Bi2Ba2Fe4O11 crystallizes in the tetragonal P4mm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(2), four equivalent O(4), and four equivalent O(6) atoms to form distorted BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Fe(1)O6 octahedra, and faces with four equivalent Fe(2)O5 square pyramids. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and four equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O5 square pyramid, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the second Fe site, Fe(2) is bonded to one O(4) and four equivalent O(2) atoms to form FeO5 square pyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with four equivalent Fe(2)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. In the third Fe site, Fe(3) is bonded to one O(5), one O(7), and four equivalent O(3) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and  a cornercorner with one Fe(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 0-15°. In the fourth Fe site, Fe(4) is bonded to one O(7) and four equivalent O(1) atoms to form distorted FeO5 square pyramids that share  a cornercorner with one Fe(3)O6 octahedra and corners with four equivalent Fe(4)O5 square pyramids. The corner-sharing octahedra are not tilted. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 4-coordinate geometry to four equivalent O(6) atoms. In the second Bi site, Bi(2) is bonded in a 4-coordinate geometry to four equivalent O(3) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(2) and two equivalent Fe(4) atoms to form distorted OBa2Fe2 trigonal pyramids that share corners with six equivalent O(2)Ba4Fe2 octahedra, corners with four equivalent O(1)Ba2Fe2 trigonal pyramids,  an edgeedge with one O(2)Ba4Fe2 octahedra, and edges with four equivalent O(1)Ba2Fe2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 6-62°. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(2) atoms to form distorted OBa4Fe2 octahedra that share corners with two equivalent O(2)Ba4Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra, corners with six equivalent O(1)Ba2Fe2 trigonal pyramids, edges with two equivalent O(2)Ba4Fe2 octahedra,  an edgeedge with one O(1)Ba2Fe2 trigonal pyramid, faces with two equivalent O(4)Ba4Fe2 octahedra, and faces with four equivalent O(2)Ba4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 16-55°. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Fe(3) and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 12-55°. In the fifth O site, O(5) is bonded in a linear geometry to one Fe(1) and one Fe(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Fe(1), and two equivalent Bi(1) atoms. In the seventh O site, O(7) is bonded in a linear geometry to one Fe(3) and one Fe(4) atom.
Bi2Ba2Fe4O11 crystallizes in the tetragonal P4mm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(2), four equivalent O(4), and four equivalent O(6) atoms to form distorted BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Fe(1)O6 octahedra, and faces with four equivalent Fe(2)O5 square pyramids. All Ba(1)-O(2) bond lengths are 2.82 Å. All Ba(1)-O(4) bond lengths are 2.84 Å. All Ba(1)-O(6) bond lengths are 3.24 Å. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Ba(2)-O(1) bond lengths are 2.63 Å. All Ba(2)-O(2) bond lengths are 2.92 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and four equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O5 square pyramid, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-15°. The Fe(1)-O(4) bond length is 2.00 Å. The Fe(1)-O(5) bond length is 2.13 Å. All Fe(1)-O(6) bond lengths are 2.01 Å. In the second Fe site, Fe(2) is bonded to one O(4) and four equivalent O(2) atoms to form FeO5 square pyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with four equivalent Fe(2)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. The Fe(2)-O(4) bond length is 2.00 Å. All Fe(2)-O(2) bond lengths are 2.01 Å. In the third Fe site, Fe(3) is bonded to one O(5), one O(7), and four equivalent O(3) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and  a cornercorner with one Fe(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 0-15°. The Fe(3)-O(5) bond length is 1.96 Å. The Fe(3)-O(7) bond length is 2.08 Å. All Fe(3)-O(3) bond lengths are 2.01 Å. In the fourth Fe site, Fe(4) is bonded to one O(7) and four equivalent O(1) atoms to form distorted FeO5 square pyramids that share  a cornercorner with one Fe(3)O6 octahedra and corners with four equivalent Fe(4)O5 square pyramids. The corner-sharing octahedra are not tilted. The Fe(4)-O(7) bond length is 1.88 Å. All Fe(4)-O(1) bond lengths are 2.04 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 4-coordinate geometry to four equivalent O(6) atoms. All Bi(1)-O(6) bond lengths are 2.45 Å. In the second Bi site, Bi(2) is bonded in a 4-coordinate geometry to four equivalent O(3) atoms. All Bi(2)-O(3) bond lengths are 2.45 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(2) and two equivalent Fe(4) atoms to form distorted OBa2Fe2 trigonal pyramids that share corners with six equivalent O(2)Ba4Fe2 octahedra, corners with four equivalent O(1)Ba2Fe2 trigonal pyramids,  an edgeedge with one O(2)Ba4Fe2 octahedra, and edges with four equivalent O(1)Ba2Fe2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 6-62°. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(2) atoms to form distorted OBa4Fe2 octahedra that share corners with two equivalent O(2)Ba4Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra, corners with six equivalent O(1)Ba2Fe2 trigonal pyramids, edges with two equivalent O(2)Ba4Fe2 octahedra,  an edgeedge with one O(1)Ba2Fe2 trigonal pyramid, faces with two equivalent O(4)Ba4Fe2 octahedra, and faces with four equivalent O(2)Ba4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 16-55°. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Fe(3) and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 12-55°. In the fifth O site, O(5) is bonded in a linear geometry to one Fe(1) and one Fe(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Fe(1), and two equivalent Bi(1) atoms. In the seventh O site, O(7) is bonded in a linear geometry to one Fe(3) and one Fe(4) atom.