Materials Data on KNbPO5 by Materials Project
KNbPO5 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.39 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.26 Å. There are two inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Nb–O bond distances ranging from 1.99–2.16 Å. In the second Nb4+ site, Nb4+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Nb–O bond distances ranging from 1.92–2.21 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four NbO6 octahedra. The corner-sharing octahedra tilt angles range from 46–48°. There is three shorter (1.55 Å) and one longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four NbO6 octahedra. The corner-sharing octahedra tilt angles range from 45–48°. All P–O bond lengths are 1.56 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Nb4+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Nb4+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Nb4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Nb4+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Nb4+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Nb4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Nb4+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Nb4+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two K1+, one Nb4+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Nb4+, and one P5+ atom.