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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Combustion in the ZrF 4 -Mg-Si and ZrF 4 -Al-Si systems for preparation of zirconium silicides

The exothermic reactions in the ZrF 4 –Mg-Si and ZrF 4 -Al-Si systems are investigated by a fast temperature recording (thermocouple) technique, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). A quenching method is used to arrest the combustion process and conduct a layer-by-layer analysis of the products by x-ray diffraction (XRD) and electron microscopy. Two seemingly similar reactive systems exhibited considerably different combustion characteristics, composition, and morphology. Based on these investigations, we propose and discuss phase formation mechanisms at the early stages for each system. Three different pathways involving the reaction of ZrF 4 with other reagents and the Mg 2 Si intermediate are identified to occur in the ZrF 4 –Mg-Si system. Contrary to the complex mechanism in the ZrF 4 –Mg-Si system, the early stage of the combustion process for the ZrF 4 -Al-Si system involves the interaction of ZrF 4 with Al-Si eutectic melt. The exothermic reaction between reduced solid Zr and Si melt is the primary heat-generating step for both systems in spite of substantial differences in the early stages of the reactions. The silicon content in the reactive mixtures governs the phase composition of products. The ZrSi 2 phase, with a high growth rate, forms first on the Zr particle surfaces and then grows by a reactive diffusion mechanism. The ZrSi 2+ Zr reaction produces silicon-lean phases (e.g., ZrSi) when the silicon supply is limited. The combustion temperature also has a considerable influence on the phase compositions of the products. High combustion temperature in the ZrF 4 +2Mg+Si mixture enables the formation of multiphase products (α-ZrSi and β-ZrSi), whereas the relatively lower temperatures in the 3ZrF 4 +4Al+3Si mixture yields a single-phase α-ZrSi. As a result, lower combustion temperatures also make the ZrF 4 -Al-Si system more advantageous for the preparation of zirconium silicides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2018

Dimethylsilanediol (DMSD) Source Assessment and Mitigation on ISS: Estimated Contributions from Personal Hygiene Products Containing Volatile Methyl Siloxanes (VMS)

Dimethylsilanediol (DMSD) is a small organosilicon compound present in humidity condensate on the International Space Station. Aqueous DMSD originates from volatile methyl siloxane (VMS) compounds in the ISS cabin atmosphere. DMSD is not effectively removed by the WPA (Water Processor Assembly), requiring removal and replacement of both WPA Multifiltration (MF) Beds for an estimated resupply penalty of approximately 70 kg/year. Analyses indicate that WPA can handle DMSD if the concentration in the condensate can by reduced by fifty percent. Personal Hygiene Products (PHPs) used by crew are suspected to be a significant source of VMS. Source removal of VMS will be required to achieve a measurable impact to the DMSD concentration in the condensate. The inventory of total crew provisions for ISS was analyzed to identify silicon containing materials and products used for personal hygiene that emit VMS. Accounting for the wide range in mass of hygiene product applied to skin or hair, the frequency of application, the product selection, the number of crew using a given product, the range in silicon mass fraction of different products, and the potential vaporization of the product, the potential total VMS emissions from personal hygiene products for a crew of six on ISS were estimated. The total daily VMS emissions from PHPs estimate ranges from 261 to 1145 mg-Si per day, compared to total estimated VMS generation rates on ISS of 800 to 1500 mg-Si per day. The main sources of VMS were determined to be antiperspirants (173 to 696 mg-Si per day), skin lotions (63 to 248 mg-Si per day), wipes (25 to 124 mg-Si per day) and hair conditioner (0 to 69 mg-Si per day). Several siloxanes-free options are available for deodorants, wet wipes, lotions, and leave-in conditioners. These products are now being assessed for crew member use in future increments.

Muirhead, Dean L.↗
DOE OSTI2026

Techno-Economic Comparison of Molten-Salt Electrolysis and Carbothermic Reduction for the Production of Metallurgical-Grade Silicon

Metallurgical-grade silicon (MG-Si) is an important source material for many industrial applications, including the manufacture of alloys, solar photovoltaics, and electronics. The process to refine raw materials into MG-Si is energy-intensive, with the predominant method of submerged-arc furnaces requiring energy consumption of approximately 11–13 kWh/kg Si. Recent research has discussed promising methods for reducing the energy required for the silicon production process, including the use of molten-salt electrolysis (MSE), a technique that offers potential savings in energy consumption without requiring carbon inputs for the process. This paper presents a techno-economic study of a potential industrial-scale MSE plant for MG-Si production to evaluate the trade-offs between capital and operating costs of the system. Capital costs are sourced from recent MG-Si plants and an existing cost model developed for MSE processes that includes the size of the plant and the operating temperature among its inputs. The results show that MSE technology has the potential to be an economically cost-competitive option for MG-Si production if the technology successfully scales to industrial production and matures enough to allow for financing costs similar to that of a comparably sized submerged-arc furnace plant.

14 SOLAR ENERGY↗
NASA NTRS1976

Production of solar-grade silicon from purified metallurgical silicon

The long-term goal of this work is to produce silicon of solar-grade quality at 3 x 10 to the 6th kg/y for less than $10/kg by, or before 1986. The approach is to improve and expand upon the technology used today to commercially produce metallurgical-grade silicon (MG-Si). This is currently being accomplished by using purer raw materials in the arc furnace process for producing MG-Si, by upgrading the furnace itself, and by unidirectionally solidifying the molten silicon exiting the furnace. Solar cells fabricated from partially purified MG-Si have shown average AM0 efficiencies in the range of 9-11%. Since further MG-Si purification yet remains possible, fabrication of cells of considerably higher conversion efficiency is deemed feasible.

Hunt, L. P.↗
DOE OSTI2024

Structural evolution of liquid silicates under conditions in Super-Earth interiors

Molten silicates at depth are crucial for planetary evolution, yet their local structure and physical properties under extreme conditions remain elusive due to experimental challenges. In this study, we utilize in situ X-ray diffraction (XRD) at the Matter in Extreme Conditions (MEC) end-station of the Linear Coherent Linac Source (LCLS) at SLAC National Accelerator Laboratory to investigate liquid silicates. Using an ultrabright X-ray source and a high-power optical laser, we probed the local atomic arrangement of shock-compressed liquid (Mg,Fe)SiO 3 with varying Fe content, at pressures from 81(9) to 385(40) GPa. We compared these findings to ab initio molecular dynamics simulations under similar conditions. Results indicate continuous densification of theO-O and Mg-Si networks beyond Earth’s interior pressure range, potentially altering melt properties at extreme conditions. This could have significant implications for early planetary evolution, leading to notable differences in differentiation processes between smaller rocky planets, such as Earth and Venus, and super-Earths, which are exoplanets withmasses nearly three times that of Earth.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1975

Low cost processes for solar-grade silicon

Upgrading metallurgical grade silicon is being pursued in four associated areas in order to improve the purity of the normally 98% material. The first two work areas involve purification of raw materials entering the process in addition to upgrading the arc furnace itself. The second two areas of process upgrading comprise improving the purity of the silicon after it leaves the arc furnace by reactive gas blowing and unidirectional freezing. The best cell produced to date was fabricated from MG-Si that had been blown with an O2-Cl2 mixture, unidirectionally solidified, and 6-float-zone passed (to determine a base boron level of 0.04 ohm/cm). The cell showed a 10.7% AMO efficiency. In the other processes category, the use of silicates as a silicon source and of electrolysis as a process were studied. The best electrolytic process uses a 1000 C fused salt of silica in cryolite.

Hunt, L. P.↗
NASA NTRS1977

Solar silicon via improved and expanded metallurgical silicon technology

A completed preliminary survey of silica sources indicates that sufficient quantities of high-purity quartz are available in the U.S. and Canada to meet goals. Supply can easily meet demand for this little-sought commodity. Charcoal, as a reductant for silica, can be purified to a sufficient level by high-temperature fluorocarbon treatment and vacuum processing. High-temperature treatment causes partial graphitization which can lead to difficulty in smelting. Smelting of Arkansas quartz and purified charcoal produced kilogram quantities of silicon having impurity levels generally much lower than in MG-Si. Half of the goal was met of increasing the boron resistivity from 0.03 ohm-cm in metallurgical silicon to 0.3 ohm-cm in solar silicon. A cost analysis of the solidification process indicate $3.50-7.25/kg Si for the Czochralski-type process and $1.50-4.25/kg Si for the Bridgman-type technique.

Hunt, L. P.↗
NASA NTRS1981

Multigrid simulation of asymptotic curved-duct flows using a semi-implicit numerical technique

Asymptotic flows inside curved ducts of rectangular as well as polar cross section are analyzed using the Navier-Stokes equations in terms of the axial velocity and vorticity and the cross-flow stream function. Numerical solutions of the three second-order coupled elliptic partial differential equations governing this flow are obtained efficiently using the coupled alternating-direction implicit (ADI) method as well as the multigrid strongly-implicit (SI) scheme. For the flow configuration studied, the ADI method is found to be more sensitive to the time steps used than is the SI scheme. Use of the multigrid-coupled-strongly-implicit (MG-SI) scheme makes it possible to efficiently obtain fine-grid solutions for configurations having strong secondary flow. It is shown that, for this asymptotic curved-duct flow, the similarity parameter of significance is the Dean's number K rather than the Reynolds number Re. Results are obtained for curved ducts with square cross sections for K up to 900, which here corresponds to Re = 9,000 for this internal flow configuration.

Ghia, K. N.↗
DOE OSTI2020

Materials Data on Mg3Si4 by Materials Project

Mg3Si4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Mg sites. In the first Mg site, Mg is bonded in a 1-coordinate geometry to three Si atoms. There are a spread of Mg–Si bond distances ranging from 2.16–2.72 Å. In the second Mg site, Mg is bonded in a 4-coordinate geometry to one Mg and two Si atoms. The Mg–Mg bond length is 2.24 Å. There are one shorter (2.22 Å) and one longer (2.26 Å) Mg–Si bond lengths. In the third Mg site, Mg is bonded in a 1-coordinate geometry to four Si atoms. There are a spread of Mg–Si bond distances ranging from 1.75–2.56 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to two Mg and four Si atoms. There are one shorter (2.39 Å) and one longer (2.45 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.36–3.15 Å. In the fifth Mg site, Mg is bonded in a 2-coordinate geometry to one Mg and two Si atoms. There are one shorter (2.13 Å) and one longer (2.31 Å) Mg–Si bond lengths. In the sixth Mg site, Mg is bonded in a 4-coordinate geometry to two Mg and two Si atoms. There are one shorter (2.55 Å) and one longer (2.79 Å) Mg–Si bond lengths. There are eight inequivalent Si sites. In the first Si site, Si is bonded in a distorted single-bond geometry to one Mg and one Si atom. The Si–Si bond length is 2.32 Å. In the second Si site, Si is bonded in a 5-coordinate geometry to three Mg and two Si atoms. The Si–Si bond length is 2.08 Å. In the third Si site, Si is bonded in a distorted single-bond geometry to two Mg atoms. In the fourth Si site, Si is bonded in a distorted single-bond geometry to two Mg atoms. In the fifth Si site, Si is bonded in a 1-coordinate geometry to three Mg atoms. In the sixth Si site, Si is bonded in a 2-coordinate geometry to three Mg atoms. In the seventh Si site, Si is bonded in a 2-coordinate geometry to two Mg atoms. In the eighth Si site, Si is bonded in a distorted single-bond geometry to one Mg and one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg5Si9 by Materials Project

Mg5Si9 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 5-coordinate geometry to two Mg and seven Si atoms. There are one shorter (3.02 Å) and one longer (3.10 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.77–3.25 Å. In the second Mg site, Mg is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.17 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.26 Å. In the fourth Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–3.01 Å. In the fifth Mg site, Mg is bonded in a 8-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.69–3.00 Å. In the sixth Mg site, Mg is bonded in a 7-coordinate geometry to nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.80–3.25 Å. In the seventh Mg site, Mg is bonded in a 1-coordinate geometry to one Mg and nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.16 Å. In the eighth Mg site, Mg is bonded in a 12-coordinate geometry to one Mg and eleven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–3.14 Å. In the ninth Mg site, Mg is bonded in a 6-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–3.17 Å. In the tenth Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.76–3.01 Å. There are eighteen inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.44–2.52 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to three Mg and six Si atoms. There are a spread of Si–Si bond distances ranging from 2.44–2.88 Å. In the third Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.47–2.50 Å. In the fourth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.43–2.74 Å. In the fifth Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.42–2.71 Å. In the sixth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.46–2.62 Å. In the seventh Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.45–2.63 Å. In the eighth Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are one shorter (2.49 Å) and one longer (2.50 Å) Si–Si bond lengths. In the ninth Si site, Si is bonded in a 9-coordinate geometry to four Mg and five Si atoms. There are one shorter (2.48 Å) and one longer (2.60 Å) Si–Si bond lengths. In the tenth Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. The Si–Si bond length is 2.39 Å. In the eleventh Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. The Si–Si bond length is 2.50 Å. In the twelfth Si site, Si is bonded in a 9-coordinate geometry to four Mg and five Si atoms. The Si–Si bond length is 2.80 Å. In the thirteenth Si site, Si is bonded in a 1-coordinate geometry to four Mg and five Si atoms. There are one shorter (2.47 Å) and one longer (2.80 Å) Si–Si bond lengths. In the fourteenth Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. The Si–Si bond length is 2.57 Å. In the fifteenth Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. In the sixteenth Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. In the seventeenth Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. The Si–Si bond length is 2.54 Å. In the eighteenth Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2Si3 by Materials Project

Mg2Si3 crystallizes in the triclinic P-1 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 Si+1.33- atoms. There are a spread of Mg–Si bond distances ranging from 2.74–3.09 Å. In the second Mg2+ site, Mg2+ is bonded to six Si+1.33- atoms to form distorted edge-sharing MgSi6 pentagonal pyramids. There are a spread of Mg–Si bond distances ranging from 2.77–2.90 Å. In the third Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight Si+1.33- atoms. There are a spread of Mg–Si bond distances ranging from 2.74–3.09 Å. In the fourth Mg2+ site, Mg2+ is bonded to six Si+1.33- atoms to form distorted edge-sharing MgSi6 pentagonal pyramids. There are a spread of Mg–Si bond distances ranging from 2.77–2.89 Å. There are six inequivalent Si+1.33- sites. In the first Si+1.33- site, Si+1.33- is bonded in a 7-coordinate geometry to four Mg2+ and three Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.45–2.47 Å. In the second Si+1.33- site, Si+1.33- is bonded in a 8-coordinate geometry to four Mg2+ and four Si+1.33- atoms. There are one shorter (2.55 Å) and one longer (2.62 Å) Si–Si bond lengths. In the third Si+1.33- site, Si+1.33- is bonded in a 9-coordinate geometry to six Mg2+ and three Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.47–2.62 Å. In the fourth Si+1.33- site, Si+1.33- is bonded in a 7-coordinate geometry to four Mg2+ and three Si+1.33- atoms. There are one shorter (2.45 Å) and two longer (2.47 Å) Si–Si bond lengths. In the fifth Si+1.33- site, Si+1.33- is bonded in a 8-coordinate geometry to four Mg2+ and four Si+1.33- atoms. In the sixth Si+1.33- site, Si+1.33- is bonded in a 9-coordinate geometry to six Mg2+ and three Si+1.33- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgSi by Materials Project

MgSi is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Mg sites. In the first Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.03 Å. In the second Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.05 Å. In the third Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.68–3.02 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.68–2.88 Å. In the fifth Mg site, Mg is bonded in a 5-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.67–3.19 Å. In the sixth Mg site, Mg is bonded in a 4-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.84–3.22 Å. There are six inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to six Mg and two equivalent Si atoms. There are one shorter (2.59 Å) and one longer (2.64 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 7-coordinate geometry to five Mg and two Si atoms. There are one shorter (2.43 Å) and one longer (2.47 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. There are one shorter (2.43 Å) and one longer (2.63 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 9-coordinate geometry to eight Mg and one Si atom. In the fifth Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. In the sixth Si site, Si is bonded in a 8-coordinate geometry to six Mg and two Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg5Si9 by Materials Project

Mg5Si9 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 4-coordinate geometry to one Mg and five Si atoms. The Mg–Mg bond length is 2.91 Å. There are a spread of Mg–Si bond distances ranging from 2.73–3.25 Å. In the second Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.71–2.94 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–3.20 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to one Mg and six Si atoms. The Mg–Mg bond length is 3.09 Å. There are a spread of Mg–Si bond distances ranging from 2.85–3.15 Å. In the fifth Mg site, Mg is bonded in a 6-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.81–3.16 Å. In the sixth Mg site, Mg is bonded in a 8-coordinate geometry to nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–3.20 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to four Mg and eight Si atoms. There are one shorter (3.03 Å) and one longer (3.16 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.80–3.21 Å. In the eighth Mg site, Mg is bonded in a 7-coordinate geometry to ten Si atoms. There are a spread of Mg–Si bond distances ranging from 2.84–3.22 Å. In the ninth Mg site, Mg is bonded in a 5-coordinate geometry to one Mg and seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.26 Å. In the tenth Mg site, Mg is bonded in a 7-coordinate geometry to one Mg and nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.27 Å. There are eighteen inequivalent Si sites. In the first Si site, Si is bonded in a 10-coordinate geometry to five Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.45–2.78 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to four Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.50–2.69 Å. In the third Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.52–2.63 Å. In the fourth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.47–2.63 Å. In the fifth Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are one shorter (2.60 Å) and one longer (2.63 Å) Si–Si bond lengths. In the sixth Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.43–2.54 Å. In the seventh Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.44–2.58 Å. In the eighth Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.40–2.45 Å. In the ninth Si site, Si is bonded in a 6-coordinate geometry to two Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.42–2.94 Å. In the tenth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. In the eleventh Si site, Si is bonded in a 2-coordinate geometry to four Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.68–2.86 Å. In the twelfth Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. In the thirteenth Si site, Si is bonded in a 1-coordinate geometry to five Mg and five Si atoms. The Si–Si bond length is 2.57 Å. In the fourteenth Si site, Si is bonded in a 10-coordinate geometry to six Mg and four Si atoms. In the fifteenth Si site, Si is bonded in a 6-coordinate geometry to two Mg and five Si atoms. In the sixteenth Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. In the seventeenth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. In the eighteenth Si site, Si is bonded in a 8-coordinate geometry to six Mg and two Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3Si4 by Materials Project

Mg3Si4 is delta Molybdenum Boride-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.78–2.98 Å. In the second Mg site, Mg is bonded in a 1-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.81–3.15 Å. In the third Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.73–2.94 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.43–2.67 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. The Si–Si bond length is 2.55 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are one shorter (2.56 Å) and one longer (2.57 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 10-coordinate geometry to five Mg and three Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg4Si3 by Materials Project

Mg4Si3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Mg sites. In the first Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.79–3.14 Å. In the second Mg site, Mg is bonded in a 4-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.76–3.17 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.76–2.93 Å. In the fourth Mg site, Mg is bonded in a 3-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.76–3.15 Å. In the fifth Mg site, Mg is bonded in a 3-coordinate geometry to three Si atoms. There are a spread of Mg–Si bond distances ranging from 2.67–2.82 Å. In the sixth Mg site, Mg is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.82–2.92 Å. In the seventh Mg site, Mg is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.88–3.11 Å. In the eighth Mg site, Mg is bonded in a 5-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.69–3.10 Å. There are six inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to five Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.47–2.67 Å. In the second Si site, Si is bonded in a 10-coordinate geometry to six Mg and two Si atoms. The Si–Si bond length is 2.48 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to eight Mg and one Si atom. The Si–Si bond length is 2.57 Å. In the fourth Si site, Si is bonded in a 9-coordinate geometry to eight Mg and one Si atom. In the fifth Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. The Si–Si bond length is 2.57 Å. In the sixth Si site, Si is bonded in a 10-coordinate geometry to six Mg and three Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg5Si6 by Materials Project

Mg5Si6 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 4-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.79–3.18 Å. In the second Mg site, Mg is bonded in a 2-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.74–3.12 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.68–3.20 Å. In the fourth Mg site, Mg is bonded in a 4-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.68–3.29 Å. In the fifth Mg site, Mg is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–3.20 Å. In the sixth Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.08 Å. In the seventh Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.71–3.02 Å. In the eighth Mg site, Mg is bonded in a 2-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.68–3.28 Å. In the ninth Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–2.99 Å. In the tenth Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.74–3.14 Å. There are twelve inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.38–2.69 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to six Mg and two Si atoms. There are one shorter (2.45 Å) and one longer (2.48 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.45–2.85 Å. In the fourth Si site, Si is bonded in a 5-coordinate geometry to seven Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.45–2.90 Å. In the fifth Si site, Si is bonded in a 10-coordinate geometry to seven Mg and three Si atoms. There are one shorter (2.43 Å) and one longer (2.58 Å) Si–Si bond lengths. In the sixth Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. The Si–Si bond length is 2.52 Å. In the seventh Si site, Si is bonded in a 12-coordinate geometry to six Mg and six Si atoms. There are a spread of Si–Si bond distances ranging from 2.80–3.00 Å. In the eighth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. The Si–Si bond length is 2.59 Å. In the ninth Si site, Si is bonded in a 10-coordinate geometry to five Mg and three Si atoms. The Si–Si bond length is 2.79 Å. In the tenth Si site, Si is bonded in a 8-coordinate geometry to five Mg and four Si atoms. The Si–Si bond length is 2.47 Å. In the eleventh Si site, Si is bonded in a 6-coordinate geometry to four Mg and four Si atoms. In the twelfth Si site, Si is bonded in a 10-coordinate geometry to six Mg and four Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgSi2 by Materials Project

MgSi2 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Mg and ten Si atoms. There are one shorter (3.06 Å) and one longer (3.07 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.71–3.15 Å. In the second Mg site, Mg is bonded in a 7-coordinate geometry to two equivalent Mg and eight Si atoms. There are one shorter (2.97 Å) and one longer (3.11 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.72–3.12 Å. In the third Mg site, Mg is bonded in a 7-coordinate geometry to three Mg and seven Si atoms. There are a spread of Mg–Mg bond distances ranging from 2.98–3.10 Å. There are a spread of Mg–Si bond distances ranging from 2.80–2.91 Å. In the fourth Mg site, Mg is bonded in a 8-coordinate geometry to three Mg and eight Si atoms. There are a spread of Mg–Mg bond distances ranging from 3.02–3.07 Å. There are a spread of Mg–Si bond distances ranging from 2.76–2.99 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Mg and ten Si atoms. There are a spread of Mg–Si bond distances ranging from 2.80–3.25 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Mg and ten Si atoms. There are a spread of Mg–Si bond distances ranging from 2.71–3.14 Å. In the seventh Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Mg and ten Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–3.11 Å. In the eighth Mg site, Mg is bonded in a 11-coordinate geometry to four Mg and seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.82–3.20 Å. There are sixteen inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.40–2.54 Å. In the second Si site, Si is bonded in a 7-coordinate geometry to four Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.43–2.64 Å. In the third Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.42–2.55 Å. In the fourth Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.40–2.70 Å. In the fifth Si site, Si is bonded in a 7-coordinate geometry to four Mg and three Si atoms. The Si–Si bond length is 2.42 Å. In the sixth Si site, Si is bonded in a 8-coordinate geometry to six Mg and two Si atoms. The Si–Si bond length is 2.42 Å. In the seventh Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. There are one shorter (2.40 Å) and one longer (2.71 Å) Si–Si bond lengths. In the eighth Si site, Si is bonded in a 7-coordinate geometry to two Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.43–2.76 Å. In the ninth Si site, Si is bonded in a 6-coordinate geometry to three Mg and three Si atoms. The Si–Si bond length is 2.46 Å. In the tenth Si site, Si is bonded in a 9-coordinate geometry to four Mg and five Si atoms. The Si–Si bond length is 2.45 Å. In the eleventh Si site, Si is bonded in a 8-coordinate geometry to six Mg and three Si atoms. There are one shorter (2.44 Å) and one longer (2.45 Å) Si–Si bond lengths. In the twelfth Si site, Si is bonded in a 7-coordinate geometry to four Mg and three Si atoms. The Si–Si bond length is 2.49 Å. In the thirteenth Si site, Si is bonded in a 1-coordinate geometry to five Mg and three Si atoms. In the fourteenth Si site, Si is bonded in a 6-coordinate geometry to three Mg and three Si atoms. In the fifteenth Si site, Si is bonded in a 8-coordinate geometry to five Mg and three Si atoms. In the sixteenth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg5Si6 by Materials Project

Mg5Si6 is delta Molybdenum Boride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.82–3.06 Å. In the second Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.72–2.96 Å. In the third Mg site, Mg is bonded in a 6-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.13 Å. In the fourth Mg site, Mg is bonded in a 3-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.63–3.07 Å. In the fifth Mg site, Mg is bonded in a 4-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.11 Å. In the sixth Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.79–3.10 Å. In the seventh Mg site, Mg is bonded in a 6-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.84–3.21 Å. In the eighth Mg site, Mg is bonded in a 3-coordinate geometry to nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.75–3.09 Å. In the ninth Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.80–2.96 Å. In the tenth Mg site, Mg is bonded in a 12-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.74–2.96 Å. There are twelve inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. There are one shorter (2.48 Å) and one longer (2.53 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 6-coordinate geometry to four Mg and two Si atoms. The Si–Si bond length is 2.39 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.58–2.75 Å. In the fourth Si site, Si is bonded in a 10-coordinate geometry to five Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.40–2.76 Å. In the fifth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.46–2.59 Å. In the sixth Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. There are one shorter (2.34 Å) and one longer (2.48 Å) Si–Si bond lengths. In the seventh Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. The Si–Si bond length is 2.40 Å. In the eighth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. The Si–Si bond length is 2.48 Å. In the ninth Si site, Si is bonded in a 6-coordinate geometry to four Mg and two Si atoms. In the tenth Si site, Si is bonded in a 9-coordinate geometry to six Mg and three Si atoms. In the eleventh Si site, Si is bonded in a 11-coordinate geometry to seven Mg and four Si atoms. In the twelfth Si site, Si is bonded in a 7-coordinate geometry to five Mg and two equivalent Si atoms.

36 MATERIALS SCIENCE↗