Ba2Nd2Fe4O11 crystallizes in the orthorhombic Cmmm space group. Ba(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) 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(2)O6 octahedra, and faces with four equivalent Fe(1)O5 trigonal bipyramids. Nd(1) is bonded in a distorted q6 geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form FeO5 trigonal bipyramids that share corners with three equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-18°. In the second Fe site, Fe(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Nd(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Fe(2) atoms to form distorted OBa2Nd2Fe2 octahedra that share corners with four equivalent O(3)Ba2Nd2Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra,  an edgeedge with one O(3)Ba2Nd2Fe2 octahedra, and faces with two equivalent O(4)Ba4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Fe(1), and one Fe(2) atom to form distorted OBa4Fe2 octahedra that share corners with four equivalent O(3)Ba2Nd2Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra, edges with four equivalent O(4)Ba4Fe2 octahedra, and faces with two equivalent O(3)Ba2Nd2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Nd(1) and two equivalent Fe(2) atoms.
Ba2Nd2Fe4O11 crystallizes in the orthorhombic Cmmm space group. Ba(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) 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(2)O6 octahedra, and faces with four equivalent Fe(1)O5 trigonal bipyramids. Both Ba(1)-O(2) bond lengths are 3.22 Å. Both Ba(1)-O(3) bond lengths are 2.90 Å. All Ba(1)-O(1) bond lengths are 3.04 Å. All Ba(1)-O(4) bond lengths are 2.83 Å. Nd(1) is bonded in a distorted q6 geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. Both Nd(1)-O(2) bond lengths are 2.61 Å. Both Nd(1)-O(3) bond lengths are 2.65 Å. Both Nd(1)-O(5) bond lengths are 2.73 Å. All Nd(1)-O(1) bond lengths are 2.59 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form FeO5 trigonal bipyramids that share corners with three equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-18°. The Fe(1)-O(4) bond length is 1.93 Å. Both Fe(1)-O(1) bond lengths are 1.97 Å. Both Fe(1)-O(2) bond lengths are 2.05 Å. In the second Fe site, Fe(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Fe(2)-O(4) bond length is 2.05 Å. The Fe(2)-O(5) bond length is 1.94 Å. Both Fe(2)-O(1) bond lengths are 2.12 Å. Both Fe(2)-O(3) bond lengths are 1.98 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Nd(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Fe(2) atoms to form distorted OBa2Nd2Fe2 octahedra that share corners with four equivalent O(3)Ba2Nd2Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra,  an edgeedge with one O(3)Ba2Nd2Fe2 octahedra, and faces with two equivalent O(4)Ba4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Fe(1), and one Fe(2) atom to form distorted OBa4Fe2 octahedra that share corners with four equivalent O(3)Ba2Nd2Fe2 octahedra, corners with four equivalent O(4)Ba4Fe2 octahedra, edges with four equivalent O(4)Ba4Fe2 octahedra, and faces with two equivalent O(3)Ba2Nd2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Nd(1) and two equivalent Fe(2) atoms.