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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mg(CO2)2 by Materials Project

MgC2O4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Mg–O bond distances ranging from 2.02–2.27 Å. C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one C3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgH2(CO2)2 by Materials Project

Mg(HCOO)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form edge-sharing MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.15 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 64–66°. There are a spread of Mg–O bond distances ranging from 2.09–2.13 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 64°. There are four shorter (2.08 Å) and two longer (2.16 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 66°. There are a spread of Mg–O bond distances ranging from 2.05–2.16 Å. There are six inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the second C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the third C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fourth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fifth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the sixth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one C2+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C2+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C2+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one C2+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one C2+ atom. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one C2+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one C2+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one C2+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C2+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one C2+ atom. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C2+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mg2+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Competitive Sorption of H 2 O and CO 2 in Clay Mineral Interlayers

The first-reported competitive CO 2 –H 2 O sorption isotherms on a naturally occurring expandable clay mineral (saponite) exchanged with Na, K, and Cs at near ambient CO 2 concentrations (1% CO 2 ) are reported by combining ATR-FTIR spectroscopy with gravimetric sorption methods. Little CO 2 sorption was observed at high relative humidity (RH) but increased significantly at low RH. Unlike prior work where CO 2 sorption was reported on samples that were previously subjected to heating and/or evacuation treatment to remove sorbed H 2 O, this study manipulated CO 2 sorption by controlling RH. CO 2 sorption increased in the order Cs- > K- > Na-exchanged saponite and was anticorrelated with the Gibbs energy of hydration of the exchangeable cation. As expected, H 2 O sorption followed the opposite trend, with increased H 2 O sorption occurring in the order Na > K > Cs. The amount of CO 2 sorbed using 1 atm CO 2 (p/p o = 1.0) ranged from 50 to 30 mg CO 2 /g clay and from 1.25 to 0.8 mg CO2 /g clay for 1% CO 2 (p/p o = 0.01) in N 2 . The sensitivity of the ATR-FTIR measurements is demonstrated by detecting the CO 2 stretch of adsorbed CO 2 from air containing 500 ppmv CO 2 . The spectral features of sorbed CO 2 were minimally affected by the nature of the exchangeable cation or variations in H 2 O content. However, the position of the HOH bending band shifted significantly from 1638 to 1610 cm –1 as H 2 O content decreased, reflecting changes in intermolecular hydrogen bonding between H 2 O molecules in the saponite interlayer. The shift in position of the HOH bending band to lower energy was coincident with increased CO 2 sorption. CO 2 sorption in clay mineral interlayers is consistent with sorption on weakly hydrated partially hydrophobic sites found on low charge density smectites and is enhanced by lower RH and by the presence of weakly hydrated exchangeable cations like Cs + or K + . In conclusion, the greatest CO 2 sorption occurs on Cs-saponite because this is the least hydrated cation of the three used in the study and indicates that CO2 sorption occurs on the neutral portion of the siloxane surface.

Johnston, Cliff T. [Purdue Univ., West Lafayette, ↗
DOE OSTI2020

Materials Data on BaMg(CO2)2 by Materials Project

BaMg(CO2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ba2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. There are four shorter (2.79 Å) and four longer (2.83 Å) Ba–O bond lengths. Mg2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Mg–O bond lengths are 2.18 Å. C2+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.32 Å. O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Mg2+, and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaMg14CoO16 by Materials Project

CaMg14CoO16 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.17 Å) and four longer (2.26 Å) Ca–O bond lengths. There are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent MgO6 octahedra, corners with two equivalent CoO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.03–2.17 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CaO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.10–2.20 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CaO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.10–2.20 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.12–2.17 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, an edgeedge with one CaO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are two shorter (2.12 Å) and four longer (2.17 Å) Mg–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.14 Å) and two longer (2.17 Å) Co–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and five Mg2+ atoms to form a mixture of corner and edge-sharing OCaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the second O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of corner and edge-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. Both O–Mg bond lengths are 2.17 Å. In the third O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of corner and edge-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.12 Å) and two longer (2.17 Å) O–Mg bond lengths. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OCaMg5 octahedra. The corner-sharing octahedra tilt angles range from 1–3°. In the fifth O2- site, O2- is bonded to two equivalent Ca2+ and four Mg2+ atoms to form OCa2Mg4 octahedra that share corners with six OCa2Mg4 octahedra and edges with twelve OCaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OCa2Mg4 octahedra and edges with twelve OCaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O2- site, O2- is bonded to four equivalent Mg2+ and two equivalent Co2+ atoms to form OMg4Co2 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded to one Ca2+ and five Mg2+ atoms to form a mixture of corner and edge-sharing OCaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. Both O–Mg bond lengths are 2.17 Å. In the ninth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of corner and edge-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. The O–Mg bond length is 2.16 Å. In the tenth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of corner and edge-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of O–Mg bond distances ranging from 2.12–2.17 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg30CoCO32 by Materials Project

Mg30CoCO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.10–2.13 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, an edgeedge with one CO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–3°. There are a spread of Mg–O bond distances ranging from 2.10–2.15 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.11–2.14 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.17 Å) Co–O bond lengths. C2+ is bonded to six O2- atoms to form CO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.09 Å) and four longer (2.15 Å) C–O bond lengths. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are one shorter (2.13 Å) and two longer (2.15 Å) O–Mg bond lengths. In the second O2- site, O2- is bonded to five Mg2+ and one C2+ atom to form OMg5C octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg5C octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.13 Å. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the fifth O2- site, O2- is bonded to five Mg2+ and one C2+ atom to form OMg5C octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg5C octahedra. The corner-sharing octahedra tilt angles range from 0–2°. All O–Mg bond lengths are 2.11 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. All O–Mg bond lengths are 2.13 Å. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5C octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.12 Å) and two longer (2.14 Å) O–Mg bond lengths. In the eighth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the ninth O2- site, O2- is bonded to four equivalent Mg2+, one Co2+, and one C2+ atom to form OMg4CoC octahedra that share corners with six OMg4CoC octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4CoC octahedra and edges with twelve OMg5C octahedra. The corner-sharing octahedral tilt angles are 0°. In the eleventh O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the twelfth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the thirteenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. The O–Mg bond length is 2.12 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg30MnCoO32 by Materials Project

Mg30MnCoO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MnO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.07 Å) and four longer (2.14 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one MnO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are five shorter (2.13 Å) and one longer (2.14 Å) Mg–O bond lengths. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are three shorter (2.13 Å) and three longer (2.14 Å) Mg–O bond lengths. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one MnO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are two shorter (2.13 Å) and four longer (2.14 Å) Mg–O bond lengths. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.14 Å) and four longer (2.19 Å) Mn–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent MnO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.13 Å) and four longer (2.14 Å) Co–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Mn2+ atom to form OMg5Mn octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Mn octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to five Mg2+ and one Mn2+ atom to form a mixture of edge and corner-sharing OMg5Mn octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are one shorter (2.07 Å) and four longer (2.14 Å) O–Mg bond lengths. In the sixth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. All O–Mg bond lengths are 2.13 Å. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one Mn2+, and one Co2+ atom to form OMg4MnCo octahedra that share corners with six OMg4MnCo octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4MnCo octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedral tilt angles are 0°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgCoO2 by Materials Project

MgCoO2 is Caswellsilverite-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four CoO6 octahedra, edges with five CoO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are a spread of Mg–O bond distances ranging from 2.11–2.14 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four CoO6 octahedra, edges with five CoO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are four shorter (2.12 Å) and two longer (2.13 Å) Mg–O bond lengths. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, edges with five MgO6 octahedra, and edges with seven CoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are a spread of Co–O bond distances ranging from 2.12–2.20 Å. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, edges with five MgO6 octahedra, and edges with seven CoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are a spread of Co–O bond distances ranging from 2.12–2.18 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and five Co2+ atoms to form OMgCo5 octahedra that share corners with six OMg3Co3 octahedra and edges with twelve OMgCo5 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to three equivalent Mg2+ and three Co2+ atoms to form a mixture of edge and corner-sharing OMg3Co3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the third O2- site, O2- is bonded to three Mg2+ and three equivalent Co2+ atoms to form a mixture of edge and corner-sharing OMg3Co3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the fourth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Annual carbon sequestration and loss rates under altered hydrology and fire regimes in southeastern USA pocosin peatlands

Peatlands drained for agriculture or forestry are susceptible to the rapid release of greenhouse gases (GHGs) through enhanced microbial decomposition and increased frequency of deep peat fires. We present evidence that rewetting drained subtropical wooded peatlands (STWPs) along the southeastern USA coast, primarily pocosin bogs, could prevent significant carbon (C) losses. To quantify GHG emissions and storage from drained and rewetted pocosin we used eddy covariance techniques, the first such estimates that have been applied to this major bog type, on a private drained (PD) site supplemented by static chamber measurements at PD and Pocosin Lakes National Wildlife Refuge. Net ecosystem exchange measurements showed that the loss was 21.2 Mg CO2 ha –1 year –1 (1 Mg = 10 6 g) in the drained pocosin. Under a rewetted scenario, where the annual mean water table depth (WTD) decreased from 60 to 30 cm, the C loss was projected to fall to 2 Mg CO 2 ha –1 year –1 , a 94% reduction. If the WTD was 20 cm, the peatlands became a net carbon sink (–3.3 Mg CO2 ha –1 year –1 ). Hence, net C reductions could reach 24.5 Mg CO 2 ha –1 year –1 , and when scaled up to the 4000 ha PD site nearly 100,000 Mg CO 2 year –1 of creditable C could be amassed. We conservatively estimate among the 0.75 million ha of southeastern STWPs, between 450 and 770 km 2 could be rewet, reducing annual GHG emissions by 0.96–1.6 Tg (1 Tg = 10 12 g) of CO 2 , through suppressed microbial decomposition and 1.7–2.8 Tg via fire prevention, respectively. Despite covering <0.01% of US land area, rewetting drained pocosin can potentially provide 2.4% of the annual CO 2 nationwide reduction target of 0.18 Pg (1 Pg = 10 15 g). Finally, suggesting pocosin restoration can contribute disproportionately to the US goal of achieving net-zero emission by 2050.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on Mg30CrCoO32 by Materials Project

Mg30CrCoO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.04–2.16 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.10–2.18 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.14 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.14 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CrO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 2–9°. There are a spread of Mg–O bond distances ranging from 2.09–2.18 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of Mg–O bond distances ranging from 2.11–2.15 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CrO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.01 Å) and four longer (2.08 Å) Cr–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.22 Å) and two longer (2.25 Å) Co–O bond lengths. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Cr octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the second O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. Both O–Mg bond lengths are 2.14 Å. In the fifth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of O–Mg bond distances ranging from 2.04–2.11 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.12 Å) and two longer (2.14 Å) O–Mg bond lengths. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 1–3°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one Cr2+, and one Co2+ atom to form OMg4CrCo octahedra that share corners with six OMg4CrCo octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the ninth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4CrCo octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the eleventh O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. The O–Mg bond length is 2.12 Å. In the twelfth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are three shorter (2.12 Å) and two longer (2.14 Å) O–Mg bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(CoN)2 by Materials Project

Mg(CoN)2 crystallizes in the tetragonal P-4m2 space group. The structure is two-dimensional and consists of one Mg(CoN)2 sheet oriented in the (0, 0, 1) direction. Mg2+ is bonded to four equivalent N3- atoms to form corner-sharing MgN4 tetrahedra. All Mg–N bond lengths are 2.18 Å. Co2+ is bonded in a linear geometry to two equivalent N3- atoms. Both Co–N bond lengths are 1.73 Å. N3- is bonded in a see-saw-like geometry to two equivalent Mg2+ and two equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg30FeCoO32 by Materials Project

Mg30FeCoO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.07–2.14 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one FeO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All Mg–O bond lengths are 2.13 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one FeO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.08 Å) and four longer (2.19 Å) Fe–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.13 Å) and two longer (2.18 Å) Co–O bond lengths. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Fe2+ atom to form a mixture of edge and corner-sharing OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Fe octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.12 Å) and one longer (2.13 Å) O–Mg bond lengths. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.13 Å. In the fifth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Fe octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.12 Å) and two longer (2.13 Å) O–Mg bond lengths. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. All O–Mg bond lengths are 2.13 Å. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one Fe2+, and one Co2+ atom to form OMg4FeCo octahedra that share corners with six OMg4FeCo octahedra and edges with twelve OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the ninth O2- site, O2- is bonded to four equivalent Mg2+, one Fe2+, and one Co2+ atom to form OMg4FeCo octahedra that share corners with six OMg4FeCo octahedra and edges with twelve OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All O–Mg bond lengths are 2.13 Å. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4FeCo octahedra and edges with twelve OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eleventh O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the twelfth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Fe octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the thirteenth O2- site, O2- is bonded to five Mg2+ and one Fe2+ atom to form a mixture of edge and corner-sharing OMg5Fe octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.13 Å) and two longer (2.14 Å) O–Mg bond lengths. In the fourteenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. The O–Mg bond length is 2.13 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg30CoCuO32 by Materials Project

Mg30CoCuO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CuO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.06 Å) and four longer (2.14 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.10–2.15 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.13 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.11 Å) and four longer (2.14 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, an edgeedge with one CuO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are one shorter (2.11 Å) and five longer (2.13 Å) Mg–O bond lengths. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Mg–O bond distances ranging from 2.11–2.14 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CuO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are four shorter (2.12 Å) and two longer (2.14 Å) Mg–O bond lengths. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CuO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.11 Å) and two longer (2.20 Å) Co–O bond lengths. Cu2+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.04 Å) and four longer (2.20 Å) Cu–O bond lengths. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Cu2+ atom to form a mixture of edge and corner-sharing OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the second O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Cu octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.13 Å) and one longer (2.15 Å) O–Mg bond lengths. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. Both O–Mg bond lengths are 2.13 Å. In the fifth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Cu octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. All O–Mg bond lengths are 2.13 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All O–Mg bond lengths are 2.13 Å. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one Co2+, and one Cu2+ atom to form OMg4CoCu octahedra that share corners with six OMg4CoCu octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the ninth O2- site, O2- is bonded to four equivalent Mg2+, one Co2+, and one Cu2+ atom to form OMg4CoCu octahedra that share corners with six OMg4CoCu octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All O–Mg bond lengths are 2.13 Å. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4CoCu octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eleventh O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the twelfth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Cu octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the thirteenth O2- site, O2- is bonded to five Mg2+ and one Cu2+ atom to form a mixture of edge and corner-sharing OMg5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are two shorter (2.11 Å) and two longer (2.12 Å) O–Mg bond lengths. In the fourteenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. The O–Mg bond length is 2.13 Å. In the fifteenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All O–Mg bond lengths are 2.13 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg14CoNiO16 by Materials Project

Mg14CoNiO16 is alpha Po-derived structured and crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are seven inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.11–2.13 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent NiO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.13 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CoO6 octahedra, edges with two equivalent NiO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are five shorter (2.12 Å) and one longer (2.14 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.12 Å) and four longer (2.13 Å) Mg–O bond lengths. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent NiO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, an edgeedge with one CoO6 octahedra, an edgeedge with one NiO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.12–2.14 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent CoO6 octahedra, corners with two equivalent NiO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Co–O bond distances ranging from 2.12–2.16 Å. Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent CoO6 octahedra, corners with two equivalent NiO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Ni–O bond distances ranging from 2.11–2.14 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second O2- site, O2- is bonded to five Mg2+ and one Ni2+ atom to form OMg5Ni octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the third O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.12 Å) and two longer (2.13 Å) O–Mg bond lengths. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fifth O2- site, O2- is bonded to four Mg2+ and two equivalent Co2+ atoms to form OMg4Co2 octahedra that share corners with six OMg4Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth O2- site, O2- is bonded to four Mg2+ and two equivalent Ni2+ atoms to form OMg4Ni2 octahedra that share corners with six OMg4Co2 octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4Ni2 octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth O2- site, O2- is bonded to four Mg2+, one Co2+, and one Ni2+ atom to form OMg4CoNi octahedra that share corners with six OMg4CoNi octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4CoNi octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°.

36 MATERIALS SCIENCE↗
DOE OSTI2021

CO2 Capture Strategies via Mineralization with Industrial Waste Brines

Large coal-fired power plants (>500 MW) account for 30% of global CO2 emissions, and long-term management of this CO2 to is urgently needed mitigate global temperature increases. Sequestration of CO2 within stable mineral carbonates (e.g., CaCO3) represents an attractive emission reduction strategy because it offers a leakage-free alternative to geological storage of CO2 in an environmentally friendly form. We have previously described a mineralization process in which divalent cations are sourced from various waste streams (e.g., produced water and brackish water) and alkalinity is induced via regenerable ion-exchange materials (Bustillos et. al. Frontiers in Energy Research. 2020, 8, 352). In our process, aqueous carbonate-bearing streams with pH > 8 are produced by contacting fresh water and carbon dioxide with various ion-exchange materials (e.g., Na form zeolites or ion exchange resins). These streams are mixed with produced water containing varying concentrations (~0.01 – 1.0 M) of Ca2+ leading to the precipitation of solid calcium carbonate (PCC). This process has the advantages of using regenerable solids in a simple and continuous process to increase the pH of water by ion exchange instead of relying on the consumption of costly and unsustainable sources of alkalinity (e.g., sodium hydroxide). While once-through column experiments showed the above benefits, the same were yet to established in a steady-state process with recycle streams. In this work, we set up a process simulation to quantify the energy requirements and CO2 emissions associated with the process and seek optimal produced water compositions and CO2 concentrations (5 – 20 vol%). The process simulation was set up in ASPEN Plus using eRNTL as the thermodynamic property method and sequential modular strategy. Ion exchange alkaline solution was simulated using sodium hydroxide and validated against the experimental data obtained from once-through kinetic experiments. Nanofiltration and reverse osmosis membrane steps were also implemented for the separation of divalent cations and production of fresh water and a regeneration stream following mineralization. Sensitivity analysis was carried out using a range of produced water compositions (0.01 – 1.0 M Ca2+, 0.001 – 0.15 M Mg2+, 0.5 – 3.5 M Na+ and 0.0004 – 0.002 M Fe2+) according to the United States Geological Survey (USGS) database. Calcium carbonate yields increased with increasing CO2 concentrations and were maximized using produced water compositions with larger Ca2+ concentrations. Maximum calcium carbonate yields produced at 5 vol%, 12 vol% and 20 vol% CO2 were 2.3 mmol/L, 5.5 mmol/L, and 9.3 mmol/L, respectively, with the formation of brucite (a magnesium hydroxide phase, Mg(OH)2) and goethite (an iron hydroxide phase, FeOOH) as the primary contaminant phases (99% calcite, 0.6% brucite, 0.4% goethite), which agree with phases detected by XRD experimentally. These results indicate high purity calcium carbonate can be precipitated using industrial waste streams. Consequentially, energy consumption and net CO2 emissions were minimized where precipitated calcium carbonate was maximized for all produced water compositions and CO2 concentrations. Minimum energy consumptions were 0.21 kWh/ton CO2 processed, with 98% of the energy input required coming from the membrane filtration steps. Produced water compositions with large Na+ concentrations (> 0.5 M) were effective at reducing energy consumptions due to faster regeneration time of ion exchange materials. Additionally, calculated net CO2 emissions were negative for the process and ranged from -0.02 kg/ton CO2 to -0.15 kg/ton CO2 processed, indicating a low emission process. We will also present techno-economic assessment showing the economic benefits of the current process as an alternative to the addition of stoichiometric bases to induce alkalinity for the precipitation of CaCO3.

Simonetti, Dante↗
DOE OSTI2020

Materials Data on Mg14MnCoO16 by Materials Project

Mg14MnCoO16 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent MnO6 octahedra, corners with two equivalent CoO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.07–2.15 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.12–2.15 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.12–2.15 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Mg–O bond distances ranging from 2.12–2.15 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, an edgeedge with one MnO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.13–2.15 Å. Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent MnO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.15 Å) and four longer (2.20 Å) Mn–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.14 Å) and two longer (2.15 Å) Co–O bond lengths. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Mn2+ atom to form a mixture of edge and corner-sharing OMg5Mn octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. Both O–Mg bond lengths are 2.15 Å. In the third O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of edge and corner-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedral tilt angles are 1°. In the fifth O2- site, O2- is bonded to four Mg2+ and two equivalent Mn2+ atoms to form OMg4Mn2 octahedra that share corners with six OMg4Mn2 octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4Mn2 octahedra and edges with twelve OMg5Mn octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O2- site, O2- is bonded to four equivalent Mg2+ and two equivalent Co2+ atoms to form OMg4Co2 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded to five Mg2+ and one Mn2+ atom to form a mixture of edge and corner-sharing OMg5Mn octahedra. The corner-sharing octahedra tilt angles range from 0–2°. Both O–Mg bond lengths are 2.14 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgCo2(PO4)2 by Materials Project

MgCo2(PO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent PO4 tetrahedra, corners with two equivalent CoO5 trigonal bipyramids, and edges with two equivalent CoO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 2.05–2.20 Å. Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share a cornercorner with one MgO6 octahedra, corners with three equivalent PO4 tetrahedra, an edgeedge with one MgO6 octahedra, an edgeedge with one PO4 tetrahedra, and an edgeedge with one CoO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 59°. There are a spread of Co–O bond distances ranging from 2.00–2.23 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent MgO6 octahedra, corners with three equivalent CoO5 trigonal bipyramids, and an edgeedge with one CoO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 34–53°. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Co2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Co2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Co2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Mg2+, one Co2+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg30VCoO32 by Materials Project

Mg30VCoO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.11 Å) and four longer (2.13 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent VO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.08–2.14 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.14 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one VO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are five shorter (2.13 Å) and one longer (2.14 Å) Mg–O bond lengths. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.13 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CoO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. All Mg–O bond lengths are 2.13 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one VO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. V2+ is bonded to six O2- atoms to form VO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.14 Å) and four longer (2.17 Å) V–O bond lengths. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent VO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.14 Å) Co–O bond lengths. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form OMg5Co octahedra that share corners with six OMg5V octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to five Mg2+ and one V2+ atom to form OMg5V octahedra that share corners with six OMg5Co octahedra and edges with twelve OMg5V octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner and edge-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner and edge-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fifth O2- site, O2- is bonded to five Mg2+ and one Co2+ atom to form a mixture of corner and edge-sharing OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are one shorter (2.11 Å) and four longer (2.13 Å) O–Mg bond lengths. In the sixth O2- site, O2- is bonded to five Mg2+ and one V2+ atom to form a mixture of corner and edge-sharing OMg5V octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.13 Å) and two longer (2.14 Å) O–Mg bond lengths. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one V2+, and one Co2+ atom to form OMg4VCo octahedra that share corners with six OMg4VCo octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth O2- site, O2- is bonded to four equivalent Mg2+, one V2+, and one Co2+ atom to form OMg4VCo octahedra that share corners with six OMg4VCo octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. All O–Mg bond lengths are 2.13 Å. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4VCo octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the eleventh O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of corner and edge-sharing OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗