DOE OSTI2020
EuAl2O4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Eu2+ sites. In the first Eu2+ site, Eu2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Eu–O bond distances ranging from 2.54–3.13 Å. In the second Eu2+ site, Eu2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Eu–O bond distances ranging from 2.49–2.83 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.76–1.78 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is two shorter (1.77 Å) and two longer (1.79 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is two shorter (1.77 Å) and two longer (1.78 Å) Al–O bond length. In the fourth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is two shorter (1.77 Å) and two longer (1.78 Å) Al–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Eu2+ and two Al3+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Eu2+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Eu2+ and two Al3+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Eu2+ and two Al3+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Eu2+ and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Eu2+ and two Al3+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Eu2+ and two Al3+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Eu2+ and two Al3+ atoms.