KBa2Bi2O9 crystallizes in the trigonal P-3m1 space group. K(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent Ba(1)O12 cuboctahedra, faces with six equivalent Ba(1)O12 cuboctahedra, and faces with six equivalent Bi(1)O6 octahedra. Ba(1) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with three equivalent K(1)O12 cuboctahedra, corners with nine equivalent Ba(1)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with five equivalent Bi(1)O6 octahedra. Bi(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form BiO6 octahedra that share corners with three equivalent Bi(1)O6 octahedra, faces with three equivalent K(1)O12 cuboctahedra, and faces with five equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent K(1), two equivalent Ba(1), and two equivalent Bi(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), three equivalent Ba(1), and one Bi(1) atom.
KBa2Bi2O9 crystallizes in the trigonal P-3m1 space group. K(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent Ba(1)O12 cuboctahedra, faces with six equivalent Ba(1)O12 cuboctahedra, and faces with six equivalent Bi(1)O6 octahedra. All K(1)-O(1) bond lengths are 3.00 Å. All K(1)-O(2) bond lengths are 3.22 Å. Ba(1) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with three equivalent K(1)O12 cuboctahedra, corners with nine equivalent Ba(1)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with five equivalent Bi(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 3.32 Å. There are three shorter (2.95 Å) and six longer (3.01 Å) Ba(1)-O(2) bond lengths. Bi(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form BiO6 octahedra that share corners with three equivalent Bi(1)O6 octahedra, faces with three equivalent K(1)O12 cuboctahedra, and faces with five equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. All Bi(1)-O(1) bond lengths are 2.12 Å. All Bi(1)-O(2) bond lengths are 2.12 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent K(1), two equivalent Ba(1), and two equivalent Bi(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), three equivalent Ba(1), and one Bi(1) atom.