Materials Data on KNbWO7 by Materials Project
KNbWO7 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. K is bonded to eight O atoms to form KO8 hexagonal bipyramids that share edges with two equivalent KO8 hexagonal bipyramids, edges with two equivalent WO6 octahedra, and edges with four equivalent NbO6 octahedra. There are a spread of K–O bond distances ranging from 2.72–2.95 Å. Nb is bonded to six O atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent WO6 octahedra, and edges with four equivalent KO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 36–39°. There are two shorter (2.00 Å) and four longer (2.01 Å) Nb–O bond lengths. W is bonded to six O atoms to form WO6 octahedra that share corners with two equivalent WO6 octahedra, corners with four equivalent NbO6 octahedra, and edges with two equivalent KO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 36–38°. There is four shorter (1.93 Å) and two longer (2.00 Å) W–O bond length. There are four inequivalent O sites. In the first O site, O is bonded in an L-shaped geometry to two equivalent K atoms. In the second O site, O is bonded in a 4-coordinate geometry to two equivalent K and two equivalent Nb atoms. In the third O site, O is bonded in a bent 150 degrees geometry to two equivalent W atoms. In the fourth O site, O is bonded in a 3-coordinate geometry to one K, one Nb, and one W atom.