Materials Data on CaMg5 by Materials Project

Abstract

CaMg5 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ca is bonded to two equivalent Ca and ten Mg atoms to form CaCa2Mg10 cuboctahedra that share corners with six equivalent CaCa2Mg10 cuboctahedra, corners with six equivalent MgCa2Mg10 cuboctahedra, edges with five MgCa3Mg9 cuboctahedra, faces with two equivalent CaCa2Mg10 cuboctahedra, and faces with eight MgCa3Mg9 cuboctahedra. Both Ca–Ca bond lengths are 3.31 Å. There are a spread of Ca–Mg bond distances ranging from 3.31–3.44 Å. There are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 11-coordinate geometry to two equivalent Ca and nine Mg atoms. There are a spread of Mg–Mg bond distances ranging from 3.07–3.31 Å. In the second Mg site, Mg is bonded to three equivalent Ca and nine Mg atoms to form MgCa3Mg9 cuboctahedra that share corners with six equivalent MgCa3Mg9 cuboctahedra, edges with two equivalent CaCa2Mg10 cuboctahedra, edges with six equivalent MgCa2Mg10 cuboctahedra, faces with five equivalent CaCa2Mg10 cuboctahedra, and faces with five MgCa3Mg9 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.19–3.37 Å. In the third Mg site, Mg is bonded to two equivalent Ca and ten Mg atoms to form distorted MgCa2Mg10 cuboctahedra that share corners with six equivalent CaCa2Mg10 cuboctahedra, corners with six equivalent MgCa2Mg10 cuboctahedra, edges with three equivalent CaCa2Mg10 cuboctahedra, edges with six equivalent MgCa3Mg9 cuboctahedra, faces with three equivalent CaCa2Mg10 cuboctahedra, and faces with five MgCa3Mg9 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.14–3.48 Å. In the fourth Mg site, Mg is bonded in a 12-coordinate geometry to one Ca and eleven Mg atoms. There are two shorter (3.21 Å) and two longer (3.31 Å) Mg–Mg bond lengths. In the fifth Mg site, Mg is bonded in a 11-coordinate geometry to two equivalent Ca and nine Mg atoms. Both Mg–Mg bond lengths are 3.31 Å.