K2CeTa5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(4), and four equivalent O(2) atoms. Ce(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form CeO12 cuboctahedra that share faces with two equivalent Ce(1)O12 cuboctahedra and faces with eight equivalent Ta(1)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with five equivalent Ta(1)O6 octahedra, and faces with two equivalent Ce(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 11-36°. In the second Ta site, Ta(2) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a linear geometry to two equivalent K(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Ce(1), and two equivalent Ta(1) atoms. In the third O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Ta(1), and one Ta(2) atom. In the fourth O site, O(3) is bonded in a distorted linear geometry to two equivalent Ce(1) and two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Ta(1) atoms.
K2CeTa5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(4), and four equivalent O(2) atoms. The K(1)-O(5) bond length is 3.04 Å. Both K(1)-O(1) bond lengths are 3.25 Å. Both K(1)-O(4) bond lengths are 2.86 Å. All K(1)-O(2) bond lengths are 2.91 Å. Ce(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form CeO12 cuboctahedra that share faces with two equivalent Ce(1)O12 cuboctahedra and faces with eight equivalent Ta(1)O6 octahedra. All Ce(1)-O(1) bond lengths are 2.64 Å. All Ce(1)-O(3) bond lengths are 2.71 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with five equivalent Ta(1)O6 octahedra, and faces with two equivalent Ce(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 11-36°. The Ta(1)-O(2) bond length is 1.92 Å. The Ta(1)-O(4) bond length is 1.99 Å. Both Ta(1)-O(1) bond lengths are 1.99 Å. There is one shorter (2.03 Å) and one longer (2.06 Å) Ta(1)-O(3) bond length. In the second Ta site, Ta(2) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. Both Ta(2)-O(5) bond lengths are 1.98 Å. All Ta(2)-O(2) bond lengths are 2.00 Å. There are five inequivalent O sites. In the first O site, O(5) is bonded in a linear geometry to two equivalent K(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Ce(1), and two equivalent Ta(1) atoms. In the third O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Ta(1), and one Ta(2) atom. In the fourth O site, O(3) is bonded in a distorted linear geometry to two equivalent Ce(1) and two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Ta(1) atoms.