Materials Data on Rb8Ta6O19 by Materials Project
Rb8Ta6O19 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Rb1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Rb–O bond distances ranging from 2.77–3.29 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Ta–O bond distances ranging from 1.84–2.35 Å. In the second Ta5+ site, Ta5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ta–O bond distances ranging from 1.83–2.40 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Rb1+ and two Ta5+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Rb1+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Rb1+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in an octahedral geometry to six Ta5+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Rb1+ and two equivalent Ta5+ atoms.