Ba3MgNb2ZnO9 crystallizes in the monoclinic Cm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to one O(6), two equivalent O(4), two equivalent O(5), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to one O(6), two equivalent O(1), two equivalent O(5), and four equivalent O(2) atoms. In the third Ba site, Ba(3) is bonded to one O(1), one O(4), two equivalent O(2), two equivalent O(3), two equivalent O(6), and four equivalent O(5) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Nb(2)O6 octahedra. Mg(1) is bonded in a 3-coordinate geometry to one Zn(1), one O(4), and two equivalent O(3) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(4), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Nb site, Nb(2) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. Zn(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one O(1), and two equivalent O(2) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(3), two equivalent Ba(2), one Nb(2), and one Zn(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(3), two equivalent Ba(2), one Nb(2), and one Zn(1) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Ba(3), two equivalent Ba(1), one Mg(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Ba(3), two equivalent Ba(1), one Mg(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 3-60°. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°.
Ba3MgNb2ZnO9 crystallizes in the monoclinic Cm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to one O(6), two equivalent O(4), two equivalent O(5), and four equivalent O(3) atoms. The Ba(1)-O(6) bond length is 2.84 Å. Both Ba(1)-O(4) bond lengths are 2.94 Å. Both Ba(1)-O(5) bond lengths are 2.81 Å. There are two shorter (2.91 Å) and two longer (2.96 Å) Ba(1)-O(3) bond lengths. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to one O(6), two equivalent O(1), two equivalent O(5), and four equivalent O(2) atoms. The Ba(2)-O(6) bond length is 2.91 Å. Both Ba(2)-O(1) bond lengths are 2.94 Å. Both Ba(2)-O(5) bond lengths are 2.92 Å. There are two shorter (2.93 Å) and two longer (2.95 Å) Ba(2)-O(2) bond lengths. In the third Ba site, Ba(3) is bonded to one O(1), one O(4), two equivalent O(2), two equivalent O(3), two equivalent O(6), and four equivalent O(5) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Nb(2)O6 octahedra. The Ba(3)-O(1) bond length is 2.81 Å. The Ba(3)-O(4) bond length is 2.99 Å. Both Ba(3)-O(2) bond lengths are 2.82 Å. Both Ba(3)-O(3) bond lengths are 2.91 Å. Both Ba(3)-O(6) bond lengths are 2.94 Å. There are two shorter (2.93 Å) and two longer (2.94 Å) Ba(3)-O(5) bond lengths. Mg(1) is bonded in a 3-coordinate geometry to one Zn(1), one O(4), and two equivalent O(3) atoms. The Mg(1)-Zn(1) bond length is 2.62 Å. The Mg(1)-O(4) bond length is 2.00 Å. Both Mg(1)-O(3) bond lengths are 1.99 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(4), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Nb(1)-O(4) bond length is 1.95 Å. The Nb(1)-O(6) bond length is 2.14 Å. Both Nb(1)-O(3) bond lengths are 1.95 Å. Both Nb(1)-O(5) bond lengths are 2.13 Å. In the second Nb site, Nb(2) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Nb(2)-O(1) bond length is 1.93 Å. The Nb(2)-O(6) bond length is 2.16 Å. Both Nb(2)-O(2) bond lengths are 1.92 Å. Both Nb(2)-O(5) bond lengths are 2.19 Å. Zn(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one O(1), and two equivalent O(2) atoms. The Zn(1)-O(1) bond length is 2.12 Å. Both Zn(1)-O(2) bond lengths are 2.13 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(3), two equivalent Ba(2), one Nb(2), and one Zn(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(3), two equivalent Ba(2), one Nb(2), and one Zn(1) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Ba(3), two equivalent Ba(1), one Mg(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Ba(3), two equivalent Ba(1), one Mg(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 3-60°. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°.