Materials Data on Sr2CaTlCu2O7 by Materials Project
TlSr2CaCu2O7 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.57–2.75 Å. Ca2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ca–O bond lengths are 2.46 Å. Cu+2.50+ is bonded to five O2- atoms to form CuO5 square pyramids that share a cornercorner with one TlO6 octahedra and corners with four equivalent CuO5 square pyramids. The corner-sharing octahedral tilt angles are 0°. There are four shorter (1.90 Å) and one longer (2.27 Å) Cu–O bond lengths. Tl3+ is bonded to six O2- atoms to form TlO6 octahedra that share corners with four equivalent TlO6 octahedra, corners with two equivalent CuO5 square pyramids, and edges with four equivalent TlO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.67 Å) Tl–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sr2+, two equivalent Ca2+, and two equivalent Cu+2.50+ atoms to form distorted OSr2Ca2Cu2 octahedra that share corners with fourteen OSr4TlCu octahedra, edges with three equivalent OSr2Ca2Cu2 octahedra, and faces with six OSr4TlCu octahedra. The corner-sharing octahedra tilt angles range from 0–66°. In the second O2- site, O2- is bonded to four equivalent Sr2+, one Cu+2.50+, and one Tl3+ atom to form distorted OSr4TlCu octahedra that share corners with thirteen OSr4TlCu octahedra, edges with eight OSr4TlCu octahedra, and faces with four equivalent OSr2Ca2Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–53°. In the third O2- site, O2- is bonded to two equivalent Sr2+ and four equivalent Tl3+ atoms to form OSr2Tl4 octahedra that share corners with twelve OSr2Tl4 octahedra and edges with twelve OSr4TlCu octahedra. The corner-sharing octahedra tilt angles range from 0–43°.