Materials Data on Sm3NbO7 by Materials Project

Abstract

Sm3NbO7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sm–O bond distances ranging from 2.36–2.45 Å. In the second Sm3+ site, Sm3+ is bonded to seven O2- atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent NbO6 octahedra, corners with three equivalent SmO7 pentagonal bipyramids, edges with two equivalent NbO6 octahedra, and edges with two equivalent SmO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 32–44°. There are a spread of Sm–O bond distances ranging from 2.31–2.66 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent SmO7 pentagonal bipyramids, and edges with four equivalent SmO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. There are a spread of Nb–O bond distances ranging from 1.95–2.09 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Sm3+ and one Nb5+ atom to form distorted OSm3Nb tetrahedra that share corners with four equivalent OSm4 tetrahedra and edges with four OSm3Nb tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Sm3+ and one Nb5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sm3+ and two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra.