DOE OSTI2020
Ca2B5SiO9(OH)5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.41–2.57 Å. In the second Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.61 Å. There are five inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one BO4 tetrahedra and corners with two equivalent SiO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.52 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one BO4 tetrahedra and a cornercorner with one SiO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.52 Å. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.38 Å) B–O bond length. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one BO4 tetrahedra and a cornercorner with one SiO4 tetrahedra. There is three shorter (1.46 Å) and one longer (1.50 Å) B–O bond length. In the fifth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.52 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four BO4 tetrahedra. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. There are five inequivalent H1+ sites. In the first 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 second 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 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 0.98 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+, one B3+, and one H1+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+, one B3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one B3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one B3+, and one Si4+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two B3+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ca2+, one B3+, and one H1+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two B3+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ca2+ and two B3+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+, one B3+, and one H1+ atom.