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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

High quality large scale single and multilayer graphene production by chemical vapor deposition

Systems and methods for synthesizing continuous graphene sheets are provided. The systems and methods include passing a catalyst substrate through a heated chemical vapor deposition chamber and exposing the substrate to a reaction gas mixture of hydrogen and hydrocarbon at a preselected location within the chamber. The reaction gas mixture can include hydrogen having a partial pressure of between about 0 Torr and 20 Torr, hydrocarbon having a partial pressure of between about 20 mTorr and about 10 Torr, and one or more buffer gases. The buffer gases can include argon or other noble gases to maintain atmospheric pressure within the chemical deposition chamber. The resulting graphene can be made with continuous mono and multilayers (up to six layers) and have single crystalline hexagonal grains with a preselected nucleation density and domain size for a range of applications.

Vlassiouk, Ivan V.↗
DOE OSTI2019

Deposition of Nb3Sn films by multilayer sequential sputtering for SRF cavity application

Nb3Sn is considered as an alternative of Nb for SRF accelerator cavity application due to its potential to obtain higher quality factors and higher accelerating gradients at a higher operating temperature. Magnetron sputtering is one of the effective techniques that can be used to fabricate Nb3Sn on SRF cavity surface. We report on the surface properties of Nb3Sn films fabricated by sputtering multiple layers of Nb and Sn on sapphire and niobium substrates followed by annealing at 950°C for 3 h. The crystal structure, film microstructure, composition and surface roughness were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). The RF performance of the Nb3Sn coated Nb substrates were measured by a surface impedance characterization system. We also report on the design of a multilayer sputter deposition system to coat a single-cell SRF cavity.

Sayeed, Md. N.↗
DOE OSTI2019

RF Characterization of an S-I-S’ Multilayer Sample

S-I-S’ multilayers promise to boost the performance of bulk superconductors in terms of maximum field and surface resistance. At HZB, RF-surface resistance measurements were performed with a Quadrupole Resonator (QPR) and an S-I-S’ sample (75 nm NbTiN on 15 nm AlN insulator on bulk Nb) prepared at JLab. Measurements were performed at 414, 845, and 1286 MHz at sample temperatures from 2 K up to well above the transition temperature of NbTiN of ~17.3 K. The Rs exhibits an unexpected temperature dependence: Rather than rising monotonically, as expected from BCS theory, a local maximum is observed. There is a temperature range where Rs decreases with increasing temperature. Such behavior indicates that an additional interaction between the superconducting layers may have to be included in the surface resistance model. Measurements of the baseline Nb sample prior to coating exhibited no such behavior; hence systematic measurement errors can be excluded as the explanation. The maximum field was limited by a hard magnetic quench near 20 mT, close to Hc1 of NbTiN, suggesting that the sample is limited by early flux penetration.

Keckert, S.↗
DOE OSTI2023

High capacity, air-stable, structurally isomorphous lithium alloy multilayer porous foams

The invention relates to composite multilayer lithium ion battery anodes that include a porous metal alloy foam, and a lithium ion conductor coating applied to the metal alloy foam. The metal alloy foam can include structurally isomorphous alloys of lithium and, optionally, lithium and magnesium. The lithium ion conductor coating can include ternary lithium silicate, such as, lithium orthosilicate. Lithium ions from the ternary lithium silicate may be deposited within the pores of the metal alloy foam. Optionally, the lithium ion conductor coating may include a dopant. The dopant can include one or more of magnesium, calcium, vanadium, niobium and fluorine, and mixtures and combinations thereof.

Kumta, Prashant N.↗
DOE OSTI2024

Solid-state nanofiber polymer multilayer composite electrolytes and cells

A solid-state electrolyte for a multilayer solid-state electrochemical cell is described herein. The electrolyte comprises a lithium electrolyte salt and nanofibers of a cubic phase lithium lanthanum zirconium oxide (c-LLZO), and a polymer interspersed with the nanofibers and electrolyte salt. Electrochemical cells comprising the solid-state electrolyte, and solid-state cathodes comprising the nanofibers of c-LLZO are also described herein.

Zhang, Yuepeng↗
DOE OSTI2025

Modeling Cyber Supply Chain Incidents with Multilayered Graph Motifs

As noted within the literature, supply chain includes people and organizations---manufacturers, integrators, and third-party vendors---that are involved in one or more stages of a product lifecycle. Since supply chains, by definition, include organizations and people, supply chain risk management activities must consider dependencies between an organization's business processes and third-party resources. Just as adversarial tactics can be implemented via techniques implemented via networked computer systems, so can such tactics be expressed via legal business relationships. A cyber incident may have an exponential impact downstream, for example, by leveraging a product's distribution channel (e.g. malicious updates in SolarWinds, buggy updates in CrowdStrike). Similarly, legitimate and legal business relationships also affect the attack surface exposure of systems, enabling long-term persistence and/or unknown impacts to product quality that are hard to detect. This paper catalogs several recent digital supply chain incidents and applies a multilayered network formalism to develop structural indicators (graph motifs) that reflect potentially-adversarial behavior. Finally, we compare and contrast the characteristics of adversarial tactics (e.g. Loss of Availability, Data Collection) that leverage cyber-physical dependencies to those that leverage legal organizational relationships.

97 - MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Structural and superconducting properties of Nb 3 Sn films grown by multilayer sequential magnetron sputtering

Nb 3 Sn thin films are fabricated by sequential sputtering followed by annealing at 850–1200°C in vacuum. The effects of the annealing temperature and time on the formation of Nb 3 Sn were examined. The film crystal structure, morphology, surface topography and composition were distinguished by X-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, and energy dispersive X-ray spectroscopy analysis. The superconducting properties of the films were characterized by measuring the surface resistivity by the four-point probe method. The highest critical temperature T c = 17.86 K was observed for the Nb 3 Sn films annealed at 950°C for 3 h. When the films were annealed above 1000°C for 3 h, Sn evaporation resulted in a Nb-rich film, degrading the superconducting performance. Annealing at 1200°C for 3 h resulted in evaporation of Sn leaving less than 1% Sn on the surface, as detected by energy dispersive spectroscopy, and for that film a T c of 7.9 K was observed.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Moderate pH changes alter the fluxes, selectivities and limiting currents in ion transport through polyelectrolyte multilayers deposited on membranes

Layer-by-layer (LBL) polyelectrolyte coatings on membranes are attractive for their high selectivities between monovalent and divalent ions. However, deposition of poly(4-styrenesulfonate) (PSS)/protonated poly(allylamine) (PAH) films on ion-exchange membranes leads to low ion fluxes that restrict productivity or current efficiency. This study shows that increasing the solution pH from 6.5 to 8.3 enhances cation fluxes and limiting currents through (PAH/PSS) 5 PAH-coated cation-exchange membranes while still achieving order of magnitude selectivity increases compared to bare membranes. In Donnan dialysis through (PAH/PSS) 5 PAH-coated Nafion, at pH 8.3 the K + /Mg 2+ selectivity is 100, and the K + flux is 22 times that at pH 6.5. Moreover, at the higher pH the electrodialysis limiting current through these membranes increases ~5-fold. This enables electrodialysis separation of K + and Mg 2+ with a current efficiency around 0.75, a selectivity of 18, and 50% K + recovery from the source phase. Transmembrane potential measurements and increases in Cl - /SO 4 2- selectivities (from 9.5 at pH 6.5 to ~70 at pH 8.3) for porous alumina membranes coated with (PSS/PAH) 5 PSS films suggest that the coating becomes cation-permselective at higher pH. Increased cation transference numbers in polyelectrolyte coatings likely lead to the enhanced limiting currents for coated Nafion at higher pH. Lastly, (PAH/PSS) 5 PAH-coated Nafion shows a Li + /Mg 2+ Donnan dialysis selectivity >700 at neutral pH and a selectivity of 10 at pH 8.3. However, the Li + flux is 6 times greater at pH 8.3, which might make operation at the higher pH desirable.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Toward a sustainable circular economy of multilayer plastic films: Life cycle and techno-economic assessment with a focus on end-of-life treatment and multiple recovery cycles

This study presents a life cycle assessment (LCA) and techno-economic analysis (TEA) of end-of-life technologies for treating polyethylene–polyamide barrier film waste, focusing on quality degradation across recovery cycles. Novel treatment methods are experimentally validated, while others are drawn from literature and industry consultations. A displacement approach, assuming no quality loss, is first applied. Results show that solvent-based recycling via the solvent-targeted recovery and precipitation (STRAP) process outperforms alternatives across environmental indicators, reducing global warming potential (GWP) by 40% compared to landfilling. Incineration performs worst in most categories, particularly eutrophication (80% higher than landfilling), due to nitrogen emissions. Experimentally validated downcycling (pelletizing) proves more economically viable. The assumption of infinite recoverability is overly optimistic. To address this, we propose a mathematical framework accounting for a finite number of recovery cycles. This refined model shows reduced GWP and cost savings for solvent recovery, making its benefits less pronounced than initially estimated. Sensitivity and uncertainty analyses reveal strong dependence on recovered material quality and solvent recovery efficiency, underscoring the need for optimized process design. Finally, hotspot analysis identifies greenhouse gas emissions from the polyamide supply chain as the dominant GWP contributor. In conclusion, the results underscore potential trade-offs across pathways and show that solvent-based recovery’s sustainability depends heavily on process conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Spectral Performance of Multilayer Amorphous Selenium and Selenium–Tellurium Photodetectors

The ability to robustly and with scalability detect single photons in the visible spectrum with wavelength resolution would transform many imaging applications. Theoretical studies propose an array of carbon nanotubes (CNTs) functionalized with semiconductor quantum dots (QDs) as a physical realization of such photon sensors. In this work, we report approaches to synthesize these CNT-QD nanostructures using DNA as a smart glue to connect CNTs to QDs.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Microstructural and Superconducting Radiofrequency Properties of Multilayer Sequentially Sputtered Nb 3 Sn films

Nb 3 Sn is considered as a potential candidate for superconducting radiofrequency cavities for particle acceleration due to its higher transition temperature of 18.3 K and higher superheating field of 400 mT. Nb 3 Sn films can be grown inside the surface of a Nb cavity by sequentially sputtering multiple layers of Nb and Sn thin films followed by annealing at 950 °C for 3 h. We report on the properties of Nb 3 Sn films grown on Nb substrates by magnetron sputtering. The films’ crystal structure, surface morphology, and composition were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The films had a polycrystalline Nb 3 Sn structure with a fine-grain surface and an atomic Sn composition of ~23%. The RF surface resistance of the films was measured for different temperatures at 7.4 GHz to understand the feasibility of this method for the SRF application. The RF surface resistance of the films was 5 mΩ at 12 K, which is about 2 orders of magnitude higher than 60 μΩ previously measured in Nb 3 Sn films grown by Sn vapor diffusion. Finally, the sputtered film had a superconducting transition at 17.2 K, which is also lower than 17.9 K observed in Nb 3 Sn film prepared by vapor diffusion.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Protective coatings with nanoscale multilayer architecture: current state and main trends

Binary systems (layers) and multicomponent layers with bilayer thicknesses varying from microns to a few nanometers are considered. A strong dependence of the microstructure formation on the deposition conditions (the magnitude of the bias potential, the flow of inert and reactive gases, the ion beam power (current density) supplied to the target) is found. General regularities in the change in the functional properties and structural state of the coatings are formulated. The conditions for the formation of a columnar structure and growth texture are noted; various mechanisms and their interpretation are proposed. Finally, the relationship among the size of nanograins, diffusion at the interphase boundary, and effects determining the physico-mechanical, tribological characteristics, as well as resistance to corrosion and oxidation, is shown.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Shear Band Formation in Thin-Film Multilayer Columns Under Compressive Loading: A Mechanistic Study

Micro-pillar compression is a popular experimental technique used for characterizing the mechanical behavior of nano- and micro-laminates. The compressive stress–strain response of the column-shaped thin-film composite can be measured, and the deformation and damage features can be revealed by post-test cross-section microscopy. The development of plastic instability in the form of localized strain concentration (shear bands), leading to eventual failure, is frequently observed. In the present study, a computational approach is used to illustrate the commonality of shear band formation from a continuum standpoint. Systematic finite element analyses are conducted, showing that the strain field tends to become localized once plastic yielding commences. Distinct shear offsets of the layered structure can be revealed from the numerical model, which is similar to those observed in experiments. The actual appearance of shear bands depends on the materials’ constitutive behavior and precise geometries. Post-yield strain hardening reduces the propensity of shear band formation, while strain softening enhances it. Imperfections such as the undulated layer geometry, as well as the frictional characteristics between the specimen and test apparatus, can also influence the shear band morphology and overall stress–strain response.

finite element modeling↗