Sm3GaO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one O(1), two equivalent O(4), and four equivalent O(3) atoms to form distorted SmO7 pentagonal bipyramids that share  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Sm(1)O7 pentagonal bipyramids, and  an edgeedge with one Ga(1)O4 tetrahedra. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ga(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form GaO4 tetrahedra that share  a cornercorner with one Sm(1)O7 pentagonal bipyramid and  an edgeedge with one Sm(1)O7 pentagonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sm(1), two equivalent Sm(2), and one Ga(1) atom to form distorted OSm3Ga tetrahedra that share corners with eight equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(4)Sm3Ga trigonal pyramids, and edges with two equivalent O(4)Sm3Ga trigonal pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Sm(2) and one Ga(1) atom. 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(1)Sm3Ga tetrahedra, corners with six equivalent O(4)Sm3Ga trigonal pyramids, edges with three equivalent O(3)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm3Ga trigonal pyramid. In the fourth O site, O(4) is bonded to one Sm(1), two equivalent Sm(2), and one Ga(1) atom to form distorted OSm3Ga trigonal pyramids that share corners with two equivalent O(1)Sm3Ga tetrahedra, corners with six equivalent O(3)Sm4 tetrahedra, corners with two equivalent O(4)Sm3Ga trigonal pyramids,  an edgeedge with one O(1)Sm3Ga tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm3Ga trigonal pyramid.
Sm3GaO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one O(1), two equivalent O(4), and four equivalent O(3) atoms to form distorted SmO7 pentagonal bipyramids that share  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Sm(1)O7 pentagonal bipyramids, and  an edgeedge with one Ga(1)O4 tetrahedra. The Sm(1)-O(1) bond length is 2.47 Å. Both Sm(1)-O(4) bond lengths are 2.50 Å. There are two shorter (2.33 Å) and two longer (2.34 Å) Sm(1)-O(3) bond lengths. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Sm(2)-O(1) bond length is 2.43 Å. There is one shorter (2.59 Å) and one longer (2.65 Å) Sm(2)-O(2) bond length. There is one shorter (2.26 Å) and one longer (2.29 Å) Sm(2)-O(3) bond length. There is one shorter (2.33 Å) and one longer (2.44 Å) Sm(2)-O(4) bond length. Ga(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form GaO4 tetrahedra that share  a cornercorner with one Sm(1)O7 pentagonal bipyramid and  an edgeedge with one Sm(1)O7 pentagonal bipyramid. The Ga(1)-O(1) bond length is 1.84 Å. The Ga(1)-O(2) bond length is 1.88 Å. Both Ga(1)-O(4) bond lengths are 1.87 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sm(1), two equivalent Sm(2), and one Ga(1) atom to form distorted OSm3Ga tetrahedra that share corners with eight equivalent O(3)Sm4 tetrahedra, corners with four equivalent O(4)Sm3Ga trigonal pyramids, and edges with two equivalent O(4)Sm3Ga trigonal pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Sm(2) and one Ga(1) atom. 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(1)Sm3Ga tetrahedra, corners with six equivalent O(4)Sm3Ga trigonal pyramids, edges with three equivalent O(3)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm3Ga trigonal pyramid. In the fourth O site, O(4) is bonded to one Sm(1), two equivalent Sm(2), and one Ga(1) atom to form distorted OSm3Ga trigonal pyramids that share corners with two equivalent O(1)Sm3Ga tetrahedra, corners with six equivalent O(3)Sm4 tetrahedra, corners with two equivalent O(4)Sm3Ga trigonal pyramids,  an edgeedge with one O(1)Sm3Ga tetrahedra,  an edgeedge with one O(3)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm3Ga trigonal pyramid.