DOI: 10.17188/1268797
title: Materials Data on CaNb2(P2O7)3 by Materials Project

description: CaNb2(P2O7)3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five PO4 tetrahedra. The corner-sharing octahedral tilt angles are 11°. There are a spread of Ca–O bond distances ranging from 2.30–2.45 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share a cornercorner with one CaO6 octahedra and corners with five PO4 tetrahedra. The corner-sharing octahedral tilt angles are 11°. There are a spread of Nb–O bond distances ranging from 1.76–2.23 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six PO4 tetrahedra. There is two shorter (1.97 Å) and four longer (2.01 Å) Nb–O bond length. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one NbO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–41°. There are a spread of P–O bond distances ranging from 1.48–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two equivalent NbO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–38°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three NbO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 8–19°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two NbO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 5–25°. There are a spread of P–O bond distances ranging from 1.48–1.61 Å. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a linear geometry to one Nb5+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Nb5+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to one Ca2+ and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Nb5+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a linear geometry to one Nb5+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Nb5+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a linear geometry to one Nb5+ and one P5+ atom.