CaGdAlO4 is (La,Ba)CuO4-derived structured and crystallizes in the tetragonal I4mm space group. Ca(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(3) atoms. Gd(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. Al(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), four equivalent Gd(1), and one Al(1) atom to form distorted OCaGd4Al octahedra that share  a cornercorner with one O(2)Ca4GdAl octahedra, corners with four equivalent O(1)CaGd4Al octahedra, corners with twelve equivalent O(3)Ca2Gd2Al2 octahedra, edges with four equivalent O(2)Ca4GdAl octahedra, edges with four equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the second O site, O(2) is bonded to four equivalent Ca(1), one Gd(1), and one Al(1) atom to form distorted OCa4GdAl octahedra that share  a cornercorner with one O(1)CaGd4Al octahedra, corners with four equivalent O(2)Ca4GdAl octahedra, corners with twelve equivalent O(3)Ca2Gd2Al2 octahedra, edges with four equivalent O(2)Ca4GdAl octahedra, edges with four equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-54°. In the third O site, O(3) is bonded to two equivalent Ca(1), two equivalent Gd(1), and two equivalent Al(1) atoms to form distorted OCa2Gd2Al2 octahedra that share corners with two equivalent O(3)Ca2Gd2Al2 octahedra, corners with six equivalent O(2)Ca4GdAl octahedra, corners with six equivalent O(1)CaGd4Al octahedra, edges with two equivalent O(3)Ca2Gd2Al2 octahedra, faces with two equivalent O(2)Ca4GdAl octahedra, faces with two equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 7-54°.
CaGdAlO4 is (La,Ba)CuO4-derived structured and crystallizes in the tetragonal I4mm space group. Ca(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(3) atoms. The Ca(1)-O(1) bond length is 2.27 Å. All Ca(1)-O(2) bond lengths are 2.63 Å. All Ca(1)-O(3) bond lengths are 2.55 Å. Gd(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. The Gd(1)-O(2) bond length is 2.26 Å. All Gd(1)-O(1) bond lengths are 2.63 Å. All Gd(1)-O(3) bond lengths are 2.48 Å. Al(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 7°. The Al(1)-O(1) bond length is 2.07 Å. The Al(1)-O(2) bond length is 1.95 Å. All Al(1)-O(3) bond lengths are 1.85 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), four equivalent Gd(1), and one Al(1) atom to form distorted OCaGd4Al octahedra that share  a cornercorner with one O(2)Ca4GdAl octahedra, corners with four equivalent O(1)CaGd4Al octahedra, corners with twelve equivalent O(3)Ca2Gd2Al2 octahedra, edges with four equivalent O(2)Ca4GdAl octahedra, edges with four equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the second O site, O(2) is bonded to four equivalent Ca(1), one Gd(1), and one Al(1) atom to form distorted OCa4GdAl octahedra that share  a cornercorner with one O(1)CaGd4Al octahedra, corners with four equivalent O(2)Ca4GdAl octahedra, corners with twelve equivalent O(3)Ca2Gd2Al2 octahedra, edges with four equivalent O(2)Ca4GdAl octahedra, edges with four equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-54°. In the third O site, O(3) is bonded to two equivalent Ca(1), two equivalent Gd(1), and two equivalent Al(1) atoms to form distorted OCa2Gd2Al2 octahedra that share corners with two equivalent O(3)Ca2Gd2Al2 octahedra, corners with six equivalent O(2)Ca4GdAl octahedra, corners with six equivalent O(1)CaGd4Al octahedra, edges with two equivalent O(3)Ca2Gd2Al2 octahedra, faces with two equivalent O(2)Ca4GdAl octahedra, faces with two equivalent O(1)CaGd4Al octahedra, and faces with four equivalent O(3)Ca2Gd2Al2 octahedra. The corner-sharing octahedral tilt angles range from 7-54°.