Materials Data on NaNb3O8 by Materials Project
NaNb3O8 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Na1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.49 Å) and four longer (2.70 Å) Na–O bond lengths. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nb–O bond distances ranging from 1.86–2.42 Å. In the second Nb5+ site, Nb5+ is bonded to eight O2- atoms to form distorted edge-sharing NbO8 hexagonal bipyramids. There are four shorter (2.10 Å) and four longer (2.12 Å) Nb–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+ and three Nb5+ atoms. In the second O2- site, O2- is bonded to two equivalent Na1+ and two equivalent Nb5+ atoms to form a mixture of distorted edge and corner-sharing ONa2Nb2 tetrahedra. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Nb5+ atoms.