DOE OSTI2020
Li4(Cu2Al)3 is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are four inequivalent Li sites. In the first Li site, Li is bonded in a 1-coordinate geometry to three equivalent Li, nine equivalent Cu, and four Al atoms. All Li–Li bond lengths are 2.93 Å. There are three shorter (2.79 Å) and six longer (2.97 Å) Li–Cu bond lengths. There are one shorter (2.62 Å) and three longer (2.86 Å) Li–Al bond lengths. In the second Li site, Li is bonded in a 1-coordinate geometry to three equivalent Li, nine equivalent Cu, and four Al atoms. There are three shorter (2.79 Å) and six longer (2.97 Å) Li–Cu bond lengths. There are one shorter (2.62 Å) and three longer (2.86 Å) Li–Al bond lengths. In the third Li site, Li is bonded in a 6-coordinate geometry to six equivalent Cu and six Al atoms. All Li–Cu bond lengths are 2.71 Å. All Li–Al bond lengths are 3.15 Å. In the fourth Li site, Li is bonded in a 6-coordinate geometry to six equivalent Cu and six Al atoms. All Li–Cu bond lengths are 2.72 Å. All Li–Al bond lengths are 3.15 Å. Cu is bonded to five Li, four equivalent Cu, and three Al atoms to form CuLi5Al3Cu4 cuboctahedra that share corners with two equivalent AlLi6Cu6 cuboctahedra, corners with thirteen equivalent CuLi5Al3Cu4 cuboctahedra, edges with five equivalent CuLi5Al3Cu4 cuboctahedra, faces with three equivalent AlLi6Cu6 cuboctahedra, and faces with ten equivalent CuLi5Al3Cu4 cuboctahedra. There are two shorter (2.42 Å) and two longer (2.48 Å) Cu–Cu bond lengths. There are one shorter (2.49 Å) and two longer (2.63 Å) Cu–Al bond lengths. There are four inequivalent Al sites. In the first Al site, Al is bonded to six Li and six equivalent Cu atoms to form AlLi6Cu6 cuboctahedra that share corners with twelve equivalent CuLi5Al3Cu4 cuboctahedra, edges with six equivalent AlLi6Cu6 cuboctahedra, and faces with eighteen equivalent CuLi5Al3Cu4 cuboctahedra. In the second Al site, Al is bonded in a 1-coordinate geometry to seven Li, six equivalent Cu, and one Al atom. All Al–Cu bond lengths are 2.63 Å. The Al–Al bond length is 2.74 Å. In the third Al site, Al is bonded in a 1-coordinate geometry to seven Li, six equivalent Cu, and one Al atom. The Al–Li bond length is 2.62 Å. The Al–Al bond length is 2.74 Å. In the fourth Al site, Al is bonded in a 1-coordinate geometry to seven Li, six equivalent Cu, and one Al atom. There are one shorter (2.62 Å) and six longer (3.15 Å) Al–Li bond lengths. All Al–Cu bond lengths are 2.63 Å.