Materials Data on Ba2CaSi4(BO7)2 by Materials Project

Abstract

Ba2CaSi4(BO7)2 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–3.22 Å. Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with four equivalent BO4 tetrahedra and corners with four equivalent SiO4 tetrahedra. There are four shorter (2.37 Å) and two longer (2.46 Å) Ca–O bond lengths. B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids, corners with two equivalent BO4 tetrahedra, and corners with two equivalent SiO4 tetrahedra. There is two shorter (1.48 Å) and two longer (1.50 Å) B–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 pentagonal pyramid, a cornercorner with one BO4 tetrahedra, and corners with two equivalent SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Ca2+, and two equivalent B3+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one B3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Ca2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ba2+ and two equivalent Si4+ atoms.