Materials Data on MgCoNi by Materials Project
MgCoNi is Hexagonal Laves-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to three equivalent Mg, seven Co, and five Ni atoms. There are two shorter (2.95 Å) and one longer (3.00 Å) Mg–Mg bond lengths. There are a spread of Mg–Co bond distances ranging from 2.81–2.87 Å. There are two shorter (2.78 Å) and three longer (2.80 Å) Mg–Ni bond lengths. In the second Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, five Co, and seven Ni atoms. The Mg–Mg bond length is 2.87 Å. There are a spread of Mg–Co bond distances ranging from 2.79–2.93 Å. There are three shorter (2.79 Å) and four longer (2.83 Å) Mg–Ni bond lengths. There are two inequivalent Co sites. In the first Co site, Co is bonded to six Mg, two equivalent Co, and four Ni atoms to form CoMg6Co2Ni4 cuboctahedra that share corners with four equivalent CoMg6Co4Ni2 cuboctahedra, corners with eight NiMg6Co6 cuboctahedra, edges with six equivalent CoMg6Co2Ni4 cuboctahedra, faces with eight CoMg6Co2Ni4 cuboctahedra, and faces with twelve NiMg6Co6 cuboctahedra. Both Co–Co bond lengths are 2.36 Å. There are a spread of Co–Ni bond distances ranging from 2.42–2.44 Å. In the second Co site, Co is bonded to six Mg, four Co, and two equivalent Ni atoms to form CoMg6Co4Ni2 cuboctahedra that share corners with eight CoMg6Co2Ni4 cuboctahedra, corners with ten NiMg6Co2Ni4 cuboctahedra, edges with two equivalent CoMg6Co4Ni2 cuboctahedra, edges with four equivalent NiMg6Co2Ni4 cuboctahedra, faces with eight NiMg6Co6 cuboctahedra, and faces with ten CoMg6Co2Ni4 cuboctahedra. There are one shorter (2.31 Å) and one longer (2.49 Å) Co–Co bond lengths. There are one shorter (2.38 Å) and one longer (2.49 Å) Co–Ni bond lengths. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to six Mg and six Co atoms to form NiMg6Co6 cuboctahedra that share corners with four equivalent CoMg6Co2Ni4 cuboctahedra, corners with fourteen NiMg6Co6 cuboctahedra, edges with six NiMg6Co6 cuboctahedra, faces with four equivalent NiMg6Co2Ni4 cuboctahedra, and faces with fourteen CoMg6Co2Ni4 cuboctahedra. In the second Ni site, Ni is bonded to six Mg, two equivalent Co, and four Ni atoms to form NiMg6Co2Ni4 cuboctahedra that share corners with eight NiMg6Co6 cuboctahedra, corners with ten CoMg6Co2Ni4 cuboctahedra, edges with two equivalent NiMg6Co2Ni4 cuboctahedra, edges with four equivalent CoMg6Co4Ni2 cuboctahedra, faces with eight CoMg6Co2Ni4 cuboctahedra, and faces with ten NiMg6Co6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.36–2.48 Å. In the third Ni site, Ni is bonded to six Mg, two equivalent Co, and four equivalent Ni atoms to form NiMg6Co2Ni4 cuboctahedra that share corners with six NiMg6Co6 cuboctahedra, corners with twelve CoMg6Co2Ni4 cuboctahedra, edges with six NiMg6Co6 cuboctahedra, faces with eight equivalent NiMg6Co2Ni4 cuboctahedra, and faces with ten CoMg6Co2Ni4 cuboctahedra.