Materials Data on MgCuAs by Materials Project
MgCuAs is Matlockite structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Mg2+ is bonded to five equivalent As3- atoms to form MgAs5 square pyramids that share corners with four equivalent MgAs5 square pyramids, corners with twelve equivalent CuAs4 tetrahedra, edges with eight equivalent MgAs5 square pyramids, and edges with four equivalent CuAs4 tetrahedra. There are one shorter (2.68 Å) and four longer (2.86 Å) Mg–As bond lengths. Cu1+ is bonded to four equivalent As3- atoms to form CuAs4 tetrahedra that share corners with twelve equivalent MgAs5 square pyramids, corners with four equivalent CuAs4 tetrahedra, edges with four equivalent MgAs5 square pyramids, and edges with four equivalent CuAs4 tetrahedra. All Cu–As bond lengths are 2.57 Å. As3- is bonded in a 9-coordinate geometry to five equivalent Mg2+ and four equivalent Cu1+ atoms.