Sm3SbO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Sm site, Sm(2) is bonded to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Sb(1)O6 octahedra,  a cornercorner with one Sm(2)O7 pentagonal bipyramid, edges with two equivalent Sb(1)O6 octahedra, and edges with three equivalent Sm(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. Sb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sm(2)O7 pentagonal bipyramids, and edges with four equivalent Sm(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Sm(1), two equivalent Sm(2), and one Sb(1) atom. In the second O site, O(2) is bonded to one Sm(1), two equivalent Sm(2), and one Sb(1) atom to form distorted OSm3Sb tetrahedra that share corners with two equivalent O(2)Sm3Sb tetrahedra, corners with two equivalent O(3)Sm4 tetrahedra, corners with two equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(2)Sm3Sb tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, and  an edgeedge with one O(5)Sm2Sb2 trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with four equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(4)Sm4 tetrahedra, and edges with two equivalent O(2)Sm3Sb tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with four equivalent O(3)Sm4 tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra, edges with two equivalent O(2)Sm3Sb tetrahedra, and  an edgeedge with one O(5)Sm2Sb2 trigonal pyramid. In the fifth O site, O(5) is bonded to two equivalent Sm(2) and two equivalent Sb(1) atoms to form distorted OSm2Sb2 trigonal pyramids that share corners with two equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(4)Sm4 tetrahedra, and edges with two equivalent O(2)Sm3Sb tetrahedra.
Sm3SbO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Sm(1)-O(1) bond lengths are 2.74 Å. Both Sm(1)-O(2) bond lengths are 2.66 Å. Both Sm(1)-O(3) bond lengths are 2.38 Å. Both Sm(1)-O(4) bond lengths are 2.42 Å. In the second Sm site, Sm(2) is bonded to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Sb(1)O6 octahedra,  a cornercorner with one Sm(2)O7 pentagonal bipyramid, edges with two equivalent Sb(1)O6 octahedra, and edges with three equivalent Sm(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. The Sm(2)-O(3) bond length is 2.32 Å. The Sm(2)-O(4) bond length is 2.28 Å. The Sm(2)-O(5) bond length is 2.55 Å. There is one shorter (2.36 Å) and one longer (2.46 Å) Sm(2)-O(1) bond length. There is one shorter (2.37 Å) and one longer (2.47 Å) Sm(2)-O(2) bond length. Sb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sm(2)O7 pentagonal bipyramids, and edges with four equivalent Sm(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. Both Sb(1)-O(1) bond lengths are 2.00 Å. Both Sb(1)-O(2) bond lengths are 2.01 Å. Both Sb(1)-O(5) bond lengths are 2.05 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Sm(1), two equivalent Sm(2), and one Sb(1) atom. In the second O site, O(2) is bonded to one Sm(1), two equivalent Sm(2), and one Sb(1) atom to form distorted OSm3Sb tetrahedra that share corners with two equivalent O(2)Sm3Sb tetrahedra, corners with two equivalent O(3)Sm4 tetrahedra, corners with two equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(2)Sm3Sb tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, and  an edgeedge with one O(5)Sm2Sb2 trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with four equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(4)Sm4 tetrahedra, and edges with two equivalent O(2)Sm3Sb tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with four equivalent O(3)Sm4 tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra, edges with two equivalent O(2)Sm3Sb tetrahedra, and  an edgeedge with one O(5)Sm2Sb2 trigonal pyramid. In the fifth O site, O(5) is bonded to two equivalent Sm(2) and two equivalent Sb(1) atoms to form distorted OSm2Sb2 trigonal pyramids that share corners with two equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(2)Sm3Sb tetrahedra, corners with two equivalent O(5)Sm2Sb2 trigonal pyramids,  an edgeedge with one O(4)Sm4 tetrahedra, and edges with two equivalent O(2)Sm3Sb tetrahedra.