DOE OSTI2020
Nd2Cu2O5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Nd–O bond distances ranging from 2.36–2.79 Å. In the second Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.32–2.96 Å. In the third Nd3+ site, Nd3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Nd–O bond distances ranging from 2.37–2.68 Å. There are three inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to six O2- atoms to form corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Cu–O bond distances ranging from 1.85–2.42 Å. In the second Cu2+ site, Cu2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.93–2.43 Å. In the third Cu2+ site, Cu2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.96–2.03 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Nd3+ and two equivalent Cu2+ atoms to form distorted ONd4Cu2 octahedra that share corners with six ONd4Cu2 octahedra, corners with two equivalent ONd2Cu3 trigonal bipyramids, an edgeedge with one ONd4Cu2 octahedra, and faces with four ONd4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 1–51°. In the second O2- site, O2- is bonded in a 5-coordinate geometry to five Nd3+ and one Cu2+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Nd3+ and four Cu2+ atoms. In the fourth O2- site, O2- is bonded to four equivalent Nd3+ and two equivalent Cu2+ atoms to form distorted ONd4Cu2 octahedra that share corners with eight equivalent ONd5Cu octahedra, edges with two equivalent ONd4Cu2 octahedra, and faces with six ONd4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four Nd3+ and two Cu2+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Nd3+ and three Cu2+ atoms to form distorted ONd2Cu3 trigonal bipyramids that share corners with two equivalent ONd4Cu2 octahedra, corners with two equivalent ONd2Cu3 trigonal bipyramids, and an edgeedge with one ONd2Cu3 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 51–54°. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Nd3+ and one Cu2+ atom. In the eighth O2- site, O2- is bonded to five Nd3+ and one Cu2+ atom to form distorted ONd5Cu octahedra that share corners with eight ONd4Cu2 octahedra, edges with four equivalent ONd5Cu octahedra, and faces with three ONd4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 44–51°.