Materials Data on CaSe2O7 by Materials Project
CaSe2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with three equivalent SeO4 tetrahedra and an edgeedge with one CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.33–2.49 Å. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Se–O bond distances ranging from 1.69–2.43 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with three equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 35–55°. There are a spread of Se–O bond distances ranging from 1.66–1.71 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Se6+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca2+ and one Se6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one Se6+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one Se6+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Se6+ atom.