Gd2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(1), one O(5), two equivalent O(2), and three equivalent O(3) atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent Gd(2)O7 hexagonal pyramids,  a cornercorner with one Ti(1)O5 trigonal bipyramid, edges with three equivalent Gd(2)O7 hexagonal pyramids, edges with four equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. In the second Gd site, Gd(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent Gd(1)O7 hexagonal pyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Gd(2)O7 hexagonal pyramids, edges with three equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. Ti(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Gd(1)O7 hexagonal pyramid, corners with three equivalent Gd(2)O7 hexagonal pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Gd(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Gd(1), two equivalent Gd(2), and one Ti(1) atom to form OGd3Ti tetrahedra that share  a cornercorner with one O(5)Gd2Ti2 tetrahedra,  a cornercorner with one O(2)Gd3Ti tetrahedra, corners with two equivalent O(1)Gd3Ti tetrahedra, corners with five equivalent O(3)Gd4 tetrahedra, edges with two equivalent O(5)Gd2Ti2 tetrahedra, and edges with two equivalent O(2)Gd3Ti tetrahedra. In the second O site, O(2) is bonded to one Gd(2), two equivalent Gd(1), and one Ti(1) atom to form OGd3Ti tetrahedra that share  a cornercorner with one O(5)Gd2Ti2 tetrahedra,  a cornercorner with one O(1)Gd3Ti tetrahedra, corners with two equivalent O(2)Gd3Ti tetrahedra, corners with five equivalent O(3)Gd4 tetrahedra,  an edgeedge with one O(3)Gd4 tetrahedra, edges with two equivalent O(5)Gd2Ti2 tetrahedra, and edges with two equivalent O(1)Gd3Ti tetrahedra. In the third O site, O(3) is bonded to one Gd(2) and three equivalent Gd(1) atoms to form OGd4 tetrahedra that share corners with two equivalent O(5)Gd2Ti2 tetrahedra, corners with two equivalent O(3)Gd4 tetrahedra, corners with five equivalent O(1)Gd3Ti tetrahedra, corners with five equivalent O(2)Gd3Ti tetrahedra,  an edgeedge with one O(5)Gd2Ti2 tetrahedra,  an edgeedge with one O(2)Gd3Ti tetrahedra, and edges with two equivalent O(3)Gd4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Gd(2) and one Ti(1) atom. In the fifth O site, O(5) is bonded to one Gd(1), one Gd(2), and two equivalent Ti(1) atoms to form distorted OGd2Ti2 tetrahedra that share  a cornercorner with one O(1)Gd3Ti tetrahedra,  a cornercorner with one O(2)Gd3Ti tetrahedra, corners with two equivalent O(5)Gd2Ti2 tetrahedra, corners with two equivalent O(3)Gd4 tetrahedra,  an edgeedge with one O(3)Gd4 tetrahedra, edges with two equivalent O(1)Gd3Ti tetrahedra, and edges with two equivalent O(2)Gd3Ti tetrahedra.
Gd2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(1), one O(5), two equivalent O(2), and three equivalent O(3) atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent Gd(2)O7 hexagonal pyramids,  a cornercorner with one Ti(1)O5 trigonal bipyramid, edges with three equivalent Gd(2)O7 hexagonal pyramids, edges with four equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The Gd(1)-O(1) bond length is 2.35 Å. The Gd(1)-O(5) bond length is 2.39 Å. Both Gd(1)-O(2) bond lengths are 2.38 Å. There is one shorter (2.37 Å) and two longer (2.38 Å) Gd(1)-O(3) bond lengths. In the second Gd site, Gd(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent Gd(1)O7 hexagonal pyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Gd(2)O7 hexagonal pyramids, edges with three equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The Gd(2)-O(2) bond length is 2.37 Å. The Gd(2)-O(3) bond length is 2.33 Å. The Gd(2)-O(5) bond length is 2.42 Å. Both Gd(2)-O(1) bond lengths are 2.31 Å. Both Gd(2)-O(4) bond lengths are 2.40 Å. Ti(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Gd(1)O7 hexagonal pyramid, corners with three equivalent Gd(2)O7 hexagonal pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Gd(1)O7 hexagonal pyramids, and edges with two equivalent Gd(2)O7 hexagonal pyramids. The Ti(1)-O(1) bond length is 1.91 Å. The Ti(1)-O(2) bond length is 1.90 Å. The Ti(1)-O(4) bond length is 1.78 Å. Both Ti(1)-O(5) bond lengths are 1.97 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Gd(1), two equivalent Gd(2), and one Ti(1) atom to form OGd3Ti tetrahedra that share  a cornercorner with one O(5)Gd2Ti2 tetrahedra,  a cornercorner with one O(2)Gd3Ti tetrahedra, corners with two equivalent O(1)Gd3Ti tetrahedra, corners with five equivalent O(3)Gd4 tetrahedra, edges with two equivalent O(5)Gd2Ti2 tetrahedra, and edges with two equivalent O(2)Gd3Ti tetrahedra. In the second O site, O(2) is bonded to one Gd(2), two equivalent Gd(1), and one Ti(1) atom to form OGd3Ti tetrahedra that share  a cornercorner with one O(5)Gd2Ti2 tetrahedra,  a cornercorner with one O(1)Gd3Ti tetrahedra, corners with two equivalent O(2)Gd3Ti tetrahedra, corners with five equivalent O(3)Gd4 tetrahedra,  an edgeedge with one O(3)Gd4 tetrahedra, edges with two equivalent O(5)Gd2Ti2 tetrahedra, and edges with two equivalent O(1)Gd3Ti tetrahedra. In the third O site, O(3) is bonded to one Gd(2) and three equivalent Gd(1) atoms to form OGd4 tetrahedra that share corners with two equivalent O(5)Gd2Ti2 tetrahedra, corners with two equivalent O(3)Gd4 tetrahedra, corners with five equivalent O(1)Gd3Ti tetrahedra, corners with five equivalent O(2)Gd3Ti tetrahedra,  an edgeedge with one O(5)Gd2Ti2 tetrahedra,  an edgeedge with one O(2)Gd3Ti tetrahedra, and edges with two equivalent O(3)Gd4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Gd(2) and one Ti(1) atom. In the fifth O site, O(5) is bonded to one Gd(1), one Gd(2), and two equivalent Ti(1) atoms to form distorted OGd2Ti2 tetrahedra that share  a cornercorner with one O(1)Gd3Ti tetrahedra,  a cornercorner with one O(2)Gd3Ti tetrahedra, corners with two equivalent O(5)Gd2Ti2 tetrahedra, corners with two equivalent O(3)Gd4 tetrahedra,  an edgeedge with one O(3)Gd4 tetrahedra, edges with two equivalent O(1)Gd3Ti tetrahedra, and edges with two equivalent O(2)Gd3Ti tetrahedra.