Materials Data on Al2W2O7 by Materials Project
W2Al2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent W4+ sites. In the first W4+ site, W4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 1.99–2.05 Å. In the second W4+ site, W4+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four WO6 octahedra, and edges with two equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 60–66°. There are a spread of W–O bond distances ranging from 1.97–2.28 Å. In the third W4+ site, W4+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four WO6 octahedra, and edges with two equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 64–70°. There are a spread of W–O bond distances ranging from 2.00–2.29 Å. In the fourth W4+ site, W4+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four WO6 octahedra, and edges with two equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 61–64°. There are four shorter (2.01 Å) and two longer (2.18 Å) W–O bond lengths. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Al–O bond distances ranging from 2.09–2.52 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent WO6 octahedra, corners with four AlO6 octahedra, and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 63–70°. There are a spread of Al–O bond distances ranging from 1.98–2.13 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent WO6 octahedra, corners with four AlO6 octahedra, and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 60–67°. There are a spread of Al–O bond distances ranging from 1.96–2.13 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with two equivalent WO6 octahedra, corners with four AlO6 octahedra, and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 67–70°. There are a spread of Al–O bond distances ranging from 1.94–2.24 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to four Al3+ atoms to form OAl4 tetrahedra that share corners with six OAl4 tetrahedra and an edgeedge with one OAl2W2 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two W4+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two W4+ and one Al3+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to two W4+ and one Al3+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two W4+ and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two W4+ and one Al3+ atom. In the seventh O2- site, O2- is bonded to two W4+ and two Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl2W2 tetrahedra.