Materials Data on KNb3O8 by Materials Project

Abstract

KNb3O8 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. K1+ is bonded to six O2- atoms to form distorted face-sharing KO6 pentagonal pyramids. There are four shorter (2.80 Å) and two longer (2.96 Å) K–O bond lengths. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Nb–O bond distances ranging from 1.84–2.35 Å. In the second Nb5+ site, Nb5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Nb–O bond distances ranging from 1.78–2.51 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to four Nb5+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Nb5+ atom.