DOE OSTI2020
K9Eu3Si12(O16F)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.78–2.99 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to seven O2- and one F1- atom. There are a spread of K–O bond distances ranging from 2.77–3.41 Å. The K–F bond length is 2.62 Å. In the third K1+ site, K1+ is bonded in a 5-coordinate geometry to four O2- and one F1- atom. There are a spread of K–O bond distances ranging from 2.81–3.05 Å. The K–F bond length is 2.59 Å. In the fourth K1+ site, K1+ is bonded in a 1-coordinate geometry to four O2- and one F1- atom. There are a spread of K–O bond distances ranging from 2.82–2.95 Å. The K–F bond length is 2.65 Å. In the fifth K1+ site, K1+ is bonded in a 8-coordinate geometry to six O2- and two equivalent F1- atoms. There are a spread of K–O bond distances ranging from 2.96–3.39 Å. Both K–F bond lengths are 2.75 Å. There are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to six O2- atoms to form distorted EuO6 octahedra that share corners with six SiO4 tetrahedra and an edgeedge with one EuO6 octahedra. There are a spread of Eu–O bond distances ranging from 2.29–2.46 Å. In the second Eu3+ site, Eu3+ is bonded to six O2- atoms to form EuO6 octahedra that share corners with six SiO4 tetrahedra. There are two shorter (2.33 Å) and four longer (2.35 Å) Eu–O bond lengths. There are six inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one EuO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There is one shorter (1.60 Å) and three longer (1.66 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three EuO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–62°. There are a spread of Si–O bond distances ranging from 1.61–1.68 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one EuO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one EuO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent EuO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–47°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one EuO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Si–O bond distances ranging from 1.60–1.67 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+, one Eu3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Eu3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a linear geometry to one K1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Eu3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Eu3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Eu3+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Eu3+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Eu3+, and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Eu3+, and one Si4+ atom. F1- is bonded in a see-saw-like geometry to four K1+ atoms.