Y3NbO7 crystallizes in the orthorhombic Cmme space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles are 70°. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(3), and four equivalent O(2) atoms. Nb(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra, and edges with four equivalent O(2)Y3Nb tetrahedra. In the second O site, O(2) is bonded to one Y(1), two equivalent Y(2), and one Nb(1) atom to form OY3Nb tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(3)Y2Nb2 tetrahedra, and edges with two equivalent O(2)Y3Nb tetrahedra. In the third O site, O(3) is bonded to two equivalent Y(2) and two equivalent Nb(1) atoms to form distorted OY2Nb2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra, edges with two equivalent O(3)Y2Nb2 tetrahedra, and edges with four equivalent O(2)Y3Nb tetrahedra.
Y3NbO7 crystallizes in the orthorhombic Cmme space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles are 70°. Both Y(1)-O(1) bond lengths are 2.28 Å. All Y(1)-O(2) bond lengths are 2.29 Å. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(3), and four equivalent O(2) atoms. The Y(2)-O(1) bond length is 2.26 Å. There is one shorter (2.10 Å) and one longer (2.56 Å) Y(2)-O(3) bond length. There are two shorter (2.27 Å) and two longer (2.46 Å) Y(2)-O(2) bond lengths. Nb(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Nb(1)-O(2) bond lengths are 2.18 Å. All Nb(1)-O(3) bond lengths are 2.20 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra, and edges with four equivalent O(2)Y3Nb tetrahedra. In the second O site, O(2) is bonded to one Y(1), two equivalent Y(2), and one Nb(1) atom to form OY3Nb tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(3)Y2Nb2 tetrahedra, and edges with two equivalent O(2)Y3Nb tetrahedra. In the third O site, O(3) is bonded to two equivalent Y(2) and two equivalent Nb(1) atoms to form distorted OY2Nb2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra, corners with eight equivalent O(2)Y3Nb tetrahedra, edges with two equivalent O(3)Y2Nb2 tetrahedra, and edges with four equivalent O(2)Y3Nb tetrahedra.