Materials Data on Eu2Si2O7 by Materials Project
Eu2Si2O7 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to seven O2- atoms to form distorted EuO7 pentagonal bipyramids that share corners with three equivalent EuO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, edges with two equivalent EuO7 pentagonal bipyramids, and edges with two SiO4 tetrahedra. There are a spread of Eu–O bond distances ranging from 2.32–2.63 Å. In the second Eu3+ site, Eu3+ is bonded to seven O2- atoms to form distorted EuO7 pentagonal bipyramids that share corners with three equivalent EuO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, edges with two equivalent EuO7 pentagonal bipyramids, and edges with two SiO4 tetrahedra. There are a spread of Eu–O bond distances ranging from 2.32–2.63 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four EuO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and edges with two EuO7 pentagonal bipyramids. There is three shorter (1.63 Å) and one longer (1.68 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four EuO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and edges with two EuO7 pentagonal bipyramids. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Eu3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Eu3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Eu3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to two Eu3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Eu3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Eu3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Eu3+ and two Si4+ atoms.