Materials Data on Eu3TaO7 by Materials Project
Eu3TaO7 crystallizes in the orthorhombic C222_1 space group. The structure is three-dimensional. there are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to seven O2- atoms to form distorted EuO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, a cornercorner with one EuO7 pentagonal bipyramid, edges with two equivalent TaO6 octahedra, and edges with three equivalent EuO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–49°. There are a spread of Eu–O bond distances ranging from 2.27–2.64 Å. In the second Eu3+ site, Eu3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Eu–O bond distances ranging from 2.38–2.79 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent EuO7 pentagonal bipyramids, and edges with four equivalent EuO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 34°. There are two shorter (1.98 Å) and four longer (2.02 Å) Ta–O bond lengths. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Eu3+ atoms to form a mixture of edge and corner-sharing OEu4 tetrahedra. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Eu3+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Eu3+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded to four Eu3+ atoms to form a mixture of edge and corner-sharing OEu4 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Eu3+ and one Ta5+ atom.