DOE OSTI2020
Cd3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to five O2- atoms to form distorted CdO5 trigonal bipyramids that share corners with five AsO4 tetrahedra, a cornercorner with one CdO5 trigonal bipyramid, and edges with two equivalent CdO5 trigonal bipyramids. There are a spread of Cd–O bond distances ranging from 2.22–2.37 Å. In the second Cd2+ site, Cd2+ is bonded to five O2- atoms to form distorted CdO5 trigonal bipyramids that share corners with five AsO4 tetrahedra and a cornercorner with one CdO5 trigonal bipyramid. There are a spread of Cd–O bond distances ranging from 2.15–2.51 Å. In the third Cd2+ site, Cd2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cd–O bond distances ranging from 2.24–2.52 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with six CdO5 trigonal bipyramids. There is three shorter (1.72 Å) and one longer (1.74 Å) As–O bond length. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four CdO5 trigonal bipyramids. There is two shorter (1.72 Å) and two longer (1.73 Å) As–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cd2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cd2+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cd2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Cd2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cd2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cd2+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Cd2+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Cd2+ and one As5+ atom.