Materials Data on Eu2HgO4 by Materials Project

Abstract

Eu2HgO4 crystallizes in the monoclinic C2/m 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 a mixture of distorted corner and edge-sharing EuO7 pentagonal bipyramids. There are a spread of Eu–O bond distances ranging from 2.31–2.50 Å. In the second Eu3+ site, Eu3+ is bonded to seven O2- atoms to form a mixture of distorted corner and edge-sharing EuO7 hexagonal pyramids. There are a spread of Eu–O bond distances ranging from 2.32–2.55 Å. Hg2+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.04 Å) and two longer (2.88 Å) Hg–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Eu3+ and one Hg2+ atom to form distorted OEu3Hg tetrahedra that share corners with three equivalent OEu4Hg2 octahedra, corners with eight OEu3Hg tetrahedra, edges with three equivalent OEu4Hg2 octahedra, and edges with two equivalent OEu4 tetrahedra. The corner-sharing octahedra tilt angles range from 12–56°. In the second O2- site, O2- is bonded to four Eu3+ atoms to form OEu4 tetrahedra that share corners with four equivalent OEu4Hg2 octahedra, corners with eight OEu3Hg tetrahedra, edges with two equivalent OEu4Hg2 octahedra, and edges with four OEu3Hg tetrahedra. The corner-sharing octahedra tilt angles range from 33–61°. In the third O2- site, O2- is bonded to three equivalent Eu3+ and one Hg2+ atom to form distorted OEu3Hg tetrahedra that share a cornercorner with one OEu4Hg2 octahedra, corners with ten OEu3Hg tetrahedra, edges with two equivalent OEu4Hg2 octahedra, and edges with three OEu3Hg tetrahedra. The corner-sharing octahedral tilt angles are 31°. In the fourth O2- site, O2- is bonded to four Eu3+ and two equivalent Hg2+ atoms to form distorted OEu4Hg2 octahedra that share corners with eight OEu3Hg tetrahedra, edges with four equivalent OEu4Hg2 octahedra, and edges with seven OEu3Hg tetrahedra.