K3Bi2P3O12 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(2), two equivalent O(3), and four equivalent O(5) atoms. In the second K site, K(2) is bonded to two equivalent O(1) and four equivalent O(6) atoms to form KO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles are 85°. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms. Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share  a cornercorner with one K(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles are 85°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent K(2)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-66°. In the second P site, P(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent K(2)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-59°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(2), one K(3), one Bi(1), and one P(2) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Bi(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Bi(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Bi(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent K(1), one Bi(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(3), two equivalent K(2), and one P(1) atom.
K3Bi2P3O12 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(2), two equivalent O(3), and four equivalent O(5) atoms. Both K(1)-O(2) bond lengths are 2.98 Å. Both K(1)-O(3) bond lengths are 2.85 Å. There are two shorter (2.78 Å) and two longer (2.86 Å) K(1)-O(5) bond lengths. In the second K site, K(2) is bonded to two equivalent O(1) and four equivalent O(6) atoms to form KO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles are 85°. Both K(2)-O(1) bond lengths are 2.84 Å. There are two shorter (2.70 Å) and two longer (2.81 Å) K(2)-O(6) bond lengths. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms. Both K(3)-O(1) bond lengths are 2.77 Å. Both K(3)-O(2) bond lengths are 2.70 Å. Both K(3)-O(3) bond lengths are 2.98 Å. Both K(3)-O(6) bond lengths are 2.89 Å. Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share  a cornercorner with one K(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles are 85°. The Bi(1)-O(1) bond length is 2.47 Å. The Bi(1)-O(2) bond length is 2.29 Å. The Bi(1)-O(3) bond length is 2.28 Å. The Bi(1)-O(5) bond length is 2.42 Å. There is one shorter (2.38 Å) and one longer (2.58 Å) Bi(1)-O(4) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent K(2)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-66°. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(4) bond length is 1.58 Å. The P(1)-O(5) bond length is 1.56 Å. The P(1)-O(6) bond length is 1.54 Å. In the second P site, P(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent K(2)O6 octahedra and corners with four equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-59°. Both P(2)-O(1) bond lengths are 1.55 Å. Both P(2)-O(3) bond lengths are 1.58 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(2), one K(3), one Bi(1), and one P(2) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Bi(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Bi(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Bi(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent K(1), one Bi(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(3), two equivalent K(2), and one P(1) atom.