Ho2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form distorted HoO6 octahedra that share corners with two equivalent Ho(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ho(2)O6 octahedra, and edges with four equivalent Ho(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. In the second Ho site, Ho(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form HoO6 octahedra that share corners with two equivalent Ho(1)O6 octahedra, corners with two equivalent Ho(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ho(1)O6 octahedra, and edges with two equivalent Ho(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-65°. Ti(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ho(1)O6 octahedra, corners with four equivalent Ho(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-65°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(3)Ho3Ti tetrahedra, corners with four equivalent O(4)Ho3Ti tetrahedra, corners with four equivalent O(1)Ho4 tetrahedra,  an edgeedge with one O(4)Ho3Ti tetrahedra, and edges with two equivalent O(3)Ho3Ti tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Ti(1) atoms. In the third O site, O(3) is bonded to one Ho(1), two equivalent Ho(2), and one Ti(1) atom to form OHo3Ti tetrahedra that share corners with two equivalent O(3)Ho3Ti tetrahedra, corners with two equivalent O(1)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Ti tetrahedra, and edges with two equivalent O(1)Ho4 tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Ho(1) and one Ti(1) atom to form OHo3Ti tetrahedra that share corners with two equivalent O(4)Ho3Ti tetrahedra, corners with four equivalent O(3)Ho3Ti tetrahedra, corners with four equivalent O(1)Ho4 tetrahedra,  an edgeedge with one O(1)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ho(2) and one Ti(1) atom.
Ho2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form distorted HoO6 octahedra that share corners with two equivalent Ho(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ho(2)O6 octahedra, and edges with four equivalent Ho(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. The Ho(1)-O(3) bond length is 2.30 Å. Both Ho(1)-O(1) bond lengths are 2.29 Å. There is one shorter (2.28 Å) and two longer (2.32 Å) Ho(1)-O(4) bond lengths. In the second Ho site, Ho(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form HoO6 octahedra that share corners with two equivalent Ho(1)O6 octahedra, corners with two equivalent Ho(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ho(1)O6 octahedra, and edges with two equivalent Ho(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-65°. There is one shorter (2.20 Å) and one longer (2.23 Å) Ho(2)-O(1) bond length. Both Ho(2)-O(3) bond lengths are 2.30 Å. Both Ho(2)-O(5) bond lengths are 2.34 Å. Ti(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ho(1)O6 octahedra, corners with four equivalent Ho(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-65°. The Ti(1)-O(3) bond length is 2.07 Å. The Ti(1)-O(4) bond length is 2.03 Å. The Ti(1)-O(5) bond length is 1.85 Å. There are two shorter (1.89 Å) and one longer (2.36 Å) Ti(1)-O(2) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(3)Ho3Ti tetrahedra, corners with four equivalent O(4)Ho3Ti tetrahedra, corners with four equivalent O(1)Ho4 tetrahedra,  an edgeedge with one O(4)Ho3Ti tetrahedra, and edges with two equivalent O(3)Ho3Ti tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Ti(1) atoms. In the third O site, O(3) is bonded to one Ho(1), two equivalent Ho(2), and one Ti(1) atom to form OHo3Ti tetrahedra that share corners with two equivalent O(3)Ho3Ti tetrahedra, corners with two equivalent O(1)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Ti tetrahedra, and edges with two equivalent O(1)Ho4 tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Ho(1) and one Ti(1) atom to form OHo3Ti tetrahedra that share corners with two equivalent O(4)Ho3Ti tetrahedra, corners with four equivalent O(3)Ho3Ti tetrahedra, corners with four equivalent O(1)Ho4 tetrahedra,  an edgeedge with one O(1)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ho(2) and one Ti(1) atom.