DOE OSTI2020
Ca4Al6SO16 crystallizes in the orthorhombic Pcc2 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.71 Å. In the second Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.44 Å. In the third Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.25–2.92 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.58 Å. There are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.77 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.75–1.77 Å. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.76–1.78 Å. In the fourth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is three shorter (1.78 Å) and one longer (1.79 Å) Al–O bond length. In the fifth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.78 Å. In the sixth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is two shorter (1.74 Å) and two longer (1.75 Å) Al–O bond length. In the seventh Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is one shorter (1.74 Å) and three longer (1.75 Å) Al–O bond length. In the eighth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.77 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.47–1.51 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and two Al3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+ and two Al3+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Al3+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one S6+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Al3+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Al3+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one S6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Ca2+ and one S6+ atom.