Mg2Zr5O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(8), one O(9), and two equivalent O(4) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(5), one O(7), and two equivalent O(11) atoms. There are five inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in an octahedral geometry to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(6) atom. In the second Zr site, Zr(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(4), one O(6), one O(8), and one O(9) atom. In the third Zr site, Zr(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(5), and two equivalent O(7) atoms. In the fourth Zr site, Zr(4) is bonded in a 7-coordinate geometry to one O(4), one O(6), one O(9), two equivalent O(2), and two equivalent O(8) atoms. In the fifth Zr site, Zr(5) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(3), one O(6), one O(7), and one O(9) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Zr(1), one Zr(2), and one Zr(3) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with two equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with two equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra, and  an edgeedge with one O(12)MgZr3 tetrahedra. In the second O site, O(2) is bonded to one Mg(1), one Zr(1), and two equivalent Zr(4) atoms to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(10)MgZr3 tetrahedra, corners with two equivalent O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with three equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Zr(1), one Zr(3), and one Zr(5) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Zr(2), and one Zr(4) atom to form OMg2Zr2 tetrahedra that share  a cornercorner with one O(1)MgZr3 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra, corners with two equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(1)MgZr3 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra,  an edgeedge with one O(9)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2), one Zr(1), and one Zr(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Zr(1), one Zr(2), one Zr(4), and one Zr(5) atom. In the seventh O site, O(7) is bonded to one Mg(2), one Zr(5), and two equivalent Zr(3) atoms to form OMgZr3 tetrahedra that share  a cornercorner with one O(9)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with two equivalent O(12)MgZr3 tetrahedra, corners with three equivalent O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(7)MgZr3 tetrahedra. In the eighth O site, O(8) is bonded to one Mg(1), one Zr(2), and two equivalent Zr(4) atoms to form distorted OMgZr3 trigonal pyramids that share  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(4)Mg2Zr2 tetrahedra, corners with three equivalent O(2)MgZr3 tetrahedra,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra,  an edgeedge with one O(9)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the ninth O site, O(9) is bonded to one Mg(1), one Zr(2), one Zr(4), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(7)MgZr3 tetrahedra, corners with two equivalent O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with three equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the tenth O site, O(10) is bonded to one Mg(2), one Zr(1), one Zr(2), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(4)Mg2Zr2 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra,  a cornercorner with one O(2)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra,  a cornercorner with one O(8)MgZr3 trigonal pyramid,  an edgeedge with one O(11)Mg2Zr2 tetrahedra, and  an edgeedge with one O(12)MgZr3 tetrahedra. In the eleventh O site, O(11) is bonded to two equivalent Mg(2), one Zr(3), and one Zr(5) atom to form OMg2Zr2 tetrahedra that share  a cornercorner with one O(1)MgZr3 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(9)MgZr3 tetrahedra, corners with two equivalent O(12)MgZr3 tetrahedra, corners with three equivalent O(7)MgZr3 tetrahedra,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(10)MgZr3 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(7)MgZr3 tetrahedra. In the twelfth O site, O(12) is bonded to one Mg(2), one Zr(2), one Zr(3), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(4)Mg2Zr2 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra, corners with two equivalent O(11)Mg2Zr2 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra,  a cornercorner with one O(8)MgZr3 trigonal pyramid,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(1)MgZr3 tetrahedra,  an edgeedge with one O(10)MgZr3 tetrahedra,  an edgeedge with one O(7)MgZr3 tetrahedra, and  an edgeedge with one O(9)MgZr3 tetrahedra.
Mg2Zr5O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(8), one O(9), and two equivalent O(4) atoms. The Mg(1)-O(1) bond length is 2.11 Å. The Mg(1)-O(2) bond length is 2.17 Å. The Mg(1)-O(8) bond length is 2.44 Å. The Mg(1)-O(9) bond length is 2.09 Å. There is one shorter (2.09 Å) and one longer (2.18 Å) Mg(1)-O(4) bond length. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(5), one O(7), and two equivalent O(11) atoms. The Mg(2)-O(10) bond length is 2.26 Å. The Mg(2)-O(12) bond length is 2.38 Å. The Mg(2)-O(5) bond length is 2.06 Å. The Mg(2)-O(7) bond length is 2.07 Å. There is one shorter (2.10 Å) and one longer (2.16 Å) Mg(2)-O(11) bond length. There are five inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in an octahedral geometry to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(6) atom. The Zr(1)-O(1) bond length is 2.11 Å. The Zr(1)-O(10) bond length is 2.08 Å. The Zr(1)-O(2) bond length is 2.15 Å. The Zr(1)-O(3) bond length is 2.09 Å. The Zr(1)-O(5) bond length is 2.08 Å. The Zr(1)-O(6) bond length is 2.16 Å. In the second Zr site, Zr(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(4), one O(6), one O(8), and one O(9) atom. The Zr(2)-O(1) bond length is 2.12 Å. The Zr(2)-O(10) bond length is 2.15 Å. The Zr(2)-O(12) bond length is 2.20 Å. The Zr(2)-O(4) bond length is 2.21 Å. The Zr(2)-O(6) bond length is 2.60 Å. The Zr(2)-O(8) bond length is 2.10 Å. The Zr(2)-O(9) bond length is 2.14 Å. In the third Zr site, Zr(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(5), and two equivalent O(7) atoms. The Zr(3)-O(1) bond length is 2.58 Å. The Zr(3)-O(11) bond length is 2.19 Å. The Zr(3)-O(12) bond length is 2.11 Å. The Zr(3)-O(3) bond length is 2.15 Å. The Zr(3)-O(5) bond length is 2.06 Å. There is one shorter (2.19 Å) and one longer (2.20 Å) Zr(3)-O(7) bond length. In the fourth Zr site, Zr(4) is bonded in a 7-coordinate geometry to one O(4), one O(6), one O(9), two equivalent O(2), and two equivalent O(8) atoms. The Zr(4)-O(4) bond length is 2.04 Å. The Zr(4)-O(6) bond length is 2.14 Å. The Zr(4)-O(9) bond length is 2.34 Å. There is one shorter (2.11 Å) and one longer (2.52 Å) Zr(4)-O(2) bond length. There is one shorter (2.15 Å) and one longer (2.24 Å) Zr(4)-O(8) bond length. In the fifth Zr site, Zr(5) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(3), one O(6), one O(7), and one O(9) atom. The Zr(5)-O(10) bond length is 2.47 Å. The Zr(5)-O(11) bond length is 2.04 Å. The Zr(5)-O(12) bond length is 2.15 Å. The Zr(5)-O(3) bond length is 2.09 Å. The Zr(5)-O(6) bond length is 2.19 Å. The Zr(5)-O(7) bond length is 2.27 Å. The Zr(5)-O(9) bond length is 2.23 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Zr(1), one Zr(2), and one Zr(3) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with two equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with two equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra, and  an edgeedge with one O(12)MgZr3 tetrahedra. In the second O site, O(2) is bonded to one Mg(1), one Zr(1), and two equivalent Zr(4) atoms to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(10)MgZr3 tetrahedra, corners with two equivalent O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with three equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Zr(1), one Zr(3), and one Zr(5) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Zr(2), and one Zr(4) atom to form OMg2Zr2 tetrahedra that share  a cornercorner with one O(1)MgZr3 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra, corners with two equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(1)MgZr3 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra,  an edgeedge with one O(9)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2), one Zr(1), and one Zr(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Zr(1), one Zr(2), one Zr(4), and one Zr(5) atom. In the seventh O site, O(7) is bonded to one Mg(2), one Zr(5), and two equivalent Zr(3) atoms to form OMgZr3 tetrahedra that share  a cornercorner with one O(9)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with two equivalent O(12)MgZr3 tetrahedra, corners with three equivalent O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(7)MgZr3 tetrahedra. In the eighth O site, O(8) is bonded to one Mg(1), one Zr(2), and two equivalent Zr(4) atoms to form distorted OMgZr3 trigonal pyramids that share  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra, corners with three equivalent O(4)Mg2Zr2 tetrahedra, corners with three equivalent O(2)MgZr3 tetrahedra,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(2)MgZr3 tetrahedra,  an edgeedge with one O(9)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the ninth O site, O(9) is bonded to one Mg(1), one Zr(2), one Zr(4), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(7)MgZr3 tetrahedra, corners with two equivalent O(4)Mg2Zr2 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(10)MgZr3 tetrahedra, corners with three equivalent O(2)MgZr3 tetrahedra, corners with two equivalent O(8)MgZr3 trigonal pyramids,  an edgeedge with one O(4)Mg2Zr2 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(8)MgZr3 trigonal pyramid. In the tenth O site, O(10) is bonded to one Mg(2), one Zr(1), one Zr(2), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(11)Mg2Zr2 tetrahedra,  a cornercorner with one O(4)Mg2Zr2 tetrahedra,  a cornercorner with one O(12)MgZr3 tetrahedra,  a cornercorner with one O(2)MgZr3 tetrahedra, corners with two equivalent O(1)MgZr3 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra, corners with two equivalent O(9)MgZr3 tetrahedra,  a cornercorner with one O(8)MgZr3 trigonal pyramid,  an edgeedge with one O(11)Mg2Zr2 tetrahedra, and  an edgeedge with one O(12)MgZr3 tetrahedra. In the eleventh O site, O(11) is bonded to two equivalent Mg(2), one Zr(3), and one Zr(5) atom to form OMg2Zr2 tetrahedra that share  a cornercorner with one O(1)MgZr3 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra,  a cornercorner with one O(9)MgZr3 tetrahedra, corners with two equivalent O(12)MgZr3 tetrahedra, corners with three equivalent O(7)MgZr3 tetrahedra,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(10)MgZr3 tetrahedra,  an edgeedge with one O(12)MgZr3 tetrahedra, and  an edgeedge with one O(7)MgZr3 tetrahedra. In the twelfth O site, O(12) is bonded to one Mg(2), one Zr(2), one Zr(3), and one Zr(5) atom to form distorted OMgZr3 tetrahedra that share  a cornercorner with one O(4)Mg2Zr2 tetrahedra,  a cornercorner with one O(10)MgZr3 tetrahedra, corners with two equivalent O(11)Mg2Zr2 tetrahedra, corners with two equivalent O(7)MgZr3 tetrahedra,  a cornercorner with one O(8)MgZr3 trigonal pyramid,  an edgeedge with one O(11)Mg2Zr2 tetrahedra,  an edgeedge with one O(1)MgZr3 tetrahedra,  an edgeedge with one O(10)MgZr3 tetrahedra,  an edgeedge with one O(7)MgZr3 tetrahedra, and  an edgeedge with one O(9)MgZr3 tetrahedra.