Materials Data on Sm2HgO4 by Materials Project
Sm2HgO4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to seven O2- atoms to form distorted edge-sharing SmO7 pentagonal bipyramids. There are a spread of Sm–O bond distances ranging from 2.30–2.55 Å. In the second Sm3+ site, Sm3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sm–O bond distances ranging from 2.29–2.57 Å. Hg2+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.02 Å) and two longer (2.90 Å) Hg–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Sm3+ and one Hg2+ atom to form distorted OSm3Hg tetrahedra that share corners with eight OSm3Hg tetrahedra and edges with two equivalent OSm4 tetrahedra. In the second O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of corner and edge-sharing OSm4 tetrahedra. In the third O2- site, O2- is bonded to three equivalent Sm3+ and one Hg2+ atom to form a mixture of distorted corner and edge-sharing OSm3Hg tetrahedra. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to four Sm3+ and two equivalent Hg2+ atoms.