DOE OSTI2020
BaCaB2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.65–3.08 Å. In the second Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.67–3.32 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form edge-sharing CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.37–2.40 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form edge-sharing CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.34–2.41 Å. There are four inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.37 Å) and one longer (1.44 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.36 Å) and one longer (1.46 Å) B–O bond length. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.37 Å) and one longer (1.44 Å) B–O bond length. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.36 Å) and one longer (1.47 Å) B–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Ca2+, and one B3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Ba2+ and two B3+ atoms. In the third O2- site, O2- is bonded to two equivalent Ba2+, one Ca2+, and one B3+ atom to form distorted corner-sharing OBa2CaB tetrahedra. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two Ca2+, and one B3+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ba2+, one Ca2+, and one B3+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ba2+, one Ca2+, and one B3+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two Ca2+, and one B3+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two Ca2+, and one B3+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Ba2+ and two B3+ atoms. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two Ca2+, and one B3+ atom.