Materials Data on NaScAs2O7 by Materials Project

Abstract

NaScAs2O7 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (2.30 Å) and two longer (2.34 Å) Na–O bond lengths. Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six equivalent AsO4 tetrahedra. There are a spread of Sc–O bond distances ranging from 2.09–2.16 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent ScO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–51°. There is three shorter (1.70 Å) and one longer (1.80 Å) As–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc3+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Sc3+, and one As5+ atom. In the third O2- site, O2- is bonded in a trigonal planar geometry to one Na1+, one Sc3+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent As5+ atoms.