Materials Data on Ba2CaTlCu2O7 by Materials Project
TlBa2CaCu2O7 crystallizes in the tetragonal P4/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 2.72–2.95 Å. Ca2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ca–O bond lengths are 2.48 Å. Cu+2.50+ is bonded in a distorted square co-planar geometry to five O2- atoms. There are four shorter (1.93 Å) and one longer (2.72 Å) Cu–O bond lengths. Tl3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TlO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.09 Å) and four longer (2.72 Å) Tl–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent Ba2+, two equivalent Ca2+, and two equivalent Cu+2.50+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to four equivalent Ba2+, one Cu+2.50+, and one Tl3+ atom. In the third O2- site, O2- is bonded to two equivalent Ba2+ and four equivalent Tl3+ atoms to form a mixture of edge and corner-sharing OBa2Tl4 octahedra. The corner-sharing octahedral tilt angles are 0°.