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DOE OSTI2020

Materials Data on Ca(BiO2)2 by Materials Project

CaBi2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine BiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There are two shorter (2.31 Å) and two longer (2.32 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six BiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four BiO6 octahedra. There are three shorter (2.39 Å) and three longer (2.40 Å) Ca–O bond lengths. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four BiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five BiO6 octahedra. There are two shorter (2.39 Å) and four longer (2.40 Å) Ca–O bond lengths. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six BiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four BiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.38–2.41 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six BiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four equivalent BiO6 octahedra. All Ca–O bond lengths are 2.40 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five BiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five BiO6 octahedra. There are three shorter (2.39 Å) and three longer (2.40 Å) Ca–O bond lengths. There are nine inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four BiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three BiO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.37–2.42 Å. In the second Bi3+ site, Bi3+ is bonded to four O2- atoms to form BiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six BiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There are a spread of Bi–O bond distances ranging from 2.27–2.30 Å. In the third Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent BiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four BiO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.32–2.50 Å. In the fourth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share corners with six BiO4 tetrahedra, edges with two equivalent BiO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.39–2.42 Å. In the fifth Bi3+ site, Bi3+ is bonded to four O2- atoms to form BiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six BiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–58°. There are a spread of Bi–O bond distances ranging from 2.27–2.32 Å. In the sixth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five BiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three BiO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.35–2.46 Å. In the seventh Bi3+ site, Bi3+ is bonded to four O2- atoms to form BiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six BiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–58°. There are a spread of Bi–O bond distances ranging from 2.26–2.30 Å. In the eighth Bi3+ site, Bi3+ is bonded to four O2- atoms to form BiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six BiO6 octahedra. The corner-sharing octahedra tilt angles range from 55–58°. There are a spread of Bi–O bond distances ranging from 2.27–2.30 Å. In the ninth Bi3+ site, Bi3+ is bonded to four O2- atoms to form BiO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine BiO6 octahedra. The corner-sharing octahedra tilt angles range from 55–60°. There are a spread of Bi–O bond distances ranging from 2.25–2.30 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the fourth O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the seventh O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the tenth O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the twelfth O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the thirteenth O2- site, O2- is bonded to two Ca2+ and two equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Bi3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(CoO2)2 by Materials Project

CaCo2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 54–73°. There are a spread of Ca–O bond distances ranging from 2.14–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six CoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.31 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four CoO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five CoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.21–2.27 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six CoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.30 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six CoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four equivalent CoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.29 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five CoO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five CoO6 octahedra. There are four shorter (2.24 Å) and two longer (2.25 Å) Ca–O bond lengths. There are nine inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four CoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.89–2.09 Å. In the second Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six CoO6 octahedra. The corner-sharing octahedra tilt angles range from 49–64°. There are a spread of Co–O bond distances ranging from 1.85–2.02 Å. In the third Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent CoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.85–2.00 Å. In the fourth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six CoO4 tetrahedra, edges with two equivalent CoO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Co–O bond distances ranging from 1.93–2.06 Å. In the fifth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six CoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Co–O bond distances ranging from 1.85–1.97 Å. In the sixth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five CoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.93–2.12 Å. In the seventh Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six CoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Co–O bond distances ranging from 1.86–2.00 Å. In the eighth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six CoO6 octahedra. The corner-sharing octahedra tilt angles range from 49–63°. There are a spread of Co–O bond distances ranging from 1.86–2.04 Å. In the ninth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 53–66°. There are a spread of Co–O bond distances ranging from 1.97–2.30 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Co3+ atoms to form distorted OCa2Co2 trigonal pyramids that share corners with two OCaCo3 tetrahedra, corners with six OCa2Co2 trigonal pyramids, an edgeedge with one OCaCo3 tetrahedra, and an edgeedge with one OCa2Co2 trigonal pyramid. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the third O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form a mixture of distorted corner and edge-sharing OCaCo3 tetrahedra. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the eighth O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent OCaCo3 tetrahedra and corners with seven OCa2Co2 trigonal pyramids. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the thirteenth O2- site, O2- is bonded to two Ca2+ and two equivalent Co3+ atoms to form distorted OCa2Co2 tetrahedra that share a cornercorner with one OCaCo3 tetrahedra and corners with eight OCa2Co2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the sixteenth O2- site, O2- is bonded to four Co3+ atoms to form distorted OCo4 trigonal pyramids that share corners with three OCaCo3 tetrahedra, corners with five OCa2Co2 trigonal pyramids, and edges with two equivalent OCaCo3 trigonal pyramids. In the seventeenth O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share corners with three OCaCo3 tetrahedra, corners with five OCa2Co2 trigonal pyramids, and edges with two OCo4 trigonal pyramids. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–68°. There are a spread of Ca–O bond distances ranging from 2.18–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.34 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.22–2.33 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.33 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.32 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.31 Å. There are twelve inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.17 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Fe–O bond distances ranging from 1.91–2.05 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.20 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.25 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.18 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–60°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 Å. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.16 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.22 Å. In the ninth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the tenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.34 Å. In the eleventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the twelfth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 1.94–2.13 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Fe2 trigonal pyramids. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Fe2 trigonal pyramids. In the fourth O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCaFe3 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the seventeenth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form corner-sharing OCa2Fe2 tetrahedra. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(SbO2)2 by Materials Project

CaSb2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to five O2- atoms to form distorted CaO5 trigonal bipyramids that share corners with three CaO6 octahedra and a cornercorner with one SbO5 square pyramid. The corner-sharing octahedra tilt angles range from 49–74°. There are a spread of Ca–O bond distances ranging from 2.35–2.76 Å. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.74 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with two equivalent CaO5 trigonal bipyramids and edges with two equivalent SbO5 square pyramids. There are a spread of Ca–O bond distances ranging from 2.33–2.47 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted edge-sharing CaO6 pentagonal pyramids. There are a spread of Ca–O bond distances ranging from 2.33–2.47 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ca–O bond distances ranging from 2.23–2.26 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share a cornercorner with one CaO5 trigonal bipyramid and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ca–O bond distances ranging from 2.34–2.51 Å. There are twelve inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 2.03–2.40 Å. In the second Sb3+ site, Sb3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.95–2.06 Å. In the third Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 1.98–2.68 Å. In the fourth Sb3+ site, Sb3+ is bonded to five O2- atoms to form distorted SbO5 square pyramids that share a cornercorner with one CaO5 trigonal bipyramid and edges with two equivalent CaO6 octahedra. There are a spread of Sb–O bond distances ranging from 1.97–2.54 Å. In the fifth Sb3+ site, Sb3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.93–2.03 Å. In the sixth Sb3+ site, Sb3+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.98–2.06 Å. In the seventh Sb3+ site, Sb3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.92–2.03 Å. In the eighth Sb3+ site, Sb3+ is bonded in a 3-coordinate geometry to three O2- atoms. There are one shorter (2.02 Å) and two longer (2.07 Å) Sb–O bond lengths. In the ninth Sb3+ site, Sb3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.98–2.07 Å. In the tenth Sb3+ site, Sb3+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 1.99–2.26 Å. In the eleventh Sb3+ site, Sb3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There is one shorter (1.93 Å) and two longer (2.03 Å) Sb–O bond length. In the twelfth Sb3+ site, Sb3+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Sb–O bond distances ranging from 1.95–2.14 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one Sb3+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Sb3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Ca2+ and two Sb3+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Sb3+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ca2+ and one Sb3+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Sb3+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Sb3+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Sb3+ atoms. In the ninth O2- site, O2- is bonded in a distorted T-shaped geometry to two Ca2+ and one Sb3+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sb3+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sb3+ atoms. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sb3+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and one Sb3+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sb3+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one Sb3+ atom. In the sixteenth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Ca2+ and two Sb3+ atoms. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Sb3+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Sb3+ atoms. In the nineteenth O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Ca2+ and two Sb3+ atoms. In the twentieth O2- site, O2- is bonded in a distorted T-shaped geometry to two Ca2+ and one Sb3+ atom. In the twenty-first O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two Sb3+ atoms. In the twenty-second O2- site, O2- is bonded in a trigonal planar geometry to one Ca2+ and two Sb3+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sb3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(BO3)2 by Materials Project

Ca(BO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.48 Å. B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.44–1.47 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to one Ca and two equivalent B atoms. In the second O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one B atom. In the third O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(BO4)2 by Materials Project

Ca(BO4)2 crystallizes in the orthorhombic Pban space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.76 Å. B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.41–1.57 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted water-like geometry to one Ca and one B atom. In the second O site, O is bonded in a distorted single-bond geometry to two equivalent Ca and one B atom. In the third O site, O is bonded in a distorted single-bond geometry to one B and one O atom. The O–O bond length is 1.35 Å. In the fourth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(IO6)2 by Materials Project

Ca(O6I)2 crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional. Ca is bonded to six O atoms to form distorted CaO6 pentagonal pyramids that share edges with two equivalent IO5 trigonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.43–2.59 Å. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one I atom. The O–I bond length is 1.80 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Ca and one O atom. The O–O bond length is 1.23 Å. In the third O site, O is bonded in an L-shaped geometry to one Ca and one I atom. The O–I bond length is 1.83 Å. In the fourth O site, O is bonded in a single-bond geometry to one O atom. In the fifth O site, O is bonded in a water-like geometry to one Ca and one I atom. The O–I bond length is 1.81 Å. In the sixth O site, O is bonded in a distorted bent 150 degrees geometry to two equivalent I atoms. There are one shorter (1.96 Å) and one longer (2.07 Å) O–I bond lengths. I is bonded to five O atoms to form IO5 trigonal bipyramids that share corners with two equivalent IO5 trigonal bipyramids and an edgeedge with one CaO6 pentagonal pyramid.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(IO2)2 by Materials Project

Ca(O2I)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two Ca(O2I)2 sheets oriented in the (0, 1, 0) direction. Ca is bonded in a square co-planar geometry to four O atoms. There are two shorter (2.32 Å) and two longer (2.37 Å) Ca–O bond lengths. There are two inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to one Ca and two equivalent I atoms. There are one shorter (1.92 Å) and one longer (2.58 Å) O–I bond lengths. In the second O site, O is bonded in a bent 120 degrees geometry to one Ca and one I atom. The O–I bond length is 1.92 Å. I is bonded in a 2-coordinate geometry to three O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Investigation of the 244 Pu ⁢( 48 Ca,𝑥⁢𝑛) 292−𝑥 Fl reaction with the LBNL SHREC detector: Investigation of decay chains of isotopes of flerovium (𝑍=114)

The 244 Pu ⁢( 48 Ca,𝑥⁢𝑛)⁢ 292−𝑥 Fl reaction was investigated at Lawrence Berkeley National Laboratory’s 88 Inch Cyclotron using the Berkeley Gas-filled Separator (BGS), the newly installed Superheavy Recoil detector, along with an upgraded digital electronics and data acquisition system. Seven decay chains were observed starting with an evaporation residue, followed by a single 𝛼 decay and a spontaneous fission. The decay characteristics of these seven decay chains led to an assignment to 288 Fl , the product of the 4⁢𝑛 reaction channel. Two additional chains were (tentatively) assigned to the decay of the 3⁢𝑛 exit channel, 289 Fl . Cross sections for the 4⁢𝑛 and 3⁢𝑛 exit channels were 𝜎 prod =6.7⁢($^{36}_{25}$) pb and 𝜎 prod =1.6⁢($^{22}_{11}$) pb, respectively. Another decay chain, tentatively assigned to the 5⁢𝑛 exit channel through the 48 Ca + 244 Pu reaction or the 3⁢𝑛 exit channel of the 48 Ca + 242 Pu reaction, was also detected. Detailed information regarding the observed decay chains and their nuclear structure aspects is discussed, along with the performance of the BGS and the new detection system.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Predominant Proton Insertion during Electrochemical Cycling of ε-VOPO 4 in a Nonaqueous Ca-Ion Electrolyte

Calcium-ion batteries (CIBs) are promising for next-generation energy storage systems. However, many reported Ca-ion storage mechanisms lack direct structural evidence, raising concerns that the observed electrochemistry may instead originate from proton insertion. Herein, we investigate the electrochemical cycling of a VOPO 4 electrode in an aprotic Ca electrolyte with trace water to clarify the charge storage mechanism. While electrochemistry, elemental analysis, and X-ray absorption spectroscopy seem to support Ca-ion intercalation in the VOPO 4 electrode, X-ray diffraction and electron microscopy unequivocally show proton insertion as the predominant charge storage mechanism. The apparent variation of Ca content in the electrode with the state of charge is attributed to the formation and dissolution of Ca-containing precipitates on the surface of VOPO 4 particles. Our work demonstrates the propensity of proton participation in the intercalation reaction in Ca-ion batteries and the necessity of structural evidence in understanding reactions in multivalent electrochemical systems.

Wang, Jiwei [Binghamton University, NY (United Sta↗
DOE OSTI2024

Enhanced Stability and Sensitivity for CA-125 Detection Under Microfluidic Shear Flow Using Polyethylene Glycol-Coated Biosensor

The microfluidic-based point-of-care (POC) diagnostic tool has garnered significant interest in recent years, offering rapid and cost-effective disease detection. There is a growing trend toward integrating microfluidic platforms with biosensors, aligning lab-on-a-chip technologies with POC diagnostic devices. Despite numerous efforts to incorporate biosensors into microfluidic systems, researchers have performed very limited investigations on the stability of biomarker detection when biosensors operate under microfluidic shear flow conditions. Gold nanoparticles (AuNPs) are a widely employed material in capacitive biosensors for antibody immobilization and sensitivity enhancement. However, AuNPs have limitations in providing stable detection of biomarkers within microfluidic shear flow due to their agglomeration nature. This study addresses these limitations by employing 2 kDa polyethylene glycol (PEG) as an intermediate biofunctional layer to immobilize CA-125 antibodies on gold-interdigitated electrodes for the stable and accurate detection of CA-125 antigens. The stabilities and sensitivities of AuNPs and PEG-coated biosensors are evaluated under both static drop and microfluidic shear flow conditions for CA-125 antigen detection. The experimental results demonstrate a capacitive signal response (5660 pF at 10 kHz) 2.2 times higher using the PEG-coated biosensor than the signal (2551 pF at 10 kHz) measured by the AuNP-coated biosensor in the detection of CA-125 antigen–antibody conjugation under static drop conditions, indicating the higher sensitivity of the PEG-coated biosensor. Additionally, the PEG-coated biosensor exhibits better consistency for the CA-125 antigen detection between static drop and microfluidic shear flow conditions (Cp decrease in percentage (ΔCp%↓) = 2.9% at 10 kHz) compared to the electrical signals measured using the AuNP-coated biosensor (ΔCp%↓ = 32.4% at 10 kHz), which suggests that the PEG-coated biosensor demonstrates higher stability for CA-125 antigen detection under microfluidic shear flow conditions. With these significant improvements brought by the PEG-coated biosensor, especially under microfluidic conditions, a substantial hurdle in developing electrical biosensors for POC diagnostic applications has been overcome, expediting further advancements in the field.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Osmosensor-mediated control of Ca 2+ spiking in pollen germination

Higher plants survive terrestrial water deficiency and fluctuation by arresting cellular activities (dehydration) and resuscitating processes (rehydration). However, how plants monitor water availability during rehydration is unknown. Although increases in hypo-osmolarity-induced cytosolic Ca 2+ concentration (HOSCA) have long been postulated to be the mechanism for sensing hypo-osmolarity in rehydration, the molecular basis remains unknown. Because osmolarity triggers membrane tension and the osmosensing specificity of osmosensing channels can only be determined in vivo, these channels have been classified as a subtype of mechanosensors. Here we identify bona fide cell surface hypo-osmosensors in Arabidopsis and find that pollen Ca 2+ spiking is controlled directly by water through these hypo-osmosensors—that is, Ca 2+ spiking is the second messenger for water status. We developed a functional expression screen in Escherichia coli for hypo-osmosensitive channels and identified OSCA2.1, a member of the hyperosmolarity-gated calcium-permeable channel (OSCA) family of proteins. We screened single and high-order OSCA mutants, and observed that the osca2.1/osca2.2 double-knockout mutant was impaired in pollen germination and HOSCA. OSCA2.1 and OSCA2.2 function as hypo-osmosensitive Ca 2+ -permeable channels in planta and in HEK293 cells. Decreasing osmolarity of the medium enhanced pollen Ca 2+ oscillations, which were mediated by OSCA2.1 and OSCA2.2 and required for germination. OSCA2.1 and OSCA2.2 convert extracellular water status into Ca 2+ spiking in pollen and may serve as essential hypo-osmosensors for tracking rehydration in plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Spectroscopic identification of Ca-bearing uranyl silicates formed in C–S–H systems

Portland cement-based grouts used for radioactive waste immobilisation contain a Ca- and Si-rich binder phase, known as calcium–silicate–hydrate (C–S–H). Depending on the blend of cement used, the Ca/Si ratio can vary considerably. A range of C–S–H minerals with Ca/Si ratios from 0.6 to 1.6 were synthesised and contacted with aqueous U(VI) at 0.5 mM and 10 mM concentrations. Solid-state 29 Si MAS-NMR spectroscopy was applied to probe the Si coordination environment in U(VI)-contacted C–S–H minerals and, in conjunction with U L III -edge X-ray absorption spectroscopy analysis, inferences of the fate of U(VI) in these systems were made. At moderate or high Ca/Si ratios, uranophane-type uranyl silicates or Ca-uranates dominated, while at the lowest Ca/Si ratios, the formation of a Ca-bearing uranyl silicate mineral, similar to haiweeite (Ca[(UO 2 ) 2 Si 5 O 12 (OH) 2 ]·3H 2 O) or Ca-bearing weeksite (Ca 2 (UO 2 ) 2 Si 6 O 15 ·10H 2 O) was identified. This study highlights the influence of Ca/Si ratio on uranyl sequestration, of interest in the development of post-closure safety models for U-bearing radioactive waste disposal.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Design and structural basis of selective 1,4-dihydropyridine inhibitors of the calcium-activated potassium channel K Ca 3.1

The 1,4-dihydropyridines, drugs with well-established bioavailability and toxicity profiles, have proven efficacy in treating human hypertension, peripheral vascular disorders, and coronary artery disease. Every 1,4-dihydropyridine in clinical use blocks L-type voltage-gated calcium channels. We now report our development, using selective optimization of a side activity (SOSA), of a class of 1,4-dihydropyridines that selectively and potently inhibit the intermediate-conductance calcium-activated K + channel K Ca 3.1, a validated therapeutic target for diseases affecting many organ systems. One of these 1,4-dihydropyridines, DHP-103, blocked K Ca 3.1 with an IC 50 of 6 nM and exhibited exquisite selectivity over calcium channels and a panel of >100 additional molecular targets. Using high-resolution structure determination by cryogenic electron microscopy together with mutagenesis and electrophysiology, we delineated the drug binding pocket for DHP-103 within the water-filled central cavity of the K Ca 3.1 channel pore, where bound drug directly impedes ion permeation. DHP-103 inhibited gain-of-function mutant K Ca 3.1 channels that cause hereditary xerocytosis, suggesting its potential use as a therapeutic for this hemolytic anemia. In a rat model of acute ischemic stroke, the second leading cause of death worldwide, DHP-103 administered 12 h postischemic insult in proof-of-concept studies reduced infarct volume, improved balance beam performance (measure of proprioception) and decreased numbers of activated microglia in infarcted areas. K Ca 3.1-selective 1,4-dihydropyridines hold promise for the many diseases for which K Ca 3.1 has been experimentally confirmed as a therapeutic target.

Ong, Seow Theng [Lee Kong Chian School of Medicine↗
DOE OSTI2022

Microscopic study of the fusion reactions 40,48 Ca+ 78 Ni and the effect of the tensor force

In this work, we provide a microscopic description of the fusion reactions between 40,48 Ca and 78 Ni. The internuclear potentials are obtained using the density-constrained (DC) time-dependent Hartree-Fock (TDHF) approach and fusion cross sections are calculated via the incoming wave boundary condition method. By performing DC-TDHF calculations at several selected incident energies, the internuclear potentials for both systems are obtained and the energy-dependence of fusion barrier are revealed. The influence of tensor force on internuclear potentials of 48 Ca+ 78 Ni is more obvious than those of 40 Ca+ 78 Ni. By comparing the calculated fusion cross sections between 40 Ca+ 78 Ni and 48 Ca+ 78 Ni, an interesting enhancement of subbarrier fusion cross sections for the former system is found, which can be explained by the narrow width of internuclear potential for 40 Ca+ 78 Ni while the barrier heights and positions are very close to each other. The tensor force suppresses the subbarrier fusion cross sections of both two systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Flg22‐induced Ca 2+ increases undergo desensitization and resensitization

The flagellin epitope flg22, a pathogen-associated molecular pattern (PAMP), binds to the receptor-like kinase FLAGELLIN SENSING2 (FLS2), and triggers Ca 2+ influx across the plasma membrane (PM). The flg22-induced increases in cytosolic Ca 2+ concentration ([Ca 2+ ]i) (FICA) play a crucial role in plant innate immunity. It's well established that the receptor FLS2 and reactive oxygen species (ROS) burst undergo sensitivity adaptation after flg22 stimulation, referred to as desensitization and resensitization, to prevent over responses to pathogens. However, whether FICA also mount adaptation mechanisms to ensure appropriate and efficient responses against pathogens remains poorly understood. Here, we analysed systematically [Ca 2+ ]i increases upon two successive flg22 treatments, recorded and characterized rapid desensitization but slow resensitization of FICA in Arabidopsis thaliana. Pharmacological analyses showed that the rapid desensitization might be synergistically regulated by ligand-induced FLS2 endocytosis as well as the PM depolarization. The resensitization of FICA might require de novo FLS2 protein synthesis. FICA resensitization appeared significantly slower than FLS2 protein recovery, suggesting additional regulatory mechanisms of other components, such as flg22-related Ca 2+ permeable channels. Taken together, we have carefully defined the FICA sensitivity adaptation, which will facilitate further molecular and genetic dissection of the Ca 2+ -mediated adaptive mechanisms in PAMP-triggered immunity.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Rationalizing Calcium Electrodeposition Behavior by Quantifying Ethereal Solvation Effects on Ca 2+ Coordination in Well-Dissociated Electrolytes

Ca-ion electrochemical systems have been pushed to the forefront of recent multivalent energy storage advances due to their use of earth-abundant redox materials and their high theoretical specific densities in relation to monovalent or even other more widely explored multivalent-charge carriers. However, significant pitfalls in metal plating and stripping arise from electrolyte decomposition and can be related to the coordination environment around Ca 2+ with both the negatively charged anion and the organic–aprotic solvent. Here, we apply multiple spectroscopic techniques in conjunction with density functional theory to evaluate the coordination environment of Ca 2+ across a class of ethereal solvents. Through the combination of X-ray absorption fine structure and time-dependent density functional theory, descriptive measures of the local geometry, coordination, and electronic structure of Ca–ethereal complexes provide distinct structural trends depending on the extent of the Ca 2+ –solvent interaction. Finally, we correlate these findings with electrochemical measurements of calcium tetrakis(hexafluoroisopropoxy)borate (CaBHFIP 2 ) salts dissolved within this class of solvents to provide insight into the preferred structural configuration of Ca 2+ electrolytic solutions for optimized electrochemical plating and stripping.

25 ENERGY STORAGE↗
DOE OSTI2021

Nebular Models of Sub-Chandrasekhar Mass Type Ia Supernovae: Clues to the Origin of Ca-rich Transients

In this work we use non-local thermal equilibrium radiative transport modeling to examine observational signatures of sub-Chandrasekhar mass double detonation explosions in the nebular phase. Results range from spectra that look like typical and subluminous Type Ia supernovae (SNe) for higher mass progenitors to spectra that look like Ca-rich transients for lower mass progenitors. This ignition mechanism produces an inherent relationship between emission features and the progenitor mass as the ratio of the nebular [Ca II ]/[Fe III ] emission lines increases with decreasing white dwarf mass. Examining the [Ca II ]/[Fe III ] nebular line ratio in a sample of observed SNe we find further evidence for the two distinct classes of SNe Ia identified in Polin et al. by their relationship between Si ii velocity and B-band magnitude, both at time of peak brightness. This suggests that SNe Ia arise from more than one progenitor channel, and provides an empirical method for classifying events based on their physical origin. Furthermore, we provide insight to the mysterious origin of Ca-rich transients. Low-mass double detonation models with only a small mass fraction of Ca (1%) produce nebular spectra that cool primarily through forbidden [Ca II ] emission.

79 ASTRONOMY AND ASTROPHYSICS↗