Materials Data on Ba2CaTl2(CuO4)2 by Materials Project

Abstract

Tl2Ba2CaCu2O8 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.77–3.10 Å. Ca2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ca–O bond lengths are 2.51 Å. Cu2+ is bonded in a rectangular see-saw-like geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.94 Å. Tl3+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing TlO6 octahedra. The corner-sharing octahedral tilt angles are 9°. There are a spread of Tl–O bond distances ranging from 2.03–2.76 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ba2+ and five equivalent Tl3+ atoms to form a mixture of distorted corner and edge-sharing OBaTl5 octahedra. The corner-sharing octahedra tilt angles range from 9–45°. In the second O2- site, O2- is bonded to two equivalent Ba2+, two equivalent Ca2+, and two equivalent Cu2+ atoms to form distorted OBa2Ca2Cu2 octahedra that share corners with ten OBaTl5 octahedra, edges with three equivalent OBa2Ca2Cu2 octahedra, and faces with four equivalent OBa2Ca2Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–66°. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four equivalent Ba2+ and one Tl3+ atom.