KCa2Ta3O10 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 6-coordinate geometry to two equivalent O(5) and four equivalent O(6) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(10), two equivalent O(2), two equivalent O(3), two equivalent O(9), and four equivalent O(8) atoms to form distorted CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with four equivalent Ta(3)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(10), two equivalent O(4), two equivalent O(9), and four equivalent O(7) atoms. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to one O(5), one O(7), two equivalent O(1), and two equivalent O(4) atoms. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(6), one O(8), two equivalent O(2), and two equivalent O(3) atoms. In the third Ta site, Ta(3) is bonded to one O(7), one O(8), two equivalent O(10), and two equivalent O(9) atoms to form TaO6 octahedra that share corners with four equivalent Ta(3)O6 octahedra and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Ta(2) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Ta(2) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent K(1) and one Ta(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to four equivalent K(1) and one Ta(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to four equivalent Ca(2), one Ta(1), and one Ta(3) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to four equivalent Ca(1), one Ta(2), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(3) atoms. In the tenth O site, O(10) is bonded in a linear geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(3) atoms.
KCa2Ta3O10 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 6-coordinate geometry to two equivalent O(5) and four equivalent O(6) atoms. Both K(1)-O(5) bond lengths are 2.64 Å. All K(1)-O(6) bond lengths are 3.04 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(10), two equivalent O(2), two equivalent O(3), two equivalent O(9), and four equivalent O(8) atoms to form distorted CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with four equivalent Ta(3)O6 octahedra. Both Ca(1)-O(10) bond lengths are 3.00 Å. Both Ca(1)-O(2) bond lengths are 2.54 Å. Both Ca(1)-O(3) bond lengths are 2.54 Å. Both Ca(1)-O(9) bond lengths are 3.00 Å. All Ca(1)-O(8) bond lengths are 2.80 Å. In the second Ca site, Ca(2) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(10), two equivalent O(4), two equivalent O(9), and four equivalent O(7) atoms. Both Ca(2)-O(1) bond lengths are 2.50 Å. Both Ca(2)-O(10) bond lengths are 3.05 Å. Both Ca(2)-O(4) bond lengths are 2.50 Å. Both Ca(2)-O(9) bond lengths are 3.05 Å. All Ca(2)-O(7) bond lengths are 2.81 Å. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to one O(5), one O(7), two equivalent O(1), and two equivalent O(4) atoms. The Ta(1)-O(5) bond length is 1.79 Å. The Ta(1)-O(7) bond length is 2.32 Å. Both Ta(1)-O(1) bond lengths are 2.02 Å. Both Ta(1)-O(4) bond lengths are 2.02 Å. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(6), one O(8), two equivalent O(2), and two equivalent O(3) atoms. The Ta(2)-O(6) bond length is 1.80 Å. The Ta(2)-O(8) bond length is 2.30 Å. Both Ta(2)-O(2) bond lengths are 2.01 Å. Both Ta(2)-O(3) bond lengths are 2.01 Å. In the third Ta site, Ta(3) is bonded to one O(7), one O(8), two equivalent O(10), and two equivalent O(9) atoms to form TaO6 octahedra that share corners with four equivalent Ta(3)O6 octahedra and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. The Ta(3)-O(7) bond length is 1.96 Å. The Ta(3)-O(8) bond length is 1.98 Å. Both Ta(3)-O(10) bond lengths are 1.97 Å. Both Ta(3)-O(9) bond lengths are 1.97 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Ta(2) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Ta(2) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent K(1) and one Ta(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to four equivalent K(1) and one Ta(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to four equivalent Ca(2), one Ta(1), and one Ta(3) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to four equivalent Ca(1), one Ta(2), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(3) atoms. In the tenth O site, O(10) is bonded in a linear geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(3) atoms.