DOI: 10.17188/1672313
title: Materials Data on Sr5Ti8O21 by Materials Project

description: Sr5Ti8O21 crystallizes in the monoclinic P2/m space group. The structure is two-dimensional and consists of one Sr5Ti8O21 sheet oriented in the (0, 0, 1) direction. there are nine inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with three SrO12 cuboctahedra, corners with two equivalent TiO4 tetrahedra, edges with two equivalent TiO4 tetrahedra, faces with two equivalent SrO12 cuboctahedra, and faces with six TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.73–3.15 Å. In the second Sr2+ site, Sr2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.58–3.05 Å. In the third Sr2+ site, Sr2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.59–3.24 Å. In the fourth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with seven SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.69–2.91 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Sr–O bond distances ranging from 2.58–3.14 Å. In the sixth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with seven SrO12 cuboctahedra, faces with two equivalent SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.57–3.07 Å. In the seventh Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.74–2.83 Å. In the eighth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with two SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.64–2.96 Å. In the ninth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with two equivalent SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.66–2.98 Å. There are nine inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to four O2- atoms to form TiO4 tetrahedra that share a cornercorner with one TiO6 octahedra, corners with three TiO4 tetrahedra, and an edgeedge with one SrO12 cuboctahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of Ti–O bond distances ranging from 1.81–1.84 Å. In the second Ti4+ site, Ti4+ is bonded to four O2- atoms to form TiO4 tetrahedra that share a cornercorner with one SrO12 cuboctahedra, a cornercorner with one TiO6 octahedra, and corners with three TiO4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Ti–O bond distances ranging from 1.82–1.85 Å. In the third Ti4+ site, Ti4+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with two TiO4 tetrahedra and an edgeedge with one TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.80–1.86 Å. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, corners with two TiO4 tetrahedra, and faces with three SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–10°. There are a spread of Ti–O bond distances ranging from 1.93–2.04 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, an edgeedge with one TiO4 tetrahedra, and a faceface with one SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–24°. There are a spread of Ti–O bond distances ranging from 1.89–2.08 Å. In the sixth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with five SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–8°. There are a spread of Ti–O bond distances ranging from 1.94–2.03 Å. In the seventh Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with four SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–24°. There are a spread of Ti–O bond distances ranging from 1.93–2.00 Å. In the eighth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ti–O bond distances ranging from 1.94–1.99 Å. In the ninth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Ti–O bond distances ranging from 1.94–2.00 Å. There are twenty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded to four Sr2+ and two equivalent Ti4+ atoms to form distorted corner-sharing OSr4Ti2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two Ti4+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Ti4+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Ti4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+ and two equivalent Ti4+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ti4+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to two Sr2+ and two Ti4+ atoms. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two Sr2+ and two Ti4+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Sr2+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded to two Sr2+ and two Ti4+ atoms to form distorted corner-sharing OSr2Ti2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two equivalent Ti4+ atoms. In the fifteenth O2- site, O2- is bonded in a 2-coordinate geometry to three Sr2+ and two Ti4+ atoms. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to three Sr2+ and two equivalent Ti4+ atoms. In the seventeenth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the nineteenth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the twentieth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the twenty-sixth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ti4+ atoms.