Ba3SrMgNb2O9 is Orthorhombic Perovskite-derived structured and crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one Mg(1), one O(1), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Mg(1), one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to one O(5), one O(7), one O(8), one O(9), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Sr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted SrO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-22°. Mg(1) is bonded in a rectangular see-saw-like geometry to one Ba(1), one Ba(2), one O(4), one O(6), one O(8), and one O(9) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Sr(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-10°. In the second Nb site, Nb(2) is bonded to one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Sr(1)O6 octahedra and corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-22°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sr(1), one Mg(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Sr(1), and one Nb(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sr(1), one Mg(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Nb(2) atom. In the eighth O site, O(8) is bonded to one Ba(1), one Ba(3), one Mg(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and edge-sharing OBa2MgNb2 trigonal bipyramids. In the ninth O site, O(9) is bonded to one Ba(1), one Ba(3), one Mg(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and edge-sharing OBa2MgNb2 trigonal bipyramids.
Ba3SrMgNb2O9 is Orthorhombic Perovskite-derived structured and crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one Mg(1), one O(1), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. The Ba(1)-Mg(1) bond length is 2.92 Å. The Ba(1)-O(1) bond length is 2.85 Å. The Ba(1)-O(3) bond length is 2.85 Å. The Ba(1)-O(4) bond length is 3.15 Å. The Ba(1)-O(5) bond length is 2.78 Å. The Ba(1)-O(6) bond length is 3.15 Å. The Ba(1)-O(8) bond length is 2.70 Å. The Ba(1)-O(9) bond length is 2.71 Å. There is one shorter (3.12 Å) and one longer (3.17 Å) Ba(1)-O(7) bond length. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Mg(1), one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. The Ba(2)-Mg(1) bond length is 3.11 Å. The Ba(2)-O(1) bond length is 2.81 Å. The Ba(2)-O(2) bond length is 2.88 Å. The Ba(2)-O(3) bond length is 2.79 Å. The Ba(2)-O(4) bond length is 2.77 Å. The Ba(2)-O(6) bond length is 2.79 Å. The Ba(2)-O(7) bond length is 3.16 Å. There is one shorter (3.25 Å) and one longer (3.39 Å) Ba(2)-O(5) bond length. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to one O(5), one O(7), one O(8), one O(9), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. The Ba(3)-O(5) bond length is 3.44 Å. The Ba(3)-O(7) bond length is 2.82 Å. The Ba(3)-O(8) bond length is 2.90 Å. The Ba(3)-O(9) bond length is 2.88 Å. There is one shorter (2.89 Å) and one longer (3.45 Å) Ba(3)-O(1) bond length. Both Ba(3)-O(2) bond lengths are 3.14 Å. There is one shorter (2.91 Å) and one longer (3.40 Å) Ba(3)-O(3) bond length. Sr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted SrO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-22°. The Sr(1)-O(1) bond length is 2.37 Å. The Sr(1)-O(2) bond length is 2.47 Å. The Sr(1)-O(3) bond length is 2.37 Å. The Sr(1)-O(4) bond length is 2.41 Å. The Sr(1)-O(5) bond length is 2.98 Å. The Sr(1)-O(6) bond length is 2.41 Å. Mg(1) is bonded in a rectangular see-saw-like geometry to one Ba(1), one Ba(2), one O(4), one O(6), one O(8), and one O(9) atom. The Mg(1)-O(4) bond length is 2.02 Å. The Mg(1)-O(6) bond length is 2.02 Å. The Mg(1)-O(8) bond length is 2.03 Å. The Mg(1)-O(9) bond length is 2.04 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Sr(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-10°. The Nb(1)-O(1) bond length is 2.00 Å. The Nb(1)-O(2) bond length is 1.99 Å. The Nb(1)-O(3) bond length is 2.00 Å. The Nb(1)-O(7) bond length is 2.18 Å. The Nb(1)-O(8) bond length is 2.19 Å. The Nb(1)-O(9) bond length is 2.19 Å. In the second Nb site, Nb(2) is bonded to one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Sr(1)O6 octahedra and corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-22°. The Nb(2)-O(4) bond length is 2.04 Å. The Nb(2)-O(5) bond length is 1.97 Å. The Nb(2)-O(6) bond length is 2.04 Å. The Nb(2)-O(7) bond length is 2.25 Å. The Nb(2)-O(8) bond length is 2.19 Å. The Nb(2)-O(9) bond length is 2.18 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Sr(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sr(1), one Mg(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Sr(1), and one Nb(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sr(1), one Mg(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Nb(2) atom. In the eighth O site, O(8) is bonded to one Ba(1), one Ba(3), one Mg(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and edge-sharing OBa2MgNb2 trigonal bipyramids. In the ninth O site, O(9) is bonded to one Ba(1), one Ba(3), one Mg(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted face and edge-sharing OBa2MgNb2 trigonal bipyramids.