HfTiO4 is Hydrophilite-derived structured and crystallizes in the triclinic P1 space group. There are four inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one O(1), one O(12), one O(13), one O(15), one O(3), and one O(7) atom to form HfO6 octahedra that share corners with two equivalent Hf(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Hf(2)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, and  an edgeedge with one Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. In the second Hf site, Hf(2) is bonded to one O(10), one O(12), one O(13), one O(3), one O(5), and one O(7) atom to form distorted HfO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra,  an edgeedge with one Hf(3)O6 octahedra, and  an edgeedge with one Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. In the third Hf site, Hf(3) is bonded to one O(10), one O(11), one O(15), one O(2), one O(7), and one O(8) atom to form distorted HfO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(3)O6 octahedra,  an edgeedge with one Hf(2)O6 octahedra, and  an edgeedge with one Hf(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. In the fourth Hf site, Hf(4) is bonded to one O(11), one O(14), one O(4), one O(6), one O(8), and one O(9) atom to form distorted HfO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Hf(3)O6 octahedra, and  an edgeedge with one Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(13), one O(16), one O(4), one O(5), and one O(9) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(2)O6 octahedra, corners with two equivalent Hf(4)O6 octahedra, corners with four equivalent Ti(4)O6 octahedra,  an edgeedge with one Hf(1)O6 octahedra, and  an edgeedge with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. In the second Ti site, Ti(2) is bonded to one O(11), one O(14), one O(16), one O(2), one O(4), and one O(6) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Hf(4)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, and  an edgeedge with one Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. In the third Ti site, Ti(3) is bonded to one O(10), one O(14), one O(15), one O(2), one O(3), and one O(8) atom to form TiO6 octahedra that share corners with two equivalent Hf(2)O6 octahedra, corners with two equivalent Hf(4)O6 octahedra, corners with four equivalent Hf(3)O6 octahedra,  an edgeedge with one Hf(1)O6 octahedra, and  an edgeedge with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(12), one O(16), one O(5), one O(6), and one O(9) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra,  an edgeedge with one Hf(2)O6 octahedra, and  an edgeedge with one Hf(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Hf(1), one Ti(1), and one Ti(4) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Hf(3), one Ti(2), and one Ti(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Hf(4), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Hf(2), one Ti(1), and one Ti(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Hf(4), one Ti(2), and one Ti(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Hf(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Hf(3), one Hf(4), and one Ti(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Hf(4), one Ti(1), and one Ti(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Hf(2), one Hf(3), and one Ti(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Hf(3), one Hf(4), and one Ti(2) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(4) atom. In the thirteenth O site, O(13) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(1) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Hf(4), one Ti(2), and one Ti(3) atom. In the fifteenth O site, O(15) is bonded in a trigonal planar geometry to one Hf(1), one Hf(3), and one Ti(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ti(2), and one Ti(4) atom.
HfTiO4 is Hydrophilite-derived structured and crystallizes in the triclinic P1 space group. There are four inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one O(1), one O(12), one O(13), one O(15), one O(3), and one O(7) atom to form HfO6 octahedra that share corners with two equivalent Hf(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Hf(2)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, and  an edgeedge with one Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. The Hf(1)-O(1) bond length is 2.10 Å. The Hf(1)-O(12) bond length is 2.04 Å. The Hf(1)-O(13) bond length is 2.12 Å. The Hf(1)-O(15) bond length is 2.07 Å. The Hf(1)-O(3) bond length is 2.15 Å. The Hf(1)-O(7) bond length is 2.03 Å. In the second Hf site, Hf(2) is bonded to one O(10), one O(12), one O(13), one O(3), one O(5), and one O(7) atom to form distorted HfO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra,  an edgeedge with one Hf(3)O6 octahedra, and  an edgeedge with one Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. The Hf(2)-O(10) bond length is 2.12 Å. The Hf(2)-O(12) bond length is 2.15 Å. The Hf(2)-O(13) bond length is 2.04 Å. The Hf(2)-O(3) bond length is 2.04 Å. The Hf(2)-O(5) bond length is 2.09 Å. The Hf(2)-O(7) bond length is 2.13 Å. In the third Hf site, Hf(3) is bonded to one O(10), one O(11), one O(15), one O(2), one O(7), and one O(8) atom to form distorted HfO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(3)O6 octahedra,  an edgeedge with one Hf(2)O6 octahedra, and  an edgeedge with one Hf(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. The Hf(3)-O(10) bond length is 2.22 Å. The Hf(3)-O(11) bond length is 2.08 Å. The Hf(3)-O(15) bond length is 2.02 Å. The Hf(3)-O(2) bond length is 2.03 Å. The Hf(3)-O(7) bond length is 2.06 Å. The Hf(3)-O(8) bond length is 2.20 Å. In the fourth Hf site, Hf(4) is bonded to one O(11), one O(14), one O(4), one O(6), one O(8), and one O(9) atom to form distorted HfO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Hf(3)O6 octahedra, and  an edgeedge with one Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. The Hf(4)-O(11) bond length is 2.20 Å. The Hf(4)-O(14) bond length is 2.03 Å. The Hf(4)-O(4) bond length is 2.03 Å. The Hf(4)-O(6) bond length is 2.20 Å. The Hf(4)-O(8) bond length is 2.09 Å. The Hf(4)-O(9) bond length is 2.06 Å. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(13), one O(16), one O(4), one O(5), and one O(9) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(2)O6 octahedra, corners with two equivalent Hf(4)O6 octahedra, corners with four equivalent Ti(4)O6 octahedra,  an edgeedge with one Hf(1)O6 octahedra, and  an edgeedge with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. The Ti(1)-O(1) bond length is 2.20 Å. The Ti(1)-O(13) bond length is 1.96 Å. The Ti(1)-O(16) bond length is 2.21 Å. The Ti(1)-O(4) bond length is 1.94 Å. The Ti(1)-O(5) bond length is 1.87 Å. The Ti(1)-O(9) bond length is 1.87 Å. In the second Ti site, Ti(2) is bonded to one O(11), one O(14), one O(16), one O(2), one O(4), and one O(6) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Hf(4)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, and  an edgeedge with one Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. The Ti(2)-O(11) bond length is 1.91 Å. The Ti(2)-O(14) bond length is 2.13 Å. The Ti(2)-O(16) bond length is 2.02 Å. The Ti(2)-O(2) bond length is 1.95 Å. The Ti(2)-O(4) bond length is 2.07 Å. The Ti(2)-O(6) bond length is 1.92 Å. In the third Ti site, Ti(3) is bonded to one O(10), one O(14), one O(15), one O(2), one O(3), and one O(8) atom to form TiO6 octahedra that share corners with two equivalent Hf(2)O6 octahedra, corners with two equivalent Hf(4)O6 octahedra, corners with four equivalent Hf(3)O6 octahedra,  an edgeedge with one Hf(1)O6 octahedra, and  an edgeedge with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. The Ti(3)-O(10) bond length is 1.90 Å. The Ti(3)-O(14) bond length is 1.96 Å. The Ti(3)-O(15) bond length is 2.09 Å. The Ti(3)-O(2) bond length is 2.13 Å. The Ti(3)-O(3) bond length is 2.00 Å. The Ti(3)-O(8) bond length is 1.92 Å. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(12), one O(16), one O(5), one O(6), and one O(9) atom to form distorted TiO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra,  an edgeedge with one Hf(2)O6 octahedra, and  an edgeedge with one Hf(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. The Ti(4)-O(1) bond length is 1.88 Å. The Ti(4)-O(12) bond length is 1.95 Å. The Ti(4)-O(16) bond length is 1.88 Å. The Ti(4)-O(5) bond length is 2.24 Å. The Ti(4)-O(6) bond length is 2.00 Å. The Ti(4)-O(9) bond length is 2.19 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Hf(1), one Ti(1), and one Ti(4) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Hf(3), one Ti(2), and one Ti(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Hf(4), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Hf(2), one Ti(1), and one Ti(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Hf(4), one Ti(2), and one Ti(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Hf(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Hf(3), one Hf(4), and one Ti(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Hf(4), one Ti(1), and one Ti(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Hf(2), one Hf(3), and one Ti(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Hf(3), one Hf(4), and one Ti(2) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(4) atom. In the thirteenth O site, O(13) is bonded in a trigonal planar geometry to one Hf(1), one Hf(2), and one Ti(1) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Hf(4), one Ti(2), and one Ti(3) atom. In the fifteenth O site, O(15) is bonded in a trigonal planar geometry to one Hf(1), one Hf(3), and one Ti(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ti(2), and one Ti(4) atom.