K2LiNd4Nb2O12 crystallizes in the monoclinic Cm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(7), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(4), and two equivalent O(7) atoms. Li(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the third Nd site, Nd(3) is bonded to one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted NdO7 pentagonal bipyramids that share  a cornercorner with one Nb(2)O5 trigonal bipyramid, corners with two equivalent Nb(1)O5 trigonal bipyramids, and  an edgeedge with one Nb(1)O5 trigonal bipyramid. In the fourth Nd site, Nd(4) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nd(3)O7 pentagonal bipyramids and  an edgeedge with one Nd(3)O7 pentagonal bipyramid. In the second Nb site, Nb(2) is bonded to one O(7), two equivalent O(2), and two equivalent O(5) atoms to form distorted NbO5 trigonal bipyramids that share  a cornercorner with one Nd(3)O7 pentagonal bipyramid. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Li(1), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(2), one Nd(4), and one Nb(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Li(1), one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom to form distorted edge-sharing ONd3Nb tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one Nd(2), and one Nb(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Nd(3), and one Nb(2) atom.
K2LiNd4Nb2O12 crystallizes in the monoclinic Cm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(7), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. The K(1)-O(7) bond length is 2.61 Å. Both K(1)-O(2) bond lengths are 2.75 Å. Both K(1)-O(4) bond lengths are 2.88 Å. Both K(1)-O(6) bond lengths are 2.95 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(4), and two equivalent O(7) atoms. The K(2)-O(6) bond length is 2.62 Å. Both K(2)-O(2) bond lengths are 2.81 Å. Both K(2)-O(4) bond lengths are 2.85 Å. Both K(2)-O(7) bond lengths are 2.95 Å. Li(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Li(1)-O(1) bond lengths are 2.13 Å. Both Li(1)-O(3) bond lengths are 2.08 Å. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Both Nd(1)-O(1) bond lengths are 2.67 Å. Both Nd(1)-O(3) bond lengths are 2.47 Å. Both Nd(1)-O(4) bond lengths are 2.55 Å. Both Nd(1)-O(5) bond lengths are 2.54 Å. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. The Nd(2)-O(6) bond length is 2.69 Å. Both Nd(2)-O(2) bond lengths are 2.47 Å. Both Nd(2)-O(3) bond lengths are 2.37 Å. Both Nd(2)-O(5) bond lengths are 2.47 Å. In the third Nd site, Nd(3) is bonded to one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted NdO7 pentagonal bipyramids that share  a cornercorner with one Nb(2)O5 trigonal bipyramid, corners with two equivalent Nb(1)O5 trigonal bipyramids, and  an edgeedge with one Nb(1)O5 trigonal bipyramid. The Nd(3)-O(7) bond length is 2.61 Å. Both Nd(3)-O(1) bond lengths are 2.41 Å. Both Nd(3)-O(3) bond lengths are 2.35 Å. Both Nd(3)-O(4) bond lengths are 2.49 Å. In the fourth Nd site, Nd(4) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Nd(4)-O(1) bond lengths are 2.77 Å. Both Nd(4)-O(2) bond lengths are 2.37 Å. Both Nd(4)-O(3) bond lengths are 2.49 Å. Both Nd(4)-O(5) bond lengths are 2.51 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nd(3)O7 pentagonal bipyramids and  an edgeedge with one Nd(3)O7 pentagonal bipyramid. The Nb(1)-O(6) bond length is 1.87 Å. Both Nb(1)-O(1) bond lengths are 2.06 Å. Both Nb(1)-O(4) bond lengths are 1.96 Å. In the second Nb site, Nb(2) is bonded to one O(7), two equivalent O(2), and two equivalent O(5) atoms to form distorted NbO5 trigonal bipyramids that share  a cornercorner with one Nd(3)O7 pentagonal bipyramid. The Nb(2)-O(7) bond length is 1.87 Å. Both Nb(2)-O(2) bond lengths are 1.97 Å. Both Nb(2)-O(5) bond lengths are 2.03 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Li(1), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(2), one Nd(4), and one Nb(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Li(1), one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom to form distorted edge-sharing ONd3Nb tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one Nd(2), and one Nb(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Nd(3), and one Nb(2) atom.