Materials Data on Ca(MnAs)2 by Materials Project
CaMn2As2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ca2+ is bonded to six equivalent As3- atoms to form CaAs6 octahedra that share corners with twelve equivalent MnAs4 tetrahedra, edges with six equivalent CaAs6 octahedra, and edges with six equivalent MnAs4 tetrahedra. All Ca–As bond lengths are 2.99 Å. Mn2+ is bonded to four equivalent As3- atoms to form MnAs4 tetrahedra that share corners with six equivalent CaAs6 octahedra, corners with six equivalent MnAs4 tetrahedra, edges with three equivalent CaAs6 octahedra, and edges with three equivalent MnAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–51°. There are one shorter (2.41 Å) and three longer (2.44 Å) Mn–As bond lengths. As3- is bonded to three equivalent Ca2+ and four equivalent Mn2+ atoms to form a mixture of distorted corner and edge-sharing AsCa3Mn4 pentagonal bipyramids.