Dy2NbGaO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted DyO8 hexagonal bipyramids that share edges with two equivalent Dy(1)O8 hexagonal bipyramids, edges with two equivalent Ga(1)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. In the second Dy site, Dy(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. Nb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Ga(1)O6 octahedra, and edges with four equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. Ga(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form GaO6 octahedra that share corners with two equivalent Ga(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and edges with two equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. There are four 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(3)Dy2Ga2 tetrahedra, corners with two equivalent O(2)Dy2Nb2 tetrahedra, corners with four equivalent O(1)Dy4 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(3)Dy2Ga2 tetrahedra,  an edgeedge with one O(2)Dy2Nb2 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the second O site, O(2) is bonded to two equivalent Dy(1) 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(2)Dy2Nb2 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the third O site, O(3) is bonded to two equivalent Dy(2) and two equivalent Ga(1) atoms to form distorted ODy2Ga2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Ga2 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the fourth O site, O(4) is bonded to one Dy(1), one Dy(2), one Nb(1), and one Ga(1) atom to form distorted ODy2NbGa tetrahedra that share corners with two equivalent O(3)Dy2Ga2 tetrahedra, corners with two equivalent O(2)Dy2Nb2 tetrahedra, corners with two equivalent O(1)Dy4 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(3)Dy2Ga2 tetrahedra,  an edgeedge with one O(2)Dy2Nb2 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with two equivalent O(4)Dy2NbGa tetrahedra.
Dy2NbGaO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted DyO8 hexagonal bipyramids that share edges with two equivalent Dy(1)O8 hexagonal bipyramids, edges with two equivalent Ga(1)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. Both Dy(1)-O(1) bond lengths are 2.21 Å. Both Dy(1)-O(2) bond lengths are 2.48 Å. All Dy(1)-O(4) bond lengths are 2.52 Å. In the second Dy site, Dy(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. Both Dy(2)-O(1) bond lengths are 2.25 Å. Both Dy(2)-O(3) bond lengths are 2.51 Å. All Dy(2)-O(4) bond lengths are 2.49 Å. Nb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Ga(1)O6 octahedra, and edges with four equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. Both Nb(1)-O(2) bond lengths are 2.04 Å. All Nb(1)-O(4) bond lengths are 1.99 Å. Ga(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form GaO6 octahedra that share corners with two equivalent Ga(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and edges with two equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. Both Ga(1)-O(3) bond lengths are 1.99 Å. All Ga(1)-O(4) bond lengths are 2.03 Å. There are four 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(3)Dy2Ga2 tetrahedra, corners with two equivalent O(2)Dy2Nb2 tetrahedra, corners with four equivalent O(1)Dy4 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(3)Dy2Ga2 tetrahedra,  an edgeedge with one O(2)Dy2Nb2 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the second O site, O(2) is bonded to two equivalent Dy(1) 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(2)Dy2Nb2 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the third O site, O(3) is bonded to two equivalent Dy(2) and two equivalent Ga(1) atoms to form distorted ODy2Ga2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with four equivalent O(3)Dy2Ga2 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(4)Dy2NbGa tetrahedra. In the fourth O site, O(4) is bonded to one Dy(1), one Dy(2), one Nb(1), and one Ga(1) atom to form distorted ODy2NbGa tetrahedra that share corners with two equivalent O(3)Dy2Ga2 tetrahedra, corners with two equivalent O(2)Dy2Nb2 tetrahedra, corners with two equivalent O(1)Dy4 tetrahedra, corners with eight equivalent O(4)Dy2NbGa tetrahedra,  an edgeedge with one O(3)Dy2Ga2 tetrahedra,  an edgeedge with one O(2)Dy2Nb2 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with two equivalent O(4)Dy2NbGa tetrahedra.