DOE OSTI2020
Rb2Ti(Si2O5)3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 3.05–3.39 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 3.00–3.46 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.94–2.01 Å. 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 TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 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 1.61–1.66 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 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 1.61–1.66 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one Ti4+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Rb1+, one Ti4+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one Ti4+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Rb1+, one Ti4+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one Ti4+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Rb1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Rb1+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two Si4+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one Ti4+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+ and two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two Si4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Rb1+ and two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two Si4+ atoms.