Materials Data on KNaNb2O6 by Materials Project
KNaNb2O6 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share corners with four equivalent KO12 cuboctahedra, faces with four equivalent KO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of K–O bond distances ranging from 2.77–3.08 Å. Na1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Na–O bond distances ranging from 2.61–3.13 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with four equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 7–14°. There are a spread of Nb–O bond distances ranging from 1.90–2.20 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with four equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 7–12°. There are a spread of Nb–O bond distances ranging from 1.89–2.23 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, two equivalent Na1+, and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, two equivalent Na1+, and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent K1+ and two Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four equivalent Na1+ and two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, two equivalent Na1+, and two equivalent Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent K1+, two equivalent Na1+, and two equivalent Nb5+ atoms.