Materials Data on Er3TaO7 by Materials Project

Abstract

Er3TaO7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Er–O bond distances ranging from 2.31–2.38 Å. In the second Er3+ site, Er3+ is bonded to seven O2- atoms to form distorted ErO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, corners with three equivalent ErO7 pentagonal bipyramids, edges with two equivalent TaO6 octahedra, and edges with two equivalent ErO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 35–45°. There are a spread of Er–O bond distances ranging from 2.22–2.62 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent ErO7 pentagonal bipyramids, and edges with four equivalent ErO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There are a spread of Ta–O bond distances ranging from 1.94–2.06 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Er3+ and one Ta5+ atom to form distorted OEr3Ta tetrahedra that share corners with four equivalent OEr4 tetrahedra and edges with four OEr3Ta tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Er3+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Er3+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded to four Er3+ atoms to form a mixture of edge and corner-sharing OEr4 tetrahedra.