Dy2YTaO7 crystallizes in the orthorhombic Cmcm space group. Dy(1) is bonded to one O(1), one O(3), one O(4), and four equivalent O(2) atoms to form distorted DyO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Dy(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Dy(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 46°. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Dy(1)O7 pentagonal bipyramids, and edges with four equivalent Dy(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Dy(1) and two equivalent Ta(1) atoms to form distorted ODy2Ta2 trigonal pyramids that share corners with two equivalent O(4)Dy2Y2 tetrahedra, corners with two equivalent O(1)Dy2Ta2 trigonal pyramids, and  an edgeedge with one O(3)Dy2Y2 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Dy(1), one Y(1), and one Ta(1) atom. In the third O site, O(3) is bonded to two equivalent Dy(1) and two equivalent Y(1) atoms to form ODy2Y2 tetrahedra that share corners with two equivalent O(3)Dy2Y2 tetrahedra, corners with four equivalent O(4)Dy2Y2 tetrahedra,  an edgeedge with one O(4)Dy2Y2 tetrahedra, and  an edgeedge with one O(1)Dy2Ta2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Dy(1) and two equivalent Y(1) atoms to form ODy2Y2 tetrahedra that share corners with two equivalent O(4)Dy2Y2 tetrahedra, corners with four equivalent O(3)Dy2Y2 tetrahedra, corners with two equivalent O(1)Dy2Ta2 trigonal pyramids, and  an edgeedge with one O(3)Dy2Y2 tetrahedra.
Dy2YTaO7 crystallizes in the orthorhombic Cmcm space group. Dy(1) is bonded to one O(1), one O(3), one O(4), and four equivalent O(2) atoms to form distorted DyO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Dy(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Dy(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 46°. The Dy(1)-O(1) bond length is 2.47 Å. The Dy(1)-O(3) bond length is 2.21 Å. The Dy(1)-O(4) bond length is 2.28 Å. There are two shorter (2.29 Å) and two longer (2.41 Å) Dy(1)-O(2) bond lengths. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. Both Y(1)-O(3) bond lengths are 2.38 Å. Both Y(1)-O(4) bond lengths are 2.33 Å. All Y(1)-O(2) bond lengths are 2.64 Å. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Dy(1)O7 pentagonal bipyramids, and edges with four equivalent Dy(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. Both Ta(1)-O(1) bond lengths are 2.01 Å. All Ta(1)-O(2) bond lengths are 2.00 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Dy(1) and two equivalent Ta(1) atoms to form distorted ODy2Ta2 trigonal pyramids that share corners with two equivalent O(4)Dy2Y2 tetrahedra, corners with two equivalent O(1)Dy2Ta2 trigonal pyramids, and  an edgeedge with one O(3)Dy2Y2 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Dy(1), one Y(1), and one Ta(1) atom. In the third O site, O(3) is bonded to two equivalent Dy(1) and two equivalent Y(1) atoms to form ODy2Y2 tetrahedra that share corners with two equivalent O(3)Dy2Y2 tetrahedra, corners with four equivalent O(4)Dy2Y2 tetrahedra,  an edgeedge with one O(4)Dy2Y2 tetrahedra, and  an edgeedge with one O(1)Dy2Ta2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Dy(1) and two equivalent Y(1) atoms to form ODy2Y2 tetrahedra that share corners with two equivalent O(4)Dy2Y2 tetrahedra, corners with four equivalent O(3)Dy2Y2 tetrahedra, corners with two equivalent O(1)Dy2Ta2 trigonal pyramids, and  an edgeedge with one O(3)Dy2Y2 tetrahedra.