GaSr2YCu2O7 crystallizes in the orthorhombic Ima2 space group. Sr(1) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(4), and four equivalent O(3) atoms. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(4) atoms. Cu(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted CuO5 square pyramids that share corners with four equivalent Cu(1)O5 square pyramids and  a cornercorner with one Ga(1)O4 tetrahedra. Ga(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form GaO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Ga(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Y(1), and two equivalent Cu(1) atoms to form distorted OSr2Y2Cu2 octahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, corners with two equivalent O(2)Sr2Ga2 tetrahedra, edges with three equivalent O(4)Sr2Y2Cu2 octahedra, faces with two equivalent O(1)Sr2Y2Cu2 octahedra, and faces with two equivalent O(4)Sr2Y2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. In the second O site, O(2) is bonded to two equivalent Sr(1) and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, and corners with two equivalent O(2)Sr2Ga2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-67°. In the third O site, O(3) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Cu(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded to two equivalent Sr(1), two equivalent Y(1), and two equivalent Cu(1) atoms to form distorted OSr2Y2Cu2 octahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, corners with two equivalent O(2)Sr2Ga2 tetrahedra, edges with three equivalent O(1)Sr2Y2Cu2 octahedra, faces with two equivalent O(1)Sr2Y2Cu2 octahedra, and faces with two equivalent O(4)Sr2Y2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-70°.
GaSr2YCu2O7 crystallizes in the orthorhombic Ima2 space group. Sr(1) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(4), and four equivalent O(3) atoms. The Sr(1)-O(2) bond length is 2.48 Å. Both Sr(1)-O(1) bond lengths are 2.80 Å. There is one shorter (2.84 Å) and one longer (2.87 Å) Sr(1)-O(4) bond length. There are a spread of Sr(1)-O(3) bond distances ranging from 2.50-3.17 Å. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(4) atoms. There are two shorter (2.40 Å) and two longer (2.41 Å) Y(1)-O(1) bond lengths. All Y(1)-O(4) bond lengths are 2.44 Å. Cu(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted CuO5 square pyramids that share corners with four equivalent Cu(1)O5 square pyramids and  a cornercorner with one Ga(1)O4 tetrahedra. The Cu(1)-O(3) bond length is 2.47 Å. Both Cu(1)-O(1) bond lengths are 1.95 Å. Both Cu(1)-O(4) bond lengths are 1.94 Å. Ga(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form GaO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Ga(1)O4 tetrahedra. There is one shorter (1.91 Å) and one longer (1.93 Å) Ga(1)-O(2) bond length. Both Ga(1)-O(3) bond lengths are 1.85 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Y(1), and two equivalent Cu(1) atoms to form distorted OSr2Y2Cu2 octahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, corners with two equivalent O(2)Sr2Ga2 tetrahedra, edges with three equivalent O(4)Sr2Y2Cu2 octahedra, faces with two equivalent O(1)Sr2Y2Cu2 octahedra, and faces with two equivalent O(4)Sr2Y2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. In the second O site, O(2) is bonded to two equivalent Sr(1) and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, and corners with two equivalent O(2)Sr2Ga2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-67°. In the third O site, O(3) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Cu(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded to two equivalent Sr(1), two equivalent Y(1), and two equivalent Cu(1) atoms to form distorted OSr2Y2Cu2 octahedra that share corners with four equivalent O(1)Sr2Y2Cu2 octahedra, corners with four equivalent O(4)Sr2Y2Cu2 octahedra, corners with two equivalent O(2)Sr2Ga2 tetrahedra, edges with three equivalent O(1)Sr2Y2Cu2 octahedra, faces with two equivalent O(1)Sr2Y2Cu2 octahedra, and faces with two equivalent O(4)Sr2Y2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-70°.