Materials Data on Si2NiSe4 by Materials Project
NiSi2Se4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ni2+ is bonded to six Se+0.50- atoms to form NiSe6 octahedra that share corners with twelve equivalent SiSe6 octahedra, edges with two equivalent NiSe6 octahedra, and faces with two equivalent SiSe6 octahedra. The corner-sharing octahedra tilt angles range from 43–55°. There are four shorter (2.41 Å) and two longer (2.91 Å) Ni–Se bond lengths. Si is bonded to six Se+0.50- atoms to form SiSe6 octahedra that share corners with six equivalent NiSe6 octahedra, edges with six equivalent SiSe6 octahedra, and a faceface with one NiSe6 octahedra. The corner-sharing octahedra tilt angles range from 43–55°. There are a spread of Si–Se bond distances ranging from 2.46–2.72 Å. There are two inequivalent Se+0.50- sites. In the first Se+0.50- site, Se+0.50- is bonded in a 5-coordinate geometry to two equivalent Ni2+ and three equivalent Si atoms. In the second Se+0.50- site, Se+0.50- is bonded in a distorted rectangular see-saw-like geometry to one Ni2+ and three equivalent Si atoms.