Materials Data on BaNb5O8 by Materials Project
BaNb5O8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with eight NbO5 square pyramids, faces with two equivalent BaO12 cuboctahedra, and faces with eight NbO5 square pyramids. There are a spread of Ba–O bond distances ranging from 2.93–2.99 Å. There are three inequivalent Nb+2.80+ sites. In the first Nb+2.80+ site, Nb+2.80+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with two equivalent BaO12 cuboctahedra, corners with six NbO5 square pyramids, an edgeedge with one NbO5 square pyramid, and faces with two equivalent BaO12 cuboctahedra. There are a spread of Nb–O bond distances ranging from 2.09–2.19 Å. In the second Nb+2.80+ site, Nb+2.80+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with two equivalent BaO12 cuboctahedra, corners with six NbO5 square pyramids, an edgeedge with one NbO5 square pyramid, and faces with two equivalent BaO12 cuboctahedra. There are a spread of Nb–O bond distances ranging from 2.09–2.19 Å. In the third Nb+2.80+ site, Nb+2.80+ is bonded in a square co-planar geometry to four O2- atoms. All Nb–O bond lengths are 2.12 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent Ba2+ and three Nb+2.80+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+2.80+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent Ba2+ and three Nb+2.80+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+2.80+ atoms.