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All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Lunar and Planetary Science XXXV: From Ancient Mists: Presolar and Nebular Processes

The session "From Ancient Mists: Presolar and Nebular Processes" included the following reports: Interpretation of the Meteoritic Extinct Radioactivity - Mean Life Relation; On the Issue of Molybdenum Isotopic Anomalies in Meteorites: Is It Still "FUN"?; (26Al/27Al)o of the Solar Nebula Inferred from Al-Mg Systematic in Bulk CAIs from CV3 Chondrites; Magnesium Isotopic Compositions of Igneous CAIs in the CR Carbonaceous Chondrites: Evidence for an Early and Late-stage Melting of CAIs; The 26Al-26Mg Chronology of a Type C CAI and POIs in Ningqiang Carbonaceous Chondrite; Bulk Compositions of CAIs and Al-rich Chondrules: Implications of the Reversal of the Anorthite / Forsterite Condensation Sequence at Low Nebular Pressures; Synthesis of Refractory Minerals by High-Temperature Condensation of a Gas of Solar Composition; Elemental and Isotopic Fractionation by Diffusion-limited Evaporation; "Nonideal" Isotopic Fractionation Behavior of Magnesium in Evaporation Residues; Determination of Primordial Refractory Inclusion Compositions; Zoning Patterns in Spinel from Type B Ca-Al-rich Inclusions: Constraints on Sub-Solidus Thermal History; Radial Migration of Materials from Inner to Outer Solar Nebula: Evidence from Meteorite Matrix; and Refractory Forsterites in Chondritic Meteorites, a Link Between CAIs and Chondrules.

Source record↗
NASA NTRS2011

Disturbances in the Isotopic Record of Asuka 881394

Asuka 881394 is a unique achondrite with a granulitic texture, very calcic approximately An(sub 98) plagioclase, and pigeonite that has not inverted to orthopyroxene. First thought to be a eucrite, recent Oisotopic studies show it has a closer affinity to angrites . Initial isotopic studies provided evidence for now extinct A-26, Mn-53, and Sm-146. A recent study confirmed an early chronology with an absolute Pb-207 - Pb-206 age of 4566.5 +/- 0.2 Ma, a new measurement of the Al-Mg formation interval as 3.7 +/- 0.1 Ma since Al-26/Al-27 = approximately 4.63 x 10(exp -5) for the E60 CAI, and a Mn-Cr formation interval of -6.0 +/- 0.2 Ma relative to LEW86010 ("LEW"). Absolute ages relative to age anchors presented by were 4563.4 +/- 0.2 Ma by Al- Mg and 4564.6 +/- 0.5 Ma by Mn-Cr. These ages are in good, but not perfect, agreement with the Pb-207 - Pb-206 age. Perhaps the most direct comparison of the early chronology of A881394 as determined by various workers is provided by reported Al-26/Al-27 values of 1.18 +/- 0.14, 1.28 +/- 0.07, and 2.1 +/- 0.4 x 10(exp -6). Analyses of mineral separates by TIMS and MC-ICPMS6] agree well, but the higher value obtained by in situ SIMS analysis is significant in light of the slight inconsistency between absolute ages inferred from the short-lived chronometers and the Pb-207 - Pb-206 age. We examine the possibility that inconsistencies in the earliest fine-scale chronology of Asuka 881394 may be related to isotopic "disturbances" observed in Ar-39 - Ar-40, Rb-97 - Sr-87, and Sm-147 - Nd-143 chronometers.

Nyquist, L. E.↗
NASA NTRS2014

Timing of Formation of a Wassonite-bearing Chondrule

Wassonite, ideally stoichiometric TiS, is a titanium monosulfide recently discovered in the Yamato 691 EH3 enstatite chondrite. Wassonite grains were located within the mesostasis of a single barred olivine chondrule. Such chondrules likely formed in the solar nebula by melting of fine grained precursor dust. The reduced nature of enstatite chondrites, and the wassonite-bearing chondrule in particular, may suggest precursor materials included Ti-bearing troilite, metallic Fe-Ni, and possibly graphite. Under the reducing conditions present in enstatite chondrites S can partition more readily into silicate melt, leading to raised Ti content of the residual Fe-FeS melt. By the time sulfide crystallized from the melt, the Ti concentration was high enough to form small grains of pure TiS - wassonite. As a mineral not previously observed in nature wassonite and its host chondrule may provide additional constraints on physical and chemical conditions in the solar nebula at a specific time and location relevant to planetary formation. Enstatite chondrites and Earth share similar isotopic compositions of Cr, Ni, Ti, O and N. Understanding the formation conditions of enstatite chondrite chondrules may therefore have wider relevance for terrestrial planet accretion and other early inner solar system processes. Here we present preliminary results of an investigation of the Al-Mg systematics of the only known wassonite-bearing chondrule. The goal of this study is to determine whether this chondrule's formation was contemporaneous with other enstatite chondrite chondrules and to establish its place in the broader timeline of solar system events.

Needham, A. W.↗
NASA NTRS2019

A Coordinated Microstructural and Isotopic Study ofa Wark-Lovering Rim on a Vigarano CAI

We carried out a coordinated mineralogical and isotopic study of a Wark-Lovering (WL) rim on a Ca,Al-rich inclusion (CAI) from the reduced CV3 chondrite Vigarano. The outermost edge of the CAI mantle is mineralogically and texturally distinct compared to the underlying mantle that is composed of coarse, zoned melilite (Åk~10-60) grains. The mantle edge contains fine-grained gehlenite with hibonite and rare grossite that likely formed by rapid crystallization from a melt enriched in Ca and Al. These gehlenite and hibonite layers are surrounded by successive layers of spinel, zoned melilite (Åk~0-10), zoned diopside that grades outwards from Al,Ti-rich to Al,Ti-poor, and forsteritic olivine intergrown with diopside. These layered textures are indicative of sequential condensation of spinel, melilite, diopside, and forsterite onto hibonite. Anorthite occurs as a discontinuous layer that corrodes adjacent melilite and Al2 diopside, and appears to have replaced them, probably even later than the forsterite layer formation. Based on these observations, we conclude that the WL rim formation was initiated by flash melting and extensive evaporation of the original inclusion edge, followed by subsequent gas-solid reactions under highly dynamic conditions. All the WL rim minerals are 16O-rich (Δ17O = ~−23‰), indicating their formation in an 16O-rich nebular reservoir. Our Al-Mg measurements of hibonite, spinel, and diopside from the WL rim, as well as spinel and Al,Ti-diopside in the core, define a single, well-correlated isochron with an inferred initial 26Al/27Al ratio of (4.94 ± 0.12) × 10−5. This indicates that the WL rim formed shortly after the host CAI. In contrast, the lack of 26Mg excesses in the WL rim anorthite suggest its later formation or later isotopic disturbance in the solar nebula, after 26Al had decayed.

Jangmi Han↗
NASA NTRS2017

Constraints on Mechanisms of Chondrule Formation from Chondrule Precursors and Chronology of Transient Heating Events in the Protoplanetary Disk

The mineralogy, petrography, and oxygen-isotope compositions of porphyritic chondrules—dominant chondrule type in most chondrite groups—suggest formation by incomplete melting of isotopically diverse precursors during localized transient heating events in dust-rich regions of the protoplanetary disk characterized by 16O-poor compositions (D17Odust+gas~ –7‰ to +4‰) relative to the inferred Sun’s value (D17O ~ –28 ± 2‰). The chondrule precursors included Ca,Al-rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), chondrules of earlier generations, fine-grained matrix-like material, and possibly fragments of pre-existing planetesimals. Like porphyritic chondrules, igneous CAIs formed by melting of isotopically diverse precursors during transient heating events, but in an isotopically distinct, solar-like reservoir of the protoplanetary disk (D17O dust + gas ~ –24‰), probably near the proto Sun. Based on a narrow range of the initial 26Al/27Alratios inferred from the internal Al-Mg isochrons in igneous CAIs, their melting started at the very beginning of Solar System formation (t0), defined by the CV CAIs with U-corrected Pb-Pb age of 4567.3 ± 0.16 Ma and the canonical 26Al/27Al ratio of (5.25 ± 0.02) ¥ 10–5, and lasted at least 0.3 Ma. The U-corrected Pb-Pb absolute and 26Al-26Mg relative ages of porphyritic chondrules from type 3 ordinary, CO, CV, and CR carbonaceous chondrites (assuming uniform distribution of 26Al in the disk at the canonical level) suggest chondrule formation started at t0 and lasted for about 4 Ma. These observations may preclude formation of the majority of porphyritic chondrules by splashing of differentiated planetesimals and by collisions between planetesimals; instead, they are consistent with melting of dust balls by bow shocks or magnetized turbulence in the disk. Some porphyritic chondrules in equilibrated (petrologic type 4–6) ordinary chondrites contain relict fragments of coarse-grained chromite, ilmenite, phosphates, and albitic plagioclase. The similar mineral assemblage is commonly observed in type 4–6 ordinary chondrites, but is absent in type 3 chondrites, suggesting these chondrules formed by incomplete melting of thermally metamorphosed ordinary chondrite material, possibly by impacts. The CB metal-rich carbonaceous chondrites contain exclusively magnesian non-porphyritic chondrules crystallized from complete melts. These chondrules formed in a gas-melt plume generated by a hypervelocity (≥20 km/s) collision between planetesimals ~4.8 Ma after t0 in a transition or a debris disk. One of the colliding bodies was probably differentiated. The CH metal-rich carbonaceous chondrites contain chondrules formed by different mechanisms. The magnesian non-porphyritic chondrules formed in the CB impact plume ~4.8 Ma after t0. The chemically diverse (magnesian, ferroan, and Al-rich) porphyritic chondrules formed by incomplete melting of isotopically diverse precursors in the protoplanetary disk, most likely prior the CB impact plume event. We conclude that there are multiple mechanisms of chondrule formation that operated over the entire life-time of the disk.

Chondrules↗
DOE OSTI2022

An influence of manufacturing tolerances on Pin-Cell k-infinity of MOX fuel using data from the FUBILA experiment program

An influence of manufacturing tolerances (MTs) was evaluated on the pin-cell k-infinity of MOX fuel through the random sampling of CASMO5 calculations. The data from the FUBILA experiment program was used as the manufacturing parameters. For the uncertainties of element/isotope mass fractions, their covariance matrices were calculated by the generalized least square method. The total k-infinity uncertainty was 120-250 pcm (percent mille). From the breakdown of k-infinity uncertainty per materials, the MTs of fuel pellet had a dominant influence. The individual influences were also evaluated for element/isotope mass fractions, an inner/outer diameter, and a density. Those of element/isotope mass fractions were less than a few dozen pcm. Since the perturbations of fuel pellet diameter and density caused large variations to the total amount of heavy metals and effect of spatial self-shielding, they had a negative correlation with the k-infinity perturbation. On the AG3 (Al-Mg alloy) over-cladding, the inner/outer diameter perturbations had both negative and positive correlations. The negative one was due to decrease in amount of light water and the positive one was due to increase in amount of AG3. Since the effect of neutron slowing-down by light water had a dominant influence, the influence of the former negative correlation was larger than that of the latter positive correlation. It is, therefore, concluded that the consideration of the MTs that had a large influence on the effect of neutron slowing-down is important for precise quantification of the pin-cell k-infinity uncertainty of MOX fuel. (author)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Materials Data on Mg13Al14 by Materials Project

Mg13Al14 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 8-coordinate geometry to fourteen Al atoms. There are eight shorter (3.02 Å) and six longer (3.06 Å) Mg–Al bond lengths. In the second Mg site, Mg is bonded in a 4-coordinate geometry to four Al atoms. All Mg–Al bond lengths are 3.04 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a distorted body-centered cubic geometry to four Mg and four Al atoms. There are three shorter (2.79 Å) and one longer (2.80 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a distorted q6 geometry to five Mg and four equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg17Al12 by Materials Project

Mg17Al12 crystallizes in the cubic I-43m space group. The structure is three-dimensional. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to four equivalent Mg and twelve equivalent Al atoms. All Mg–Mg bond lengths are 3.14 Å. All Mg–Al bond lengths are 3.20 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six equivalent Al atoms. All Mg–Mg bond lengths are 3.06 Å. All Mg–Al bond lengths are 3.10 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five equivalent Al atoms. There are two shorter (3.14 Å) and four longer (3.16 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.89–3.18 Å. Al is bonded in a 11-coordinate geometry to eight Mg and three equivalent Al atoms. There are one shorter (2.70 Å) and two longer (2.76 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg41Al67 by Materials Project

Mg41Al67 crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded to three Mg and nine Al atoms to form distorted MgMg3Al9 cuboctahedra that share corners with four MgMg3Al9 cuboctahedra, corners with eight AlMg6Al6 cuboctahedra, edges with seven MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with six MgMg3Al9 cuboctahedra, and faces with eleven AlMg4Al8 cuboctahedra. There are one shorter (3.04 Å) and two longer (3.08 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.88–2.99 Å. In the second Mg site, Mg is bonded to eight Mg and four Al atoms to form distorted MgMg8Al4 cuboctahedra that share corners with four equivalent MgMg3Al9 cuboctahedra, corners with eight AlMg6Al6 cuboctahedra, edges with twelve MgMg3Al9 cuboctahedra, edges with twelve AlMg6Al6 cuboctahedra, faces with eight AlMg6Al6 cuboctahedra, and faces with ten MgMg8Al4 cuboctahedra. There are four shorter (3.02 Å) and four longer (3.16 Å) Mg–Mg bond lengths. All Mg–Al bond lengths are 2.97 Å. In the third Mg site, Mg is bonded to six Mg and six Al atoms to form MgMg6Al6 cuboctahedra that share corners with three equivalent MgMg6Al6 cuboctahedra, corners with six equivalent AlMg5Al7 cuboctahedra, edges with nine MgMg3Al9 cuboctahedra, edges with fifteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. All Mg–Al bond lengths are 3.02 Å. In the fourth Mg site, Mg is bonded to twelve Al atoms to form MgAl12 cuboctahedra that share corners with twelve AlMg6Al6 cuboctahedra, edges with twenty-four MgMg3Al9 cuboctahedra, faces with two equivalent MgMg8Al4 cuboctahedra, and faces with sixteen AlMg6Al6 cuboctahedra. All Mg–Al bond lengths are 2.98 Å. There are fifteen inequivalent Al sites. In the first Al site, Al is bonded to six Mg and six Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg6Al6 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. There are a spread of Al–Mg bond distances ranging from 2.97–2.99 Å. There are a spread of Al–Al bond distances ranging from 2.89–3.06 Å. In the second Al site, Al is bonded to six Mg and six Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg4Al8 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. There are two shorter (2.99 Å) and two longer (3.02 Å) Al–Mg bond lengths. There are a spread of Al–Al bond distances ranging from 2.89–3.06 Å. In the third Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlAl12 cuboctahedra. All Al–Mg bond lengths are 2.98 Å. There are a spread of Al–Al bond distances ranging from 2.88–3.08 Å. In the fourth Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlMg4Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.88–3.08 Å. In the fifth Al site, Al is bonded to five Mg and seven Al atoms to form distorted AlMg5Al7 cuboctahedra that share corners with four equivalent MgMg6Al6 cuboctahedra, corners with six AlAl12 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with seven MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. There are two shorter (2.94 Å) and two longer (2.97 Å) Al–Al bond lengths. In the sixth Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlMg4Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.88–3.08 Å. In the seventh Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg6Al6 cuboctahedra, edges with twelve MgMg3Al9 cuboctahedra, edges with twelve AlMg6Al6 cuboctahedra, faces with five MgMg3Al9 cuboctahedra, and faces with eleven AlMg4Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.89–3.05 Å. In the eighth Al site, Al is bonded to six Mg and six Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg6Al6 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg5Al7 cuboctahedra. Both Al–Mg bond lengths are 2.99 Å. There are one shorter (2.98 Å) and two longer (3.06 Å) Al–Al bond lengths. In the ninth Al site, Al is bonded to six Mg and six Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg6Al6 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. The Al–Al bond length is 3.06 Å. In the tenth Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with twelve equivalent AlMg5Al7 cuboctahedra, edges with twenty-four equivalent MgMg3Al9 cuboctahedra, and faces with twelve AlMg4Al8 cuboctahedra. All Al–Al bond lengths are 2.88 Å. In the eleventh Al site, Al is bonded to six Mg and six Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with six MgMg3Al9 cuboctahedra, corners with six AlMg6Al6 cuboctahedra, edges with eight MgMg3Al9 cuboctahedra, edges with fourteen AlMg6Al6 cuboctahedra, faces with nine MgMg3Al9 cuboctahedra, and faces with nine AlMg6Al6 cuboctahedra. The Al–Mg bond length is 2.97 Å. There are a spread of Al–Al bond distances ranging from 2.89–3.06 Å. In the twelfth Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg4Al8 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlAl12 cuboctahedra. All Al–Mg bond lengths are 2.98 Å. There are a spread of Al–Al bond distances ranging from 2.88–3.08 Å. In the thirteenth Al site, Al is bonded in a distorted rectangular see-saw-like geometry to four equivalent Mg and eight Al atoms. Both Al–Al bond lengths are 2.92 Å. In the fourteenth Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlMg4Al8 cuboctahedra. All Al–Mg bond lengths are 2.98 Å. There are two shorter (2.88 Å) and one longer (3.08 Å) Al–Al bond lengths. In the fifteenth Al site, Al is bonded to four equivalent Mg and eight Al atoms to form distorted AlMg4Al8 cuboctahedra that share corners with five MgMg3Al9 cuboctahedra, corners with seven AlMg6Al6 cuboctahedra, edges with six MgMg3Al9 cuboctahedra, edges with sixteen AlMg6Al6 cuboctahedra, faces with six equivalent MgMg3Al9 cuboctahedra, and faces with ten AlMg4Al8 cuboctahedra. All Al–Mg bond lengths are 2.98 Å. The Al–Al bond length is 3.08 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3Al by Materials Project

AlMg3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mg is bonded to eight equivalent Mg and four equivalent Al atoms to form MgMg8Al4 cuboctahedra that share corners with twelve equivalent MgMg8Al4 cuboctahedra, edges with eight equivalent AlMg12 cuboctahedra, edges with sixteen equivalent MgMg8Al4 cuboctahedra, faces with four equivalent AlMg12 cuboctahedra, and faces with fourteen equivalent MgMg8Al4 cuboctahedra. All Mg–Mg bond lengths are 3.09 Å. All Mg–Al bond lengths are 3.09 Å. Al is bonded to twelve equivalent Mg atoms to form AlMg12 cuboctahedra that share corners with twelve equivalent AlMg12 cuboctahedra, edges with twenty-four equivalent MgMg8Al4 cuboctahedra, faces with six equivalent AlMg12 cuboctahedra, and faces with twelve equivalent MgMg8Al4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAl by Materials Project

MgAl is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Mg–Al bond lengths are 2.93 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAl2 by Materials Project

MgAl2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Mg is bonded to two equivalent Mg and ten Al atoms to form distorted MgMg2Al10 cuboctahedra that share corners with four equivalent AlMg4Al8 cuboctahedra, corners with eight equivalent MgMg2Al10 cuboctahedra, edges with four equivalent MgMg2Al10 cuboctahedra, edges with twelve equivalent AlMg4Al8 cuboctahedra, faces with five equivalent AlMg4Al8 cuboctahedra, and faces with seven equivalent MgMg2Al10 cuboctahedra. Both Mg–Mg bond lengths are 3.07 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.09 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Mg and eight Al atoms to form AlMg4Al8 cuboctahedra that share corners with four equivalent MgMg2Al10 cuboctahedra, corners with four equivalent AlMg4Al8 cuboctahedra, edges with twelve equivalent MgMg2Al10 cuboctahedra, faces with five equivalent MgMg2Al10 cuboctahedra, and faces with eight equivalent AlMg4Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.91–2.95 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to six equivalent Mg and six Al atoms. Both Al–Al bond lengths are 3.11 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg16Al13 by Materials Project

Mg16Al13 crystallizes in the cubic I-43m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five equivalent Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.16 Å. There are a spread of Mg–Al bond distances ranging from 2.89–3.18 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to three equivalent Mg and seven Al atoms. There are six shorter (3.10 Å) and one longer (3.14 Å) Mg–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to seven Mg and three equivalent Al atoms. There are one shorter (2.71 Å) and two longer (2.75 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a tetrahedral geometry to four equivalent Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAl by Materials Project

MgAl crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Mg is bonded to six equivalent Mg and six equivalent Al atoms to form MgMg6Al6 cuboctahedra that share corners with eighteen equivalent MgMg6Al6 cuboctahedra, edges with six equivalent MgMg6Al6 cuboctahedra, edges with twelve equivalent AlMg6Al6 cuboctahedra, faces with eight equivalent MgMg6Al6 cuboctahedra, and faces with twelve equivalent AlMg6Al6 cuboctahedra. All Mg–Mg bond lengths are 3.02 Å. All Mg–Al bond lengths are 3.02 Å. Al is bonded to six equivalent Mg and six equivalent Al atoms to form distorted AlMg6Al6 cuboctahedra that share corners with eighteen equivalent AlMg6Al6 cuboctahedra, edges with six equivalent AlMg6Al6 cuboctahedra, edges with twelve equivalent MgMg6Al6 cuboctahedra, faces with eight equivalent AlMg6Al6 cuboctahedra, and faces with twelve equivalent MgMg6Al6 cuboctahedra. All Al–Al bond lengths are 3.02 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg18Al11 by Materials Project

Mg18Al11 is gamma-brass-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are twelve inequivalent Mg sites. In the first Mg site, Mg is bonded in a 7-coordinate geometry to five Mg and eleven Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.17–3.22 Å. There are a spread of Mg–Al bond distances ranging from 3.17–3.30 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and four Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.04–3.21 Å. There are a spread of Mg–Al bond distances ranging from 2.89–3.22 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to five Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.07–3.14 Å. There are a spread of Mg–Al bond distances ranging from 3.08–3.20 Å. In the fourth Mg site, Mg is bonded in a 3-coordinate geometry to six Mg and three Al atoms. There are one shorter (2.92 Å) and two longer (3.03 Å) Mg–Mg bond lengths. There are one shorter (2.78 Å) and two longer (2.84 Å) Mg–Al bond lengths. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to eight Mg and four Al atoms. There are a spread of Mg–Mg bond distances ranging from 2.96–3.20 Å. There are two shorter (2.96 Å) and two longer (3.19 Å) Mg–Al bond lengths. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.09–3.17 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.19 Å. In the seventh Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. Both Mg–Mg bond lengths are 3.08 Å. There are a spread of Mg–Al bond distances ranging from 3.07–3.14 Å. In the eighth Mg site, Mg is bonded in a 12-coordinate geometry to eight Mg and four Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.09–3.16 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.21 Å. In the ninth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are one shorter (3.11 Å) and two longer (3.16 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.93–3.22 Å. In the tenth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. The Mg–Mg bond length is 3.02 Å. There are a spread of Mg–Al bond distances ranging from 3.09–3.12 Å. In the eleventh Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. The Mg–Mg bond length is 3.17 Å. There are a spread of Mg–Al bond distances ranging from 2.88–3.20 Å. In the twelfth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Al bond distances ranging from 2.87–3.20 Å. There are six inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.76 Å. In the second Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.71 Å) and one longer (2.79 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a 11-coordinate geometry to nine Mg and two Al atoms. The Al–Al bond length is 2.81 Å. In the fourth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.71–2.78 Å. In the fifth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. In the sixth Al site, Al is bonded in a 11-coordinate geometry to nine Mg and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg13Al16 by Materials Project

Mg13Al16 crystallizes in the cubic I-43m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to six equivalent Mg and six Al atoms. There are two shorter (3.11 Å) and four longer (3.14 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.90–3.11 Å. In the second Mg site, Mg is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.10 Å) and twelve longer (3.17 Å) Mg–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to six Mg and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.66–3.06 Å. In the second Al site, Al is bonded in a 4-coordinate geometry to four Mg and six equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAl by Materials Project

MgAl crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg is bonded to five equivalent Al atoms to form a mixture of edge and corner-sharing MgAl5 trigonal bipyramids. There are two shorter (2.75 Å) and three longer (2.88 Å) Mg–Al bond lengths. Al is bonded to five equivalent Mg atoms to form a mixture of edge and corner-sharing AlMg5 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAl3 by Materials Project

Al3Mg is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Mg is bonded to twelve Al atoms to form MgAl12 cuboctahedra that share corners with four equivalent MgAl12 cuboctahedra, corners with eight equivalent AlMg4Al8 cuboctahedra, edges with eight equivalent MgAl12 cuboctahedra, edges with sixteen equivalent AlMg4Al8 cuboctahedra, faces with four equivalent MgAl12 cuboctahedra, and faces with fourteen AlMg4Al8 cuboctahedra. There are four shorter (2.92 Å) and eight longer (2.93 Å) Mg–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Mg and eight equivalent Al atoms to form AlMg4Al8 cuboctahedra that share corners with four equivalent AlMg4Al8 cuboctahedra, corners with eight equivalent MgAl12 cuboctahedra, edges with twenty-four AlMg4Al8 cuboctahedra, faces with six equivalent MgAl12 cuboctahedra, and faces with twelve AlMg4Al8 cuboctahedra. All Al–Al bond lengths are 2.93 Å. In the second Al site, Al is bonded to four equivalent Mg and eight Al atoms to form AlMg4Al8 cuboctahedra that share corners with twelve equivalent AlMg4Al8 cuboctahedra, edges with eight equivalent MgAl12 cuboctahedra, edges with sixteen AlMg4Al8 cuboctahedra, faces with four equivalent MgAl12 cuboctahedra, and faces with fourteen AlMg4Al8 cuboctahedra. All Al–Al bond lengths are 2.92 Å.

36 MATERIALS SCIENCE↗