MgCa crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent Ca(3), two equivalent Mg(1), and four equivalent Mg(2) atoms. In the second Ca site, Ca(2) is bonded in a 4-coordinate geometry to four equivalent Ca(3), two equivalent Mg(1), and two equivalent Mg(3) atoms. In the third Ca site, Ca(3) is bonded to two equivalent Ca(1), two equivalent Ca(3), four equivalent Ca(2), two equivalent Mg(2), and two equivalent Mg(3) atoms to form a mixture of distorted face and corner-sharing CaCa8Mg4 cuboctahedra. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Mg(2), and four equivalent Mg(3) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ca(3), four equivalent Ca(1), two equivalent Mg(1), and two equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), two equivalent Mg(2), and four equivalent Mg(1) atoms.
MgCa crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent Ca(3), two equivalent Mg(1), and four equivalent Mg(2) atoms. Both Ca(1)-Ca(3) bond lengths are 3.64 Å. Both Ca(1)-Mg(1) bond lengths are 3.32 Å. All Ca(1)-Mg(2) bond lengths are 3.50 Å. In the second Ca site, Ca(2) is bonded in a 4-coordinate geometry to four equivalent Ca(3), two equivalent Mg(1), and two equivalent Mg(3) atoms. All Ca(2)-Ca(3) bond lengths are 3.59 Å. Both Ca(2)-Mg(1) bond lengths are 3.35 Å. Both Ca(2)-Mg(3) bond lengths are 3.47 Å. In the third Ca site, Ca(3) is bonded to two equivalent Ca(1), two equivalent Ca(3), four equivalent Ca(2), two equivalent Mg(2), and two equivalent Mg(3) atoms to form a mixture of distorted face and corner-sharing CaCa8Mg4 cuboctahedra. Both Ca(3)-Ca(3) bond lengths are 3.89 Å. Both Ca(3)-Mg(2) bond lengths are 3.70 Å. Both Ca(3)-Mg(3) bond lengths are 3.74 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Mg(2), and four equivalent Mg(3) atoms. Both Mg(1)-Mg(2) bond lengths are 3.37 Å. All Mg(1)-Mg(3) bond lengths are 3.47 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ca(3), four equivalent Ca(1), two equivalent Mg(1), and two equivalent Mg(3) atoms. Both Mg(2)-Mg(3) bond lengths are 3.21 Å. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), two equivalent Mg(2), and four equivalent Mg(1) atoms.