Materials Data on K4Nb8Si(P2O17)2 by Materials Project
K4Nb8Si(P2O17)2 crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 12-coordinate geometry to four equivalent O2- atoms. All K–O bond lengths are 2.66 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 2.91–3.17 Å. In the third K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 3.00 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with four NbO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–35°. There are a spread of Nb–O bond distances ranging from 1.93–2.06 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three NbO6 octahedra, a cornercorner with one SiO4 tetrahedra, and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–35°. There are a spread of Nb–O bond distances ranging from 1.90–2.15 Å. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent NbO6 octahedra. The corner-sharing octahedral tilt angles are 26°. All Si–O bond lengths are 1.66 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four NbO6 octahedra. The corner-sharing octahedral tilt angles are 41°. There is two shorter (1.54 Å) and two longer (1.56 Å) P–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Nb5+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Nb5+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Nb5+, and one Si4+ atom.