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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

First-principles calculations of structural, electrical, and optical properties of ultra-wide bandgap (Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloys

Alloys between Ga 2 O 3 and Al 2 O 3 (AGO) present a rich material space exhibiting numerous structural phases with unique optoelectronic properties that make them attractive candidates as ultra-wide bandgap (UWBG) semiconductors for next-generation power devices. Here we review the properties of AGO, focusing on theoretical results on the thermodynamics of Al incorporation and its consequences on the electronic structure. We review predictions and progress in experimentally realizing these alloys, as well as how composition influences important optoelectronic variables such as the band gap, band offsets, transport properties, and n-type dopability. A number of these parameters, such as the breakdown field (related to the band gap) and electron mobility, are discussed in assessing AGO in terms of relevant power device figures of merit. Altogether, the rapid progress and predicted properties highlight the promise of AGO as a model UWBG semiconductor platform with the potential to revolutionize power devices.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Mitigate Stress Corrosion Cracking (SCC) in High-Strength Al castings (CRADA 508)

This project will develop approaches to overcome the barriers to simultaneous high-strength and high resistance to stress corrosion cracking (SCC) in Al casting alloys. Thus, success in this project will enable fabrication of light-weight components that are otherwise made of either heavier cast iron, or lower-strength Al alloys which need to be oversized (and hence, are heavier) to compensate for lower strength. This project will leverage the availability of advanced analytical instruments and scientific expertise available only through the LightMAT Consortium. If successful, this project has the potential to enable light-weighting of multiple components in light-duty cars and trucks across all makes and models.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The Preston-Tonks-Wallace (PTW) Model Parameterization of Al-6061 With Sesame EoS

In this report, we make a recommendation for the PTW model parameters for an aluminum alloy, Al 6061-T6 based on the quasi-static and split-Hopkin pressure bar experimental data, provided by the experimentalists in MST-8, LANL. Al 6061 is an aluminum alloy with magnesium and silicon, and the temper designation T6 means it has gone through heat treatment followed by quenching, cooling, and aging. (Note that T4 is naturally aged and T6, artificially.) We adopted the shear modulus and melt curve models that are necessary to parameterize the PTW model, from Sesame EoS. In the lack of those information on this particular aluminum alloy, we used what is available for pure aluminum.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Hybrid Al Casting + AM Components for Automotive Applications

Although casting Aluminum (Al) alloys is widely used for automotive application, the conventional casting process is showing limitations for modern vehicle production. A hybrid manufacturing method that is capable of fabricating automotive structures with tailored functionality and tuned attributes at a high production rate is proposed in this project, utilizing the merits of conventional casting methods and additive manufacturing (AM) methods. Ford is interested in supplementing conventional casting processes (e.g., shape casting, high pressure die casting) with local modifications to geometry and microstructure using additive manufacturing techniques. Two additive manufacturing methods, wire-arc and laser hot-wire directed energy deposition AM process, were evaluated by deposition of 4043 filler wire onto high-pressure die cast and permanent mold cast Al-Si alloys. The feasibility of this hybrid manufacturing method was determined through trial deposition and evaluation of defects, microstructure, and mechanical properties. Laser hot-wire deposition was found to be beneficial for this application with low porosity, a refined microstructure, and mechanical properties similar to those reported in the literature for 4043. The mechanical properties of the interface between the A356 casting and deposited 4043 were found to be controlled by the weaker deposit material.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Rapid Laser Reactive Sintering of Garnet Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 and Li 6.1 La 3 Zr 2 Al 0.3 O 12 and Solid-State Electrolytes

All solid-state lithium-ion batteries (ASSLIBs) have gained significant interest in recent years due to their wide range of applications, including mobile devices, electric vehicles, and grid storage. Garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolyte (SSE) continues to be a significant player in the fabrication of ASSLIBs with excellent ionic conductivity on the order of 10 -3 S•cm -1 with the integration of dopants and sintering aids to assist conductivity and structural evolution during the sintering procedure. Traditional sintering techniques, such as solid-state sintering (SSS), have been proven to yield desirable crystal structures. However, the low ionic conductivity results from inferior microstructure, and lithium loss is a significant challenge. Recently, a relatively novel sintering process called rapid laser sintering (RLS) has shown great potential for achieving fully dense solid oxide electrolytes with less lithium loss, resulting in high ionic conductivity [1] [2] [3] [4]. Here, we applied a modified RLS method using precursor powders instead of pre-synthesized LLZO powders to fabricate Al-doped LLZO (Li 6.1 La 3 Zr 2 Al 0.3 O 12 + 13 wt% Li 2 CO 3 ) and Ta-doped LLZO (Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 + 5 wt% LiOH•H 2 O) dense electrolytes. This rapid laser reactive sintering (RLRS) could potentially reduce the number of processing steps and therefore lower the manufacturing cost. We hope the rapid high-temperature sintering can densify the electrolyte and avoid the lithium loss for achieving high lithium-ion conductivity. In this work, we optimized a combination of laser parameters (speed and power), initial precursor composition, and controlled atmospheres to discover the optimal conditions for reaching the efficacious crystal structure, microstructure, and ionic conductivity.

25 ENERGY STORAGE↗
DOE OSTI2025

Expansion of the Direct Feed High-Level Waste Glass Composition in the High Al Range

Baseline glass compositions have been developed and demonstrated for successful immobilization of Hanford high-level waste (HLW) prepared through a pretreatment process. Recent enhanced waste glass formulations have shown promise to increase the waste loading of pretreated sludge compositions from a broader range of HLW feeds. This project proposes to increase the loading of minimally pretreated Hanford HLW in glass by expanding the existing database and glass property-composition models. Estimated direct-feed high level waste (DFHLW) compositions were generated by the Hanford Tank Operations Contractor and used by Pacific Northwest National Laboratory to determine target glass compositions. Gaps in existing data were identified including one high-priority gap in the high Al compositional region. This report summarizes the data collected during the characterization of the DFHLW High Al Glass Matrix. These glasses were intentionally designed with high aluminum concentrations (15 to 30 wt%) and a high likelihood of nepheline formation, which is known to negatively affect glass durability. Some glasses were expected to either fail or approach property constraints to fill data gaps in poorly understood regions of the compositional space due to lack of data. Out of the 50 glasses tested, 14 glasses formed nepheline, while the model predicted nepheline formation in 20 glasses. All quenched glasses met the product consistency test durability constraint; however, 8 glasses failed this constraint after undergoing the canister centerline cooling treatment. Additionally, 17 glasses did not meet the viscosity constraints, 4 failed the EC constraints, and 2 exceeded the allowable T2% for spinel crystal formation. All glasses satisfied the SO 3 solubility limit. The resulting dataset provides valuable information to improve model accuracy and reduce prediction uncertainty. These insights will ultimately support the development of more robust glass formulation strategies, enabling higher waste loadings, reducing operational risks, and expanding the processing envelope.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Field studies of PERC and Al-BSF PV module performance loss using power and I-V timeseries

We have studied the degradation of both full-sized modules and minimodules with PERC and Al-BSF cell variations in fields while considering packaging strategies. We demonstrate the implementations of data-driven tools to analyze large numbers of modules and volumes of timeseries data to obtain the performance loss and degradation pathways. This data analysis pipeline enables quantitative comparison and ranking of module variations, as well as mapping and deeper understanding of degradation mechanisms. The best performing module is a half-cell PERC, which shows a performance loss rate ( PLR ) of −0.27 ± 0.12% per annum (%/ a ) after initial losses have stabilized. Minimodule studies showed inconsistent performance rankings due to significant power loss contributions via series resistance, however, recombination losses remained stable. Overall, PERC cell variations outperform or are not distinguishable from Al-BSF cell variations.

Curran, Alan J.↗
DOE OSTI2022

A New Perspective of Post-Weld Baking Effect on Al-Steel Resistance Spot Weld Properties through Machine Learning and Finite Element Modeling

The root cause of post-weld baking on the mechanical performance of Al-steel dissimilar resistance spot welds (RSWs) has been determined by machine learning (ML) and finite element modeling (FEM) in this study. A deep neural network (DNN) model was constructed to associate the spot weld performance with the joint attributes, stacking materials, and other conditions, using a comprehensive experimental dataset. The DNN model positively identified that the post-weld baking reduces the joint performance, and the extent of degradation depends on the thickness of stacking materials. A three-dimensional finite element (FE) model was then used to investigate the root cause and the mechanism of the baking effect. It revealed that the formation of high thermal stresses during baking, from the mismatch of thermal expansion between steel and Al alloy, causes damage and cracking of the brittle intermetallic compound (IMC) formed at the interface of the weld nugget during welding. This in turn reduces the joint performance by promoting undesirable interfacial fracture when the welds were subjected to externally applied loads. The FEM model further revealed that increase in structural stiffness, because of increase in steel sheet thickness, reduces the thermal stresses at the interface caused by the thermal expansion mismatch and consequently lessens the detrimental effect of post-weld baking on the joint performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Development of Precipitation-Strengthened Al 0.8 NbTiVM (M = Co, Ni) Light-Weight Refractory High-Entropy Alloys

Single-phase solid-solution refractory high-entropy alloys (RHEAs) have been receiving significant attention due to their excellent mechanical properties and phase stability at elevated temperatures. Recently, many studies have been reported regarding the precipitation-enhanced alloy design strategy to further improve the mechanical properties of RHEAs at elevated temperatures. In this study, we attempted to develop precipitation-hardened light-weight RHEAs via addition of Ni or Co into Al 0.8 NbTiV HEA. The added elements were selected due to their smaller atomic radius and larger mixing enthalpy, which is known to stimulate the formation of precipitates. The addition of the Ni or Co leads to the formation of the sigma precipitates with homogeneous distribution. The formation and homogeneous distribution of sigma particles plays a critical role in improvement of yield strength. Furthermore, the Al 0.8 NbTiVM 0.2 (M = Co, Ni) HEAs show excellent specific yield strength compared to single-phase AlNbTiV and NbTiVZr RHEA alloys and conventional Ni-based superalloy (Inconel 718) at elevated temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The Timing of Potential Last Nucleosynthetic Injections into the Protosolar Molecular Cloud Inferred from 41 Ca– 26 Al Systematics of Bulk CAIs

Short-lived radionuclides (SLRs) provide important information about the chronology of the early solar system. Among them, 41 Ca, due to its decay to 41 K with a half-life of only 0.1 Ma, is particularly valuable in constraining the timescales and origins of both SLRs and the formation of the oldest solar system materials, the Ca–Al-rich inclusions (CAIs). The initial abundance of 41Ca in the solar system, expressed as the ( 41 Ca/ 40 Ca)I ratio, is the key to unveiling the origin of this nuclide. Here, we report a new solar system ( 41 Ca/ 40 Ca)I ratio of 2.0 × 10 −8 derived from the K isotope compositions of two CAIs. This new ratio is about four times higher than the previous value inferred from a mineral isochron. Such a high ( 41 Ca/ 40 Ca)I ratio in the CAIs exceeds that expected for the protosolar molecular cloud by ∼1000×, implying very late injection of the 41 Ca (and possibly other SLRs) into the protosolar molecular cloud. The correlated enrichments of 41 Ca and 26 Al in the bulk CAI samples hint at a common stellar origin of both SLRs. The injection time estimated from our new data depends on the stellar source—it ranges from 0.6 Ma for a Wolf–Rayet wind to 1.0 Ma for a TP-AGB star ejecta.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Gupta-et-al_2024_EarthsFuture

Results from Gupta et al. submitted to Earth's Future. All code to reproduce the experiment and make the figures can be found here: https://github.com/rg727/Gupta-etal_2024_EarthsFuture The data provided in this repository are (1) Weather Regime Data , (2) Hydroclimate Data, and (3) CALFEWS output. In (1), there are Markov chains of daily weather regimes generated over the 600-year paleo-period. In (2), there are three sets of data: Historical daily CDEC data for 12 input locations into CALFEWS, 600-year long daily paleo data (streamflow and snow) for each input location, and (3) 600-year long daily climate-change data (4 degree temperature increase + 7% precipitation scaling applied to (2)) which serves as the "climate change scenario" in the study. Please reference the GitHub repository on how to use these data to reproduce the results. The CALFEWS output for the Paleo and Climate Change scenarios is stored in (3). More information can be found in the Gupta-et-al_2024_EarthsFuture-README file.

Gupta, Rohini↗
DOE OSTI2025

Nucleation and Antiphase Twin Control in Bi 2 Se 3 via Step‐Terminated Al 2 O 3 Substrates

The epitaxial synthesis of high-quality 2D layered materials is an essential driver of both fundamental physics studies and technological applications. Bi 2 Se 3 , a prototypical 2D layered topological insulator, is sensitive to defects imparted during the growth, either thermodynamically or due to the film-substrate interaction. Here, in this study, it is shown that step-terminated Al 2 O 3 substrates with a high miscut angle (3°) can effectively suppress a particular hard-to-mitigate defect, the antiphase twin. Systematic investigations across a range of growth temperatures and substrate miscut angles confirm that atomic step edges act as preferential nucleation sites, stabilizing a single twin domain. First-principles calculations suggest that there is a significant energy barrier for twin boundary formation at step edges, supporting the experimental observations. Detailed structural characterization indicates that this twin-selectivity is lost through the mechanism of the 2D layers overgrowing the step edges, leading to higher twin density as the thickness increases. These findings highlight the complex energy landscape unique to 2D materials that is driven by the interplay between substrate properties, nucleation dynamics, and defect formation, and overcoming and controlling these are critical to improve material quality for quantum and electronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(Ag3S2)3 by Materials Project

Ag9AlS6 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nine inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.51–2.71 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–2.78 Å. In the third Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.47–3.11 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are one shorter (2.51 Å) and two longer (2.68 Å) Ag–S bond lengths. In the fifth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.46–2.92 Å. In the sixth Ag1+ site, Ag1+ is bonded in a distorted bent 150 degrees geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.46–3.25 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.48–2.95 Å. In the eighth Ag1+ site, Ag1+ is bonded in a distorted linear geometry to two S2- atoms. There are one shorter (2.41 Å) and one longer (2.47 Å) Ag–S bond lengths. In the ninth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–2.61 Å. Al3+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of Al–S bond distances ranging from 2.24–2.30 Å. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to four Ag1+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to four Ag1+ and one Al3+ atom. In the third S2- site, S2- is bonded in a distorted see-saw-like geometry to three Ag1+ and one Al3+ atom. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to four Ag1+ and one Al3+ atom. In the fifth S2- site, S2- is bonded in a 7-coordinate geometry to six Ag1+ and one Al3+ atom. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(SeCl)4 by Materials Project

AlCl4(Se)4 crystallizes in the orthorhombic Pca2_1 space group. The structure is zero-dimensional and consists of thirty-two selenium molecules and eight AlCl4 clusters. In each AlCl4 cluster, Al3+ is bonded in a tetrahedral geometry to four Cl1- atoms. There are a spread of Al–Cl bond distances ranging from 2.13–2.17 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(FeO2)2 by Materials Project

AlFe2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six FeO6 octahedra. All Fe–O bond lengths are 2.11 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six equivalent O2- atoms to form FeO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six equivalent FeO6 octahedra. All Fe–O bond lengths are 2.07 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–55°. There is one shorter (1.79 Å) and three longer (1.82 Å) Al–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe+2.50+ and one Al3+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three equivalent Fe+2.50+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(CoO2)2 by Materials Project

Co2AlO4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Co+2.50+ sites. In the first Co+2.50+ site, Co+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.85 Å) and two longer (1.91 Å) Co–O bond length. In the second Co+2.50+ site, Co+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.85 Å) and two longer (1.91 Å) Co–O bond length. Al3+ is bonded in a distorted square co-planar geometry to four O2- atoms. All Al–O bond lengths are 1.88 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Co+2.50+ and one Al3+ atom. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to two Co+2.50+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(NiO2)2 by Materials Project

Ni2AlO4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Ni+2.50+ sites. In the first Ni+2.50+ site, Ni+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.84 Å) and two longer (1.88 Å) Ni–O bond length. In the second Ni+2.50+ site, Ni+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.84 Å) and two longer (1.88 Å) Ni–O bond length. Al3+ is bonded in a 4-coordinate geometry to four O2- atoms. All Al–O bond lengths are 1.89 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ni+2.50+ and one Al3+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ni+2.50+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(NF2)3 by Materials Project

AlNF6N2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight ammonia molecules and one AlNF6 framework. In the AlNF6 framework, Al3+ is bonded to six equivalent F1- atoms to form AlF6 octahedra that share corners with six equivalent NF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Al–F bond lengths are 1.86 Å. N1+ is bonded to six equivalent F1- atoms to form NF6 octahedra that share corners with six equivalent AlF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All N–F bond lengths are 1.92 Å. F1- is bonded in a linear geometry to one Al3+ and one N1+ atom.

36 MATERIALS SCIENCE↗