Materials Data on Eu2Al4O9 by Materials Project
Eu2Al4O9 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Eu3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Eu–O bond distances ranging from 2.25–2.54 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four equivalent AlO4 tetrahedra and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.90–1.98 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four equivalent AlO6 octahedra and a cornercorner with one AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–56°. There is one shorter (1.73 Å) and three longer (1.78 Å) Al–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Al3+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Eu3+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Eu3+ and two equivalent Al3+ atoms.