Materials Data on Al2CuSi2O8F by Materials Project

Abstract

CuAl2Si2O8F crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Cu3+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with six SiO4 tetrahedra and edges with two AlO5F octahedra. There are a spread of Cu–O bond distances ranging from 1.93–2.51 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to five O2- and one F1- atom to form AlO5F octahedra that share corners with two equivalent AlO5F octahedra, corners with four SiO4 tetrahedra, an edgeedge with one AlO5F octahedra, and an edgeedge with one CuO5 square pyramid. The corner-sharing octahedra tilt angles range from 24–34°. There are a spread of Al–O bond distances ranging from 1.77–2.00 Å. The Al–F bond length is 1.83 Å. In the second Al3+ site, Al3+ is bonded to five O2- and one F1- atom to form AlO5F octahedra that share corners with two equivalent AlO5F octahedra, corners with four SiO4 tetrahedra, an edgeedge with one AlO5F octahedra, and an edgeedge with one CuO5 square pyramid. The corner-sharing octahedra tilt angles range from 24–34°. There are a spread of Al–O bond distances ranging from 1.79–1.94 Å. The Al–F bond length is 1.83 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four AlO5F octahedra, corners with three equivalent CuO5 square pyramids, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–56°. There are a spread of Si–O bond distances ranging from 1.64–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four AlO5F octahedra, corners with three equivalent CuO5 square pyramids, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–51°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu3+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu3+, one Al3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu3+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Al3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu3+, one Al3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Cu3+, one Al3+, and one Si4+ atom. F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms.