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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Building interface bonding and shield for stable Li-rich Mn-based oxide cathode

Implementation of Li-rich Mn-based oxide cathode with high-energy-density has been restrained by capacity/voltage degradation that results from irreversible lattice oxygen loss and structure rearrangements. To resolve these challenges, in this work, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 encapsulated by amorphous Co x B (CB-LRM) is rationally designed via autocatalytic plating for highly reversible cationic/anionic hybrid cathode material. Band coherency is ingeniously evoked by interface-reconstruction between bulk structure and amorphous coating layer, which lower the energy of O $2p$ states. Furthermore, this is associated with strengthened orbital hybridization of O $2p$-Mn $3d$ and increased formation energy of oxygen vacancy, which mitigates the lattice oxygen loss considerably. Additionally, interface shielding effects that protect electrode against electrolyte corrosion and the reduction of surface oxygen are also present with fully coverage of amorphous Co x B coating layer. As a result, the as-designed CBLRM cathode exhibits excellent cycle stability after 100 loops with only 0.154% per cycle capacity fade and improved voltage degradation. Given this, this work provides a potential avenue for rational design of lattice oxygen-based electrode materials with high-energy-density.

25 ENERGY STORAGE↗
DOE OSTI2016

Atomic and electronic structure of Lomer dislocations at CdTe bicrystal interface

Extended defects are of considerable importance in determining the electronic properties of semiconductors, especially in photovoltaics (PVs), due to their effects on electron-hole recombination. We employ model systems to study the effects of dislocations in CdTe by constructing grain boundaries using wafer bonding. Atomic-resolution scanning transmission electron microscopy (STEM) of a [1–10]/ (110) 4.8° tilt grain boundary reveals that the interface is composed of three distinct types of Lomer dislocations. Geometrical phase analysis is used to map strain fields, while STEM and density functional theory (DFT) modeling determine the atomic structure at the interface. The electronic structure of the dislocation cores calculated using DFT shows significant mid-gap states and different charge-channeling tendencies. Cl-doping is shown to reduce the midgap states, while maintaining the charge separation effects. In conclusion, this report offers novel avenues for exploring grain boundary effects in CdTe-based solar cells by fabricating controlled bicrystal interfaces and systematic atomic-scale analysis.

36 MATERIALS SCIENCE↗
NASA NTRS1994

NASA's Man-Systems Integration Standards: A Human Factors Engineering Standard for Everyone in the Nineties

During the second half of the 1980s, a document was created by the National Aeronautics and Space Administration (NASA) to aid in the application of good human factors engineering and human interface practices to the design and development of hardware and systems for use in all United States manned space flight programs. This comprehensive document, known as NASA-STD-3000, the Man-Systems Integration Standards (MSIS), attempts to address, from a human factors engineering/human interface standpoint, all of the various types of equipment with which manned space flight crew members must deal. Basically, all of the human interface situations addressed in the MSIS are present in terrestrially based systems also. The premise of this paper is that, starting with this already created standard, comprehensive documents addressing human factors engineering and human interface concerns could be developed to aid in the design of almost any type of equipment or system which humans interface with in any terrestrial environment. Utilizing the systems and processes currently in place in the MSIS Development Facility at the Johnson Space Center in Houston, TX, any number of MSIS volumes addressing the human factors / human interface needs of any terrestrially based (or, for that matter, airborne) system could be created.

Cletis R. Booher↗
DOE OSTI2016

The thermodynamic stability of intermediate solid solutions in LiFePO 4 nanoparticles

Theoretical predictions from first principles and recent advances in in situ electrochemical characterization techniques have confirmed the presence of solid-solution states during electrochemical (de)lithiation of LiFePO 4 nanoparticles. Surprisingly, however, such thermodynamically unfavorable solid solution states have been observed at rates as low as 0.1C. Given the high diffusivity of Li in LiFePO 4 and the thermodynamic instability of homogeneous solid solution states, spinodal decomposition to a thermodynamically favorable two-phase state is expected to occur on time scales as rapid as 1–100 ms. Here, we resolve this apparent paradox by demonstrating that, given the symmetry of the low-energy solid-solution Li/Va orderings and the 1D character of Li diffusion, spinodal decomposition from a solid solution preferentially leads to the formation of a diffuse ac interface with a large intermediate solid-solution region, as opposed to the commonly assumed bc interface. Our first principles predictions not only rationalize the persistence of solid-solution states at low-to-moderate C-rates in high-rate LiFePO 4 electrodes, but also explain the observations of large intermediate solid-solution regions at an ac interface in single Li x FePO 4 particles quenched from a high-temperature solid solution.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Structure-guided utilization of lignocellulose for catalysis, energy, and biomaterials

As a complex composite of cellulose, hemicellulose, and lignin, plant lignocellulose has long served as a major resource for biomass conversion, materials engineering, and bio-based product development. High-resolution structural insights enabled by solid-state nuclear magnetic resonance (ssNMR) now allow the mapping of polymer interfaces, identification of functional group accessibility, and tracking of molecular organization during processing, all of which are critical factors for optimizing catalytic strategies. These insights could drive transformative progress in lignocellulose-based applications, including selective depolymerization, improved pretreatment design, and efficient upcycling of lignin into resins, plastics, and biomedical materials. In industry-relevant contexts, such as biofuel generation and renewable material manufacturing, understanding the hydration dynamics, cross-linking patterns, and structural heterogeneity is also essential. The ability to visualize these features in native biomass presents a unique opportunity to develop new strategies for sustainability and performance. As the structural toolbox continues to expand, it is becoming a central enabler for innovations in renewable energy, green chemistry, and advanced bioproducts.

bioproduct↗
DOE OSTI2014

Carrier accumulation near electrodes in ferroelectric films due to polarization boundary conditions

We study the effect of surface polarization on the distribution of free carriers in a wide bandgap semiconductor ferroelectric (FE) film using a thermodynamic approach. We show that free carriers, namely, holes and electrons from ionizable impurities or atomic vacancies can accumulate near the film-electrode interface, if FE polarization profile has a very steep change near the surface that is specified by the extrapolation length. Such an outcome is just the opposite of what happens in a Schottky junction in a partially or fully depleted film. This is also an entirely different effect than what has been often studied in similar structures, where the work function and screening length of the electrode metal determines the electronic character of the interface. Even for low-to-moderate densities of ionizable defects with states within the bandgap close to the band edges, high densities of carriers can localize close to the electrodes in a single domain state FE film when above a critical thickness. For very low densities of such ionizable defects, short extrapolation lengths cause electrical domain formation with minimal carrier accumulation because of the already weak depolarizing fields. This is also true for films below a critical thickness with low-to-moderate densities of ionizable impurities, i.e., electrical domains get stabilized regardless of defect density. The implications of our findings for polarization controlled Schottky to Ohmic-like transition of an interface and experimental results are discussed. It is also found that interfaces of an n-type FE heterostructure can behave like a p-type depending on the barrier heights and impurity density. We conclude that, for low-to-moderate ionizable impurity densities, it is the rate of change of polarization at the interface with position rather than solely its presence that leads to carrier accumulation and that both interfaces can become Ohmic-like with opposite signs of carriers.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

An Eulerian multimaterial framework for simulating high-explosive aquarium tests

Aquarium tests of cylindrical high-explosive charges provide optical data of the detonation front velocity and shape, propagation of the shock wave in the surrounding water, and expansion rates of the detonation products behind the front. Data from aquarium experiments is often used for calibration of reactive burn models based on phenomenological equations of state (EOS) and reaction rate laws. This paper presents a multimaterial numerical modeling framework to solve the 2D axisymmetric reactive Euler equations for high-explosive aquarium tests, in particular for ammonium nitrate - fuel oil (ANFO) explosives. An extension of the Ghost Fluid Method (GFM) is used to handle the dynamic material interfaces for the ANFO explosion products, the charge-confining material (polymethyl methacrylate PMMA), and the surrounding water. This study analyzes the sensitivity of calculations (both computational efficiency and numerical accuracy) to different algorithms for the material interface models including the original GFM versus Riemann solver-based strategies. A novel method for defining the left and right states in the interfacial Riemann problem eliminates the need for sorting or nodal interpolation during the projection along the material interface. Numerical tests indicate that populating the interface node values using the Riemann solution mitigate the overheating error observed in steady-state calculations. Solution convergence and computational efficiency are explored as a function of the spatial and temporal order of the schemes. Results from the computational model with analytical equations of state and fitted reaction rate parameters show very good quantitative agreement with experimentally observed detonation front velocity, reaction products expansion, and shock wave propagation in the surrounding water for a cylindrical ANFO charge encased in PMMA. Finally, the proposed modeling framework, in conjunction with experimental tests, provides a reliable tool to assess equations of state and reaction rate expressions for reactive burn models of confined high explosives.

42 ENGINEERING↗
DOE OSTI2017

Interface Control of Ferroelectricity in an SrRuO 3 /BaTiO 3 /SrRuO 3 Capacitor and its Critical Thickness

Here, the atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (P O 2 ) during growth plays an important role in controlling the interfacial terminations of SrRuO 3 /BaTiO 3 /SrRuO 3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high P O 2 (around 150 mTorr), usually exhibits a mixture of RuO 2 -BaO and SrO-TiO 2 terminations. By reducing P O 2 , the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO 2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Thermal conductivity of nitride films of Ti, Cr, and W deposited by reactive magnetron sputtering

Nitride films of Ti, Cr, and W were deposited using reactive magnetron sputtering from metal targets in argon and nitrogen plasma. TiN films with (200) orientation were achieved on silicon (100) at the substrate temperature of 500 and 600 °C. The films were polycrystalline at lower temperature. An amorphous interface layer was observed between the TiN film and Si wafer deposited at 600 °C. TiN film deposited at 600 °C showed the nitrogen to Ti ratio to be near unity, but films deposited at lower temperature were nitrogen deficient. CrN film with (200) orientation and good stoichiometry was achieved at 600 °C on Si(111) wafer but the film deposited at 500 °C showed cubic CrN and hexagonal Cr{sub 2}N phases with smaller grain size and amorphous back ground in the x-ray diffraction pattern. An amorphous interface layer was not observed in the cubic CrN film on Si(111) deposited at 600 °C. Nitride film of tungsten deposited at 600 °C on Si(100) wafer was nitrogen deficient, contained both cubic W{sub 2}N and hexagonal WN phases with smaller grain size. Nitride films of tungsten deposited at 500 °C were nonstoichiometric and contained cubic W{sub 2}N and unreacted W phases. There was no amorphous phase formed along the interface for the tungsten nitride film deposited at 600 °C on the Si wafer. Thermal conductivity and interface thermal conductance of all the nitride films of Ti, Cr, and W were determined by transient thermoreflectance technique. The thermal conductivity of the films as function of deposition temperature, microstructure, nitrogen stoichiometry and amorphous interaction layer at the interface was determined. Tungsten nitride film containing both cubic and hexagonal phases was found to exhibit much higher thermal conductivity and interface thermal conductance. The amorphous interface layer was found to reduce effective thermal conductivity of TiN and CrN films.

36 MATERIALS SCIENCE↗
DOE OSTI2024

An efficient construction of nano-interfaces for excellent coking tolerance of cermet anodes

Solid oxide fuel cells (SOFCs) are promising energy conversion devices for the effective and convenient utilization of hydrocarbons (for example, methane) to electricity. However, the development of direct methane SOFCs is primarily hindered by the poor coking tolerance of the state-of-the-art Ni-based cermet anodes. Herein, we efficiently construct nano-interfaces in the anode by infiltrating a Ni 0.6 Y 0.064 Zr 0.336 O 2-δ (NYZ) catalyst onto the traditional Ni-based cermet anode to effectively enhance the coking tolerance. After being reduced in H 2 , Ni and Y 0.16 Zr 0.84 O 2-δ (YSZ) nanoparticles (NPs) are in situ formed on the surface of the Ni-YSZ substrate. The roughened anode demonstrates significantly improved fuel oxidation activity and coking tolerance, due likely to the formation of nano-interfaces. Specifically, when applied in the Ni-YSZ-based anode-supported SOFCs, a high peak power density of 1.785 W cm –2 and a stable operation of ~ 240 h with no observable degradation is achieved at 750 °C in nearly dry methane (3% H 2 O). Finally, a density functional theory study suggests that the excellent coking tolerance is attributed to the formation of OH species on Ni/YSZ nano-interfaces, which would further interact with intermediate carbon species to generate COH intermediates.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2025

Advanced Analysis of X-ray Fluorescence Measurements of the Interfacial Density of Eu Ions at Liquid–Liquid Interfaces for Solvent Back-Extraction

X-ray fluorescence near total reflection (XFNTR) is the primary technique used to measure the element-specific interfacial density of ions at liquid−liquid interfaces. Fluorescence from ions in the bulk liquids can complicate the determination of the interfacial density; consequently, measurements have been previously limited to samples without ions in the upper phase and with concentrations on the order of 10 μM or less in the lower phase. We modify the analysis of XFNTR data to account for ions in both bulk phases, then demonstrate its use in the context of rare-earth separations processes. In a model of ion stripping (i.e., back-extraction), dodecane solutions of di(2-ethylhexyl)- phosphoric acid (HDEHP) loaded with Eu(III) at the 1 mM level are placed in contact with either pure water or aqueous solutions of nitric or citric acid at pH 3. XFNTR measurements of equilibrated, quiescent samples reveal that citric acid solutions produce a disproportionately large depletion of ions from the interface compared to that from the bulk organic solution, whereas stripping by pure water or nitric acid solutions is negligible. As a result, this advance in the methodology of XFNTR may have broad applicability to the investigation of metal ions in chemical and biological processes at liquid−liquid interfaces.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Enhancing Cycle Life in Superoxide‐Based Na–O 2 Batteries by Reducing Interface Reactivity

Abstract Sodium–oxygen (Na–O 2 ) batteries are considered a promising energy storage alternative to current state‐of‐the‐art technologies owing to their high theoretical energy density, along with the natural abundance and low price of Na metal. The chemistry of these batteries depends on sodium superoxide (NaO 2 ) or peroxide (Na 2 O 2 ) being formed/decomposed. Most Na–O 2 batteries form NaO 2 , but reversibility is usually quite limited due to side reactions at interfaces. By using new materials, including a highly active catalyst based on vanadium phosphide (VP) nanoparticles, an ether/ionic liquid‐based electrolyte, and an effective sodium bromide (NaBr) anode protection layer, the sources of interface reactivity can be reduced to achieve a Na–O 2 battery cell that is rechargeable for 1070 cycles with a high energy efficiency of more than 83%. Density functional theory calculations, along with experimental characterization confirm the three factors leading to the long cycle life, including the effectiveness of the NaBr protective layer on the anode, a tetraglyme/EMIM‐BF 4 based electrolyte that prevents oxidation of the VP cathode catalyst surface, and the EMIM‐BF 4 ionic liquid aiding in avoiding electrolyte decomposition on NaO 2 .

Azaribeni, Adel [Department of Chemical and Biolog↗
DOE OSTI2024

Layer Resolved Cr Oxidation State Modulation in Epitaxial SrFe 0.67 Cr 0.33 O 3−δ Thin Films

Understanding how doping influences physicochemical properties of ABO 3 perovskite oxides is critical for tailoring their functionalities. In this study, SrFe 0.67 Cr 0.33 O 3−δ epitaxial thin films were used to examine the effects of Fe and Cr competition on structure and B-site cation oxidation states. The films exhibit a perovskite-like structure near the film/substrate interface, while a brownmillerite-like structure with horizontal oxygen vacancy channels predominates near the surface. Electron energy loss spectroscopy shows Fe remains Fe 3+ , while Cr varies from ∼Cr 3+ (tetrahedral layers) to ∼Cr 4+ (octahedral layers) within brownmillerite phases and becomes ∼Cr 4.5+ in perovskite-like phases. Theoretical simulations indicate that Cr–O bond arrangements and the way oxygen vacancies interact with Cr and Fe drive Cr charge disproportionation. High-valent Cr cations introduce additional densities of states near the Fermi level, reducing the optical bandgap from ∼2.0 eV (SrFeO 2.5 ) to ∼1.7 eV (SrFe 0.67 Cr 0.33 O 3−δ ). In conclusion, these findings offer insights into B-site cation doping in the perovskite oxide framework.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Towards a high-performance garnet-based solid-state Li metal battery: A perspective on recent advances

Garnet-based solid-state Li metal batteries have been widely considered one of the most promising next-generation energy storage systems. However, the performance of these batteries is plagued by various limitations caused by the solid-state electrolyte (SSE). The poor wetting of lithium on the garnet surface diminishes the contact between the anode and electrolyte, leading to extremely high anode interfacial resistance. Similarly, the point-to-point contact between the cathode and electrolyte leads to high impedance on the cathode side. Moreover, although the SSE serves a firm barrier separating the anode and cathode, lithium dendrites can still grow through, causing a short circuit. Lastly, the solid/solid interface cannot be well maintained under cycling at high current density and capacity. Recently, remarkable progress has been achieved in garnet electrolyte to resolve these problems towards the aim of a high-performance solid-state Li metal battery. In this perspective, we highlight various recent advances in the field of garnet-based solid-state battery, including improving the anode/electrolyte interface, lithium dendrite detection, reducing cathode impedance, and electrolyte architecture design.

25 ENERGY STORAGE↗
NASA NTRS1992

Benard convection in binary mixtures with Soret effects and solidification

Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

Zimmermann, G.↗
NASA NTRS2004

Future Concepts for Realtime Data Interfaces for Control Centers

Existing methods of exchanging realtime data between the major control centers in the International Space Station program have resulted in a patchwork of local formats being imposed on each Mission Control Center. This puts the burden on a data customer to comply with the proprietary data formats of each data supplier. This has increased the cost and complexity for each participant, limited access to mission data and hampered the development of efficient and flexible operations concepts. Ideally, a universal format should be promoted in the industry to prevent the unnecessary burden of each center processing a different data format standard for every external interface with another center. With the broad acceptance of XML and other conventions used in other industries, it is now time for the Aerospace industry to fully engage and establish such a standard. This paper will briefly consider the components that would be required by such a standard (XML schema, data dictionaries, etc.) in order to accomplish the goal of a universal low-cost interface, and acquire broad industry acceptance. We will then examine current approaches being developed by standards bodies and other groups. The current state of CCSDS panel work will be reviewed, with a survey of the degree of industry acceptance. Other widely accepted commercial approaches will be considered, sometimes complimentary to the standards work, but sometimes not. The question is whether de facto industry standards are in concert with, or in conflict with the direction of the standards bodies. And given that state of affairs, the author will consider whether a new program establishing its Mission Control Center should implement a data interface based on those standards. The author proposes that broad industry support to unify the various efforts will enable collaboration between control centers and space programs to a wider degree than is currently available. This will reduce the cost for programs to provide realtime access to their data, hence reducing the cost of access to space, and benefiting the industry as a whole.

Kearney, Mike W., III↗
DOE OSTI2020

Electro-chemo-mechanical evolution of sulfide solid electrolyte/Li metal interfaces: operando analysis and ALD interlayer effects

Sulfide solid electrolytes (SE) show promise for high-performance solid-state batteries because of their high ionic conductivity and ease of processing. However, sulfide electrolytes have suffered from chemical and electrochemical instability against Li metal anodes. In this paper, we use a suite of in situ/operando microscopy and spectroscopy techniques to demonstrate that Al 2 O 3 interlayers deposited using atomic layer deposition (ALD) delay degradation at the Li/LGPS interface by modifying the solid electrolyte interphase (SEI) chemistry and morphology. Optical and scanning electron microscopy are used to rationalize the electrochemical response of the system, which is attributed to a delayed onset of mechanical degradation at the interface when ALD interlayers are used. Operando X-ray photoelectron spectroscopy demonstrates that the dynamic evolution of SEI chemistry is impacted by the presence of the ALD interlayer. In situ Auger spectroscopy and operando optical microscopy provide visual evidence of spatial heterogeneity of Li plating, which is attributed to the chemo-mechanical degradation of the ALD interphase. The implications of these observations provide valuable insights toward the development of robust interlayers for solid-state batteries.

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

Ab Initio Insights to Metal Passivation: Diffusion and Defect Formation in Amorphous Zirconia and Alumina

Metal passivation refers to the formation of protective oxide films on metals, which shield them from further corrosion and oxidation, playing a crucial role in maintaining their stability. The mesoscopic Point Defect Model has successfully predicted passivity as a steady state process where oxide growth from oxygen vacancies at the metal/film interface competes with oxide dissolution at the film/environment interface. In this work, informed by the Point Defect Model parameters, we use first-principles calculations to calculate defect formation and atomic diffusion in amorphous materials and correlate these descriptors with the behavior and growth of the oxide film. Focusing on amorphous zirconia and alumina, we demonstrate that defect formation energies exhibit significant variability in amorphous systems. In alumina, vacancies dominate, with cation and anion vacancies occurring at comparable concentrations. Diffusion calculations for stoichiometric amorphous alumina and zirconia, as well as oxygen-deficient zirconia, reveal faster diffusion in the oxygen-deficient case, highlighting the impact of defects on transport. Comparison of calculated self-diffusion coefficients for the dominant defect species with experimentally measured oxide thicknesses shows a clear correlation, suggesting that first-principles-derived diffusivity information can serve as a key descriptor for surface passivation film growth.

Farnell, Mackinzie S. [University of California, B↗