DOE OSTI2020
Zn2As2O7 crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. there are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 trigonal bipyramids that share corners with five AsO4 tetrahedra and edges with two ZnO5 trigonal bipyramids. There are a spread of Zn–O bond distances ranging from 1.94–2.21 Å. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 trigonal bipyramids that share corners with five AsO4 tetrahedra and edges with two ZnO5 trigonal bipyramids. There are a spread of Zn–O bond distances ranging from 1.97–2.12 Å. There are three inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one AsO4 tetrahedra and corners with four ZnO5 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.69–1.82 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one AsO4 tetrahedra and corners with six ZnO5 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.71–1.78 Å. In the third As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one AsO4 tetrahedra and corners with five ZnO5 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.68–1.80 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one As5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Zn2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Zn2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two As5+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent As5+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to two Zn2+ and one As5+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Zn2+ and one As5+ atom.