Materials Data on Er2Cu(GeO3)4 by Materials Project
Er2Cu(GeO3)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Er3+ is bonded to seven O2- atoms to form distorted ErO7 pentagonal bipyramids that share corners with six GeO4 tetrahedra, edges with two equivalent ErO7 pentagonal bipyramids, and an edgeedge with one GeO4 tetrahedra. There are a spread of Er–O bond distances ranging from 2.23–2.55 Å. Cu2+ is bonded in a square co-planar geometry to four O2- atoms. All Cu–O bond lengths are 1.98 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four equivalent ErO7 pentagonal bipyramids and corners with two equivalent GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.76–1.80 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent ErO7 pentagonal bipyramids, corners with two equivalent GeO4 tetrahedra, and an edgeedge with one ErO7 pentagonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.75–1.82 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Er3+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Er3+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Er3+ and two Ge4+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Er3+, one Cu2+, and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Er3+, one Cu2+, and one Ge4+ atom.