Materials Data on K3Nb8O21 by Materials Project

Abstract

K3Nb8O21 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. K1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of K–O bond distances ranging from 2.89–3.28 Å. There are two inequivalent Nb+4.88+ sites. In the first Nb+4.88+ site, Nb+4.88+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 24–41°. There are a spread of Nb–O bond distances ranging from 1.94–2.14 Å. In the second Nb+4.88+ site, Nb+4.88+ is bonded to six equivalent O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles are 36°. All Nb–O bond lengths are 2.02 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+ and two Nb+4.88+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two equivalent Nb+4.88+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one K1+ and three equivalent Nb+4.88+ atoms.