Y2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(3), two equivalent O(5), and three equivalent O(4) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(2)O7 hexagonal pyramids,  a cornercorner with one Ti(1)O5 trigonal bipyramid, edges with three equivalent Y(2)O7 hexagonal pyramids, edges with four equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. In the second Y site, Y(2) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 hexagonal pyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Y(2)O7 hexagonal pyramids, edges with three equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. Ti(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Y(1)O7 hexagonal pyramid, corners with three equivalent Y(2)O7 hexagonal pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Y(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), and two equivalent Ti(1) atoms to form distorted OY2Ti2 tetrahedra that share  a cornercorner with one O(3)Y3Ti tetrahedra,  a cornercorner with one O(5)Y3Ti tetrahedra, corners with two equivalent O(1)Y2Ti2 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(3)Y3Ti tetrahedra, and edges with two equivalent O(5)Y3Ti tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Y(2) and one Ti(1) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Ti(1) atom to form OY3Ti tetrahedra that share  a cornercorner with one O(1)Y2Ti2 tetrahedra,  a cornercorner with one O(5)Y3Ti tetrahedra, corners with two equivalent O(3)Y3Ti tetrahedra, corners with five equivalent O(4)Y4 tetrahedra, edges with two equivalent O(1)Y2Ti2 tetrahedra, and edges with two equivalent O(5)Y3Ti tetrahedra. In the fourth O site, O(4) is bonded to one Y(2) and three equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y2Ti2 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with five equivalent O(3)Y3Ti tetrahedra, corners with five equivalent O(5)Y3Ti tetrahedra,  an edgeedge with one O(1)Y2Ti2 tetrahedra,  an edgeedge with one O(5)Y3Ti tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(2), two equivalent Y(1), and one Ti(1) atom to form OY3Ti tetrahedra that share  a cornercorner with one O(1)Y2Ti2 tetrahedra,  a cornercorner with one O(3)Y3Ti tetrahedra, corners with two equivalent O(5)Y3Ti tetrahedra, corners with five equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(1)Y2Ti2 tetrahedra, and edges with two equivalent O(3)Y3Ti tetrahedra.
Y2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(3), two equivalent O(5), and three equivalent O(4) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(2)O7 hexagonal pyramids,  a cornercorner with one Ti(1)O5 trigonal bipyramid, edges with three equivalent Y(2)O7 hexagonal pyramids, edges with four equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The Y(1)-O(1) bond length is 2.36 Å. The Y(1)-O(3) bond length is 2.31 Å. Both Y(1)-O(5) bond lengths are 2.35 Å. There is one shorter (2.34 Å) and two longer (2.35 Å) Y(1)-O(4) bond lengths. In the second Y site, Y(2) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 hexagonal pyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Y(2)O7 hexagonal pyramids, edges with three equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The Y(2)-O(1) bond length is 2.37 Å. The Y(2)-O(4) bond length is 2.31 Å. The Y(2)-O(5) bond length is 2.32 Å. Both Y(2)-O(2) bond lengths are 2.36 Å. Both Y(2)-O(3) bond lengths are 2.27 Å. Ti(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Y(1)O7 hexagonal pyramid, corners with three equivalent Y(2)O7 hexagonal pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Y(2)O7 hexagonal pyramids. The Ti(1)-O(2) bond length is 1.78 Å. The Ti(1)-O(3) bond length is 1.90 Å. The Ti(1)-O(5) bond length is 1.90 Å. Both Ti(1)-O(1) bond lengths are 1.95 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), and two equivalent Ti(1) atoms to form distorted OY2Ti2 tetrahedra that share  a cornercorner with one O(3)Y3Ti tetrahedra,  a cornercorner with one O(5)Y3Ti tetrahedra, corners with two equivalent O(1)Y2Ti2 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(3)Y3Ti tetrahedra, and edges with two equivalent O(5)Y3Ti tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Y(2) and one Ti(1) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Ti(1) atom to form OY3Ti tetrahedra that share  a cornercorner with one O(1)Y2Ti2 tetrahedra,  a cornercorner with one O(5)Y3Ti tetrahedra, corners with two equivalent O(3)Y3Ti tetrahedra, corners with five equivalent O(4)Y4 tetrahedra, edges with two equivalent O(1)Y2Ti2 tetrahedra, and edges with two equivalent O(5)Y3Ti tetrahedra. In the fourth O site, O(4) is bonded to one Y(2) and three equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y2Ti2 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with five equivalent O(3)Y3Ti tetrahedra, corners with five equivalent O(5)Y3Ti tetrahedra,  an edgeedge with one O(1)Y2Ti2 tetrahedra,  an edgeedge with one O(5)Y3Ti tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(2), two equivalent Y(1), and one Ti(1) atom to form OY3Ti tetrahedra that share  a cornercorner with one O(1)Y2Ti2 tetrahedra,  a cornercorner with one O(3)Y3Ti tetrahedra, corners with two equivalent O(5)Y3Ti tetrahedra, corners with five equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(1)Y2Ti2 tetrahedra, and edges with two equivalent O(3)Y3Ti tetrahedra.