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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Strength measurement of the $E^{lab}_α = 830$ keV resonance in the 22 Ne (α,n) 25 Mg reaction using a stilbene detector

The interplay between the 22 Ne (α,γ) 26 Mg reaction and the competing 22 Ne ⁢(α,n) 25 Mg reaction determines the efficiency of the latter as a neutron source at the temperatures of stellar helium burning. In both cases, the rates are dominated by the α-cluster resonance at 830 keV. This resonance plays a particularly important role in determining the strength of the neutron flux for both the weak and main s process as well as the n process. Recent experimental studies based on transfer reactions suggest that the neutron and γ-ray strengths for this resonance are approximately equal. In this study, the 22 Ne (α,n) 25 Mg resonance strength has been remeasured and found to be similar to the previous direct studies. Finally, this reinforces an 830 keV resonance strength that is approximately a factor of 3 larger for the 22 Ne ⁢(α,n) 25 Mg reaction than for the 22 Ne (α,γ) 26 Mg reaction.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Ab initio prediction of an order-disorder transition in Mg 2 Ge O 4 : Implication for the nature of super-Earth's mantles

Here we present an ab initio prediction of an order-disorder transition (ODT) from a I¯42d-type to Th 3 P 4 -type phase in the cation sublattices of Mg 2 GeO 4 , a post-post-perovskite phase. This uncommon type of prediction is achieved by carrying out a high-throughput sampling of atomic configurations in a 56-atom supercell followed by a Boltzmann ensemble statistics calculation. Mg 2 GeO 4 is a low-pressure analog of I¯42d-type Mg 2 SiO 4 , a predicted major planet-forming phase of super-Earths' mantles. Therefore, a similar ODT is anticipated in I¯42d-type Mg 2 SiO 4 as well, which should impact the internal structure and dynamics of these planets. Furthermore, the prediction of this Th 3 P 4 -type phase in Mg 2 GeO 4 further enhances the relationship between the crystal structures of Earth/planet-forming silicates and oxides at extreme pressures and those of rare-earth sesquisulfides at low pressures.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Selectively patterned Mg-doped GaN by SiN x -driven hydrogen injection

In this work, we demonstrate a method to achieve selectively patterned Mg-doped GaN layers using hydrogen drive-in through plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SiN x ) films. Activated Mg-doped GaN layers were selectively deactivated by patterned PECVD SiN x films with low-temperature annealing and showed high-resistive behavior. Spatially resolved photoluminescence measurements were used to optically verify the deactivation of Mg acceptors and showed distinct features corresponding to activated and deactivated Mg in GaN. The method suggested here provides a simple and effective method to achieve patterned Mg-doped GaN regions without thermal and plasma damage, which could cause degradation of device performance. The proposed method could provide a way to achieve future high-performance GaN lateral and vertical devices that rely on laterally patterned doping.

42 ENGINEERING↗
DOE OSTI2021

An Electrochemically Activated Nanofilm for Sustainable Mg Anode with Fast Charge Transfer Kinetics

Highly reversible Mg plating/stripping is key for rechargeable Mg batteries and has typically been successfully demonstrated using transient electrochemical techniques such as cyclic voltammetry measurements. Furthermore, little effort has been invested in studying the stability of the electrode/electrolyte interface over an extended time. We report here the development of an in situ generated surface film for Mg anodes based on electrodeposited bismuth (E_Bi). This film improves the interfacial stability of Mg in contact with the electrolyte, particularly over an extended time, and possesses fast charge-transfer kinetics (<30 Ω∙cm 2 ) and low non-time-sensitive interfacial film resistance (ca. 5 Ω∙cm 2 ) for active Mg species.

25 ENERGY STORAGE↗
DOE OSTI2025

DESI Mg II Absorbers: Extinction Characteristics and Quasar Redshift Accuracy

In this paper, we study how absorption-line systems affect the spectra and redshifts of quasi-stellar objects (QSOs), using catalogs of Mg II absorbers from the early data release and first data release of the Dark Energy Spectroscopic Instrument. We determine the reddening effect of an absorption system by fitting an unreddened template spectrum to a sample of 50,674 QSO spectra that contain Mg II absorbers. We find that reddening caused by intervening absorbers (v off > 3500 km s −1 ) has an average color excess of $\overline{E(B-V)}$ = 0.04 mag. We find that the E(B − V) tends to be greater for absorbers at low redshifts, or those having Mg II absorption lines with higher equivalent widths, but shows no clear trend with v off for intervening systems. However, the $\overline{E(B-V)}$ of associated absorbers, those at v off < 3500 km s −1 , shows a strong trend with v off , increasing rapidly with decreasing v off and peaking (∼0.15 mag) around v off = 0 km s −1 . We demonstrate that Mg II absorbers impact redshift estimation for QSOs by investigating the distributions of v off for associated absorbers. We find that at z > 1.5, these distributions broaden and bifurcate in a nonphysical manner. In an effort to mitigate this effect, we mask pixels associated with the Mg II absorption lines and recalculate the QSO redshifts. We find that we can recover voff populations in better agreement with those for z < 1.5 absorbers and in doing so typically shift background QSO redshifts by Δz ≈ ± 0.005.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Tracing the Evolution of the Cool Gas in CGM and IGM Environments through Mg II Absorption from Redshift z = 0.75 to z = 1.65 Using DESI-Y1 Data

We present a measurement of the mean absorption of cool gas traced by Mg II (λλ2796, 2803) around emission line galaxies (ELGs), spanning spatial scales from 20 kpc to 10 Mpc. The measurement is based on crossmatching the positions ELGs at z = 0.75–1.65 and the metal absorption in the spectra of background quasars with data provided by the Year 1 sample of the Dark Energy Spectroscopic Instrument. The ELGs are divided into two redshift intervals: 0.75 < z < 1.0 and 1.0 < z < 1.65. We find that the composite quasar spectra constructed by stacking the ELG-QSO pairs evolve with redshift, with z > 1 having a systematically higher signal of Mg II absorption. Within 1 Mpc, the covering fraction of the cool gas at z > 1 is higher than that of z < 1. The enhancement becomes less apparent especially if the projected distance r p > 1 Mpc. ELGs with higher stellar mass and star formation rate (SFR) yield higher clustering of Mg ii absorbers at z < 1. For z > 1, the covering fractions with different SFRs show little difference. The higher Mg II absorption at higher redshift supports the observations of higher star formation at cosmic noon. Converting the Mg II absorbers to unsaturated Si II , our estimate indicates that the metal abundance of Si II ranges from 0.7 to 1.2 × 10 −6 from z = 0.9 to 1.3. The growth of low-ionization metal abundance strongly suggests a metal-enriched circumgalactic medium and an increased presence of cool gas in the intergalactic medium toward higher redshifts.

circumgalactic medium↗
DOE OSTI2025

The CAI Database: 26 Al– 26 Mg Isotope Systematics

We present a publicly available calcium–aluminum-rich inclusion (CAI) database that focuses on the initial 26 Al/ 27 Al 0 ratio in CAIs, designed in a way that researchers in cosmochemistry and astrophysics may find useful. To date, the database contains 497 CAIs from 75 peer-reviewed papers. The CAIs are from all chondrite groups and cover different CAI types, textures, and sizes. The database includes the paper; the host meteorite; the CAI name and type; the 26 Al/ 27 Al 0 , δ 26 Mg$^*_0$, and δ 25 Mg values and their uncertainties; the number of regression points; the maximum 27 Al/ 24 Mg; the mean-squared weighted deviation; the CAI size; and CAI descriptions. We grouped the CAIs in different ways to discuss 26 Al/ 27 Al 0 ratio distributions with implications for the CAI formation timeline. Overall, we agree with previous authors that CAIs have a bimodal 26 Al distribution: CAIs with robust isochrons (n = 151) have a median 26 Al/ 27 Al 0 = 4.8 × 10 −5 (with a 1σ standard error of 0.1), while those with isotopic anomalies (n = 87) have a median 26 Al/ 27 Al 0 = 0.3 × 10 −5 (with a 1σ standard error of 0.2). However, the large standard deviation of both groups (1.3 and 2.3, respectively) indicates that the 26 Al/ 27 Al 0 values scatter significantly within each population. CAI types and groups can have distinct 26 Al/ 27 Al 0 and δ 26 Mg$^*_0$, but the unmelted inclusions (n = 33) have the highest median 26 Al/ 27 Al 0 = 5.1 × 10 −5 and a low median δ 26 Mg$^*_0$ = −0.05‰. We find slightly different 26 Al/ 27 Al 0 distributions between CAI chondrite types, but no differences between petrographic types or sizes. These observations can help us to understand CAI formation in the context of astrophysical models.

Astronomy and AstroPhysics↗
DOE OSTI2020

Materials Data on Mg(ScGa)2 by Materials Project

Mg(ScGa)2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Mg is bonded in a square co-planar geometry to four equivalent Ga atoms. All Mg–Ga bond lengths are 2.82 Å. Sc is bonded in a 6-coordinate geometry to six equivalent Ga atoms. There are two shorter (2.84 Å) and four longer (2.92 Å) Sc–Ga bond lengths. Ga is bonded in a 9-coordinate geometry to two equivalent Mg, six equivalent Sc, and one Ga atom. The Ga–Ga bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(HO)2 by Materials Project

Mg(OH)2 crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one Mg(OH)2 sheet oriented in the (0, 0, 1) direction. Mg2+ is bonded in a distorted q6 geometry to three equivalent H1+ and six O2- atoms. All Mg–H bond lengths are 1.97 Å. There are three shorter (2.11 Å) and three longer (2.23 Å) Mg–O bond lengths. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to three equivalent Mg2+ and one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to three equivalent Mg2+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three equivalent Mg2+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(InSe2)2 by Materials Project

Mg(InSe2)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Mg(InSe2)2 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one MgSe4 tetrahedra, corners with five InSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent InSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.74–2.79 Å. In the second Mg2+ site, Mg2+ is bonded to four Se2- atoms to form MgSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent InSe6 octahedra, and corners with six InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are a spread of Mg–Se bond distances ranging from 2.58–2.62 Å. There are four inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to six Se2- atoms to form InSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four InSe4 tetrahedra, edges with two equivalent InSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of In–Se bond distances ranging from 2.75–2.83 Å. In the second In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one InSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.60–2.68 Å. In the third In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one InSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.61–2.68 Å. In the fourth In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent InSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.62–2.67 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three In3+ atoms. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent In3+ atoms to form distorted SeMg2In2 trigonal pyramids that share corners with seven SeMg2In2 tetrahedra, corners with two equivalent SeMg2In2 trigonal pyramids, an edgeedge with one SeMgIn3 tetrahedra, and edges with two SeMg2In2 trigonal pyramids. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the fourth Se2- site, Se2- is bonded to two equivalent Mg2+ and two In3+ atoms to form a mixture of distorted edge and corner-sharing SeMg2In2 trigonal pyramids. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the sixth Se2- site, Se2- is bonded to two equivalent Mg2+ and two In3+ atoms to form distorted SeMg2In2 tetrahedra that share corners with two equivalent SeMgIn3 tetrahedra, corners with seven SeMg2In2 trigonal pyramids, edges with two SeMg2In2 tetrahedra, and an edgeedge with one SeMg2In2 trigonal pyramid. In the seventh Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the eighth Se2- site, Se2- is bonded to one Mg2+ and three In3+ atoms to form a mixture of distorted edge and corner-sharing SeMgIn3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)4 by Materials Project

Mg(FeO2)4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Mg is bonded to six equivalent O atoms to form MgO6 octahedra that share corners with six equivalent FeO6 octahedra and edges with six equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Mg–O bond lengths are 2.15 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share edges with two equivalent MgO6 octahedra and edges with six FeO6 octahedra. There is four shorter (1.95 Å) and two longer (1.96 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six equivalent O atoms to form FeO6 octahedra that share corners with six equivalent MgO6 octahedra and edges with six equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Fe–O bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O is bonded in a rectangular see-saw-like geometry to one Mg and three Fe atoms. In the second O site, O is bonded in a distorted T-shaped geometry to three equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(CuO2)2 by Materials Project

MgCu2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.38 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.18–2.42 Å. In the third Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.43 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.20–2.40 Å. There are eight inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the second Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.94–2.05 Å. In the third Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fourth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fifth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.07 Å. In the sixth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the seventh Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the eighth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.90–2.07 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the sixth O2- site, O2- is bonded to two Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the ninth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the tenth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the eleventh O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the twelfth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the thirteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fifteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(C2O3)2 by Materials Project

Mg(CO3)2(C)2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of four ethyne molecules and two Mg(CO3)2 sheets oriented in the (1, 0, 0) direction. In each Mg(CO3)2 sheet, Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.04–2.16 Å. C+2.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+2.50+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Mg2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BH4)2 by Materials Project

Mg(BH4)2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional and consists of two Mg(BH4)2 frameworks. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.07 Å) and four longer (2.12 Å) Mg–H bond lengths. In the second Mg2+ site, Mg2+ is bonded in a body-centered cubic geometry to eight equivalent H+0.50+ atoms. All Mg–H bond lengths are 2.11 Å. B3- is bonded to four H+0.50+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. There is three shorter (1.22 Å) and one longer (1.23 Å) B–H bond length. There are three inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BH4)2 by Materials Project

Mg(BH4)2 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional and consists of two Mg(BH4)2 frameworks. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.08 Å) and four longer (2.12 Å) Mg–H bond lengths. In the second Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form distorted MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.09 Å) and four longer (2.12 Å) Mg–H bond lengths. B3- is bonded to four H+0.50+ atoms to form BH4 tetrahedra that share edges with two MgH8 hexagonal bipyramids. There is two shorter (1.22 Å) and two longer (1.23 Å) B–H bond length. There are four inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the fourth H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(AlSn)2 by Materials Project

Mg(AlSn)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg is bonded to six equivalent Sn atoms to form MgSn6 octahedra that share corners with twelve equivalent AlSn4 tetrahedra, edges with six equivalent MgSn6 octahedra, and edges with six equivalent AlSn4 tetrahedra. All Mg–Sn bond lengths are 3.08 Å. Al is bonded to four equivalent Sn atoms to form AlSn4 tetrahedra that share corners with six equivalent MgSn6 octahedra, corners with six equivalent AlSn4 tetrahedra, edges with three equivalent MgSn6 octahedra, and edges with three equivalent AlSn4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–57°. There are three shorter (2.78 Å) and one longer (2.85 Å) Al–Sn bond lengths. Sn is bonded to three equivalent Mg and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SnMg3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(Hg11N3)2 by Materials Project

Mg(Hg11N3)2 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Mg is bonded in a square co-planar geometry to four equivalent N atoms. All Mg–N bond lengths are 2.25 Å. There are five inequivalent Hg sites. In the first Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.79 Å. The Hg–N bond length is 2.22 Å. In the second Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.94 Å. The Hg–N bond length is 2.23 Å. In the third Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 3.11 Å. The Hg–N bond length is 2.48 Å. In the fourth Hg site, Hg is bonded to six Hg atoms to form HgHg6 octahedra that share a cornercorner with one NHg5 square pyramid. The Hg–Hg bond length is 2.90 Å. In the fifth Hg site, Hg is bonded to four equivalent Hg atoms to form distorted HgHg4 tetrahedra that share corners with four equivalent NHg5 square pyramids. There are two inequivalent N sites. In the first N site, N is bonded to five Hg atoms to form distorted NHg5 square pyramids that share a cornercorner with one HgHg6 octahedra and corners with four equivalent HgHg4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second N site, N is bonded in a distorted T-shaped geometry to one Mg and two equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(MnSn)6 by Materials Project

MgMn6Sn6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Mg is bonded to eight Sn atoms to form edge-sharing MgSn8 hexagonal bipyramids. There are two shorter (2.93 Å) and six longer (3.14 Å) Mg–Sn bond lengths. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.74–2.81 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 7-coordinate geometry to one Mg and six equivalent Mn atoms. In the second Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Mg and six equivalent Mn atoms. In the third Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Mn atoms.

36 MATERIALS SCIENCE↗