CaMg6Nb is beta Cu3Ti-derived structured and crystallizes in the orthorhombic Amm2 space group. Ca(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form CaMg10Nb2 cuboctahedra that share corners with four equivalent Mg(2)Ca2Mg10 cuboctahedra, corners with six equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with two equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with four equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Nb2 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Nb(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form MgCa2Mg10 cuboctahedra that share corners with four equivalent Ca(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with two equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Nb(1)Ca2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Ca(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Nb(1) atoms to form distorted MgCa2Mg8Nb2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with four equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with two equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, and faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form MgMg10Nb2 cuboctahedra that share corners with four equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Ca(1)Mg10Nb2 cuboctahedra. Nb(1) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form NbCa2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with six equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with four equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Mg(2)Ca2Mg10 cuboctahedra.
CaMg6Nb is beta Cu3Ti-derived structured and crystallizes in the orthorhombic Amm2 space group. Ca(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form CaMg10Nb2 cuboctahedra that share corners with four equivalent Mg(2)Ca2Mg10 cuboctahedra, corners with six equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with two equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with four equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Nb2 cuboctahedra. Both Ca(1)-Mg(2) bond lengths are 3.24 Å. There are two shorter (3.13 Å) and two longer (3.35 Å) Ca(1)-Mg(1) bond lengths. All Ca(1)-Mg(3) bond lengths are 3.22 Å. Both Ca(1)-Nb(1) bond lengths are 3.22 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Nb(1) atoms. There is one shorter (3.04 Å) and one longer (3.44 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.22 Å) and one longer (3.26 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.20 Å. Both Mg(1)-Mg(4) bond lengths are 3.22 Å. Both Mg(1)-Nb(1) bond lengths are 3.10 Å. In the second Mg site, Mg(2) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form MgCa2Mg10 cuboctahedra that share corners with four equivalent Ca(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with two equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Nb(1)Ca2Mg10 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.20 Å. All Mg(2)-Mg(3) bond lengths are 3.18 Å. In the third Mg site, Mg(3) is bonded to two equivalent Ca(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Nb(1) atoms to form distorted MgCa2Mg8Nb2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with four equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with two equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, and faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra. There is one shorter (3.18 Å) and one longer (3.30 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.21 Å) and one longer (3.27 Å) Mg(3)-Mg(4) bond length. There is one shorter (3.13 Å) and one longer (3.35 Å) Mg(3)-Nb(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form MgMg10Nb2 cuboctahedra that share corners with four equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Nb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Mg(2)Ca2Mg10 cuboctahedra, edges with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Mg(2)Ca2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Ca(1)Mg10Nb2 cuboctahedra. Both Mg(4)-Nb(1) bond lengths are 3.24 Å. Nb(1) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form NbCa2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with six equivalent Nb(1)Ca2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, edges with four equivalent Ca(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, faces with two equivalent Ca(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Nb(1)Ca2Mg10 cuboctahedra, faces with four equivalent Mg(3)Ca2Mg8Nb2 cuboctahedra, and faces with six equivalent Mg(2)Ca2Mg10 cuboctahedra.