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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Thermodynamic and kinetic properties of layered-CaCo2O4 for the Ca-ion batteries: a systematic first-principles study

One of the more promising directions in multivalent energy storage is systems based on Ca ion intercalation due to the potential for high voltage and capacity. A major challenge for enabling such a battery is to find cathode materials capable of fast ionic diffusion and reversible insertion of Ca ions. Here, on the basis of first-principles calculations, we have demonstrated that layered CaCo 2 O 4 exhibits favorable thermodynamic and kinetic properties that should enable topotactic Ca ion intercalation reactions. The P3-type layered Ca x Co 2 O 4 (0 < x < 1) with either of space groups of P 1 or P 2 1 / m are stable at multiple Ca concentrations and show a smooth voltage plateau higher than 3 V up to X = 0.5. The energy barriers of the single Ca ion migration are as low as 0.36 eV and 0.27 eV at the dilute and high vacancy concentration limits, respectively. Therefore, although varying the vacancy environments of the diffusing atom influences the migration barriers, they do not exceed 0.6 eV. Stochastic analysis of Ca hopping events performed by ab initio molecular dynamics (AIMD) simulation has shown that the migration barriers are lower than 0.32 eV. Therefore, the Ca diffusivity at room temperature extrapolated from the AIMD results is comparable to Li diffusivity (>10 -10 cm 2 s -1 ) in conventional Li cathode materials, suggesting the feasibility of layered Ca x Co 2 O 4 as multivalent cathode materials. Finally, the structural factors that enable fast diffusion are discussed.

25 ENERGY STORAGE↗
DOE OSTI2022

Newly discovered Ca ii absorbers in the early Universe: statistics, element abundances, and dust

ABSTRACT We report discoveries of 165 new quasar Ca ii absorbers from the Sloan Digital Sky Survey (SDSS) Data Releases 7 and 12. Our ca ii rest-frame equivalent width distribution supports the weak and strong subpopulations, split at ${W}^{\lambda 3934}_{0}=0.7$ Å. Comparison of both populations’ dust depletion shows clear consistency for weak absorber association with halo-type gas in the Milky Way (MW), while strong absorbers have environments consistent with halo and disc-type gas. We probed our high-redshift Ca ii absorbers for 2175 Å dust bumps, discovering 12 2175 Å dust absorbers (2DAs). This clearly shows that some Ca ii absorbers follow the Large Magellanic Cloud (LMC) extinction law rather than the Small Magellanic Cloud extinction law. About 33 per cent of our strong Ca ii absorbers exhibit the 2175 Å dust bump, while only 6 per cent of weak Ca ii absorbers show this bump. 2DA detection further supports the theory that strong Ca ii absorbers are associated with disc components and are dustier than the weak population. Comparing average Ca ii absorber dust depletion patterns to that of Damped Ly α absorbers (DLAs), Mg ii absorbers, and 2DAs shows that Ca ii absorbers generally have environments with more dust than DLAs and Mg ii absorbers, but less dust than 2DAs. Comparing 2175 Å dust bump strengths from different samples and also the MW and LMC, the bump strength appears to grow stronger as the redshift decreases, indicating dust growth and the global chemical enrichment of galaxies in the Universe over time.

Astronomy & Astrophysics↗
DOE OSTI2022

Exploiting dissipative reactions to perform in-beam γ-ray spectroscopy of the neutron-deficient isotopes 38,39 Ca

The neutron-deficient Ca isotopes continue to attract attention due to their importance for testing isospin symmetry and their relevance in capture reactions of interest for nova nucleosynthesis and the shape of light curves in Type I x-ray bursts. To date, spectroscopic information on 38,39 Ca is largely limited to data on lower-spin excited states. Here, we report in-beam γ-ray spectroscopy of complementary higher-spin, complex-structure states in 39 Ca populated in fast-beam-induced, momentum-dissipative processes leading to neutron pickup onto excited configurations of the projectile, 9 Be( 38 Ca*, 39 Ca + γ)X. Such a dissipative reaction was recently characterized for the case of inelastic scattering of 38 Ca off 9 Be, 9 Be( 38 Ca, 38 Ca + γ)X. Additional data and discussion on the nuclear structure of 38 Ca is also presented. Furthermore, an explanation for the more-complex-structure states, populated with small cross sections in one-nucleon knockout reactions, and observed in the tails of their longitudinal momentum distributions, is also offered.

20 ≤ A ≤ 38↗
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 eight 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 56–58°. 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 three CaO4 tetrahedra, corners with three BiO4 tetrahedra, and edges with six BiO6 octahedra. There are two shorter (2.39 Å) and four longer (2.40 Å) Ca–O bond lengths. In the third 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 55–59°. All Ca–O bond lengths are 2.31 Å. In the fourth 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 a spread of Ca–O bond distances ranging from 2.39–2.41 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. There are five shorter (2.40 Å) and one longer (2.41 Å) Ca–O bond lengths. In the sixth 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 2.39–2.41 Å. In the seventh 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 a spread of Ca–O bond distances ranging from 2.39–2.41 Å. In the eighth 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 (2.38 Å) and three longer (2.41 Å) Ca–O bond lengths. There are twelve inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share corners with three CaO4 tetrahedra, corners with three BiO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four BiO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.36–2.46 Å. In the second 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 2.33–2.50 Å. In the third 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 three shorter (2.28 Å) and one longer (2.30 Å) Bi–O bond lengths. In the fourth 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 2.38–2.43 Å. In the fifth 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 three shorter (2.25 Å) and one longer (2.31 Å) Bi–O bond lengths. In the sixth 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 three shorter (2.28 Å) and one longer (2.32 Å) Bi–O bond lengths. In the seventh 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 2.39–2.43 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 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 2.36–2.46 Å. In the tenth 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 55–59°. There are a spread of Bi–O bond distances ranging from 2.27–2.30 Å. In the eleventh 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 2.35–2.47 Å. In the twelfth 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 one shorter (2.26 Å) and three longer (2.27 Å) Bi–O bond lengths. There are twenty-four 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 to two Ca2+ and two equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. 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 in a distorted rectangular see-saw-like geometry to four Bi3+ atoms. In the fifth O2- site, O2- is bonded to two Ca2+ and two Bi3+ atoms to form distorted OCa2Bi2 trigonal pyramids that share corners with seven OCaBi3 trigonal pyramids and an edgeedge with one OCa2Bi2 trigonal pyramid. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the ninth O2- site, O2- is bonded in a 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 distorted OCa2Bi2 trigonal pyramids that share corners with six OCa2Bi2 trigonal pyramids and edges with two OCaBi3 trigonal pyramids. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the fourteenth O2- site, O2- is bonded to one Ca2+ and three Bi3+ atoms to form a mixture of distorted edge and corner-sharing OCaBi3 trigonal pyramids. 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 rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the seventeenth 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 eighteenth 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 nineteenth 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 twentieth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Bi3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Bi3+ atoms. In the twenty-fourth 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 eight 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 57–74°. There are a spread of Ca–O bond distances ranging from 2.14–2.28 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with three CaO4 tetrahedra, corners with three CoO4 tetrahedra, and edges with six CoO6 octahedra. There are four shorter (2.24 Å) and two longer (2.25 Å) Ca–O bond lengths. In the third 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 52–74°. There are a spread of Ca–O bond distances ranging from 2.14–2.25 Å. In the fourth 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 2.22–2.29 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 2.23–2.30 Å. In the sixth 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 seventh 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. All Ca–O bond lengths are 2.25 Å. In the eighth 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 four shorter (2.23 Å) and two longer (2.30 Å) Ca–O bond lengths. There are twelve inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three CaO4 tetrahedra, corners with three CoO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.89–2.05 Å. In the second 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 1.84–2.02 Å. In the third 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 1.85–2.04 Å. In the fourth 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 fifth 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 56–65°. There are a spread of Co–O bond distances ranging from 1.94–2.39 Å. In the sixth 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 48–66°. There are a spread of Co–O bond distances ranging from 1.85–1.98 Å. In the seventh 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 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 48–65°. There are a spread of Co–O bond distances ranging from 1.86–2.03 Å. In the ninth 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 1.91–2.13 Å. In the tenth 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 1.86–2.05 Å. In the eleventh 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 twelfth 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 55–64°. There are a spread of Co–O bond distances ranging from 1.94–2.41 Å. There are twenty-four 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 a cornercorner with one OCa2Co2 tetrahedra, corners with eleven OCo4 trigonal pyramids, and edges with three OCa2Co2 trigonal pyramids. In the second O2- site, O2- is bonded to two Ca2+ and two equivalent Co3+ atoms to form distorted OCa2Co2 trigonal pyramids that share a cornercorner with one OCaCo3 tetrahedra, corners with eleven OCo4 trigonal pyramids, and edges with three OCa2Co2 trigonal pyramids. In the third O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share a cornercorner with one OCa2Co2 tetrahedra, corners with eleven OCo4 trigonal pyramids, and edges with three OCa2Co2 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Co3+ atoms to form a mixture of distorted corner and edge-sharing OCo4 trigonal pyramids. In the fifth O2- site, O2- is bonded to two Ca2+ and two Co3+ atoms to form distorted OCa2Co2 trigonal pyramids that share a cornercorner with one OCaCo3 tetrahedra, corners with seven OCaCo3 trigonal pyramids, an edgeedge with one OCaCo3 tetrahedra, and an edgeedge with one OCa2Co2 trigonal pyramid. In the sixth O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form a mixture of distorted corner and edge-sharing OCaCo3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the eighth O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form a mixture of distorted corner and edge-sharing OCaCo3 trigonal pyramids. In the ninth O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 tetrahedra that share corners with eight OCaCo3 trigonal pyramids and edges with two equivalent OCa2Co2 trigonal pyramids. 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 distorted 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 in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the fourteenth 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 OCo4 trigonal pyramids. 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 in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Co3+ atoms. In the nineteenth O2- site, O2- is bonded to two Ca2+ and two equivalent Co3+ atoms to form distorted corner-sharing OCa2Co2 tetrahedra. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Co3+ atoms. In the twenty-second O2- site, O2- is bonded to four Co3+ atoms to form distorted OCo4 trigonal pyramids that share corners with two equivalent OCa2Co2 tetrahedra, corners with six OCaCo3 trigonal pyramids, and edges with two equivalent OCaCo3 trigonal pyramids. In the twenty-third O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent OCa2Co2 tetrahedra, corners with six OCo4 trigonal pyramids, and edges with two OCo4 trigonal pyramids. In the twenty-fourth 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(SbO2)2 by Materials Project

CaSb2O4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are eight inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.58 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, a cornercorner with one SbO4 tetrahedra, and an edgeedge with one SbO5 square pyramid. There are a spread of Ca–O bond distances ranging from 2.41–2.95 Å. In the third Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with three equivalent SbO5 square pyramids. The corner-sharing octahedra tilt angles range from 63–68°. There are a spread of Ca–O bond distances ranging from 2.33–2.45 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one SbO4 tetrahedra, corners with two equivalent CaO4 tetrahedra, an edgeedge with one CaO6 octahedra, and an edgeedge with one SbO5 square pyramid. There are a spread of Ca–O bond distances ranging from 2.28–2.70 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent SbO4 tetrahedra, edges with two CaO6 octahedra, and edges with four equivalent SbO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.79 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with three equivalent SbO4 tetrahedra, edges with two CaO6 octahedra, and edges with two equivalent SbO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.21–2.55 Å. In the seventh Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent SbO4 tetrahedra and an edgeedge with one CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.55 Å. In the eighth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share edges with two CaO6 octahedra and edges with two equivalent SbO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.45 Å. There are twelve inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sb–O bond distances ranging from 2.06–2.77 Å. In the second Sb3+ site, Sb3+ is bonded to five O2- atoms to form SbO5 square pyramids that share corners with three equivalent CaO4 tetrahedra and edges with two CaO6 octahedra. There are a spread of Sb–O bond distances ranging from 2.00–2.38 Å. In the third Sb3+ site, Sb3+ is bonded to four O2- atoms to form distorted SbO4 tetrahedra that share corners with four equivalent SbO6 octahedra and corners with six CaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–72°. There are a spread of Sb–O bond distances ranging from 1.98–2.39 Å. In the fourth Sb3+ site, Sb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sb–O bond distances ranging from 2.09–2.84 Å. In the fifth Sb3+ site, Sb3+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are one shorter (1.98 Å) and two longer (2.03 Å) Sb–O bond lengths. In the sixth Sb3+ site, Sb3+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are one shorter (2.01 Å) and two longer (2.06 Å) Sb–O bond lengths. In the seventh Sb3+ site, Sb3+ is bonded to six O2- atoms to form distorted SbO6 octahedra that share corners with two equivalent SbO4 tetrahedra, edges with two equivalent SbO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Sb–O bond distances ranging from 2.05–2.65 Å. In the eighth Sb3+ site, Sb3+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 2.01–2.81 Å. In the ninth Sb3+ site, Sb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sb–O bond distances ranging from 2.04–2.78 Å. In the tenth Sb3+ site, Sb3+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are two shorter (2.02 Å) and one longer (2.05 Å) Sb–O bond lengths. In the eleventh Sb3+ site, Sb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sb–O bond distances ranging from 1.95–2.71 Å. In the twelfth Sb3+ site, Sb3+ is bonded to four O2- atoms to form distorted SbO4 tetrahedra that share corners with three CaO6 octahedra. The corner-sharing octahedra tilt angles range from 55–68°. There are a spread of Sb–O bond distances ranging from 2.03–2.51 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Sb3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Sb2 tetrahedra. In the second O2- site, O2- is bonded to two Ca2+ and two equivalent Sb3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Sb2 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the fifth O2- site, O2- is bonded to two Ca2+ and two Sb3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Sb2 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and three Sb3+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the tenth O2- site, O2- is bonded to two Ca2+ and two Sb3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Sb2 tetrahedra. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the twelfth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Ca2+ and two Sb3+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Sb3+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two equivalent Sb3+ atoms. In the fifteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and three Sb3+ atoms. In the sixteenth O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Ca2+ and two equivalent Sb3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Sb3+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Ca2+ and two Sb3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two equivalent Sb3+ atoms. In the twentieth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Sb3+ atoms. In the twenty-first O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Ca2+ and two equivalent Sb3+ atoms. In the twenty-second O2- site, O2- is bonded in a 1-coordinate geometry to four Sb3+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Sb3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Sb3+ 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 eight 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 56–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.30 Å. In the third 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 54–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.23 Å. In the fourth 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 2.23–2.32 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 2.28–2.31 Å. In the sixth 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 seventh 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 2.24–2.30 Å. In the eighth 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 2.28–2.34 Å. There are sixteen inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.23 Å. In the second 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 1.97–2.20 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.21 Å. In the fourth 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 51–60°. There are a spread of Fe–O bond distances ranging from 1.91–2.06 Å. In the fifth 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 1.94–2.18 Å. In the sixth 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 54–60°. There are a spread of Fe–O bond distances ranging from 1.94–2.10 Å. In the seventh 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 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 Å. In the eighth 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 1.95–2.18 Å. In the ninth 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 2.04–2.18 Å. In the tenth 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 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.03 Å. In the eleventh 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 twelfth 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 1.97–2.20 Å. In the thirteenth 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 1.97–2.20 Å. In the fourteenth 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 51–60°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the fifteenth 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 1.97–2.19 Å. In the sixteenth 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 thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the second O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the third O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. 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 one Ca2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. 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 to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three 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 one Ca2+ and three Fe3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. 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 one Ca2+ and three Fe3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form corner-sharing OCa2Fe2 tetrahedra. In the twenty-fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the thirtieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-second 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(BO5)2 by Materials Project

Ca(BO5)2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two Ca(BO5)2 sheets oriented in the (1, 0, 0) direction. Ca is bonded in a 2-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.24–3.06 Å. B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.31–1.43 Å. There are five inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Ca and one B atom. In the second O site, O is bonded in a single-bond geometry to one Ca and one B atom. In the third 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 fourth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the fifth O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(GePt)2 by Materials Project

Ca(PtGe)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight Pt and eight Ge atoms. There are a spread of Ca–Pt bond distances ranging from 3.21–3.43 Å. There are a spread of Ca–Ge bond distances ranging from 3.21–3.42 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Ca and four equivalent Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.53–2.56 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Ca and five Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.44–2.56 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Ca and five Pt atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Ca and four equivalent Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(GePt)2 by Materials Project

Ca(PtGe)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ca is bonded in a 7-coordinate geometry to eight Pt and eight Ge atoms. There are a spread of Ca–Pt bond distances ranging from 3.24–3.45 Å. There are a spread of Ca–Ge bond distances ranging from 3.23–3.39 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Ca and five Ge atoms. There are one shorter (2.46 Å) and four longer (2.56 Å) Pt–Ge bond lengths. In the second Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Ca and four equivalent Ge atoms. There are two shorter (2.55 Å) and two longer (2.56 Å) Pt–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Ca and five Pt atoms. In the second Ge site, Ge is bonded to four equivalent Ca and four equivalent Pt atoms to form a mixture of distorted face and edge-sharing GeCa4Pt4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NO5)2 by Materials Project

(CaN2O9)2O2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two hydrogen peroxide molecules and two CaN2O9 clusters. In each CaN2O9 cluster, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.84 Å. There are two inequivalent N sites. In the first N site, N is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.23 Å) and two longer (1.29 Å) N–O bond length. In the second N site, N is bonded in a trigonal planar geometry to three O atoms. There are a spread of N–O bond distances ranging from 1.22–1.30 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one N atom. In the second O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.30 Å) and one longer (1.31 Å) O–O bond length. In the third O site, O is bonded in an L-shaped geometry to one Ca and one O atom. In the fourth O site, O is bonded in an L-shaped geometry to one Ca and one N atom. In the fifth O site, O is bonded in an L-shaped geometry to one Ca and one N atom. In the sixth O site, O is bonded in a water-like geometry to one Ca and one O atom. In the seventh O site, O is bonded in a single-bond geometry to one N atom. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to two equivalent Ca and one N atom. In the ninth O site, O is bonded in a water-like geometry to one Ca and one N atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Ordering in liquid and its heredity impact on phase transformation of Mg-Al-Ca alloys

It is a long-sought goal to achieve desired mechanical properties through tailoring phase formation in alloys, especially for complicated multi-phase alloys. In fact, unveiling nucleation of competitive crystalline phases during solidification hinges on the nature of liquid. Here we employ ab initio molecular dynamics simulations (AIMD) to reveal liquid configuration of the Mg-Al-Ca alloys and explore its effect on the transformation of Ca-containing Laves phase from Al 2 Ca to Mg 2 Ca with increasing Ca/Al ratio (r Ca/Al ). There is structural similarity between liquid and crystalline phase in terms of the local arrangement environment, and the connection schemes of polyhedras. The forming signature of Mg 2 Ca, as hinted by the topological and chemical short-range order originating from liquid, ascends monotonically with increasing r Ca/Al . However, Al 2 Ca crystal-like order increase at first and then decrease at the crossover of r Ca/Al = 0.74, corresponding to experimental composition of phase transition from Al 2 Ca to Mg 2 Ca. The origin of phase transformation across different compositions lies in the dense packing of atomic configurations and preferential bonding of chemical species in both liquid and solid. The present finding provides a feasible scenario for manipulating phase formation to achieve high performance alloys by tailoring the crystal-like order in liquid.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Solid-State Calcium-Ion Diffusion in Ca 1.5 Ba 0.5 Si 5 O 3 N 6

Rechargeable batteries based on multivalent working ions are promising candidates for next-generation high-energy-density batteries. Development of these technologies, however, is largely limited by the low diffusion rate of multivalent ions in solid-state materials, thereby necessitating a better understanding of the design principles that control multivalent-ion mobility. We report Ca 1.5 Ba 0.5 Si 5 O 3 N 6 as a potential calcium solid-state conductor and investigate its Ca migration mechanism by means of ab initio computations and neutron diffraction. This compound contains partially occupied Ca sites in close proximity to each other, providing a unique mechanism for Ca migration. Nuclear density maps obtained with the maximum entropy method from neutron powder diffraction data provide strong evidence for low-energy percolating one-dimensional pathways for Ca-ion migration. Ab initio molecular dynamics simulations further support a low Ca-ion migration barrier of ~400 meV when Ca vacancies are present and reveal a unique "vacancy-adjacent"concerted ion migration mechanism. This work provides a new understanding of solid-state Ca-ion diffusion and insights into the future design of novel cation configurations that utilize the interactions between mobile ions to enable fast multivalent-ion conduction in solid-state materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Synthesis and Transport Properties of the Family of Zintl Phases Ca 3 RESb 3 (RE = La–Nd, Sm, Gd–Tm, Lu): Exploring the Roles of Crystallographic Disorder and Core 4f Electrons for Enhancing Thermoelectric Performance

Zintl phases with complex crystal structures have been studied as promising candidate-materials for thermoelectric (TE) applications. Here, we report the syntheses of the family of rare-earth metal Zintl phases with the general formula Ca 4–x RE x Sb 3 (x ≈ 1; RE = La–Nd, Sm, Gd–Tm, Lu). The structural elucidation is based on refinements of single-crystal X-ray diffraction data for 12 unique chemical compositions. The cubic structure is confirmed as belonging to the anti-Th 3 P 4 structure type (space group I4¯3d, no. 220, Z = 4), where the Ca and RE atoms share the same atomic site with ca. 75% and 25% occupancies, respectively. Such crystallographic disordering of divalent Ca and trivalent RE atoms in the structure provides a pathway to intricate bonding. The latter, together with the presence of heavy elements such as Sb and the lanthanides, are expected to enhance the scattering probability of phonons, thereby leading to as low thermal conductivity κ as that of the ordered RE 4 Sb 3 . The drive of the hypothetical parent compound Ca 4 Sb 3 to be stabilized by alloying with rare-earth metals can be understood following the Zintl-Klemm concept, as the resultant formula may be rationalized as (Ca 2+ ) 3 RE 3+ (Sb 3– ) 3 , indicating the realization of closed-shell electronic configurations for all elements. This notion is confirmed by electronic structure calculations, which reveal narrow bandgaps E g = 0.77 and 0.53 eV for Ca 3 LaSb 3 and Ca 3 LuSb 3 , respectively. Additionally, the incorporation of RE atoms into the structure drives the phase into a state of a degenerate semiconductor with dominant hole charge carriers.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Yb Substitution and Ultralow Thermal Conductivity of the Ca 3– x Yb x AlSb 3 (0 ≤ x ≤ 0.81(1)) System

Here, a series of Yb-substituted Zintl phases in the Ca 3–x Yb x AlSb 3 (0 ≤ x ≤ 0.81(1)) system has been synthesized by initial arc melting and post-heat treatment, and their isotypic crystal structures were characterized by both powder and single crystal X-ray diffraction analysis. All four title compounds adopted the Ca 3 AlAs 3 -type structure (space group Pnma, Pearson code oP28, Z = 4). The overall structure can be described as a combination of the 1-dimensional (1D) infinite chain of ∞ 1 [Al(Sb 2 Sb 2/2 )] formed by two vertices sharing [AlSb 4 ] tetrahedral moieties and three Ca 2+ /Yb 2+ mixed sites located in between these 1D chains. The charge balance and the resultant independency of the 1D chains in the title system were explained by the Zintl-Klemm formalism [Ca 2+ /Yb 2+ ] 3 [(4b-Al 1– )(1b-Sb 2– ) 2 (2b-Sb 1– ) 2/2 ]. A series of DFT calculations proved that (1) the band overlap between the d-orbital states from two types of cations and the p-orbital states from Sb at the high symmetry Γ point implied a heavily doped degenerate semiconducting behavior of the quaternary Ca 2 YbAlSb 3 model and (2) the site preference of Yb for the M1 site was due to the electronic-factor criterion based on the Q values of each atomic site. The electron localization function calculations also proved that the two different shapes of lone pairs of the Sb atoms—the “umbrella-shape” and the “C-shape”—are determined by local geometry and the coordination environment on the anionic frameworks. Thermoelectric measurements of the quaternary title compound Ca 2.19(1) Yb 0.81 AlSb 3 showed an approximately two times larger ZT value than that of ternary Ca 3 AlSb 3 at 623 K due to increased electrical conductivity and ultralow thermal conductivity originated from Yb substitution for Ca.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Chemical composition, coordination, and stability of Ca–organic associations in the presence of dissolving calcite

Environmental biotic and abiotic factors and soil physical, mineralogical, and chemical properties control the chemical composition of soil organic matter (SOM). Particularly, soil mineralogy and the presence of multivalent cations affect SOM labile fraction composition, stability, and environmental persistence. The persistence of SOM in aridic or limestone deposit derived soils, i.e., calcareous soils, has been partially attributed to SOM stabilization through adsorption or inclusion into the calcite mineral structure. Recently, however, it was shown that Ca(aq) released during calcite dissolution formed aqueous Ca–organic associations with OM components, which were unbound to mineral surface sites. This study investigates the structure, composition, and coordination of these associations by characterizing lyophilized Ca–organic containing solutions with spectromicroscopy [Scanning Transmission X-ray Microscopy (STXM)] and with a nanoimaging chemical probe [Infrared scattering-Scanning Nearfield Optical Microscopy (IR s-SNOM)]. Chemical stability of Ca–organic associations is furthermore determined with pyrolysis mass spectrometry analysis. The results demonstrate that Ca–organic associations are formed in the presence of dissolving calcite and OM components relevant to soil chemistry, i.e., lignin and amino acids. This study further reveals a spatial homogeneity of solution-derived (bi) carbonate in Ca–organic associations indicating for the first time that an inorganic anion, such as (bi)carbonate, may be part of these associations. Most likely, Ca ions are bound to both the (bi)carbonate and the organic components. These Ca (bi)carbonate–organic associations seem to have greater chemical stability than the pristine organic mixtures and, possibly, a higher environmental stability and reduced mineralization rate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Proton and neutron contributions to the quadrupole transition strengths in 39 Ca and 39 K studied by lifetime measurements of mirror transitions

The E2 transition matrix elements of isobaric multiplets are expected to follow a linear trend as a function of isospin projection. However, measurements of the 2 + → 0 + transitions in the A = 38 triplet of Ca, K, and Ar show a deviation from this trend with an enhanced transition strength in 38 Ca with respect to its mirror 38 Ar. We have studied analogue 11/2 – → 7/2 – E2 transitions in 39 Ca and its mirror partner 39 K to determine if this enhancement persists in neighboring Ca isotopes. Recoil-distance lifetime measurements of 39 Ca and 39 K were performed utilizing a 42 Sc secondary beam, the TRIPLEX plunger, the GRETINA array, and the S800 spectrograph. Our data provide a lifetime measurement of the (11/2 – ) state in 39 Ca as well as an improved lifetime result for the (9/2 – ) state, while the 39 K data are used to validate the present analysis. Furthermore, a comparison of the present data to shell-model calculations suggests an enhanced transition strength in 39 Ca, pointing to both proton and neutron contributions to core excitations across the Z = N = 20 shell gaps in close proximity to 40 Ca.

39 ≤ A ≤ 58↗
DOE OSTI2022

OSCA1 is an osmotic specific sensor: a method to distinguish Ca 2+ -mediated osmotic and ionic perception

Genetic mutants defective in stimulus-induced Ca 2+ increases have been gradually isolated, allowing the identification of cell-surface sensors/receptors, such as the osmosensor OSCA1. However, determining the Ca 2+ -signaling specificity to various stimuli in these mutants remains a challenge. For instance, less is known about the exact selectivity between osmotic and ionic stresses in the osca1 mutant. Here, we have developed a method to distinguish the osmotic and ionic effects by analyzing Ca 2+ increases, and demonstrated that osca1 is impaired primarily in Ca 2+ increases induced by the osmotic but not ionic stress. We recorded Ca 2+ increases induced by sorbitol (osmotic effect, OE) and NaCl/CaCl 2 (OE + ionic effect, IE) in Arabidopsis wild-type and osca1 seedlings. Here we assumed the NaCl/CaCl 2 total effect (TE) = OE + IE, then developed procedures for Ca 2+ imaging, image analysis and mathematic fitting/modeling, and found osca1 defects mainly in OE. The osmotic specificity of osca1 suggests that osmotic and ionic perceptions are independent. The precise estimation of these two stress effects is applicable not only to new Ca 2+ -signaling mutants with distinct stimulus specificity but also the complex Ca 2+ signaling crosstalk among multiple concurrent stresses that occur naturally, and will enable us to specifically fine tune multiple signal pathways to improve crop yields.

Arabidopsis↗