Materials Data on KNaTi4(PO4)6 by Materials Project
KNaTi4(PO4)6 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. K1+ is bonded in a distorted hexagonal planar geometry to six equivalent O2- atoms. All K–O bond lengths are 2.69 Å. Na1+ is bonded in a hexagonal planar geometry to six equivalent O2- atoms. All Na–O bond lengths are 2.64 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. There is three shorter (1.94 Å) and three longer (1.98 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 six equivalent PO4 tetrahedra. There is three shorter (1.93 Å) and three longer (1.98 Å) Ti–O bond length. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 27–29°. There is two shorter (1.54 Å) and two 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 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 2-coordinate geometry to one Na1+, one Ti4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ti4+, and one P5+ atom.