Gd2SrAl2O7 crystallizes in the tetragonal I4/mmm space group. Sr(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Al(1)O6 octahedra. Gd(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. Al(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form AlO6 octahedra that share corners with five equivalent Al(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Gd(1), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to five equivalent Gd(1) and one Al(1) atom to form distorted OGd5Al octahedra that share  a cornercorner with one O(3)Sr4Al2 octahedra, corners with four equivalent O(2)Gd5Al octahedra, and edges with eight equivalent O(2)Gd5Al octahedra. The corner-sharing octahedral tilt angles range from 0-19°. In the third O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Al(1) atoms to form distorted OSr4Al2 octahedra that share corners with two equivalent O(2)Gd5Al octahedra, corners with four equivalent O(3)Sr4Al2 octahedra, and edges with four equivalent O(3)Sr4Al2 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Al(1) atoms to form distorted OSr4Al2 octahedra that share corners with two equivalent O(2)Gd5Al octahedra, corners with four equivalent O(3)Sr4Al2 octahedra, and edges with four equivalent O(3)Sr4Al2 octahedra. The corner-sharing octahedra are not tilted.
Gd2SrAl2O7 crystallizes in the tetragonal I4/mmm space group. Sr(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Al(1)O6 octahedra. All Sr(1)-O(3) bond lengths are 2.65 Å. All Sr(1)-O(1) bond lengths are 2.79 Å. Gd(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. All Gd(1)-O(1) bond lengths are 2.42 Å. There is one shorter (2.27 Å) and four longer (2.68 Å) Gd(1)-O(2) bond lengths. Al(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form AlO6 octahedra that share corners with five equivalent Al(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Al(1)-O(2) bond length is 2.16 Å. The Al(1)-O(3) bond length is 1.89 Å. All Al(1)-O(1) bond lengths are 1.88 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Gd(1), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to five equivalent Gd(1) and one Al(1) atom to form distorted OGd5Al octahedra that share  a cornercorner with one O(3)Sr4Al2 octahedra, corners with four equivalent O(2)Gd5Al octahedra, and edges with eight equivalent O(2)Gd5Al octahedra. The corner-sharing octahedral tilt angles range from 0-19°. In the third O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Al(1) atoms to form distorted OSr4Al2 octahedra that share corners with two equivalent O(2)Gd5Al octahedra, corners with four equivalent O(3)Sr4Al2 octahedra, and edges with four equivalent O(3)Sr4Al2 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Al(1) atoms to form distorted OSr4Al2 octahedra that share corners with two equivalent O(2)Gd5Al octahedra, corners with four equivalent O(3)Sr4Al2 octahedra, and edges with four equivalent O(3)Sr4Al2 octahedra. The corner-sharing octahedra are not tilted. All O(3)-Sr(1) bond lengths are 2.65 Å. Both O(3)-Al(1) bond lengths are 1.89 Å.