Materials Data on K2Nb2O5 by Materials Project

Abstract

K2Nb2O5 crystallizes in the orthorhombic Ima2 space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.59–3.09 Å. There are two inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with four equivalent NbO6 octahedra and corners with two equivalent NbO4 tetrahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Nb–O bond distances ranging from 2.05–2.12 Å. In the second Nb4+ site, Nb4+ is bonded to four O2- atoms to form NbO4 tetrahedra that share corners with two equivalent NbO6 octahedra and corners with two equivalent NbO4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. There is two shorter (1.95 Å) and two longer (1.96 Å) Nb–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent K1+ and two equivalent Nb4+ atoms to form distorted OK4Nb2 octahedra that share corners with two equivalent OK4Nb2 octahedra, corners with four equivalent OK2Nb2 tetrahedra, edges with two equivalent OK4Nb2 octahedra, and faces with four equivalent OK4Nb2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four equivalent K1+ and two Nb4+ atoms. In the third O2- site, O2- is bonded to two equivalent K1+ and two equivalent Nb4+ atoms to form distorted OK2Nb2 tetrahedra that share corners with eight equivalent OK4Nb2 octahedra and corners with two equivalent OK2Nb2 tetrahedra. The corner-sharing octahedra tilt angles range from 17–82°.