Materials Data on Sr5Ti7O19 by Materials Project
Sr5Ti7O19 crystallizes in the orthorhombic Pmmm space group. The structure is two-dimensional and consists of one Sr5Ti7O19 sheet oriented in the (0, 0, 1) direction. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with seven SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with six TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.73–3.11 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with eleven SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.71–2.83 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.76–2.82 Å. There are four inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a 4-coordinate geometry to four O2- atoms. There is two shorter (1.80 Å) and two longer (1.98 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–6°. There is two shorter (1.92 Å) and four longer (2.00 Å) Ti–O bond length. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Ti–O bond distances ranging from 1.92–1.99 Å. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There is two shorter (1.92 Å) and four longer (1.99 Å) Ti–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sr2+ and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr2+ and two Ti4+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two equivalent Ti4+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms.