ZnBi4O9 crystallizes in the monoclinic P2/c space group. Zn(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles are 42°. In the second Bi site, Bi(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Bi(1) and two equivalent Bi(2) atoms to form a mixture of distorted corner and edge-sharing OBi4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Zn(1), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded to one Zn(1), one Bi(1), and two equivalent Bi(2) atoms to form distorted OZnBi3 tetrahedra that share  a cornercorner with one O(3)ZnBi3 tetrahedra, corners with three equivalent O(1)Bi4 tetrahedra, corners with three equivalent O(4)ZnBi3 tetrahedra,  an edgeedge with one O(3)ZnBi3 tetrahedra, and edges with two equivalent O(4)ZnBi3 tetrahedra. In the fourth O site, O(4) is bonded to one Zn(1), one Bi(1), and two equivalent Bi(2) atoms to form OZnBi3 tetrahedra that share  a cornercorner with one O(1)Bi4 tetrahedra,  a cornercorner with one O(4)ZnBi3 tetrahedra, corners with three equivalent O(3)ZnBi3 tetrahedra,  an edgeedge with one O(1)Bi4 tetrahedra,  an edgeedge with one O(4)ZnBi3 tetrahedra, and edges with two equivalent O(3)ZnBi3 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Bi(2) and two equivalent Bi(1) atoms.
ZnBi4O9 crystallizes in the monoclinic P2/c space group. Zn(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Zn(1)-O(2) bond lengths are 1.95 Å. Both Zn(1)-O(3) bond lengths are 2.47 Å. Both Zn(1)-O(4) bond lengths are 2.46 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Bi(1)-O(1) bond length is 2.17 Å. The Bi(1)-O(2) bond length is 2.10 Å. The Bi(1)-O(3) bond length is 2.13 Å. The Bi(1)-O(4) bond length is 2.20 Å. There is one shorter (2.12 Å) and one longer (2.22 Å) Bi(1)-O(5) bond length. In the second Bi site, Bi(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms. The Bi(2)-O(1) bond length is 2.63 Å. The Bi(2)-O(2) bond length is 2.59 Å. The Bi(2)-O(5) bond length is 2.29 Å. There is one shorter (2.28 Å) and one longer (2.70 Å) Bi(2)-O(3) bond length. There is one shorter (2.27 Å) and one longer (2.58 Å) Bi(2)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Bi(1) and two equivalent Bi(2) atoms to form a mixture of distorted corner and edge-sharing OBi4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Zn(1), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded to one Zn(1), one Bi(1), and two equivalent Bi(2) atoms to form distorted OZnBi3 tetrahedra that share  a cornercorner with one O(3)ZnBi3 tetrahedra, corners with three equivalent O(1)Bi4 tetrahedra, corners with three equivalent O(4)ZnBi3 tetrahedra,  an edgeedge with one O(3)ZnBi3 tetrahedra, and edges with two equivalent O(4)ZnBi3 tetrahedra. In the fourth O site, O(4) is bonded to one Zn(1), one Bi(1), and two equivalent Bi(2) atoms to form OZnBi3 tetrahedra that share  a cornercorner with one O(1)Bi4 tetrahedra,  a cornercorner with one O(4)ZnBi3 tetrahedra, corners with three equivalent O(3)ZnBi3 tetrahedra,  an edgeedge with one O(1)Bi4 tetrahedra,  an edgeedge with one O(4)ZnBi3 tetrahedra, and edges with two equivalent O(3)ZnBi3 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Bi(2) and two equivalent Bi(1) atoms.