ErDyO3 crystallizes in the hexagonal P6_3cm space group. Er(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form corner-sharing ErO5 trigonal bipyramids. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 7-coordinate geometry to one O(3), three equivalent O(1), and three equivalent O(2) atoms. In the second Dy site, Dy(2) is bonded in a 7-coordinate geometry to one O(4), three equivalent O(1), and three equivalent O(2) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Er(1), one Dy(2), and two equivalent Dy(1) atoms to form ODy3Er tetrahedra that share corners with two equivalent O(4)DyEr3 tetrahedra, corners with four equivalent O(2)Dy3Er tetrahedra, corners with six equivalent O(1)Dy3Er tetrahedra, edges with three equivalent O(2)Dy3Er tetrahedra, and edges with two equivalent O(3)DyEr3 trigonal pyramids. In the second O site, O(2) is bonded to one Er(1), one Dy(2), and two equivalent Dy(1) atoms to form ODy3Er tetrahedra that share corners with four equivalent O(1)Dy3Er tetrahedra, corners with six equivalent O(2)Dy3Er tetrahedra, corners with four equivalent O(3)DyEr3 trigonal pyramids,  an edgeedge with one O(4)DyEr3 tetrahedra, and edges with three equivalent O(1)Dy3Er tetrahedra. In the third O site, O(3) is bonded to three equivalent Er(1) and one Dy(1) atom to form distorted ODyEr3 trigonal pyramids that share corners with three equivalent O(4)DyEr3 tetrahedra, corners with six equivalent O(2)Dy3Er tetrahedra, corners with three equivalent O(3)DyEr3 trigonal pyramids, and edges with three equivalent O(1)Dy3Er tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Er(1) and one Dy(2) atom to form ODyEr3 tetrahedra that share corners with six equivalent O(1)Dy3Er tetrahedra, corners with six equivalent O(3)DyEr3 trigonal pyramids, and edges with three equivalent O(2)Dy3Er tetrahedra.
ErDyO3 crystallizes in the hexagonal P6_3cm space group. Er(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form corner-sharing ErO5 trigonal bipyramids. The Er(1)-O(1) bond length is 2.21 Å. The Er(1)-O(2) bond length is 2.19 Å. The Er(1)-O(4) bond length is 2.18 Å. Both Er(1)-O(3) bond lengths are 2.16 Å. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 7-coordinate geometry to one O(3), three equivalent O(1), and three equivalent O(2) atoms. The Dy(1)-O(3) bond length is 2.72 Å. All Dy(1)-O(1) bond lengths are 2.38 Å. All Dy(1)-O(2) bond lengths are 2.35 Å. In the second Dy site, Dy(2) is bonded in a 7-coordinate geometry to one O(4), three equivalent O(1), and three equivalent O(2) atoms. The Dy(2)-O(4) bond length is 2.49 Å. All Dy(2)-O(1) bond lengths are 2.30 Å. All Dy(2)-O(2) bond lengths are 2.46 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Er(1), one Dy(2), and two equivalent Dy(1) atoms to form ODy3Er tetrahedra that share corners with two equivalent O(4)DyEr3 tetrahedra, corners with four equivalent O(2)Dy3Er tetrahedra, corners with six equivalent O(1)Dy3Er tetrahedra, edges with three equivalent O(2)Dy3Er tetrahedra, and edges with two equivalent O(3)DyEr3 trigonal pyramids. In the second O site, O(2) is bonded to one Er(1), one Dy(2), and two equivalent Dy(1) atoms to form ODy3Er tetrahedra that share corners with four equivalent O(1)Dy3Er tetrahedra, corners with six equivalent O(2)Dy3Er tetrahedra, corners with four equivalent O(3)DyEr3 trigonal pyramids,  an edgeedge with one O(4)DyEr3 tetrahedra, and edges with three equivalent O(1)Dy3Er tetrahedra. In the third O site, O(3) is bonded to three equivalent Er(1) and one Dy(1) atom to form distorted ODyEr3 trigonal pyramids that share corners with three equivalent O(4)DyEr3 tetrahedra, corners with six equivalent O(2)Dy3Er tetrahedra, corners with three equivalent O(3)DyEr3 trigonal pyramids, and edges with three equivalent O(1)Dy3Er tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Er(1) and one Dy(2) atom to form ODyEr3 tetrahedra that share corners with six equivalent O(1)Dy3Er tetrahedra, corners with six equivalent O(3)DyEr3 trigonal pyramids, and edges with three equivalent O(2)Dy3Er tetrahedra.