K2CeNb5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. Ce(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form CeO12 cuboctahedra that share faces with two equivalent Ce(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent Ce(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-36°. In the second Nb site, Nb(2) is bonded to two equivalent O(5) and four equivalent O(3) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the second O site, O(5) is bonded in a linear geometry to two equivalent K(1) and two equivalent Nb(2) atoms. In the third O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ce(1) and two equivalent Nb(1) atoms. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Ce(1), and two equivalent Nb(1) atoms. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Nb(1), and one Nb(2) atom.
K2CeNb5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. The K(1)-O(5) bond length is 3.08 Å. Both K(1)-O(2) bond lengths are 3.25 Å. Both K(1)-O(4) bond lengths are 2.86 Å. All K(1)-O(3) bond lengths are 2.94 Å. Ce(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form CeO12 cuboctahedra that share faces with two equivalent Ce(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. All Ce(1)-O(2) bond lengths are 2.62 Å. All Ce(1)-O(1) bond lengths are 2.71 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent Ce(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-36°. The Nb(1)-O(3) bond length is 1.92 Å. The Nb(1)-O(4) bond length is 2.00 Å. There is one shorter (2.04 Å) and one longer (2.08 Å) Nb(1)-O(1) bond length. Both Nb(1)-O(2) bond lengths are 2.01 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(5) and four equivalent O(3) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. Both Nb(2)-O(5) bond lengths are 1.99 Å. All Nb(2)-O(3) bond lengths are 2.02 Å. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the second O site, O(5) is bonded in a linear geometry to two equivalent K(1) and two equivalent Nb(2) atoms. In the third O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ce(1) and two equivalent Nb(1) atoms. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Ce(1), and two equivalent Nb(1) atoms. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Nb(1), and one Nb(2) atom.