DOE OSTI2020
Sr2CaCu2(BiO5)2 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are four inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.37–2.73 Å. In the second Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.36–2.74 Å. In the third Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.35–2.74 Å. In the fourth Sr2+ site, Sr2+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Sr–O bond lengths are 2.57 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.46 Å) and four longer (2.48 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Ca–O bond distances ranging from 2.21–2.73 Å. There are four inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.92 Å) and one longer (2.10 Å) Cu–O bond lengths. In the second Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.91 Å) and one longer (2.24 Å) Cu–O bond lengths. In the third Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.92 Å) and one longer (2.19 Å) Cu–O bond lengths. In the fourth Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.91 Å) and one longer (2.21 Å) Cu–O bond lengths. There are four inequivalent Bi5+ sites. In the first Bi5+ site, Bi5+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.28–2.75 Å. In the second Bi5+ site, Bi5+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.30–2.73 Å. In the third Bi5+ site, Bi5+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.33–2.73 Å. In the fourth Bi5+ site, Bi5+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.30–2.73 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to four Bi5+ atoms to form OBi4 tetrahedra that share corners with two equivalent OSr4CuBi octahedra, corners with four equivalent OBi4 tetrahedra, and edges with four equivalent OBi4 tetrahedra. The corner-sharing octahedral tilt angles are 54°. In the second O2- site, O2- is bonded to four Bi5+ atoms to form OBi4 tetrahedra that share corners with four OSr4CuBi octahedra, corners with four equivalent OBi4 tetrahedra, and edges with four equivalent OBi4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–55°. In the third O2- site, O2- is bonded to four Ca2+ and two equivalent Cu2+ atoms to form a mixture of distorted edge, corner, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–66°. In the fourth O2- site, O2- is bonded to two equivalent Sr2+, two equivalent Ca2+, and two equivalent Cu2+ atoms to form distorted OSr2Ca2Cu2 octahedra that share corners with twelve OCa4Cu2 octahedra, edges with three OCa4Cu2 octahedra, and faces with six OSr2Ca2Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–66°. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Ca2+, one Cu2+, and one Bi5+ atom. In the sixth O2- site, O2- is bonded to four equivalent Sr2+, one Cu2+, and one Bi5+ atom to form distorted OSr4CuBi octahedra that share corners with twelve OSr2Ca2Cu2 octahedra, corners with four equivalent OBi4 tetrahedra, edges with four equivalent OSr4CuBi octahedra, and faces with four equivalent OSr2Ca2Cu2 octahedra. The corner-sharing octahedra tilt angles range from 23–51°. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one Sr2+ and four equivalent Bi5+ atoms. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to one Sr2+ and four equivalent Bi5+ atoms. In the ninth O2- site, O2- is bonded to four Sr2+ and two equivalent Cu2+ atoms to form a mixture of distorted edge, corner, and face-sharing OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–63°. In the tenth O2- site, O2- is bonded to four Sr2+ and two equivalent Cu2+ atoms to form a mixture of distorted edge, corner, and face-sharing OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–63°. In the eleventh O2- site, O2- is bonded to four equivalent Sr2+, one Cu2+, and one Bi5+ atom to form distorted OSr4CuBi octahedra that share corners with twelve OSr4Cu2 octahedra, corners with four equivalent OBi4 tetrahedra, edges with four equivalent OSr4CuBi octahedra, and faces with four equivalent OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 23–51°. In the twelfth O2- site, O2- is bonded to four equivalent Sr2+, one Cu2+, and one Bi5+ atom to form distorted OSr4CuBi octahedra that share corners with twelve OSr4Cu2 octahedra, corners with four equivalent OBi4 tetrahedra, edges with four equivalent OSr4CuBi octahedra, and faces with four equivalent OSr4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 24–51°. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Ca2+ and four equivalent Bi5+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Sr2+ and four equivalent Bi5+ atoms.