DOE OSTI2020
K3Lu(SiO3)3 crystallizes in the orthorhombic Pmn2_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 2.73–3.02 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.00–3.42 Å. In the third K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.67–3.25 Å. In the fourth 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 2.81–3.31 Å. In the fifth 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 2.97–3.21 Å. Lu3+ is bonded to six O2- atoms to form LuO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Lu–O bond distances ranging from 2.17–2.24 Å. There are three 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 LuO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–46°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent LuO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–56°. There is two shorter (1.61 Å) and two longer (1.68 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent LuO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–46°. There are a spread of Si–O bond distances ranging from 1.61–1.69 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two K1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three K1+ and two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Lu3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two K1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to three K1+ and two equivalent Si4+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two K1+, one Lu3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to three K1+, one Lu3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to three K1+, one Lu3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to three K1+, one Lu3+, and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Lu3+, and one Si4+ atom.