DOE OSTI2020
BaSi2(H3O4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ba2+ is bonded in a 11-coordinate geometry to one H1+ and ten O2- atoms. The Ba–H bond length is 2.84 Å. There are a spread of Ba–O bond distances ranging from 2.79–3.28 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is one shorter (1.62 Å) and three longer (1.66 Å) Si–O bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one Ba2+ and two O2- atoms. There is one shorter (1.01 Å) and one longer (1.63 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.56 Å) H–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two equivalent Ba2+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ba2+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Si4+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Si4+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a water-like geometry to two equivalent Ba2+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Si4+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Si4+, and one H1+ atom.