DOE OSTI2020
Ba8Gd4(Cu4O9)3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.73–3.01 Å. In the second Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.77–3.03 Å. In the third Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.77–3.04 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.73–3.02 Å. There are three inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.45 Å) Gd–O bond lengths. In the second Gd3+ site, Gd3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Gd–O bond distances ranging from 2.42–2.46 Å. In the third Gd3+ site, Gd3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Gd–O bond distances ranging from 2.42–2.46 Å. There are four inequivalent Cu+2.17+ sites. In the first Cu+2.17+ site, Cu+2.17+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are a spread of Cu–O bond distances ranging from 1.95–2.42 Å. In the second Cu+2.17+ site, Cu+2.17+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are a spread of Cu–O bond distances ranging from 1.95–2.34 Å. In the third Cu+2.17+ site, Cu+2.17+ is bonded in a T-shaped geometry to three O2- atoms. There is two shorter (1.82 Å) and one longer (1.88 Å) Cu–O bond length. In the fourth Cu+2.17+ site, Cu+2.17+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.88 Å) and two longer (1.97 Å) Cu–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, two Gd3+, and two Cu+2.17+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, two equivalent Gd3+, and two Cu+2.17+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+, two Gd3+, and two equivalent Cu+2.17+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, two Gd3+, and two equivalent Cu+2.17+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+, two Gd3+, and two equivalent Cu+2.17+ atoms. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+, two Gd3+, and two equivalent Cu+2.17+ atoms. In the seventh O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Cu+2.17+ atoms. In the eighth O2- site, O2- is bonded to four Ba2+ and two Cu+2.17+ atoms to form a mixture of distorted corner and edge-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Cu+2.17+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Cu+2.17+ atoms.