DOE OSTI2020
Li(NiSi)6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to eight Si+1.33- atoms to form LiSi8 hexagonal bipyramids that share corners with twelve equivalent NiSi6 octahedra, edges with three equivalent LiSi8 hexagonal bipyramids, and faces with twelve NiSi6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two shorter (2.61 Å) and six longer (2.80 Å) Li–Si bond lengths. In the second Li1+ site, Li1+ is bonded to eight Si+1.33- atoms to form LiSi8 hexagonal bipyramids that share corners with twelve equivalent NiSi6 octahedra and faces with twelve equivalent NiSi6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are two shorter (2.61 Å) and six longer (2.79 Å) Li–Si bond lengths. There are two inequivalent Ni+1.17+ sites. In the first Ni+1.17+ site, Ni+1.17+ is bonded to six Si+1.33- atoms to form distorted NiSi6 octahedra that share corners with two equivalent LiSi8 hexagonal bipyramids, corners with fourteen NiSi6 octahedra, edges with two equivalent NiSi6 octahedra, faces with two equivalent LiSi8 hexagonal bipyramids, and faces with four equivalent NiSi6 octahedra. The corner-sharing octahedra tilt angles range from 32–67°. There are a spread of Ni–Si bond distances ranging from 2.34–2.53 Å. In the second Ni+1.17+ site, Ni+1.17+ is bonded to six Si+1.33- atoms to form distorted NiSi6 octahedra that share corners with two equivalent LiSi8 hexagonal bipyramids, corners with fourteen NiSi6 octahedra, edges with two equivalent NiSi6 octahedra, faces with two LiSi8 hexagonal bipyramids, and faces with four NiSi6 octahedra. The corner-sharing octahedra tilt angles range from 32–68°. There are a spread of Ni–Si bond distances ranging from 2.36–2.54 Å. There are four inequivalent Si+1.33- sites. In the first Si+1.33- site, Si+1.33- is bonded in a 1-coordinate geometry to one Li1+, six equivalent Ni+1.17+, and one Si+1.33- atom. The Si–Si bond length is 2.37 Å. In the second Si+1.33- site, Si+1.33- is bonded in a 1-coordinate geometry to one Li1+, six Ni+1.17+, and one Si+1.33- atom. The Si–Si bond length is 2.38 Å. In the third Si+1.33- site, Si+1.33- is bonded in a 7-coordinate geometry to one Li1+ and six Ni+1.17+ atoms. In the fourth Si+1.33- site, Si+1.33- is bonded in a 8-coordinate geometry to two equivalent Li1+ and six Ni+1.17+ atoms.