SrSmGa3O7 crystallizes in the orthorhombic Cmm2 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(3), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms. Sm(1) is bonded in a 8-coordinate geometry to one O(4), one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing GaO4 tetrahedra. In the second Ga site, Ga(2) is bonded to one O(4), one O(5), and two equivalent O(1) atoms to form distorted corner-sharing GaO4 tetrahedra. In the third Ga site, Ga(3) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form corner-sharing GaO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sm(1), one Ga(1), and one Ga(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sm(1), one Ga(1), and one Ga(3) atom. In the third O site, O(3) is bonded to two equivalent Sr(1) and two equivalent Ga(3) atoms to form distorted OSr2Ga2 tetrahedra that share corners with two equivalent O(6)Sr2SmGa tetrahedra, corners with two equivalent O(5)SrSm2Ga tetrahedra, and edges with two equivalent O(6)Sr2SmGa tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Ga(2) atoms to form OSm2Ga2 tetrahedra that share corners with two equivalent O(6)Sr2SmGa tetrahedra, corners with two equivalent O(5)SrSm2Ga tetrahedra, and edges with two equivalent O(5)SrSm2Ga tetrahedra. In the fifth O site, O(5) is bonded to one Sr(1), two equivalent Sm(1), and one Ga(2) atom to form OSrSm2Ga tetrahedra that share  a cornercorner with one O(4)Sm2Ga2 tetrahedra,  a cornercorner with one O(3)Sr2Ga2 tetrahedra, corners with four equivalent O(6)Sr2SmGa tetrahedra,  an edgeedge with one O(4)Sm2Ga2 tetrahedra, and  an edgeedge with one O(5)SrSm2Ga tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sr(1), one Sm(1), and one Ga(3) atom to form distorted OSr2SmGa tetrahedra that share  a cornercorner with one O(4)Sm2Ga2 tetrahedra,  a cornercorner with one O(3)Sr2Ga2 tetrahedra, corners with four equivalent O(5)SrSm2Ga tetrahedra,  an edgeedge with one O(3)Sr2Ga2 tetrahedra, and  an edgeedge with one O(6)Sr2SmGa tetrahedra.
SrSmGa3O7 crystallizes in the orthorhombic Cmm2 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(3), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms. The Sr(1)-O(3) bond length is 2.55 Å. The Sr(1)-O(5) bond length is 2.66 Å. Both Sr(1)-O(1) bond lengths are 2.57 Å. Both Sr(1)-O(2) bond lengths are 2.99 Å. Both Sr(1)-O(6) bond lengths are 2.73 Å. Sm(1) is bonded in a 8-coordinate geometry to one O(4), one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms. The Sm(1)-O(4) bond length is 2.42 Å. The Sm(1)-O(6) bond length is 2.37 Å. Both Sm(1)-O(1) bond lengths are 2.93 Å. Both Sm(1)-O(2) bond lengths are 2.42 Å. Both Sm(1)-O(5) bond lengths are 2.51 Å. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing GaO4 tetrahedra. Both Ga(1)-O(1) bond lengths are 1.85 Å. Both Ga(1)-O(2) bond lengths are 1.87 Å. In the second Ga site, Ga(2) is bonded to one O(4), one O(5), and two equivalent O(1) atoms to form distorted corner-sharing GaO4 tetrahedra. The Ga(2)-O(4) bond length is 1.88 Å. The Ga(2)-O(5) bond length is 1.82 Å. Both Ga(2)-O(1) bond lengths are 1.86 Å. In the third Ga site, Ga(3) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form corner-sharing GaO4 tetrahedra. The Ga(3)-O(3) bond length is 1.84 Å. The Ga(3)-O(6) bond length is 1.81 Å. Both Ga(3)-O(2) bond lengths are 1.89 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sm(1), one Ga(1), and one Ga(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sm(1), one Ga(1), and one Ga(3) atom. In the third O site, O(3) is bonded to two equivalent Sr(1) and two equivalent Ga(3) atoms to form distorted OSr2Ga2 tetrahedra that share corners with two equivalent O(6)Sr2SmGa tetrahedra, corners with two equivalent O(5)SrSm2Ga tetrahedra, and edges with two equivalent O(6)Sr2SmGa tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Ga(2) atoms to form OSm2Ga2 tetrahedra that share corners with two equivalent O(6)Sr2SmGa tetrahedra, corners with two equivalent O(5)SrSm2Ga tetrahedra, and edges with two equivalent O(5)SrSm2Ga tetrahedra. In the fifth O site, O(5) is bonded to one Sr(1), two equivalent Sm(1), and one Ga(2) atom to form OSrSm2Ga tetrahedra that share  a cornercorner with one O(4)Sm2Ga2 tetrahedra,  a cornercorner with one O(3)Sr2Ga2 tetrahedra, corners with four equivalent O(6)Sr2SmGa tetrahedra,  an edgeedge with one O(4)Sm2Ga2 tetrahedra, and  an edgeedge with one O(5)SrSm2Ga tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sr(1), one Sm(1), and one Ga(3) atom to form distorted OSr2SmGa tetrahedra that share  a cornercorner with one O(4)Sm2Ga2 tetrahedra,  a cornercorner with one O(3)Sr2Ga2 tetrahedra, corners with four equivalent O(5)SrSm2Ga tetrahedra,  an edgeedge with one O(3)Sr2Ga2 tetrahedra, and  an edgeedge with one O(6)Sr2SmGa tetrahedra.