Ba3UDyFeO9 crystallizes in the trigonal P3m1 space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(6) and six equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the third Ba site, Ba(3) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(4) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra,  a faceface with one Fe(1)O6 octahedra, faces with three equivalent U(2)O6 octahedra, and faces with three equivalent Fe(2)O6 octahedra. In the fourth Ba site, Ba(4) is bonded in a distorted q6 geometry to three equivalent O(4) and six equivalent O(2) atoms. In the fifth Ba site, Ba(5) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(6) atoms. In the sixth Ba site, Ba(6) is bonded in a distorted q6 geometry to three equivalent O(1) and six equivalent O(6) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded in an octahedral geometry to three equivalent O(1) and three equivalent O(6) atoms. In the second U site, U(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form UO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 3-coordinate geometry to three equivalent O(3) and six equivalent O(5) atoms. In the second Dy site, Dy(2) is bonded in a 3-coordinate geometry to three equivalent O(5) and six equivalent O(3) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra and  a faceface with one Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 5°. In the second Fe site, Fe(2) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent U(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-5°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), one Ba(6), two equivalent Ba(1), and one U(1) atom to form a mixture of distorted edge, face, and corner-sharing OBa4U square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(4), and one U(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Ba(3), one Dy(1), two equivalent Dy(2), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded to one Ba(4), two equivalent Ba(3), one U(2), and one Fe(2) atom to form a mixture of distorted edge, face, and corner-sharing OBa3UFe square pyramids. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ba(5), one Dy(2), two equivalent Dy(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(5), two equivalent Ba(6), and one U(1) atom to form a mixture of distorted edge, face, and corner-sharing OBa4U square pyramids.
Ba3UDyFeO9 crystallizes in the trigonal P3m1 space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(6) and six equivalent O(1) atoms. All Ba(1)-O(6) bond lengths are 2.73 Å. All Ba(1)-O(1) bond lengths are 3.01 Å. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. All Ba(2)-O(1) bond lengths are 2.63 Å. All Ba(2)-O(2) bond lengths are 2.65 Å. In the third Ba site, Ba(3) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(4) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra,  a faceface with one Fe(1)O6 octahedra, faces with three equivalent U(2)O6 octahedra, and faces with three equivalent Fe(2)O6 octahedra. All Ba(3)-O(2) bond lengths are 3.20 Å. All Ba(3)-O(3) bond lengths are 2.87 Å. All Ba(3)-O(4) bond lengths are 3.01 Å. In the fourth Ba site, Ba(4) is bonded in a distorted q6 geometry to three equivalent O(4) and six equivalent O(2) atoms. All Ba(4)-O(4) bond lengths are 2.76 Å. All Ba(4)-O(2) bond lengths are 3.00 Å. In the fifth Ba site, Ba(5) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(6) atoms. All Ba(5)-O(5) bond lengths are 2.68 Å. All Ba(5)-O(6) bond lengths are 2.64 Å. In the sixth Ba site, Ba(6) is bonded in a distorted q6 geometry to three equivalent O(1) and six equivalent O(6) atoms. All Ba(6)-O(1) bond lengths are 2.75 Å. All Ba(6)-O(6) bond lengths are 3.01 Å. There are two inequivalent U sites. In the first U site, U(1) is bonded in an octahedral geometry to three equivalent O(1) and three equivalent O(6) atoms. All U(1)-O(1) bond lengths are 2.09 Å. All U(1)-O(6) bond lengths are 2.08 Å. In the second U site, U(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form UO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. All U(2)-O(2) bond lengths are 2.04 Å. All U(2)-O(4) bond lengths are 2.15 Å. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 3-coordinate geometry to three equivalent O(3) and six equivalent O(5) atoms. All Dy(1)-O(3) bond lengths are 2.19 Å. All Dy(1)-O(5) bond lengths are 3.06 Å. In the second Dy site, Dy(2) is bonded in a 3-coordinate geometry to three equivalent O(5) and six equivalent O(3) atoms. All Dy(2)-O(5) bond lengths are 2.19 Å. All Dy(2)-O(3) bond lengths are 3.09 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra and  a faceface with one Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 5°. All Fe(1)-O(3) bond lengths are 2.25 Å. All Fe(1)-O(5) bond lengths are 1.97 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent U(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-5°. All Fe(2)-O(3) bond lengths are 2.08 Å. All Fe(2)-O(4) bond lengths are 2.04 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), one Ba(6), two equivalent Ba(1), and one U(1) atom to form a mixture of distorted edge, face, and corner-sharing OBa4U square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(4), and one U(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Ba(3), one Dy(1), two equivalent Dy(2), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded to one Ba(4), two equivalent Ba(3), one U(2), and one Fe(2) atom to form a mixture of distorted edge, face, and corner-sharing OBa3UFe square pyramids. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ba(5), one Dy(2), two equivalent Dy(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(5), two equivalent Ba(6), and one U(1) atom to form a mixture of distorted edge, face, and corner-sharing OBa4U square pyramids.