DOE OSTI2020
Y2Ge2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.33–2.65 Å. In the second Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with five GeO4 tetrahedra, an edgeedge with one YO7 pentagonal bipyramid, and an edgeedge with one GeO4 tetrahedra. There are a spread of Y–O bond distances ranging from 2.26–2.44 Å. In the third Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.27–2.41 Å. In the fourth Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.23–2.98 Å. There are four inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent YO7 pentagonal bipyramids and an edgeedge with one YO7 pentagonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.73–1.81 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent YO7 pentagonal bipyramids and a cornercorner with one GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.75–1.88 Å. In the third Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one YO7 pentagonal bipyramid and a cornercorner with one GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.75–1.80 Å. In the fourth Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.75–1.83 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ge4+ atom. In the second O2- site, O2- is bonded to three Y3+ and one Ge4+ atom to form distorted edge-sharing OY3Ge tetrahedra. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ge4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one Ge4+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two Ge4+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ge4+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ge4+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ge4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to three Y3+ and one Ge4+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ge4+ atom. In the fourteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two Ge4+ atoms.