Dy3NbO7 crystallizes in the orthorhombic Cmme space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted corner-sharing DyO6 octahedra. The corner-sharing octahedral tilt angles are 69°. In the second Dy site, Dy(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 Dy(1) and two equivalent Dy(2) atoms to form ODy4 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra, and edges with four equivalent O(2)Dy3Nb tetrahedra. In the second O site, O(2) is bonded to one Dy(1), two equivalent Dy(2), and one Nb(1) atom to form ODy3Nb tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, edges with two equivalent O(3)Dy2Nb2 tetrahedra, and edges with two equivalent O(2)Dy3Nb tetrahedra. In the third O site, O(3) is bonded to two equivalent Dy(2) and two equivalent Nb(1) atoms to form distorted ODy2Nb2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra, edges with two equivalent O(3)Dy2Nb2 tetrahedra, and edges with four equivalent O(2)Dy3Nb tetrahedra.
Dy3NbO7 crystallizes in the orthorhombic Cmme space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted corner-sharing DyO6 octahedra. The corner-sharing octahedral tilt angles are 69°. Both Dy(1)-O(1) bond lengths are 2.27 Å. All Dy(1)-O(2) bond lengths are 2.28 Å. In the second Dy site, Dy(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(3), and four equivalent O(2) atoms. The Dy(2)-O(1) bond length is 2.26 Å. There is one shorter (2.09 Å) and one longer (2.57 Å) Dy(2)-O(3) bond length. There are two shorter (2.26 Å) and two longer (2.46 Å) Dy(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 Dy(1) and two equivalent Dy(2) atoms to form ODy4 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra, and edges with four equivalent O(2)Dy3Nb tetrahedra. In the second O site, O(2) is bonded to one Dy(1), two equivalent Dy(2), and one Nb(1) atom to form ODy3Nb tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, edges with two equivalent O(3)Dy2Nb2 tetrahedra, and edges with two equivalent O(2)Dy3Nb tetrahedra. In the third O site, O(3) is bonded to two equivalent Dy(2) and two equivalent Nb(1) atoms to form distorted ODy2Nb2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Nb2 tetrahedra, corners with eight equivalent O(2)Dy3Nb tetrahedra, edges with two equivalent O(3)Dy2Nb2 tetrahedra, and edges with four equivalent O(2)Dy3Nb tetrahedra.