Materials Data on CaB4O7 by Materials Project
CaB4O7 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Ca2+ is bonded in a 5-coordinate geometry to nine O2- atoms. There are a spread of Ca–O bond distances ranging from 2.43–2.96 Å. There are two inequivalent B3+ sites. In the first 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 1.43–1.55 Å. In the second 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 1.45–1.56 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ca2+ and two B3+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ca2+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two equivalent B3+ atoms. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three B3+ atoms.