longer (3.15 Å) Hf–Hf bond lengths. There are a spread of Hf–Cr bond distances ranging from 2.94–3.08 Å. There are a spread of Hf–Al bond distances ranging from 2.92–3.10 Å. In the third Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Cr, and five Al atoms. There are two shorter (3.15 Å) and one longer (3.19 Å) Hf–Hf bond lengths. There are a spread of Hf–Cr bond distances ranging from 2.94–3.08 Å. There are a spread of Hf–Al bond distances ranging from 2.92–3.10 Å. In the fourth Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, five Cr, and seven Al atoms. Both Hf–Hf bond lengths are 3.15 Å. There are a spread of Hf–Cr bond distances ranging from 2.95–3.04 Å. There are a spread of Hf–Al bond distances ranging from 2.99–3.07 Å. In the fifth Hf site, Hf is bonded in a 12-coordinate geometry to four Hf, seven Cr, and five Al atoms. The Hf–Hf bond length is 3.03 Å. There are a spread of Hf–Cr bond distances ranging from 2.94–3.08 Å. There are a spread of Hf–Al bond distances ranging from 2.92–3.10 Å. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six Hf and six Al atoms to form CrHf6Al6 cuboctahedra that share corners with four equivalent AlHf6Al2Cr4 cuboctahedra, corners with fourteen CrHf6Al6 cuboctahedra, edges with six CrHf6Al6 cuboctahedra, faces with four equivalent CrHf6Al2Cr4 cuboctahedra, and faces with fourteen AlHf6Al2Cr4 cuboctahedra. There are a spread of Cr–Al bond distances ranging from 2.51–2.64 Å. In the second Cr site, Cr is bonded to six Hf, four Cr, and two equivalent Al atoms to form distorted CrHf6Al2Cr4 cuboctahedra that share corners with eight CrHf6Al6 cuboctahedra, corners with ten AlHf6Al2Cr4 cuboctahedra, edges with two equivalent CrHf6Al2Cr4 cuboctahedra, edges with four equivalent AlHf6Al4Cr2 cuboctahedra, faces with eight AlHf6Al2Cr4 cuboctahedra, and faces with ten CrHf6Al6 cuboctahedra. There are a spread of Cr–Cr bond distances ranging from 2.35–2.78 Å. Both Cr–Al bond lengths are 2.58 Å. In the third Cr site, Cr is bonded to six Hf, four equivalent Cr, and two equivalent Al atoms to form CrHf6Al2Cr4 cuboctahedra that share corners with six CrHf6Al6 cuboctahedra, corners with twelve AlHf6Al2Cr4 cuboctahedra, edges with six CrHf6Al6 cuboctahedra, faces with eight equivalent CrHf6Al2Cr4 cuboctahedra, and faces with ten AlHf6Al2Cr4 cuboctahedra. Both Cr–Al bond lengths are 2.60 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Hf, four Cr, and two equivalent Al atoms to form AlHf6Al2Cr4 cuboctahedra that share corners with four equivalent AlHf6Al4Cr2 cuboctahedra, corners with eight CrHf6Al6 cuboctahedra, edges with six equivalent AlHf6Al2Cr4 cuboctahedra, faces with eight AlHf6Al2Cr4 cuboctahedra, and faces with twelve CrHf6Al6 cuboctahedra. Both Al–Al bond lengths are 2.69 Å. In the second Al site, Al is bonded to six Hf, two equivalent Cr, and four Al atoms to form AlHf6Al4Cr2 cuboctahedra that share corners with eight AlHf6Al2Cr4 cuboctahedra, corners with ten CrHf6Al2Cr4 cuboctahedra, edges with two equivalent AlHf6Al4Cr2 cuboctahedra, edges with four equivalent CrHf6Al2Cr4 cuboctahedra, faces with eight CrHf6Al6 cuboctahedra, and faces with ten AlHf6Al2Cr4 cuboctahedra. There are one shorter (2.52 Å) and one longer (2.61 Å) Al–Al bond lengths.