Mg2Ca is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to three equivalent Ca(1), four equivalent Mg(2), and five equivalent Mg(1) atoms to form distorted CaCa3Mg9 cuboctahedra that share corners with six equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with six equivalent Mg(1)Ca5Mg7 cuboctahedra, edges with four equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with five equivalent Mg(1)Ca5Mg7 cuboctahedra, faces with six equivalent Ca(1)Ca3Mg9 cuboctahedra, and faces with eight equivalent Mg(1)Ca5Mg7 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to five equivalent Ca(1), three equivalent Mg(2), and four equivalent Mg(1) atoms to form distorted MgCa5Mg7 cuboctahedra that share corners with six equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with six equivalent Mg(1)Ca5Mg7 cuboctahedra, edges with five equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with six equivalent Mg(1)Ca5Mg7 cuboctahedra, faces with five equivalent Mg(1)Ca5Mg7 cuboctahedra, and faces with eight equivalent Ca(1)Ca3Mg9 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to four equivalent Ca(1), three equivalent Mg(1), and four equivalent Mg(2) atoms.
Mg2Ca is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to three equivalent Ca(1), four equivalent Mg(2), and five equivalent Mg(1) atoms to form distorted CaCa3Mg9 cuboctahedra that share corners with six equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with six equivalent Mg(1)Ca5Mg7 cuboctahedra, edges with four equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with five equivalent Mg(1)Ca5Mg7 cuboctahedra, faces with six equivalent Ca(1)Ca3Mg9 cuboctahedra, and faces with eight equivalent Mg(1)Ca5Mg7 cuboctahedra. There are two shorter (3.48 Å) and one longer (3.59 Å) Ca(1)-Ca(1) bond length. There are two shorter (3.40 Å) and two longer (3.41 Å) Ca(1)-Mg(2) bond lengths. There are a spread of Ca(1)-Mg(1) bond distances ranging from 3.54-3.58 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to five equivalent Ca(1), three equivalent Mg(2), and four equivalent Mg(1) atoms to form distorted MgCa5Mg7 cuboctahedra that share corners with six equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with six equivalent Mg(1)Ca5Mg7 cuboctahedra, edges with five equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with six equivalent Mg(1)Ca5Mg7 cuboctahedra, faces with five equivalent Mg(1)Ca5Mg7 cuboctahedra, and faces with eight equivalent Ca(1)Ca3Mg9 cuboctahedra. There are two shorter (3.20 Å) and one longer (3.26 Å) Mg(1)-Mg(2) bond length. There are two shorter (3.28 Å) and two longer (3.48 Å) Mg(1)-Mg(1) bond lengths. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to four equivalent Ca(1), three equivalent Mg(1), and four equivalent Mg(2) atoms. There are two shorter (3.12 Å) and two longer (3.48 Å) Mg(2)-Mg(2) bond lengths.