DOE OSTI2020
Y2HgO4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted edge-sharing YO7 pentagonal bipyramids. There are a spread of Y–O bond distances ranging from 2.25–2.52 Å. In the second Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.23–2.58 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 (2.81 Å) Hg–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Y3+ and two equivalent Hg2+ atoms to form distorted OY4Hg2 octahedra that share corners with eight OY3Hg tetrahedra, edges with four equivalent OY4Hg2 octahedra, and edges with seven OY3Hg tetrahedra. In the second O2- site, O2- is bonded to three equivalent Y3+ and one Hg2+ atom to form distorted OY3Hg tetrahedra that share a cornercorner with one OY4Hg2 octahedra, corners with ten OY3Hg tetrahedra, edges with two equivalent OY4Hg2 octahedra, and edges with three OY3Hg tetrahedra. The corner-sharing octahedral tilt angles are 32°. In the third O2- site, O2- is bonded to three Y3+ and one Hg2+ atom to form distorted OY3Hg tetrahedra that share corners with three equivalent OY4Hg2 octahedra, corners with eight OY3Hg tetrahedra, edges with three equivalent OY4Hg2 octahedra, and edges with two equivalent OY4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–56°. In the fourth O2- site, O2- is bonded to four Y3+ atoms to form OY4 tetrahedra that share corners with four equivalent OY4Hg2 octahedra, corners with eight OY3Hg tetrahedra, edges with two equivalent OY4Hg2 octahedra, and edges with four OY3Hg tetrahedra. The corner-sharing octahedra tilt angles range from 32–59°.