K3Bi2(AsO4)3 is Esseneite-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(4), two equivalent O(5), and four equivalent O(6) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the third K site, K(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form KO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and edges with two equivalent K(3)O6 octahedra. The corner-sharing octahedral tilt angles are 81°. Bi(1) is bonded to one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form distorted BiO6 octahedra that share  a cornercorner with one K(3)O6 octahedra, corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles are 81°. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form AsO4 tetrahedra that share corners with two equivalent K(3)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-66°. In the second As site, As(2) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form AsO4 tetrahedra that share corners with two equivalent K(3)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-60°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Bi(1) and one As(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Bi(1), and one As(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Bi(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Bi(1), and one As(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Bi(1), and one As(1) atom.
K3Bi2(AsO4)3 is Esseneite-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(4), two equivalent O(5), and four equivalent O(6) atoms. Both K(1)-O(4) bond lengths are 3.08 Å. Both K(1)-O(5) bond lengths are 2.90 Å. There are two shorter (2.77 Å) and two longer (2.94 Å) K(1)-O(6) bond lengths. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Both K(2)-O(1) bond lengths are 2.87 Å. Both K(2)-O(3) bond lengths are 2.82 Å. Both K(2)-O(4) bond lengths are 2.73 Å. Both K(2)-O(5) bond lengths are 3.08 Å. In the third K site, K(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form KO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and edges with two equivalent K(3)O6 octahedra. The corner-sharing octahedral tilt angles are 81°. Both K(3)-O(3) bond lengths are 2.86 Å. There are two shorter (2.70 Å) and two longer (2.77 Å) K(3)-O(1) bond lengths. Bi(1) is bonded to one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form distorted BiO6 octahedra that share  a cornercorner with one K(3)O6 octahedra, corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles are 81°. The Bi(1)-O(3) bond length is 2.49 Å. The Bi(1)-O(4) bond length is 2.29 Å. The Bi(1)-O(5) bond length is 2.27 Å. The Bi(1)-O(6) bond length is 2.45 Å. There is one shorter (2.36 Å) and one longer (2.58 Å) Bi(1)-O(2) bond length. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form AsO4 tetrahedra that share corners with two equivalent K(3)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-66°. The As(1)-O(1) bond length is 1.70 Å. The As(1)-O(2) bond length is 1.75 Å. The As(1)-O(4) bond length is 1.74 Å. The As(1)-O(6) bond length is 1.72 Å. In the second As site, As(2) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form AsO4 tetrahedra that share corners with two equivalent K(3)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-60°. Both As(2)-O(3) bond lengths are 1.71 Å. Both As(2)-O(5) bond lengths are 1.75 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Bi(1) and one As(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Bi(1), and one As(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Bi(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Bi(1), and one As(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Bi(1), and one As(1) atom.