Materials Data on Sm3TaO7 by Materials Project

Abstract

Sm3TaO7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to seven O2- atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, corners with three equivalent SmO7 pentagonal bipyramids, edges with two equivalent TaO6 octahedra, and edges with two equivalent SmO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. There are a spread of Sm–O bond distances ranging from 2.28–2.72 Å. In the second Sm3+ site, Sm3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.40 Å) and four longer (2.72 Å) Sm–O bond lengths. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent SmO7 pentagonal bipyramids, and edges with four equivalent SmO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 29°. There is two shorter (1.98 Å) and four longer (2.00 Å) Ta–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Sm3+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Sm3+ and two equivalent Ta5+ atoms.