Materials Data on KBa2Nb3O9 by Materials Project
KBa2Nb3O9 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share corners with six equivalent KO12 cuboctahedra, corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with eight NbO6 octahedra. There are six shorter (2.92 Å) and six longer (2.94 Å) K–O bond lengths. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with three equivalent KO12 cuboctahedra, corners with nine equivalent BaO12 cuboctahedra, faces with three equivalent KO12 cuboctahedra, faces with three equivalent BaO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.89–2.92 Å. There are two inequivalent Nb+4.33+ sites. In the first Nb+4.33+ site, Nb+4.33+ is bonded to six equivalent O2- atoms to form NbO6 octahedra that share corners with six equivalent NbO6 octahedra, faces with two equivalent KO12 cuboctahedra, and faces with six equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. All Nb–O bond lengths are 2.06 Å. In the second Nb+4.33+ site, Nb+4.33+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra, faces with three equivalent KO12 cuboctahedra, and faces with five equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are three shorter (2.05 Å) and three longer (2.07 Å) Nb–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one K1+, three equivalent Ba2+, and two Nb+4.33+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two equivalent K1+, two equivalent Ba2+, and two equivalent Nb+4.33+ atoms.