K2Na2MgNd2Nb2O10 crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4) and four equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(3) atoms. Mg(1) is bonded in a 4-coordinate geometry to one K(2) and four equivalent O(1) atoms. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(3) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted trigonal bipyramidal geometry to one O(4) and four equivalent O(3) atoms. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Mg(1), one Nd(1), one Nd(2), and one Nb(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent K(1), two equivalent K(2), one Na(2), and one Nb(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(2), one Na(2), one Nd(1), one Nd(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), one Na(1), and one Nb(1) atom.
K2Na2MgNd2Nb2O10 crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. Both K(1)-O(2) bond lengths are 2.95 Å. Both K(1)-O(4) bond lengths are 2.92 Å. In the second K site, K(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. The K(2)-Mg(1) bond length is 3.11 Å. Both K(2)-O(2) bond lengths are 3.13 Å. Both K(2)-O(4) bond lengths are 2.90 Å. All K(2)-O(3) bond lengths are 3.11 Å. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4) and four equivalent O(1) atoms. The Na(1)-O(4) bond length is 2.93 Å. All Na(1)-O(1) bond lengths are 2.36 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(3) atoms. The Na(2)-O(2) bond length is 2.76 Å. All Na(2)-O(3) bond lengths are 2.33 Å. Mg(1) is bonded in a 4-coordinate geometry to one K(2) and four equivalent O(1) atoms. All Mg(1)-O(1) bond lengths are 2.15 Å. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. All Nd(1)-O(1) bond lengths are 2.49 Å. All Nd(1)-O(3) bond lengths are 2.66 Å. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(3) atoms. All Nd(2)-O(1) bond lengths are 2.69 Å. All Nd(2)-O(3) bond lengths are 2.37 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted trigonal bipyramidal geometry to one O(4) and four equivalent O(3) atoms. The Nb(1)-O(4) bond length is 1.86 Å. All Nb(1)-O(3) bond lengths are 1.99 Å. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. The Nb(2)-O(2) bond length is 1.89 Å. All Nb(2)-O(1) bond lengths are 2.09 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Mg(1), one Nd(1), one Nd(2), and one Nb(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent K(1), two equivalent K(2), one Na(2), and one Nb(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(2), one Na(2), one Nd(1), one Nd(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), one Na(1), and one Nb(1) atom.