DOI: 10.17188/1718263
title: Materials Data on Ba3Ta4Ti4O21 by Materials Project

description: Ba3Ti4Ta4O21 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ba–O bond distances ranging from 2.79–3.21 Å. In the second Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ba–O bond distances ranging from 2.82–3.24 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with four TaO6 octahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 22–44°. There are a spread of Ti–O bond distances ranging from 1.89–2.10 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra, corners with three TaO6 octahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 21–45°. There are a spread of Ti–O bond distances ranging from 1.86–2.09 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra and corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 37–41°. There are a spread of Ta–O bond distances ranging from 1.98–2.03 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with three TiO6 octahedra, and edges with two TiO6 octahedra. The corner-sharing octahedra tilt angles range from 22–45°. There are a spread of Ta–O bond distances ranging from 1.92–2.06 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ba2+, one Ti4+, and one Ta5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Ti4+, and one Ta5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+ and two Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ba2+, one Ti4+, and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ba2+, one Ti4+, and one Ta5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ba2+ and two equivalent Ti4+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two Ti4+, and one Ta5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two Ti4+, and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two Ti4+, and one Ta5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Ti4+, and one Ta5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+ and two Ta5+ atoms.