Sr6Bi2O11 crystallizes in the tetragonal P4/nmm space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. In the second Sr site, Sr(2) is bonded in a distorted hexagonal planar geometry to two equivalent O(3) and four equivalent O(2) atoms. In the third Sr site, Sr(3) is bonded to one O(4) and four equivalent O(1) atoms to form distorted SrO5 trigonal bipyramids that share corners with four equivalent Bi(1)O6 octahedra and  a cornercorner with one Bi(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 23°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form BiO6 octahedra that share corners with four equivalent Sr(3)O5 trigonal bipyramids. In the second Bi site, Bi(2) is bonded to one O(4) and four equivalent O(2) atoms to form distorted BiO5 trigonal bipyramids that share  a cornercorner with one Sr(3)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Sr(3), four equivalent Sr(1), and one Bi(1) atom. In the second O site, O(2) is bonded to one Sr(2), two equivalent Sr(1), and one Bi(2) atom to form a mixture of corner and edge-sharing OSr3Bi tetrahedra. In the third O site, O(3) is bonded in a distorted linear geometry to one Sr(2), four equivalent Sr(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Sr(3) and one Bi(2) atom.
Sr6Bi2O11 crystallizes in the tetragonal P4/nmm space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. Both Sr(1)-O(2) bond lengths are 2.54 Å. Both Sr(1)-O(3) bond lengths are 3.12 Å. There are two shorter (2.63 Å) and two longer (3.18 Å) Sr(1)-O(1) bond lengths. In the second Sr site, Sr(2) is bonded in a distorted hexagonal planar geometry to two equivalent O(3) and four equivalent O(2) atoms. Both Sr(2)-O(3) bond lengths are 2.47 Å. All Sr(2)-O(2) bond lengths are 2.58 Å. In the third Sr site, Sr(3) is bonded to one O(4) and four equivalent O(1) atoms to form distorted SrO5 trigonal bipyramids that share corners with four equivalent Bi(1)O6 octahedra and  a cornercorner with one Bi(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 23°. The Sr(3)-O(4) bond length is 2.27 Å. All Sr(3)-O(1) bond lengths are 2.35 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form BiO6 octahedra that share corners with four equivalent Sr(3)O5 trigonal bipyramids. Both Bi(1)-O(3) bond lengths are 2.09 Å. All Bi(1)-O(1) bond lengths are 2.16 Å. In the second Bi site, Bi(2) is bonded to one O(4) and four equivalent O(2) atoms to form distorted BiO5 trigonal bipyramids that share  a cornercorner with one Sr(3)O5 trigonal bipyramid. The Bi(2)-O(4) bond length is 2.04 Å. All Bi(2)-O(2) bond lengths are 2.12 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Sr(3), four equivalent Sr(1), and one Bi(1) atom. In the second O site, O(2) is bonded to one Sr(2), two equivalent Sr(1), and one Bi(2) atom to form a mixture of corner and edge-sharing OSr3Bi tetrahedra. In the third O site, O(3) is bonded in a distorted linear geometry to one Sr(2), four equivalent Sr(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Sr(3) and one Bi(2) atom.