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All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

The two-dimensional tunnel structures of K3Sb5O14 and K2Sb4O11

The structures of K3Sb5O14 and K2Sb4O11 have been solved by the single-crystal X-ray direct method and the heavy-atom method, respectively. The structure of K3Sb5O14 is orthorhombic, with space group Pbam and cell parameters a = 24.247 (4), b = 7.157 (2), c = 7.334 (2) A, Z = 4. The structure of K2Sb4O11 is monoclinic, with space group C2/m and cell parameters a = 19.473 (4), b = 7.542 (1), c = 7.198 (1) A, beta = 94.82 (2) deg, Z = 4. A full-matrix least-squares refinement gave R = 0.072 and R = 0.067, respectively. In both structures, oxygen atoms form an octahedron around each Sb atom and an irregular polyhedron around each K atom. By sharing corners and edges, the octahedra form a skeleton network having intersecting b-axis and c-axis tunnels. The K(+) ions, which have more than ten oxygen near neighbors, are located in these tunnels. Evidence for K(+)-ion transport within and between tunnels comes from ion exchange of the alkali ions in molten salts and anisotropic temperature factors that are anomalously large in the direction of the tunnels.

Hong, H. Y.-P.↗
DOE OSTI2020

Materials Data on K2Sb4O11 by Materials Project

K2Sb4O11 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.87–3.27 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.97–3.38 Å. There are three inequivalent Sb5+ sites. In the first Sb5+ site, Sb5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing SbO6 octahedra. The corner-sharing octahedra tilt angles range from 48–55°. There are a spread of Sb–O bond distances ranging from 1.98–2.12 Å. In the second Sb5+ site, Sb5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing SbO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Sb–O bond distances ranging from 1.94–2.15 Å. In the third Sb5+ site, Sb5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing SbO6 octahedra. The corner-sharing octahedra tilt angles range from 33–48°. There are a spread of Sb–O bond distances ranging from 1.97–2.06 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Sb5+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two equivalent K1+ and two equivalent Sb5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two equivalent Sb5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Sb5+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to three Sb5+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sb5+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and two Sb5+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Sb5+ atoms.

36 MATERIALS SCIENCE↗