CaYAlO4 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. Y(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 8°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), four equivalent Y(1), and one Al(1) atom to form distorted OCaY4Al octahedra that share  a cornercorner with one O(2)Ca4YAl octahedra, corners with four equivalent O(1)CaY4Al octahedra, corners with twelve equivalent O(3)Ca2Y2Al2 octahedra, edges with four equivalent O(2)Ca4YAl octahedra, edges with four equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 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 Y(1), and one Al(1) atom to form distorted OCa4YAl octahedra that share  a cornercorner with one O(1)CaY4Al octahedra, corners with four equivalent O(2)Ca4YAl octahedra, corners with twelve equivalent O(3)Ca2Y2Al2 octahedra, edges with four equivalent O(2)Ca4YAl octahedra, edges with four equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 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 Y(1), and two equivalent Al(1) atoms to form distorted OCa2Y2Al2 octahedra that share corners with two equivalent O(3)Ca2Y2Al2 octahedra, corners with six equivalent O(2)Ca4YAl octahedra, corners with six equivalent O(1)CaY4Al octahedra, edges with two equivalent O(3)Ca2Y2Al2 octahedra, faces with two equivalent O(2)Ca4YAl octahedra, faces with two equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 octahedra. The corner-sharing octahedral tilt angles range from 8-54°.
CaYAlO4 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 2.25 Å. All Ca(1)-O(2) bond lengths are 2.62 Å. All Ca(1)-O(3) bond lengths are 2.56 Å. Y(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. The Y(1)-O(2) bond length is 2.24 Å. All Y(1)-O(1) bond lengths are 2.62 Å. All Y(1)-O(3) bond lengths are 2.45 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 8°. The Al(1)-O(1) bond length is 2.05 Å. The Al(1)-O(2) bond length is 1.96 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 Y(1), and one Al(1) atom to form distorted OCaY4Al octahedra that share  a cornercorner with one O(2)Ca4YAl octahedra, corners with four equivalent O(1)CaY4Al octahedra, corners with twelve equivalent O(3)Ca2Y2Al2 octahedra, edges with four equivalent O(2)Ca4YAl octahedra, edges with four equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 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 Y(1), and one Al(1) atom to form distorted OCa4YAl octahedra that share  a cornercorner with one O(1)CaY4Al octahedra, corners with four equivalent O(2)Ca4YAl octahedra, corners with twelve equivalent O(3)Ca2Y2Al2 octahedra, edges with four equivalent O(2)Ca4YAl octahedra, edges with four equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 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 Y(1), and two equivalent Al(1) atoms to form distorted OCa2Y2Al2 octahedra that share corners with two equivalent O(3)Ca2Y2Al2 octahedra, corners with six equivalent O(2)Ca4YAl octahedra, corners with six equivalent O(1)CaY4Al octahedra, edges with two equivalent O(3)Ca2Y2Al2 octahedra, faces with two equivalent O(2)Ca4YAl octahedra, faces with two equivalent O(1)CaY4Al octahedra, and faces with four equivalent O(3)Ca2Y2Al2 octahedra. The corner-sharing octahedral tilt angles range from 8-54°.