Materials Data on Sr4Cu2O7 by Materials Project
Sr4Cu2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.50–2.79 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.50–2.80 Å. Cu3+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are a spread of Cu–O bond distances ranging from 1.82–2.20 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five Sr2+ and one Cu3+ atom to form distorted OSr5Cu octahedra that share corners with eight OSr5Cu octahedra, edges with eight OSr5Cu octahedra, and a faceface with one OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 5–62°. In the second O2- site, O2- is bonded to five Sr2+ and one Cu3+ atom to form distorted OSr5Cu octahedra that share corners with eight OSr5Cu octahedra, edges with eight OSr5Cu octahedra, and a faceface with one OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 5–61°. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four Sr2+ and two equivalent Cu3+ atoms. In the fourth O2- site, O2- is bonded to four Sr2+ and two equivalent Cu3+ atoms to form a mixture of distorted corner and face-sharing OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 44–62°.