CaYAl3O7 crystallizes in the orthorhombic Cmm2 space group. Ca(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(4) atoms. Y(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(3) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(3), one O(6), and two equivalent O(1) atoms to form corner-sharing AlO4 tetrahedra. In the third Al site, Al(3) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(5) is bonded to two equivalent Ca(1) and two equivalent Al(3) atoms to form distorted OCa2Al2 tetrahedra that share corners with two equivalent O(4)Ca2YAl tetrahedra, corners with two equivalent O(3)CaY2Al tetrahedra, and edges with two equivalent O(4)Ca2YAl tetrahedra. In the second O site, O(6) is bonded to two equivalent Y(1) and two equivalent Al(2) atoms to form distorted OY2Al2 tetrahedra that share corners with two equivalent O(4)Ca2YAl tetrahedra, corners with two equivalent O(3)CaY2Al tetrahedra, and edges with two equivalent O(3)CaY2Al tetrahedra. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Y(1), one Al(1), and one Al(2) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Y(1), one Al(1), and one Al(3) atom. In the fifth O site, O(3) is bonded to one Ca(1), two equivalent Y(1), and one Al(2) atom to form distorted OCaY2Al tetrahedra that share  a cornercorner with one O(5)Ca2Al2 tetrahedra,  a cornercorner with one O(6)Y2Al2 tetrahedra, corners with four equivalent O(4)Ca2YAl tetrahedra,  an edgeedge with one O(3)CaY2Al tetrahedra, and  an edgeedge with one O(6)Y2Al2 tetrahedra. In the sixth O site, O(4) is bonded to two equivalent Ca(1), one Y(1), and one Al(3) atom to form distorted OCa2YAl tetrahedra that share  a cornercorner with one O(5)Ca2Al2 tetrahedra,  a cornercorner with one O(6)Y2Al2 tetrahedra, corners with four equivalent O(3)CaY2Al tetrahedra,  an edgeedge with one O(5)Ca2Al2 tetrahedra, and  an edgeedge with one O(4)Ca2YAl tetrahedra.
CaYAl3O7 crystallizes in the orthorhombic Cmm2 space group. Ca(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(4) atoms. The Ca(1)-O(3) bond length is 2.54 Å. The Ca(1)-O(5) bond length is 2.45 Å. Both Ca(1)-O(1) bond lengths are 2.43 Å. Both Ca(1)-O(2) bond lengths are 2.92 Å. Both Ca(1)-O(4) bond lengths are 2.62 Å. Y(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(3) atoms. The Y(1)-O(4) bond length is 2.32 Å. The Y(1)-O(6) bond length is 2.37 Å. Both Y(1)-O(1) bond lengths are 2.85 Å. Both Y(1)-O(2) bond lengths are 2.35 Å. Both Y(1)-O(3) bond lengths are 2.47 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. Both Al(1)-O(1) bond lengths are 1.76 Å. Both Al(1)-O(2) bond lengths are 1.77 Å. In the second Al site, Al(2) is bonded to one O(3), one O(6), and two equivalent O(1) atoms to form corner-sharing AlO4 tetrahedra. The Al(2)-O(3) bond length is 1.75 Å. The Al(2)-O(6) bond length is 1.77 Å. Both Al(2)-O(1) bond lengths are 1.76 Å. In the third Al site, Al(3) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. The Al(3)-O(4) bond length is 1.74 Å. The Al(3)-O(5) bond length is 1.75 Å. Both Al(3)-O(2) bond lengths are 1.78 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded to two equivalent Ca(1) and two equivalent Al(3) atoms to form distorted OCa2Al2 tetrahedra that share corners with two equivalent O(4)Ca2YAl tetrahedra, corners with two equivalent O(3)CaY2Al tetrahedra, and edges with two equivalent O(4)Ca2YAl tetrahedra. In the second O site, O(6) is bonded to two equivalent Y(1) and two equivalent Al(2) atoms to form distorted OY2Al2 tetrahedra that share corners with two equivalent O(4)Ca2YAl tetrahedra, corners with two equivalent O(3)CaY2Al tetrahedra, and edges with two equivalent O(3)CaY2Al tetrahedra. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Y(1), one Al(1), and one Al(2) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Y(1), one Al(1), and one Al(3) atom. In the fifth O site, O(3) is bonded to one Ca(1), two equivalent Y(1), and one Al(2) atom to form distorted OCaY2Al tetrahedra that share  a cornercorner with one O(5)Ca2Al2 tetrahedra,  a cornercorner with one O(6)Y2Al2 tetrahedra, corners with four equivalent O(4)Ca2YAl tetrahedra,  an edgeedge with one O(3)CaY2Al tetrahedra, and  an edgeedge with one O(6)Y2Al2 tetrahedra. In the sixth O site, O(4) is bonded to two equivalent Ca(1), one Y(1), and one Al(3) atom to form distorted OCa2YAl tetrahedra that share  a cornercorner with one O(5)Ca2Al2 tetrahedra,  a cornercorner with one O(6)Y2Al2 tetrahedra, corners with four equivalent O(3)CaY2Al tetrahedra,  an edgeedge with one O(5)Ca2Al2 tetrahedra, and  an edgeedge with one O(4)Ca2YAl tetrahedra.