Materials Data on Ca2TiAlSi2O9F by Materials Project

Abstract

Ca2TiAlSi2O9F crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.37–2.66 Å. The Ca–F bond length is 2.29 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.68 Å. Ti4+ is bonded to five O2- and one F1- atom to form TiO5F octahedra that share corners with two equivalent AlO5F octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Ti–O bond distances ranging from 1.74–2.02 Å. The Ti–F bond length is 2.13 Å. Al3+ is bonded to five O2- and one F1- atom to form AlO5F octahedra that share corners with two equivalent TiO5F octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Al–O bond distances ranging from 1.84–1.97 Å. The Al–F bond length is 1.85 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 two equivalent TiO5F octahedra and corners with two equivalent AlO5F octahedra. The corner-sharing octahedra tilt angles range from 38–56°. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TiO5F octahedra and corners with two equivalent AlO5F octahedra. The corner-sharing octahedra tilt angles range from 30–51°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Al3+ atom. F1- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Al3+ atom.