Materials Data on Ca(MnAl2)4 by Materials Project

Abstract

Ca(MnAl2)4 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca is bonded in a 4-coordinate geometry to eight equivalent Mn and twelve Al atoms. All Ca–Mn bond lengths are 3.36 Å. There are four shorter (2.92 Å) and eight longer (3.28 Å) Ca–Al bond lengths. Mn is bonded to two equivalent Ca, two equivalent Mn, and eight Al atoms to form distorted MnCa2Mn2Al8 cuboctahedra that share corners with eight equivalent AlCa2Mn4Al6 cuboctahedra, corners with ten equivalent MnCa2Mn2Al8 cuboctahedra, edges with four equivalent MnCa2Mn2Al8 cuboctahedra, edges with four equivalent AlCa2Mn4Al6 cuboctahedra, faces with six equivalent MnCa2Mn2Al8 cuboctahedra, and faces with eight equivalent AlCa2Mn4Al6 cuboctahedra. Both Mn–Mn bond lengths are 2.59 Å. There are four shorter (2.55 Å) and four longer (2.65 Å) Mn–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to two equivalent Ca, four equivalent Mn, and six Al atoms to form distorted AlCa2Mn4Al6 cuboctahedra that share corners with eight equivalent MnCa2Mn2Al8 cuboctahedra, corners with ten equivalent AlCa2Mn4Al6 cuboctahedra, edges with three equivalent AlCa2Mn4Al6 cuboctahedra, edges with four equivalent MnCa2Mn2Al8 cuboctahedra, faces with seven equivalent AlCa2Mn4Al6 cuboctahedra, and faces with eight equivalent MnCa2Mn2Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.75–2.83 Å. In the second Al site, Al is bonded in a 10-coordinate geometry to one Ca, four equivalent Mn, and five Al atoms. The Al–Al bond length is 2.92 Å.