Hf9W4O3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a distorted bent 150 degrees geometry to two equivalent W(1) and two equivalent O(1) atoms. In the second Hf site, Hf(2) is bonded in a 2-coordinate geometry to one W(2), three equivalent W(1), and two equivalent O(1) atoms. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 12-coordinate geometry to two equivalent Hf(1), six equivalent Hf(2), two equivalent W(1), and two equivalent W(2) atoms. In the second W site, W(2) is bonded to six equivalent Hf(2) and six equivalent W(1) atoms to form WHf6W6 cuboctahedra that share edges with six equivalent O(1)Hf6 octahedra and faces with two equivalent W(2)Hf6W6 cuboctahedra. O(1) is bonded to two equivalent Hf(1) and four equivalent Hf(2) atoms to form OHf6 octahedra that share corners with six equivalent O(1)Hf6 octahedra and edges with two equivalent W(2)Hf6W6 cuboctahedra. The corner-sharing octahedral tilt angles range from 37-43°.
Hf9W4O3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a distorted bent 150 degrees geometry to two equivalent W(1) and two equivalent O(1) atoms. Both Hf(1)-W(1) bond lengths are 2.89 Å. Both Hf(1)-O(1) bond lengths are 2.24 Å. In the second Hf site, Hf(2) is bonded in a 2-coordinate geometry to one W(2), three equivalent W(1), and two equivalent O(1) atoms. The Hf(2)-W(2) bond length is 3.14 Å. There is one shorter (3.03 Å) and two longer (3.11 Å) Hf(2)-W(1) bond lengths. Both Hf(2)-O(1) bond lengths are 2.33 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 12-coordinate geometry to two equivalent Hf(1), six equivalent Hf(2), two equivalent W(1), and two equivalent W(2) atoms. Both W(1)-W(1) bond lengths are 2.89 Å. Both W(1)-W(2) bond lengths are 2.70 Å. In the second W site, W(2) is bonded to six equivalent Hf(2) and six equivalent W(1) atoms to form WHf6W6 cuboctahedra that share edges with six equivalent O(1)Hf6 octahedra and faces with two equivalent W(2)Hf6W6 cuboctahedra. O(1) is bonded to two equivalent Hf(1) and four equivalent Hf(2) atoms to form OHf6 octahedra that share corners with six equivalent O(1)Hf6 octahedra and edges with two equivalent W(2)Hf6W6 cuboctahedra. The corner-sharing octahedral tilt angles range from 37-43°.