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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Reassessing the proposed “CY chondrites”: Evidence for multiple meteorite types and parent bodies from Cr-Ti-H-C-N isotopes and bulk elemental compositions

Here, we report a coordinated bulk Cr-Ti-H-C-N isotopic and compositional study of six carbonaceous chondrites from Antarctica that are often considered to be related and termed Yamato-like carbonaceous (CY) chondrites. These meteorites are known to have undergone extensive aqueous alteration followed by different degrees of thermal alteration, to be similar to one another in regard to mineralogy, and share affinities with both the Ivuna-like carbonaceous (CI) and Mighei-like carbonaceous (CM) chondrites. While mineralogically similar, a key difference among these samples is that chondrules have been found in some of these samples, but not in others. The aim of this study is to evaluate the relationship of these meteorites to one another, and investigate how they relate to the CI and CM chondrite groups. We find that with the addition of the isotopic compositions of these ‘CY’ chondrites, there is now a continuum of isotopic compositions among the carbonaceous chondrites. The CI chondrites are no longer separate in O isotopic compositions from the other carbonaceous chondrite groups in plots of Cr-O and Ti-O. We also find that the ‘CY’ chondrites represent two distinct populations, which correlate with their heating stage. However, the peak temperatures experienced by each population can only explain the differences in H and C isotopes and abundances and N abundances between samples, and cannot have caused the differences in N, Cr, and Ti isotopes, or all the volatile element depletions of the sample’s bulk compositions. Instead, we conclude that the compositional and isotopic data of these two populations correlate with their known chondrule abundances, indicating distinct precursors for each population. We find it most likely that these samples originate from two distinct asteroids, implying that among the six samples studied here, there are not five related samples to constitute a new meteorite group. The chondrule-free heating Stage III samples are most likely heated CI chondrites, while the chondrule-bearing heating Stage IV samples could be heated CM chondrites.

58 GEOSCIENCES↗
DOE OSTI2022

Assessing the interfacial corrosion mechanism of Inconel 617 in chloride molten salt corrosion using multi-modal advanced characterization techniques

The United States Department of Energy (DOE) has committed to expanding the domestic clean energy portfolio in response to the rising challenges of energy security in the wake of climate change. Accordingly, the construction of a series of Generation IV reactor technologies are being demonstrated, including sodium-cooled, small modular, and molten chloride fast reactors (MCFRs). To date, there are no fully qualified structural materials for constructing MCFRs. A number of commercial structural alloys have been considered for the construction of MCFRs, including alloys from the Inconel and Hastelloy series. Informed qualification of structural materials for the construction of MCFRs in the future can only be ensured by expanding the current fundamental knowledgebase of information pertaining to material performance under environmental stressors relevant to operation of the reactor, including corrosion susceptibility. The purpose of this investigation is to illustrate how a correlative multi-modal electron microscopy characterization approach, including the novel application of focused-ion beam 3D reconstruction capabilities, can elucidate the corrosion mechanism of a candidate structural material Inconel 617 for MCFR in NaCl-MgCl 2 eutectic salt at 700°C for 1,000 h. Evidence of intergranular corrosion, Ni and Fe dealloying, and Cr-O enrichment along the grain boundary, which most likely corresponds to Cr 2 O 3 , is a phenomenon that has been documented in other Ni-based superalloys exposed to chloride molten salt systems. Additional corrosion products, including the formation of insoluble MgAl 2 O 4 , within the porous network produced by the salt attack is a novel observation. In addition, Mo 3 Si 5 and τ 2 precipitates are detected in the alloy bulk and are dissolved by the salt. Furthermore, the lack of detection of design γ' precipitates in Inconel 617 after 1,000 h could indicate that the molten salt corrosion mechanism has indirectly induced a phase transformation of Al 2 TiNi (τ 2 ) and Ni 3 (Al,Ti) (γ’) phase. This investigation provides a comprehensive understanding of molten salt corrosion mechanisms in a complex material system such as a commercial structural alloy for applications in MCFRs.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Cost-Effective Thermomechanical Processing of Nanostructured Ferritic Alloys: Microstructure and Mechanical Properties Investigation

Nanostructured ferritic alloys (NFAs), such as oxide-dispersion strengthened (ODS) alloys, play a vital role in advanced fission and fusion reactors, offering superior properties when incorporating nanoparticles under irradiation. Despite their importance, the high cost of mass-producing NFAs through mechanical milling presents a challenge. This study delves into the microstructure-mechanical property correlations of three NFAs produced using a novel, cost-effective approach combining severe plastic deformation (SPD) with the continuous thermomechanical processing (CTMP) method. Analysis using scanning electron microscopy (SEM)-electron backscatter diffraction (EBSD) revealed nano-grain structures and phases, while scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectroscopy (EDS) quantified the size and density of Ti-N, Y-O, and Cr-O fine particles. Atom probe tomography (APT) further confirmed the absence of finer Y-O particles and characterized the chemical composition of the particles, suggesting possible nitride dispersion strengthening. Correlation of microstructure and mechanical testing results revealed that CTMP alloys, despite having lower nanoparticle densities, exhibit strength and ductility comparable to mechanically milled ODS alloys, likely due to their fine grain structure. However, higher nanoparticle densities may be necessary to prevent cavity swelling under high-temperature irradiation and helium gas production. Further enhancements in uniform nanoparticle distribution and increased sink strength are recommended to mitigate cavity swelling, advancing their suitability for nuclear applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO by Materials Project

CrO is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cr2+ is bonded to six equivalent O2- atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Cr–O bond lengths are 2.23 Å. O2- is bonded to six equivalent Cr2+ atoms to form a mixture of corner and edge-sharing OCr6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 is Rutile structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Cr4+ is bonded to six equivalent O2- atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There is two shorter (1.92 Å) and four longer (1.95 Å) Cr–O bond length. O2- is bonded in a distorted trigonal planar geometry to three equivalent Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr2O3 by Materials Project

Cr2O3 is Corundum structured and crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Cr3+ is bonded to six equivalent O2- atoms to form a mixture of edge, corner, and face-sharing CrO6 octahedra. The corner-sharing octahedra tilt angles range from 47–61°. There are three shorter (2.01 Å) and three longer (2.06 Å) Cr–O bond lengths. O2- is bonded to four equivalent Cr3+ atoms to form a mixture of distorted edge and corner-sharing OCr4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO3 by Materials Project

CrO3 crystallizes in the orthorhombic Ama2 space group. The structure is one-dimensional and consists of two CrO3 ribbons oriented in the (0, 0, 1) direction. Cr6+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. There is two shorter (1.59 Å) and two longer (1.77 Å) Cr–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Cr6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr3O by Materials Project

Cr3O is Upper Bainite-like structured and crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Cr is bonded in a distorted bent 120 degrees geometry to two equivalent O atoms. Both Cr–O bond lengths are 2.16 Å. O is bonded to six equivalent Cr atoms to form corner-sharing OCr6 octahedra. The corner-sharing octahedral tilt angles are 48°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 is Brookite-like structured and crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of two CrO2 sheets oriented in the (0, 0, 1) direction. Cr4+ is bonded to six O2- atoms to form edge-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.77–2.17 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Cr4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr19O48 by Materials Project

Cr19O48 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nineteen inequivalent Cr+5.05+ sites. In the first Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 29–53°. There are a spread of Cr–O bond distances ranging from 1.65–1.69 Å. In the second Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–55°. There are a spread of Cr–O bond distances ranging from 1.58–1.75 Å. In the third Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–56°. There are a spread of Cr–O bond distances ranging from 1.59–1.75 Å. In the fourth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form distorted corner-sharing CrO6 pentagonal pyramids. There are a spread of Cr–O bond distances ranging from 1.96–2.06 Å. In the fifth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.87–2.03 Å. In the sixth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–52°. There are a spread of Cr–O bond distances ranging from 1.65–1.68 Å. In the seventh Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–50°. There are a spread of Cr–O bond distances ranging from 1.59–1.73 Å. In the eighth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–63°. There are a spread of Cr–O bond distances ranging from 1.65–1.78 Å. In the ninth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.75–2.06 Å. In the tenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.97–2.09 Å. In the eleventh Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–53°. There are a spread of Cr–O bond distances ranging from 1.59–1.73 Å. In the twelfth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–56°. There are a spread of Cr–O bond distances ranging from 1.60–1.85 Å. In the thirteenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–48°. There are a spread of Cr–O bond distances ranging from 1.59–1.75 Å. In the fourteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one CrO6 octahedra and corners with six CrO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Cr–O bond distances ranging from 1.96–2.16 Å. In the fifteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one CrO6 octahedra and corners with six CrO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Cr–O bond distances ranging from 1.96–2.16 Å. In the sixteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.95–2.01 Å. In the seventeenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–47°. There are a spread of Cr–O bond distances ranging from 1.65–1.68 Å. In the eighteenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–48°. There is two shorter (1.66 Å) and two longer (1.68 Å) Cr–O bond length. In the nineteenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–53°. There are a spread of Cr–O bond distances ranging from 1.65–1.71 Å. There are forty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted linear geometry to two Cr+5.05+ atoms. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the seventeenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the twentieth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-first O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-third O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-fourth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-fifth O2- site, O2- is bonded in a trigonal planar geometry to three Cr+5.05+ atoms. In the twenty-sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-seventh O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the twenty-ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirtieth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-fifth O2- site, O2- is bonded in a linear geometry to two Cr+5.05+ atoms. In the thirty-sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the fortieth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-first O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the forty-second O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-third O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-fourth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the forty-fifth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the forty-sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr19O48 by Materials Project

Cr19O48 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nineteen inequivalent Cr+5.05+ sites. In the first Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.92–2.13 Å. In the second Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–65°. There are a spread of Cr–O bond distances ranging from 1.63–1.77 Å. In the third Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–49°. There are a spread of Cr–O bond distances ranging from 1.60–1.76 Å. In the fourth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–52°. There are a spread of Cr–O bond distances ranging from 1.58–1.73 Å. In the fifth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six CrO4 tetrahedra and edges with two equivalent CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.97–2.04 Å. In the sixth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.87–2.07 Å. In the seventh Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–51°. There are a spread of Cr–O bond distances ranging from 1.58–1.71 Å. In the eighth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–60°. There are a spread of Cr–O bond distances ranging from 1.58–1.79 Å. In the ninth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–56°. There are a spread of Cr–O bond distances ranging from 1.65–1.69 Å. In the tenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–55°. There are a spread of Cr–O bond distances ranging from 1.65–1.71 Å. In the eleventh Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–58°. There are a spread of Cr–O bond distances ranging from 1.58–1.80 Å. In the twelfth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–54°. There are a spread of Cr–O bond distances ranging from 1.60–1.78 Å. In the thirteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.82–2.04 Å. In the fourteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one CrO6 octahedra and corners with six CrO4 tetrahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.92–2.13 Å. In the fifteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one CrO6 octahedra, corners with six CrO4 tetrahedra, and edges with two equivalent CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.95–2.08 Å. In the sixteenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–50°. There are a spread of Cr–O bond distances ranging from 1.60–1.77 Å. In the seventeenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–52°. There are a spread of Cr–O bond distances ranging from 1.59–1.72 Å. In the eighteenth Cr+5.05+ site, Cr+5.05+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–60°. There are a spread of Cr–O bond distances ranging from 1.64–1.77 Å. In the nineteenth Cr+5.05+ site, Cr+5.05+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.85–2.27 Å. There are forty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+5.05+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to two Cr+5.05+ atoms. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the sixteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the seventeenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+5.05+ atoms. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the twentieth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-first O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-second O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-third O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the twenty-eighth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the twenty-ninth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the thirtieth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+5.05+ atoms. In the thirty-first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-second O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-third O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr+5.05+ atoms. In the thirty-fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the thirty-ninth O2- site, O2- is bonded in a distorted linear geometry to two Cr+5.05+ atoms. In the fortieth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+5.05+ atoms. In the forty-second O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-third O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr+5.05+ atoms. In the forty-fourth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the forty-fifth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the forty-sixth O2- site, O2- is bonded in a single-bond geometry to one Cr+5.05+ atom. In the forty-seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr+5.05+ atoms. In the forty-eighth O2- site, O2- is bonded in a trigonal planar geometry to three Cr+5.05+ atoms.

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DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 is trigonal omega-like structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Cr4+ is bonded to six equivalent O2- atoms to form edge-sharing CrO6 octahedra. All Cr–O bond lengths are 1.95 Å. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO3 by Materials Project

CrO3 crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two CrO3 sheets oriented in the (0, 0, 1) direction. Cr6+ is bonded to five O2- atoms to form corner-sharing CrO5 trigonal bipyramids. There is two shorter (1.71 Å) and three longer (1.98 Å) Cr–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Cr6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 is trigonal omega-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three CrO2 sheets oriented in the (0, 0, 1) direction. Cr4+ is bonded to six equivalent O2- atoms to form edge-sharing CrO6 octahedra. All Cr–O bond lengths are 1.95 Å. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO3 by Materials Project

CrO3 is alpha Rhenium trioxide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cr6+ is bonded to six equivalent O2- atoms to form corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Cr–O bond lengths are 1.83 Å. O2- is bonded in a linear geometry to two equivalent Cr6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–56°. There is two shorter (1.70 Å) and two longer (1.80 Å) Cr–O bond length. In the second Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent CrO4 tetrahedra and edges with two equivalent CrO6 octahedra. There are two shorter (2.00 Å) and four longer (2.04 Å) Cr–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrO2 by Materials Project

CrO2 is Hydrophilite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.89–1.97 Å. In the second Cr4+ site, Cr4+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.89–1.97 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr3O8 by Materials Project

Cr3O8 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Cr3O8 sheets oriented in the (1, 0, 0) direction. there are two inequivalent Cr+5.33+ sites. In the first Cr+5.33+ site, Cr+5.33+ is bonded to six O2- atoms to form edge-sharing CrO6 octahedra. There is four shorter (1.88 Å) and two longer (1.89 Å) Cr–O bond length. In the second Cr+5.33+ site, Cr+5.33+ is bonded to six O2- atoms to form distorted edge-sharing CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.81–2.08 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two equivalent Cr+5.33+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Cr+5.33+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to two Cr+5.33+ atoms.

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