KNa(BiO3)2 crystallizes in the orthorhombic Cmmm space group. K(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. Na(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), two equivalent Na(1), and two equivalent Bi(1) atoms to form distorted OK2Na2Bi2 octahedra that share corners with six equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(2)K2Bi2 tetrahedra, corners with four equivalent O(3)Na2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, edges with four equivalent O(2)K2Bi2 tetrahedra, and edges with four equivalent O(3)Na2Bi2 tetrahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent K(1) and two equivalent Bi(1) atoms to form distorted OK2Bi2 tetrahedra that share corners with four equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(3)Na2Bi2 tetrahedra, corners with six equivalent O(2)K2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, and  an edgeedge with one O(2)K2Bi2 tetrahedra. The corner-sharing octahedral tilt angles are 65°. In the third O site, O(3) is bonded to two equivalent Na(1) and two equivalent Bi(1) atoms to form distorted ONa2Bi2 tetrahedra that share corners with four equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(2)K2Bi2 tetrahedra, corners with six equivalent O(3)Na2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, and  an edgeedge with one O(3)Na2Bi2 tetrahedra. The corner-sharing octahedral tilt angles are 66°.
KNa(BiO3)2 crystallizes in the orthorhombic Cmmm space group. K(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. All K(1)-O(1) bond lengths are 2.94 Å. All K(1)-O(2) bond lengths are 2.65 Å. Na(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. All Na(1)-O(1) bond lengths are 2.94 Å. All Na(1)-O(3) bond lengths are 2.60 Å. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. Both Bi(1)-O(1) bond lengths are 2.14 Å. Both Bi(1)-O(2) bond lengths are 2.14 Å. Both Bi(1)-O(3) bond lengths are 2.17 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), two equivalent Na(1), and two equivalent Bi(1) atoms to form distorted OK2Na2Bi2 octahedra that share corners with six equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(2)K2Bi2 tetrahedra, corners with four equivalent O(3)Na2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, edges with four equivalent O(2)K2Bi2 tetrahedra, and edges with four equivalent O(3)Na2Bi2 tetrahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent K(1) and two equivalent Bi(1) atoms to form distorted OK2Bi2 tetrahedra that share corners with four equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(3)Na2Bi2 tetrahedra, corners with six equivalent O(2)K2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, and  an edgeedge with one O(2)K2Bi2 tetrahedra. The corner-sharing octahedral tilt angles are 65°. In the third O site, O(3) is bonded to two equivalent Na(1) and two equivalent Bi(1) atoms to form distorted ONa2Bi2 tetrahedra that share corners with four equivalent O(1)K2Na2Bi2 octahedra, corners with four equivalent O(2)K2Bi2 tetrahedra, corners with six equivalent O(3)Na2Bi2 tetrahedra, edges with four equivalent O(1)K2Na2Bi2 octahedra, and  an edgeedge with one O(3)Na2Bi2 tetrahedra. The corner-sharing octahedral tilt angles are 66°.