Materials Data on Hf9W4O3 by Materials Project
Hf9W4O3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a distorted bent 150 degrees geometry to two equivalent W and two equivalent O atoms. Both Hf–W bond lengths are 2.89 Å. Both Hf–O bond lengths are 2.24 Å. In the second Hf site, Hf is bonded in a 2-coordinate geometry to four W and two equivalent O atoms. There are a spread of Hf–W bond distances ranging from 3.03–3.14 Å. Both Hf–O bond lengths are 2.33 Å. There are two inequivalent W sites. In the first W site, W is bonded in a 12-coordinate geometry to eight Hf and four W atoms. There are two shorter (2.70 Å) and two longer (2.89 Å) W–W bond lengths. In the second W site, W is bonded to six equivalent Hf and six equivalent W atoms to form WHf6W6 cuboctahedra that share edges with six equivalent OHf6 octahedra and faces with two equivalent WHf6W6 cuboctahedra. O is bonded to six Hf atoms to form OHf6 octahedra that share corners with six equivalent OHf6 octahedra and edges with two equivalent WHf6W6 cuboctahedra. The corner-sharing octahedra tilt angles range from 37–43°.