DOI: 10.17188/1192183
title: Materials Data on Ho2Si2O7 by Materials Project

description: Ho2Si2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.29–2.69 Å. In the second Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 octahedra that share corners with seven SiO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.20–2.40 Å. In the third Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.21–2.90 Å. In the fourth Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.25–2.39 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent HoO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent HoO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–65°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one HoO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Si–O bond distances ranging from 1.62–1.75 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one HoO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Ho3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Ho3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two Si4+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one Si4+ atom.