K2Ti8O17 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(9) atoms. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(4), one O(8), one O(9), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-27°. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(7), one O(8), and two equivalent O(6) atoms to form a mixture of distorted corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 33°. In the third Ti site, Ti(3) is bonded to one O(2), one O(3), one O(6), and three equivalent O(7) atoms to form a mixture of distorted corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 33°. In the fourth Ti site, Ti(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and two equivalent O(8) atoms. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a linear geometry to four equivalent K(1) and two equivalent Ti(1) atoms. In the second O site, O(1) is bonded to two equivalent K(1), one Ti(1), and one Ti(2) atom to form distorted OK2Ti2 tetrahedra that share corners with two equivalent O(1)K2Ti2 tetrahedra,  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(6)Ti4 trigonal pyramids, and  an edgeedge with one O(8)Ti4 trigonal pyramid. In the third O site, O(2) is bonded in a water-like geometry to one Ti(2) and one Ti(3) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Ti(3), and one Ti(4) atom. In the fifth O site, O(4) is bonded in a distorted linear geometry to two equivalent K(1), one Ti(1), and one Ti(4) atom. In the sixth O site, O(5) is bonded in a distorted T-shaped geometry to one Ti(4) and two equivalent Ti(1) atoms. In the seventh O site, O(6) is bonded to one Ti(3), one Ti(4), and two equivalent Ti(2) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(1)K2Ti2 tetrahedra,  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(6)Ti4 trigonal pyramids, edges with two equivalent O(7)Ti4 trigonal pyramids, and edges with two equivalent O(8)Ti4 trigonal pyramids. In the eighth O site, O(7) is bonded to one Ti(2) and three equivalent Ti(3) atoms to form distorted OTi4 trigonal pyramids that share  a cornercorner with one O(1)K2Ti2 tetrahedra,  a cornercorner with one O(6)Ti4 trigonal pyramid,  a cornercorner with one O(8)Ti4 trigonal pyramid, corners with two equivalent O(7)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti4 trigonal pyramids, and edges with two equivalent O(7)Ti4 trigonal pyramids. In the ninth O site, O(8) is bonded to one Ti(1), one Ti(2), and two equivalent Ti(4) atoms to form distorted OTi4 trigonal pyramids that share  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(8)Ti4 trigonal pyramids,  an edgeedge with one O(1)K2Ti2 tetrahedra, and edges with two equivalent O(6)Ti4 trigonal pyramids.
K2Ti8O17 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(9) atoms. Both K(1)-O(1) bond lengths are 2.67 Å. Both K(1)-O(3) bond lengths are 2.74 Å. Both K(1)-O(4) bond lengths are 2.96 Å. Both K(1)-O(9) bond lengths are 3.19 Å. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(4), one O(8), one O(9), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-27°. The Ti(1)-O(1) bond length is 1.97 Å. The Ti(1)-O(4) bond length is 1.95 Å. The Ti(1)-O(8) bond length is 2.18 Å. The Ti(1)-O(9) bond length is 1.85 Å. Both Ti(1)-O(5) bond lengths are 1.94 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(7), one O(8), and two equivalent O(6) atoms to form a mixture of distorted corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 33°. The Ti(2)-O(1) bond length is 1.80 Å. The Ti(2)-O(2) bond length is 1.83 Å. The Ti(2)-O(7) bond length is 2.17 Å. The Ti(2)-O(8) bond length is 2.23 Å. Both Ti(2)-O(6) bond lengths are 1.97 Å. In the third Ti site, Ti(3) is bonded to one O(2), one O(3), one O(6), and three equivalent O(7) atoms to form a mixture of distorted corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 33°. The Ti(3)-O(2) bond length is 1.83 Å. The Ti(3)-O(3) bond length is 1.81 Å. The Ti(3)-O(6) bond length is 2.14 Å. There are two shorter (1.97 Å) and one longer (2.21 Å) Ti(3)-O(7) bond length. In the fourth Ti site, Ti(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and two equivalent O(8) atoms. The Ti(4)-O(3) bond length is 1.93 Å. The Ti(4)-O(4) bond length is 1.77 Å. The Ti(4)-O(5) bond length is 2.06 Å. The Ti(4)-O(6) bond length is 2.26 Å. Both Ti(4)-O(8) bond lengths are 1.96 Å. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a linear geometry to four equivalent K(1) and two equivalent Ti(1) atoms. In the second O site, O(1) is bonded to two equivalent K(1), one Ti(1), and one Ti(2) atom to form distorted OK2Ti2 tetrahedra that share corners with two equivalent O(1)K2Ti2 tetrahedra,  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(6)Ti4 trigonal pyramids, and  an edgeedge with one O(8)Ti4 trigonal pyramid. In the third O site, O(2) is bonded in a water-like geometry to one Ti(2) and one Ti(3) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Ti(3), and one Ti(4) atom. In the fifth O site, O(4) is bonded in a distorted linear geometry to two equivalent K(1), one Ti(1), and one Ti(4) atom. In the sixth O site, O(5) is bonded in a distorted T-shaped geometry to one Ti(4) and two equivalent Ti(1) atoms. In the seventh O site, O(6) is bonded to one Ti(3), one Ti(4), and two equivalent Ti(2) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(1)K2Ti2 tetrahedra,  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(6)Ti4 trigonal pyramids, edges with two equivalent O(7)Ti4 trigonal pyramids, and edges with two equivalent O(8)Ti4 trigonal pyramids. In the eighth O site, O(7) is bonded to one Ti(2) and three equivalent Ti(3) atoms to form distorted OTi4 trigonal pyramids that share  a cornercorner with one O(1)K2Ti2 tetrahedra,  a cornercorner with one O(6)Ti4 trigonal pyramid,  a cornercorner with one O(8)Ti4 trigonal pyramid, corners with two equivalent O(7)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti4 trigonal pyramids, and edges with two equivalent O(7)Ti4 trigonal pyramids. In the ninth O site, O(8) is bonded to one Ti(1), one Ti(2), and two equivalent Ti(4) atoms to form distorted OTi4 trigonal pyramids that share  a cornercorner with one O(7)Ti4 trigonal pyramid, corners with two equivalent O(8)Ti4 trigonal pyramids,  an edgeedge with one O(1)K2Ti2 tetrahedra, and edges with two equivalent O(6)Ti4 trigonal pyramids.