Materials Data on Ho2HgO4 by Materials Project

Abstract

Ho2HgO4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted edge-sharing HoO7 pentagonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.23–2.53 Å. In the second Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.22–2.58 Å. Hg2+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.03 Å) and two longer (2.79 Å) Hg–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with four equivalent OHo4Hg2 octahedra, corners with eight OHo3Hg tetrahedra, edges with two equivalent OHo4Hg2 octahedra, and edges with four OHo3Hg tetrahedra. The corner-sharing octahedra tilt angles range from 32–59°. In the second O2- site, O2- is bonded to four Ho3+ and two equivalent Hg2+ atoms to form distorted OHo4Hg2 octahedra that share corners with eight OHo3Hg tetrahedra, edges with four equivalent OHo4Hg2 octahedra, and edges with seven OHo3Hg tetrahedra. In the third O2- site, O2- is bonded to three equivalent Ho3+ and one Hg2+ atom to form distorted OHo3Hg tetrahedra that share a cornercorner with one OHo4Hg2 octahedra, corners with ten OHo3Hg tetrahedra, edges with two equivalent OHo4Hg2 octahedra, and edges with three OHo3Hg tetrahedra. The corner-sharing octahedral tilt angles are 32°. In the fourth O2- site, O2- is bonded to three Ho3+ and one Hg2+ atom to form distorted OHo3Hg tetrahedra that share corners with three equivalent OHo4Hg2 octahedra, corners with eight OHo3Hg tetrahedra, edges with three equivalent OHo4Hg2 octahedra, and edges with two equivalent OHo4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–56°.