DOE OSTI2020
Pb2Sr2HoCu3O8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.66–2.84 Å. In the second Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.66–2.83 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.39–2.42 Å. In the second Ho3+ site, Ho3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.39–2.41 Å. There are four inequivalent Cu+1.67+ sites. In the first Cu+1.67+ site, Cu+1.67+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.87 Å. In the second Cu+1.67+ site, Cu+1.67+ is bonded to five O2- atoms to form CuO5 square pyramids that share a cornercorner with one PbO5 square pyramid and corners with four equivalent CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.35 Å) Cu–O bond lengths. In the third Cu+1.67+ site, Cu+1.67+ is bonded to five O2- atoms to form CuO5 square pyramids that share a cornercorner with one PbO5 square pyramid and corners with four equivalent CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.35 Å) Cu–O bond lengths. In the fourth Cu+1.67+ site, Cu+1.67+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.87 Å. There are two inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded to five O2- atoms to form distorted PbO5 square pyramids that share a cornercorner with one CuO5 square pyramid, corners with four equivalent PbO5 square pyramids, and edges with four equivalent PbO5 square pyramids. There are a spread of Pb–O bond distances ranging from 2.19–3.10 Å. In the second Pb2+ site, Pb2+ is bonded to five O2- atoms to form distorted PbO5 square pyramids that share a cornercorner with one CuO5 square pyramid, corners with four equivalent PbO5 square pyramids, and edges with four equivalent PbO5 square pyramids. There are a spread of Pb–O bond distances ranging from 2.19–3.10 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two Sr2+, two Ho3+, and two Cu+1.67+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to two Sr2+, two Ho3+, and two Cu+1.67+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to two Sr2+, two Ho3+, and two Cu+1.67+ atoms. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to two Sr2+, two Ho3+, and two Cu+1.67+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Sr2+, one Cu+1.67+, and four Pb2+ atoms. In the sixth O2- site, O2- is bonded to four Sr2+, one Cu+1.67+, and one Pb2+ atom to form a mixture of distorted edge and corner-sharing OSr4CuPb octahedra. The corner-sharing octahedral tilt angles are 20°. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Sr2+, one Cu+1.67+, and four Pb2+ atoms. In the eighth O2- site, O2- is bonded to four Sr2+, one Cu+1.67+, and one Pb2+ atom to form a mixture of distorted edge and corner-sharing OSr4CuPb octahedra. The corner-sharing octahedral tilt angles are 20°.