Materials Data on NbNi by Materials Project
NiNb is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are seven inequivalent Nb sites. In the first Nb site, Nb is bonded in a 8-coordinate geometry to eight Nb and six equivalent Ni atoms. There are a spread of Nb–Nb bond distances ranging from 2.61–3.11 Å. All Nb–Ni bond lengths are 2.69 Å. In the second Nb site, Nb is bonded in a 8-coordinate geometry to eight Nb and six equivalent Ni atoms. There are a spread of Nb–Nb bond distances ranging from 2.83–3.13 Å. All Nb–Ni bond lengths are 2.67 Å. In the third Nb site, Nb is bonded in a 6-coordinate geometry to nine Nb and six Ni atoms. All Nb–Nb bond lengths are 2.83 Å. All Nb–Ni bond lengths are 2.77 Å. In the fourth Nb site, Nb is bonded in a 6-coordinate geometry to nine Nb and six Ni atoms. All Nb–Ni bond lengths are 2.78 Å. In the fifth Nb site, Nb is bonded in a 6-coordinate geometry to four Nb and twelve Ni atoms. All Nb–Nb bond lengths are 2.91 Å. There are a spread of Nb–Ni bond distances ranging from 2.73–2.96 Å. In the sixth Nb site, Nb is bonded in a 9-coordinate geometry to seven Nb and nine equivalent Ni atoms. There are three shorter (2.85 Å) and three longer (2.92 Å) Nb–Nb bond lengths. There are three shorter (2.85 Å) and six longer (3.02 Å) Nb–Ni bond lengths. In the seventh Nb site, Nb is bonded to six equivalent Nb and six equivalent Ni atoms to form distorted NbNb6Ni6 cuboctahedra that share corners with twelve equivalent NiNb8Ni4 cuboctahedra, edges with six equivalent NbNb6Ni6 cuboctahedra, and faces with eighteen equivalent NiNb8Ni4 cuboctahedra. All Nb–Ni bond lengths are 2.56 Å. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to eight Nb and four equivalent Ni atoms to form distorted NiNb8Ni4 cuboctahedra that share corners with two equivalent NbNb6Ni6 cuboctahedra, corners with thirteen NiNb8Ni4 cuboctahedra, edges with five NiNb7Ni5 cuboctahedra, faces with three equivalent NbNb6Ni6 cuboctahedra, and faces with ten equivalent NiNb8Ni4 cuboctahedra. There are two shorter (2.42 Å) and two longer (2.48 Å) Ni–Ni bond lengths. In the second Ni site, Ni is bonded to seven Nb and five Ni atoms to form NiNb7Ni5 cuboctahedra that share corners with fifteen NiNb8Ni4 cuboctahedra, edges with five NiNb7Ni5 cuboctahedra, and faces with thirteen NiNb7Ni5 cuboctahedra. There are one shorter (2.44 Å) and four longer (2.45 Å) Ni–Ni bond lengths. In the third Ni site, Ni is bonded to six equivalent Nb and six equivalent Ni atoms to form NiNb6Ni6 cuboctahedra that share corners with twelve equivalent NiNb7Ni5 cuboctahedra, edges with six equivalent NiNb6Ni6 cuboctahedra, and faces with eighteen equivalent NiNb7Ni5 cuboctahedra.