Materials Data on KNb4Bi5O18 by Materials Project
Bi5KNb4O18 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. K1+ is bonded in a 12-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.63–2.99 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 20–30°. There are a spread of Nb–O bond distances ranging from 1.87–2.24 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 19–30°. There are a spread of Nb–O bond distances ranging from 1.89–2.24 Å. There are three inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Bi–O bond distances ranging from 2.20–2.88 Å. In the second Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.21–2.61 Å. In the third Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.21–2.60 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Nb5+, and one Bi3+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, two Nb5+, and one Bi3+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+, two equivalent Nb5+, and one Bi3+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+, two equivalent Nb5+, and one Bi3+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Nb5+ and two Bi3+ atoms. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Nb5+ and two Bi3+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Nb5+ and one Bi3+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Nb5+ atoms. In the ninth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of distorted edge and corner-sharing OBi4 tetrahedra. In the tenth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of distorted edge and corner-sharing OBi4 tetrahedra.