KCa2Nb3O10 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(6), one O(7), two equivalent O(5), and two equivalent O(9) atoms. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to one O(10), one O(6), one O(7), two equivalent O(3), two equivalent O(4), and two equivalent O(8) atoms. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(10), and two equivalent O(9) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 17-31°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(8), and two equivalent O(6) atoms. In the third Nb site, Nb(3) is bonded in a 6-coordinate geometry to one O(2), one O(4), one O(5), one O(8), and two equivalent O(7) atoms. There are ten inequivalent O sites. In the first O site, O(5) is bonded to two equivalent Ca(1), one Nb(2), and one Nb(3) atom to form a mixture of edge and corner-sharing OCa2Nb2 tetrahedra. In the second O site, O(6) is bonded to one Ca(1), one Ca(2), and two equivalent Nb(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Nb2 trigonal pyramids. In the third O site, O(7) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Nb(3) atoms. In the fourth O site, O(8) is bonded in a distorted linear geometry to two equivalent Ca(2), one Nb(2), and one Nb(3) atom. In the fifth O site, O(9) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms. In the sixth O site, O(10) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Nb(1) atoms. In the seventh O site, O(1) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Nb(2) atom. In the eighth O site, O(2) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Nb(3) atom. In the ninth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ca(2), one Nb(1), and one Nb(2) atom. In the tenth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2), one Nb(1), and one Nb(3) atom.
KCa2Nb3O10 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. There is one shorter (2.83 Å) and two longer (2.87 Å) K(1)-O(1) bond lengths. There is one shorter (2.80 Å) and two longer (2.84 Å) K(1)-O(2) bond lengths. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(6), one O(7), two equivalent O(5), and two equivalent O(9) atoms. The Ca(1)-O(10) bond length is 2.66 Å. The Ca(1)-O(6) bond length is 2.46 Å. The Ca(1)-O(7) bond length is 2.61 Å. Both Ca(1)-O(5) bond lengths are 2.42 Å. Both Ca(1)-O(9) bond lengths are 2.55 Å. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to one O(10), one O(6), one O(7), two equivalent O(3), two equivalent O(4), and two equivalent O(8) atoms. The Ca(2)-O(10) bond length is 2.82 Å. The Ca(2)-O(6) bond length is 2.52 Å. The Ca(2)-O(7) bond length is 2.51 Å. Both Ca(2)-O(3) bond lengths are 2.56 Å. Both Ca(2)-O(4) bond lengths are 2.43 Å. Both Ca(2)-O(8) bond lengths are 2.77 Å. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(10), and two equivalent O(9) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 17-31°. The Nb(1)-O(3) bond length is 1.98 Å. The Nb(1)-O(4) bond length is 1.97 Å. Both Nb(1)-O(10) bond lengths are 2.00 Å. There is one shorter (1.92 Å) and one longer (2.17 Å) Nb(1)-O(9) bond length. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(8), and two equivalent O(6) atoms. The Nb(2)-O(1) bond length is 1.80 Å. The Nb(2)-O(3) bond length is 2.42 Å. The Nb(2)-O(5) bond length is 2.07 Å. The Nb(2)-O(8) bond length is 1.98 Å. Both Nb(2)-O(6) bond lengths are 2.03 Å. In the third Nb site, Nb(3) is bonded in a 6-coordinate geometry to one O(2), one O(4), one O(5), one O(8), and two equivalent O(7) atoms. The Nb(3)-O(2) bond length is 1.80 Å. The Nb(3)-O(4) bond length is 2.41 Å. The Nb(3)-O(5) bond length is 2.07 Å. The Nb(3)-O(8) bond length is 2.01 Å. Both Nb(3)-O(7) bond lengths are 2.03 Å. There are ten inequivalent O sites. In the first O site, O(5) is bonded to two equivalent Ca(1), one Nb(2), and one Nb(3) atom to form a mixture of edge and corner-sharing OCa2Nb2 tetrahedra. In the second O site, O(6) is bonded to one Ca(1), one Ca(2), and two equivalent Nb(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Nb2 trigonal pyramids. In the third O site, O(7) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Nb(3) atoms. In the fourth O site, O(8) is bonded in a distorted linear geometry to two equivalent Ca(2), one Nb(2), and one Nb(3) atom. In the fifth O site, O(9) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms. In the sixth O site, O(10) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Nb(1) atoms. In the seventh O site, O(1) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Nb(2) atom. In the eighth O site, O(2) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Nb(3) atom. In the ninth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ca(2), one Nb(1), and one Nb(2) atom. In the tenth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ca(2), one Nb(1), and one Nb(3) atom.