Materials Data on KRbTi4(PO4)6 by Materials Project
RbKTi4(PO4)6 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Rb1+ is bonded to twelve O2- atoms to form distorted RbO12 cuboctahedra that share corners with six equivalent TiO6 octahedra, edges with six equivalent PO4 tetrahedra, and faces with two equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are six shorter (2.84 Å) and six longer (3.45 Å) Rb–O bond lengths. K1+ is bonded to six equivalent O2- atoms to form distorted KO6 cuboctahedra that share corners with six equivalent PO4 tetrahedra and faces with two equivalent TiO6 octahedra. All K–O bond lengths are 2.83 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent PO4 tetrahedra and a faceface with one RbO12 cuboctahedra. There is three shorter (1.95 Å) and three longer (1.97 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent RbO12 cuboctahedra, corners with six equivalent PO4 tetrahedra, and a faceface with one KO6 cuboctahedra. There is three shorter (1.96 Å) and three longer (1.97 Å) Ti–O bond length. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one KO6 cuboctahedra, corners with four TiO6 octahedra, and an edgeedge with one RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 22–34°. There is three shorter (1.54 Å) and one longer (1.55 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+, one Ti4+, and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Rb1+, one Ti4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Ti4+, and one P5+ atom.