Mg14YNbO16 is alpha Po-derived structured and crystallizes in the orthorhombic Pmmm space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(5)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two O(2,2); two equivalent O(7); and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form MgO6 octahedra that share corners with two equivalent Mg(4)O6 octahedra, corners with four equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, edges with two equivalent Mg(6)O6 octahedra, edges with two equivalent Y(1)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the fifth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra, corners with four equivalent Mg(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Y(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(5)O6 octahedra, corners with four equivalent Mg(6)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the seventh Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(7)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra,  an edgeedge with one Y(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-5°. Y(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form YO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(5)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Nb(1) is bonded to two O(2,2); two equivalent O(5); and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), two equivalent Mg(7), and one Y(1) atom to form OYMg5 octahedra that share corners with two equivalent O(2)Mg5Nb octahedra, corners with four equivalent O(1)YMg5 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(4)Y2Mg4 octahedra, edges with two equivalent O(8)YMg4Nb octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one Nb(1) atom to form OMg5Nb octahedra that share corners with two equivalent O(1)YMg5 octahedra; corners with four O(2,2)Mg5Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(8)YMg4Nb octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one Nb(1) atom to form OMg5Nb octahedra that share corners with two equivalent O(1)YMg5 octahedra; corners with four O(2,2)Mg5Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(8)YMg4Nb octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the fourth O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(5)Mg4Nb2 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra,  an edgeedge with one O(4)Y2Mg4 octahedra, edges with two equivalent O(2)Mg5Nb octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)YMg4Nb octahedra, and edges with two equivalent O(1)YMg5 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the fifth O site, O(4) is bonded to two equivalent Mg(3), two equivalent Mg(5), and two equivalent Y(1) atoms to form OY2Mg4 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(4)Y2Mg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(8)YMg4Nb octahedra, and edges with four equivalent O(1)YMg5 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(5) is bonded to two equivalent Mg(3), two equivalent Mg(6), and two equivalent Nb(1) atoms to form OMg4Nb2 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(4)Y2Mg4 octahedra; edges with four O(2,2)Mg5Nb octahedra; edges with four equivalent O(3)Mg6 octahedra; and edges with four equivalent O(8)YMg4Nb octahedra. The corner-sharing octahedra are not tilted. In the seventh O site, O(6) is bonded to two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms to form OMg6 octahedra that share corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, corners with two equivalent O(4)Y2Mg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(1)YMg5 octahedra. The corner-sharing octahedra are not tilted. In the eighth O site, O(7) is bonded to two equivalent Mg(2), two equivalent Mg(4), and two equivalent Mg(6) atoms to form OMg6 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra; corners with two equivalent O(6)Mg6 octahedra; corners with two equivalent O(7)Mg6 octahedra; edges with four O(2,2)Mg5Nb octahedra; edges with four equivalent O(3)Mg6 octahedra; and edges with four equivalent O(9)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the ninth O site, O(8) is bonded to two equivalent Mg(3), two equivalent Mg(7), one Y(1), and one Nb(1) atom to form OYMg4Nb octahedra that share corners with two equivalent O(9)Mg6 octahedra; corners with four equivalent O(8)YMg4Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two O(2,2)Mg5Nb octahedra; edges with two equivalent O(4)Y2Mg4 octahedra; edges with two equivalent O(1)YMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the tenth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with two equivalent O(8)YMg4Nb octahedra; corners with four equivalent O(9)Mg6 octahedra; edges with two O(2,2)Mg5Nb octahedra; edges with two equivalent O(6)Mg6 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(1)YMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°.
Mg14YNbO16 is alpha Po-derived structured and crystallizes in the orthorhombic Pmmm space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(5)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(1) bond lengths are 2.08 Å. Both Mg(1)-O(6) bond lengths are 2.21 Å. Both Mg(1)-O(9) bond lengths are 2.19 Å. In the second Mg site, Mg(2) is bonded to two O(2,2); two equivalent O(7); and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2,2) bond lengths are 2.05 Å. Both Mg(2)-O(7) bond lengths are 2.21 Å. Both Mg(2)-O(9) bond lengths are 2.20 Å. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form MgO6 octahedra that share corners with two equivalent Mg(4)O6 octahedra, corners with four equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, edges with two equivalent Mg(6)O6 octahedra, edges with two equivalent Y(1)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Mg(3)-O(4) bond length is 2.29 Å. The Mg(3)-O(5) bond length is 2.10 Å. Both Mg(3)-O(3) bond lengths are 2.18 Å. Both Mg(3)-O(8) bond lengths are 2.21 Å. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. The Mg(4)-O(6) bond length is 2.21 Å. The Mg(4)-O(7) bond length is 2.18 Å. Both Mg(4)-O(3) bond lengths are 2.18 Å. Both Mg(4)-O(9) bond lengths are 2.21 Å. In the fifth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra, corners with four equivalent Mg(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Y(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Mg(5)-O(4) bond length is 2.28 Å. The Mg(5)-O(6) bond length is 2.07 Å. Both Mg(5)-O(1) bond lengths are 2.21 Å. Both Mg(5)-O(3) bond lengths are 2.19 Å. In the sixth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(5)O6 octahedra, corners with four equivalent Mg(6)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. The Mg(6)-O(5) bond length is 2.21 Å. The Mg(6)-O(7) bond length is 2.14 Å. Both Mg(6)-O(2) bond lengths are 2.21 Å. Both Mg(6)-O(3) bond lengths are 2.21 Å. In the seventh Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(7)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra,  an edgeedge with one Y(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-5°. The Mg(7)-O(1) bond length is 2.25 Å. The Mg(7)-O(2) bond length is 2.14 Å. The Mg(7)-O(8) bond length is 2.25 Å. The Mg(7)-O(9) bond length is 2.10 Å. Both Mg(7)-O(3) bond lengths are 2.21 Å. Y(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form YO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(5)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Y(1)-O(1) bond lengths are 2.27 Å. Both Y(1)-O(4) bond lengths are 2.21 Å. Both Y(1)-O(8) bond lengths are 2.18 Å. Nb(1) is bonded to two O(2,2); two equivalent O(5); and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Y(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Nb(1)-O(2,2) bond lengths are 2.31 Å. Both Nb(1)-O(5) bond lengths are 2.21 Å. Both Nb(1)-O(8) bond lengths are 2.22 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), two equivalent Mg(7), and one Y(1) atom to form OYMg5 octahedra that share corners with two equivalent O(2)Mg5Nb octahedra, corners with four equivalent O(1)YMg5 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(4)Y2Mg4 octahedra, edges with two equivalent O(8)YMg4Nb octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one Nb(1) atom to form OMg5Nb octahedra that share corners with two equivalent O(1)YMg5 octahedra; corners with four O(2,2)Mg5Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(8)YMg4Nb octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one Nb(1) atom to form OMg5Nb octahedra that share corners with two equivalent O(1)YMg5 octahedra; corners with four O(2,2)Mg5Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(8)YMg4Nb octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. Both O(2)-Mg(6) bond lengths are 2.21 Å. Both O(2)-Mg(7) bond lengths are 2.14 Å. In the fourth O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(5)Mg4Nb2 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra,  an edgeedge with one O(4)Y2Mg4 octahedra, edges with two equivalent O(2)Mg5Nb octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)YMg4Nb octahedra, and edges with two equivalent O(1)YMg5 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the fifth O site, O(4) is bonded to two equivalent Mg(3), two equivalent Mg(5), and two equivalent Y(1) atoms to form OY2Mg4 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(4)Y2Mg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(8)YMg4Nb octahedra, and edges with four equivalent O(1)YMg5 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(5) is bonded to two equivalent Mg(3), two equivalent Mg(6), and two equivalent Nb(1) atoms to form OMg4Nb2 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(4)Y2Mg4 octahedra; edges with four O(2,2)Mg5Nb octahedra; edges with four equivalent O(3)Mg6 octahedra; and edges with four equivalent O(8)YMg4Nb octahedra. The corner-sharing octahedra are not tilted. In the seventh O site, O(6) is bonded to two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms to form OMg6 octahedra that share corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, corners with two equivalent O(4)Y2Mg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(1)YMg5 octahedra. The corner-sharing octahedra are not tilted. In the eighth O site, O(7) is bonded to two equivalent Mg(2), two equivalent Mg(4), and two equivalent Mg(6) atoms to form OMg6 octahedra that share corners with two equivalent O(5)Mg4Nb2 octahedra; corners with two equivalent O(6)Mg6 octahedra; corners with two equivalent O(7)Mg6 octahedra; edges with four O(2,2)Mg5Nb octahedra; edges with four equivalent O(3)Mg6 octahedra; and edges with four equivalent O(9)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the ninth O site, O(8) is bonded to two equivalent Mg(3), two equivalent Mg(7), one Y(1), and one Nb(1) atom to form OYMg4Nb octahedra that share corners with two equivalent O(9)Mg6 octahedra; corners with four equivalent O(8)YMg4Nb octahedra; edges with two equivalent O(5)Mg4Nb2 octahedra; edges with two O(2,2)Mg5Nb octahedra; edges with two equivalent O(4)Y2Mg4 octahedra; edges with two equivalent O(1)YMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the tenth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with two equivalent O(8)YMg4Nb octahedra; corners with four equivalent O(9)Mg6 octahedra; edges with two O(2,2)Mg5Nb octahedra; edges with two equivalent O(6)Mg6 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(1)YMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°.