CaY2O4 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Y(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to two equivalent Ca(1) and four equivalent Y(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1) and three equivalent Y(1) atoms to form distorted OCa2Y3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Y2 tetrahedra, corners with two equivalent O(2)Ca2Y3 trigonal bipyramids,  an edgeedge with one O(3)Ca2Y2 tetrahedra, and edges with five equivalent O(2)Ca2Y3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Y(1) atoms to form OCa2Y2 tetrahedra that share corners with two equivalent O(3)Ca2Y2 tetrahedra, corners with ten equivalent O(2)Ca2Y3 trigonal bipyramids, and edges with two equivalent O(2)Ca2Y3 trigonal bipyramids.
CaY2O4 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Ca(1)-O(1) bond lengths are 3.01 Å. Both Ca(1)-O(3) bond lengths are 2.30 Å. All Ca(1)-O(2) bond lengths are 2.62 Å. Y(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. The Y(1)-O(3) bond length is 2.22 Å. Both Y(1)-O(1) bond lengths are 2.37 Å. There are two shorter (2.27 Å) and one longer (2.35 Å) Y(1)-O(2) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to two equivalent Ca(1) and four equivalent Y(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1) and three equivalent Y(1) atoms to form distorted OCa2Y3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Y2 tetrahedra, corners with two equivalent O(2)Ca2Y3 trigonal bipyramids,  an edgeedge with one O(3)Ca2Y2 tetrahedra, and edges with five equivalent O(2)Ca2Y3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Y(1) atoms to form OCa2Y2 tetrahedra that share corners with two equivalent O(3)Ca2Y2 tetrahedra, corners with ten equivalent O(2)Ca2Y3 trigonal bipyramids, and edges with two equivalent O(2)Ca2Y3 trigonal bipyramids.