Materials Data on CaCuAs2O7 by Materials Project
CaCuAs2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.86 Å. Cu2+ is bonded to five O2- atoms to form distorted CuO5 square pyramids that share corners with five AsO4 tetrahedra. There are a spread of Cu–O bond distances ranging from 1.95–2.40 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 two equivalent CuO5 square pyramids and a cornercorner with one AsO4 tetrahedra. There are a spread of As–O bond distances ranging from 1.70–1.81 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent CuO5 square pyramids and a cornercorner with one AsO4 tetrahedra. There are a spread of As–O bond distances ranging from 1.69–1.79 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Cu2+, and one As5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cu2+, and one As5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Cu2+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cu2+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Cu2+, and one As5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two As5+ atoms.