Sr6Bi2O11 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted hexagonal planar geometry to one O(3), one O(4), one O(8), one O(9), and two equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(8), two equivalent O(1), and two equivalent O(7) atoms. In the third Sr site, Sr(3) is bonded in a distorted see-saw-like geometry to one O(1), one O(5), and two equivalent O(7) atoms. In the fourth Sr site, Sr(4) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(6), one O(8), one O(9), two equivalent O(5), and two equivalent O(7) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one O(4), one O(6), one O(9), and two equivalent O(2) atoms. In the second Bi site, Bi(2) is bonded in an octahedral geometry to one O(1), one O(3), one O(5), one O(8), and two equivalent O(7) atoms. There are nine inequivalent O sites. In the first O site, O(9) is bonded to one Sr(1), two equivalent Sr(4), and one Bi(1) atom to form distorted OSr3Bi tetrahedra that share corners with two equivalent O(5)Sr5Bi octahedra, corners with two equivalent O(2)Sr3Bi tetrahedra, corners with two equivalent O(4)Sr3Bi tetrahedra,  an edgeedge with one O(5)Sr5Bi octahedra, and edges with two equivalent O(2)Sr3Bi tetrahedra. The corner-sharing octahedral tilt angles are 12°. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Sr(3), four equivalent Sr(2), and one Bi(2) atom. In the third O site, O(2) is bonded to one Sr(1), one Sr(2), one Sr(4), and one Bi(1) atom to form distorted OSr3Bi tetrahedra that share corners with two equivalent O(5)Sr5Bi octahedra,  a cornercorner with one O(4)Sr3Bi tetrahedra,  a cornercorner with one O(9)Sr3Bi tetrahedra, corners with two equivalent O(2)Sr3Bi tetrahedra,  an edgeedge with one O(4)Sr3Bi tetrahedra, and  an edgeedge with one O(9)Sr3Bi tetrahedra. The corner-sharing octahedral tilt angles range from 66-76°. In the fourth O site, O(3) is bonded in a distorted linear geometry to one Sr(1), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom. In the fifth O site, O(4) is bonded to one Sr(1), two equivalent Sr(2), and one Bi(1) atom to form a mixture of distorted corner and edge-sharing OSr3Bi tetrahedra. In the sixth O site, O(5) is bonded to one Sr(3), four equivalent Sr(4), and one Bi(2) atom to form distorted OSr5Bi octahedra that share corners with two equivalent O(9)Sr3Bi tetrahedra, corners with four equivalent O(2)Sr3Bi tetrahedra, edges with two equivalent O(5)Sr5Bi octahedra, and  an edgeedge with one O(9)Sr3Bi tetrahedra. In the seventh O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), and one Bi(1) atom. In the eighth O site, O(7) is bonded in a 6-coordinate geometry to one Sr(3), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom. In the ninth O site, O(8) is bonded in a distorted linear geometry to one Sr(1), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom.
Sr6Bi2O11 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted hexagonal planar geometry to one O(3), one O(4), one O(8), one O(9), and two equivalent O(2) atoms. The Sr(1)-O(3) bond length is 2.37 Å. The Sr(1)-O(4) bond length is 2.52 Å. The Sr(1)-O(8) bond length is 2.36 Å. The Sr(1)-O(9) bond length is 2.52 Å. Both Sr(1)-O(2) bond lengths are 2.54 Å. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(8), two equivalent O(1), and two equivalent O(7) atoms. The Sr(2)-O(2) bond length is 2.74 Å. The Sr(2)-O(3) bond length is 2.99 Å. The Sr(2)-O(4) bond length is 2.75 Å. The Sr(2)-O(6) bond length is 2.96 Å. The Sr(2)-O(8) bond length is 3.13 Å. There is one shorter (2.70 Å) and one longer (3.06 Å) Sr(2)-O(1) bond length. There is one shorter (2.68 Å) and one longer (3.09 Å) Sr(2)-O(7) bond length. In the third Sr site, Sr(3) is bonded in a distorted see-saw-like geometry to one O(1), one O(5), and two equivalent O(7) atoms. The Sr(3)-O(1) bond length is 2.33 Å. The Sr(3)-O(5) bond length is 2.32 Å. Both Sr(3)-O(7) bond lengths are 2.32 Å. In the fourth Sr site, Sr(4) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(6), one O(8), one O(9), two equivalent O(5), and two equivalent O(7) atoms. The Sr(4)-O(2) bond length is 2.72 Å. The Sr(4)-O(3) bond length is 3.10 Å. The Sr(4)-O(6) bond length is 2.94 Å. The Sr(4)-O(8) bond length is 2.98 Å. The Sr(4)-O(9) bond length is 2.75 Å. There is one shorter (2.72 Å) and one longer (3.03 Å) Sr(4)-O(5) bond length. There is one shorter (2.72 Å) and one longer (3.06 Å) Sr(4)-O(7) bond length. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one O(4), one O(6), one O(9), and two equivalent O(2) atoms. The Bi(1)-O(4) bond length is 2.11 Å. The Bi(1)-O(6) bond length is 2.11 Å. The Bi(1)-O(9) bond length is 2.11 Å. Both Bi(1)-O(2) bond lengths are 2.11 Å. In the second Bi site, Bi(2) is bonded in an octahedral geometry to one O(1), one O(3), one O(5), one O(8), and two equivalent O(7) atoms. The Bi(2)-O(1) bond length is 2.13 Å. The Bi(2)-O(3) bond length is 2.07 Å. The Bi(2)-O(5) bond length is 2.13 Å. The Bi(2)-O(8) bond length is 2.06 Å. Both Bi(2)-O(7) bond lengths are 2.13 Å. There are nine inequivalent O sites. In the first O site, O(9) is bonded to one Sr(1), two equivalent Sr(4), and one Bi(1) atom to form distorted OSr3Bi tetrahedra that share corners with two equivalent O(5)Sr5Bi octahedra, corners with two equivalent O(2)Sr3Bi tetrahedra, corners with two equivalent O(4)Sr3Bi tetrahedra,  an edgeedge with one O(5)Sr5Bi octahedra, and edges with two equivalent O(2)Sr3Bi tetrahedra. The corner-sharing octahedral tilt angles are 12°. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Sr(3), four equivalent Sr(2), and one Bi(2) atom. In the third O site, O(2) is bonded to one Sr(1), one Sr(2), one Sr(4), and one Bi(1) atom to form distorted OSr3Bi tetrahedra that share corners with two equivalent O(5)Sr5Bi octahedra,  a cornercorner with one O(4)Sr3Bi tetrahedra,  a cornercorner with one O(9)Sr3Bi tetrahedra, corners with two equivalent O(2)Sr3Bi tetrahedra,  an edgeedge with one O(4)Sr3Bi tetrahedra, and  an edgeedge with one O(9)Sr3Bi tetrahedra. The corner-sharing octahedral tilt angles range from 66-76°. In the fourth O site, O(3) is bonded in a distorted linear geometry to one Sr(1), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom. In the fifth O site, O(4) is bonded to one Sr(1), two equivalent Sr(2), and one Bi(1) atom to form a mixture of distorted corner and edge-sharing OSr3Bi tetrahedra. In the sixth O site, O(5) is bonded to one Sr(3), four equivalent Sr(4), and one Bi(2) atom to form distorted OSr5Bi octahedra that share corners with two equivalent O(9)Sr3Bi tetrahedra, corners with four equivalent O(2)Sr3Bi tetrahedra, edges with two equivalent O(5)Sr5Bi octahedra, and  an edgeedge with one O(9)Sr3Bi tetrahedra. In the seventh O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), and one Bi(1) atom. In the eighth O site, O(7) is bonded in a 6-coordinate geometry to one Sr(3), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom. In the ninth O site, O(8) is bonded in a distorted linear geometry to one Sr(1), two equivalent Sr(2), two equivalent Sr(4), and one Bi(2) atom.