Materials Data on Ca(MgBi)2 by Materials Project
CaMg2Bi2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ca is bonded to six equivalent Bi atoms to form CaBi6 octahedra that share corners with twelve equivalent MgBi4 tetrahedra, edges with six equivalent CaBi6 octahedra, and edges with six equivalent MgBi4 tetrahedra. All Ca–Bi bond lengths are 3.33 Å. Mg is bonded to four equivalent Bi atoms to form MgBi4 tetrahedra that share corners with six equivalent CaBi6 octahedra, corners with six equivalent MgBi4 tetrahedra, edges with three equivalent CaBi6 octahedra, and edges with three equivalent MgBi4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–56°. There are three shorter (2.96 Å) and one longer (3.01 Å) Mg–Bi bond lengths. Bi is bonded to three equivalent Ca and four equivalent Mg atoms to form a mixture of distorted edge and corner-sharing BiCa3Mg4 pentagonal bipyramids.