Materials Data on Na2Nb4O11 by Materials Project
Na2Nb4O11 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.51–2.76 Å. There are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to seven O2- atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent NbO6 octahedra, corners with two NbO7 pentagonal bipyramids, and edges with four NbO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Nb–O bond distances ranging from 1.99–2.46 Å. In the second Nb5+ site, Nb5+ is bonded to seven O2- atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent NbO6 octahedra, corners with two equivalent NbO7 pentagonal bipyramids, and edges with four equivalent NbO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are a spread of Nb–O bond distances ranging from 1.99–2.45 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. There are four shorter (2.01 Å) and two longer (2.02 Å) Nb–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two Nb5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three Nb5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to three Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two Nb5+ atoms.