Materials Data on Ca2As2O7 by Materials Project
Ca2As2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with six equivalent AsO4 tetrahedra and edges with three equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.34–2.42 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with six equivalent CaO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–60°. There is three shorter (1.70 Å) and one longer (1.77 Å) As–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ca2+ and one As5+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent As5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ca2+ and one As5+ atom.