DOE OSTI2020
EuBa3B9O18 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.80–3.06 Å. In the second Ba2+ site, Ba2+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are three shorter (2.77 Å) and three longer (2.94 Å) Ba–O bond lengths. Eu3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Eu–O bond lengths are 2.35 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.33–1.42 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.33–1.42 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Ba2+ and one B3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+, one Eu3+, and one B3+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Ba2+ and two equivalent B3+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ba2+ and two equivalent B3+ atoms.