Materials Data on Sr3Ta2Ti6O21 by Materials Project

Sr3Ti6Ta2O21 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. Sr is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of Sr–O bond distances ranging from 2.67–3.13 Å. Ti is bonded to six O atoms to form TiO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with three equivalent TiO6 octahedra, and edges with two equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–49°. There are a spread of Ti–O bond distances ranging from 1.84–2.04 Å. Ta is bonded to six equivalent O atoms to form TaO6 octahedra that share corners with six equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 43°. All Ta–O bond lengths are 1.99 Å. There are three inequivalent O sites. In the first O site, O is bonded in a 4-coordinate geometry to one Sr and three equivalent Ti atoms. In the second O site, O is bonded in a 2-coordinate geometry to two equivalent Sr, one Ti, and one Ta atom. In the third O site, O is bonded in a bent 150 degrees geometry to two equivalent Sr and two equivalent Ti atoms.