Materials Data on Cu2As by Materials Project

Abstract

Cu2As crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. there are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded to four equivalent As3- atoms to form distorted CuAs4 tetrahedra that share corners with twelve equivalent CuAs5 square pyramids, corners with four equivalent CuAs4 tetrahedra, edges with four equivalent CuAs5 square pyramids, and edges with four equivalent CuAs4 tetrahedra. All Cu–As bond lengths are 2.56 Å. In the second Cu+1.50+ site, Cu+1.50+ is bonded to five equivalent As3- atoms to form CuAs5 square pyramids that share corners with four equivalent CuAs5 square pyramids, corners with twelve equivalent CuAs4 tetrahedra, edges with eight equivalent CuAs5 square pyramids, and edges with four equivalent CuAs4 tetrahedra. There are one shorter (2.44 Å) and four longer (2.69 Å) Cu–As bond lengths. As3- is bonded in a 9-coordinate geometry to nine Cu+1.50+ atoms.