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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Stochastic 3D reconstruction of cracked polycrystalline NMC particles using 2D SEM data

Li-ion battery performance is strongly influenced by the 3D microstructure of its cathode particles. Cracks within these particles develop during calendaring and cycling, reducing connectivity but increasing reactive surface, making their impact on battery performance complex. Understanding these contradictory effects requires a quantitative link between particle morphology and battery performance. However, informative 3D imaging techniques are time-consuming, costly and rarely available, such that analyses often have to rely on 2D image data. This paper presents a novel stereological approach for generating virtual 3D cathode particles exhibiting crack networks that are statistically equivalent to those observed in 2D sections of experimentally measured particles. Consequently, 2D image data suffices for deriving a full 3D characterization of cracked cathodes particles. Such virtually generated 3D particles could serve as geometry input for spatially resolved electro-chemo-mechanical simulations to enhance our understanding of structure-property relationships of cathodes in Li-ion batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Discovering polyelemental nanostructures with redistributed plasmonic modes through combinatorial synthesis

Coupling plasmonic and functional materials provides a promising way to generate multifunctional structures. However, finding plasmonic nanomaterials and elucidating the roles of various geometric and dielectric configurations are tedious. This work describes a combinatorial approach to rapidly exploring and identifying plasmonic heteronanomaterials. Symmetry-broken noble/non-noble metal particle heterojunctions (~100 nanometers) were synthesized on multiwindow silicon chips with silicon nitride membranes. The metal types and the interface locations were controlled to establish a nanoparticle library, where the particle morphology and scattering color can be rapidly screened. By correlating structural data with near- and far-field single-particle spectroscopy data, we found that certain low-energy plasmonic modes could be supported across the heterointerface, while others are localized. Furthermore, we found a series of triangular heteronanoplates stabilized by epitaxial Moiré superlattices, which show strong plasmonic responses despite largely comprising a lossy metal (~70 atomic %). These architectures can become the basis for multifunctional and cost-effective plasmonic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High-Energy X-ray Diffraction Microscopy for Nuclear Forensics (FY23 Project Report)

Morphological information on nuclear material has been identified using visible light and scanning electron microscopy. These identify qualitative differences in particle morphology. Three-dimensional imaging of materials through alternating scanning electron microscopy imaging and focused ion beam milling has also been used. Unfortunately, these techniques are time- and labor-intensive, with significant sample preparation required and lengthy analysis times. Further, the resulting 3D images are qualitative, require manual identification, and do not capture statistically-representative populations. High energy X-ray 3D imaging using a direct-beam or diffracted-beam (High-Energy Diffraction Microscopy) have been developed at the Advanced Photon Source and can produce quantitative information on grains (phase, location, etc.) and pores (size distribution, sphericity) in a material. These techniques require only minutes to characterize a sample volume and are non-destructive, thus suitable for a wide range of existing samples and for confirmatory analyses to be carried out using conventional microscopy techniques.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Preparation of pigments for space-stable thermal control coatings

The identification and control of vapor phase reaction kinetics to produce pigments by homogeneous nucleation were achieved. A vapor phase apparatus was designed, fabricated, and calibrated through 1800 C. Vapor phase reactions were analyzed, calculations made, and powders of alumina, rutile, zinc orthotitanate (in a mixed phase), calcium tungstate, and lanthana were produced by homogeneous nucleation. Electron microscopy shows uniform particle morphology and size, and supports anticipated advantages of vapor-phase homogeneous nucleation; namely, purity, freedom from defects, and uniform particle sizing without grinding.

Campbell, W. B.↗
DOE OSTI2025

Tunable shear thickening, aging, and rejuvenation in suspensions of shape-memory-endowed liquid crystalline particles

The morphological features of particles, notably shape anisotropy, critically influence the rheological properties of dense suspensions, spanning both natural and engineered systems. This work explores the potential of using shape memory particles to dynamically regulate suspension fluid flow through controllable shape transformations. First, we synthesize shape-memory particles with programmable anisotropy from liquid crystal elastomers, such that the stiffness and shapes of the particles can be tuned by manipulating temperature. Our findings reveal that suspensions from such particles exhibit significant tunability in shear thickening behavior, transitioning from discontinuous shear thickening to a Newtonian-like response within a narrow temperature range of 60 ° C. This capability to modulate rheological responses in situ presents an approach for addressing processing challenges in many applications where control over flow behavior is paramount. Furthermore, we also show that suspensions composed of these anisotropic particles can undergo physical aging, and evolve into a glassy state. This state can be escaped upon activation of the shape memory effect. This reversibility underscores the potential for using such materials to engineer systems that can enter or come out of kinetic arrest by leveraging internal mechanical responses to external stimuli. The insights gained here not only broaden our understanding of the interplay between particle geometry and suspension dynamics but also pave the way for leveraging ensembles of stimuli-responsive objects to precisely control collective behaviors in many-body systems.

Science & Technology - Other Topics↗
DOE OSTI2022

Molten-Salt Synthesis of O 3 -Type Layered Oxide Single Crystal Cathodes with Controlled Morphology towards Long-Life Sodium-Ion Batteries

Sodium layered oxides show great promise as affordable alternatives to lithium layered oxides, but their poor cycle life and air stability limit their practical potential. Micron-scale single crystals with greater packing density and lower surface area can overcome these challenges and improve performance compared to the traditional polycrystalline morphology. Herein, the authors present the synthesis of layered O 3 -type Na(Ni 0.3 Fe 0.4 Mn 0.3 )O 2 single-crystals with greatly improved cycle life and air stability. A molten-salt synthesis technique is adopted with excess sodium hydroxide to obtain platelet-like single crystals. Because the main mechanisms of both capacity fade and air degradation occur as a result of surface reactions at the opening of the sodium diffusion channels, particle morphology is found to be a critical metric for materials performance. More important than particle size or total surface area, the smaller proportion of exposed edge planes in the platelet morphology greatly reduces the amount of harmful surface reactions. Furthermore, the molten-salt method is found to eliminate the need for coprecipitated precursors and even form better morphology, starting from metal oxides instead of coprecipitated hydroxides.

25 ENERGY STORAGE↗
DOE OSTI2025

Synthesis of Yttrium Oxide Particles for Interfacial Water Radiolysis Studies

Radiolysis of water produces hydrogen gas (H2), posing safety issues for nuclear reactors. Metal oxides can impact H2 formation when water is present on metal oxide surfaces. This presentation focuses on the development of a controllable synthesis of spherical yttrium oxide (Y2O3), that later will be tested for H2 production in water radiolysis. Y2O3 was synthesized via hydrothermal hydrolysis precipitation to form yttrium hydroxide (Y(OH)3), followed by high temperature decomposition to form Y2O3. Various synthesis conditions were tested to determine their impact on particle morphology including reaction time, cooling rate, reactant concentration, and inert atmospheres. Through short reaction times and rapid cooling rate, spherical, relatively uniform particles of 350 nm were obtained. Despite inert atmospheres, carbonate formation occurred in all particles. A calcination temperature of 800°C is necessary to remove impurities. Future work will aim to reduce carbonate formation and improve particle uniformity. The synthetic procedure will be translated to other metal ions to study their impact on interfacial radiolysis.

08 - HYDROGEN↗
NASA NTRS2000

Measurements and Modeling of Aerosol Absorption and Single Scattering Albedo at Ambient Relative Hum

Uncertainties in the aerosol single scattering albedo have been identified to be an important source of errors in current large-scale model estimates of the direct aerosol radiative forcing of climate. A number of investigators have obtained estimates of the single scattering albedo from a variety of remote sensing and in situ measurements during aerosol field experiments. During the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX, 1996) for example, estimates of the aerosol single scattering albedo were obtained (1) as a best-fit parameter in comparing radiative flux changes measured by airborne pyranometer to those computed from independently measured aerosol properties; (2) from estimates of the aerosol complex index of refraction derived using a combination of airborne sunphotometer, lidar backscatter and in situ size distribution measurements; and (3) from airborne measurements of aerosol scattering and absorption using nephelometers and absorption photometers. In this paper, we briefly compare the results of the latter two methods for two TARFOX case studies, since those techniques provide height-resolved information about the aerosol single scattering albedo. Estimates of the aerosol single scattering albedo from nephelometer and absorption photometer measurements require knowledge of the scattering and absorption humidification (i.e., the increase in these properties in response to an increase in ambient relative humidity), since both measurements are usually carried out at a relative humidity different from the ambient atmosphere. In principle, the scattering humidification factor can be measured, but there is currently no technique widely available to measure the absorption of an aerosol sample as a function of relative humidity. Frequently, for lack of better knowledge, the absorption humidification is assumed to be unity (meaning that there is no change in aerosol absorption due to an increase in ambient relative humidity). This assumption then enters the estimate of the single scattering albedo at ambient relative humidity. To investigate the validity of this assumption we have carried out modeling studies of the absorption humidification factor, assuming that the aerosols contain an insoluble soot core and a coating which determines its hygroscopic growth behavior. The aerosol optical properties are then computed on the basis of the shell/core particle morphology using a Mie-code for concentric shells. From basic physical principles, it is conceivable that aerosol absorption increases when an atmospheric aerosol particle collects a non-absorbing shell, since the soot core is then exposed to an increased (focused) electric field strength. Indeed, our preliminary modeling studies show that the absorption of an atmospheric aerosol particle composed of a soot core and an aqueous sulfuric acid shell may increase by a factor of 50% due to a change in ambient relative humidity from 30 to 95%. We will show how this increased absorption is a function of the initial particle size and soot mass fraction.

Redemann, J.↗
DOE OSTI2022

Effect of charge and anisotropic diffusivity on ion exchange kinetics in nuclear waste form materials

Motifs of radionuclide absorption particles (absorbers or fillers) for the nuclear waste treatment usually have crystal structures with nano-sized tunnels for fast ion diffusion. On the other hand, the accumulation of ions generates an electric field which affects the ion diffusion. Therefore, the strong anisotropic kinetic properties and the electric field affect ion exchange kinetics, especially in an assembly of these particles which may block the fast diffusion tunnels for each other. In this work, we developed a mesoscale model to describe the effect of anisotropic kinetic properties and electric field on ion exchange kinetics. With the model we simulated the effect of anisotropic diffusivity, electrochemical potential, particle morphology, size and aggregation on ion exchange kinetics during batch experiments. Here, tt is found that 1) ion exchange results in charge accumulation inside the particle because different ions have different diffusivities and different diffusion driving forces. The electric neutrality is not preserved; 2) the electric field speeds up the slower diffusion ions (either uptake or release) and slows down the faster diffusion ions to reduce charge accumulation and maintains charge neutrality; 3) the ion exchange becomes very slow at the later stages because a) diffusion driving force (electrochemical gradient, Cs + concentration in the solution and Na + inside the particle) continuously decreases, as observed in batch experiments; and b) the diffusivity decreases due to the Cs + concentration dependence of ion diffusivity. This can explain the observed experimental phenomena that the radionuclide capacity usually cannot be reached; 4) for needle-like particle and their clusters, both surface area and diffusion distance along the direction with the fastest diffusivities have significant impact on the ion exchange kinetics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Insights into Mechanisms of Screw Feeder Plugging by Heated Pine Forestry Residues Using in-situ and Correlative Microscopy

Increasing concerns about global carbon emissions due to fossil fuel use has created interest in renewable fuel alternatives, such as lignocellulosic biomass. With an estimated global biomass production probability ten-fold higher than projected need, functionalizing and scaling biomass conversion processes, like pyrolysis, is a promising component of a diverse sustainable energy program (Kan, Strezov, & Evans, 2016). Pyrolysis reactors employed in biomass conversion often encounter the known problem of screw feeder plugging, halting work and reducing efficiency of biorefineries. Although the screw feeder is not heated directly, conductive heat transfer from the fluidized bed pyrolysis reactor creates a temperature gradient, where particles experience temperatures between 22°C and 500°C from the time they enter the feeder to being emptied into the reactor (Digman, Joo, & Kim, 2009; Nieminen & Folke, 1982). The impact of unintentional heating on this highly variable feedstock may result in particle morphology modification, surface texture transformation, and the evolution of viscous compounds and may contribute to screw feeder plugging (Haas, Nimlos, & Donohoe, 2009; Ingram et al., 2008). We hypothesized that particles of various anatomical fractions (including needles, branches, bark, cambium, and whitewood) will experience dramatic changes during this heating regime, which will be characterized by decreased particle size, increased surface roughness, degradation of key structural macromolecules, and generation of viscous compounds that would result in increased particle friction and cohesion, contributing to screw feeder plugging.

biofuels↗
DOE OSTI2020

Particle size of several plutonium-238 oxide fuel samples from oxalate precipitation processes

Particle size of 238 PuO 2 powders is an important factor in determining the structural integrity of fuel pellets hot-pressed from the oxide powder. Understanding the evolution of particle size during aqueous processing is a first step in assuring control of particle size throughout the pellet formation process. Measured particle sizes are reported here, and discussed in terms of measured particle size changes occurring during calcining, observed aggregation of particulate, and particle morphology. Morphology and aggregation are related to surface energy, which governs granule formation and hot pressing behavior. Results are discussed in terms of reported dependence of oxide morphology on process temperatures and reagent concentrations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Experimental Testing of Particle Erosion and Attrition in CSP Systems

In CSP systems using solid particles for heat transfer, erosion from the falling particles can damage the system components upon impact, and from sliding against the component walls. Furthermore, the resulting attrition of particles can change the thermal performance due to alterations in particle morphology. The research on these issues has been limited to industrial applications, and don’t necessarily coincide with the operating conditions in CSP systems. In this work, we investigated the durability of the particles selected as the heat transfer media, as well as special substrate materials that are of interest as lining materials to the particle storage tanks and hoppers. Three different erosion phenomena were studied: impact, abrasion, and attrition erosion. The low-temperature experiments revealed negligible losses from attrition and abrasion erosion. Although the substrates indicated visible surface damage from impact erosion, the actual material mass loss was small even after a throughput of 500kg of particles 63 days of 1MW CSP plant operation assuming 14 hours per day of operation. Erosion is typically classified as impact, abrasion, or attrition erosion. For example, the CSP systems utilizing solid particles as heat transfer media will likely experience impact erosion on the receiver hopper and heat exchanger walls as the solid particles fall from the reservoir. Additionally, there will be sliding erosion along the receiver walls as particles move through the hopper, and lastly, there will also be attrition erosion as the particles rub against each other. The extent of erosion depends on many factors including but not limited to particle shape and size, material hardness/brittleness and ductility, and particle impact speed and angle. Mechanistic erosion equations that are available in the literature are mostly derived from data pertaining to specific experiments and therefore can’t be applied to all applications without suitable adjustments. Survey of the literature relating to particle-based receivers revealed that the most prevalent approach has been to choose low velocities to limit erosion, but to our knowledge, little effort has been put in to fully characterize erosion at the expected operating conditions. A relatively recent work investigated the erosion of wire mesh proposed for use in a particle receiver, where the results actually showed an increase in mass as oxidation occurred on the mesh surface but the work did not investigate the particle attrition rate, and the erosion rate of a solid substrate. The end goal of this work is to develop a comprehensive particle and substrate durability model that will allow a comprehensive understanding of particle-based CSP operating conditions on component durability.

14 SOLAR ENERGY↗
DOE OSTI2020

Experimental testing of particle attrition in CSP systems at high temperature

An alternate and sustainable form of energy is CSP systems, which capture and store the sun’s energy in the form of heat. Increasing the operational temperature of CSP systems will increase the efficiency of electricity production while operating at temperatures exceeding 700 degrees Celsius also creates novel operational problems. One approach for high-temperature CSP systems is to utilize solid particles as the primary heat transfer medium. As particles flow through this system, the movement of particles creates erosion in the forms of impact, abrasion, and attrition erosion. In the real world, while all three forms of erosion will occur simultaneously, it is imperative to understand the individual effect of each erosion over the lifetime of the powerplant. Besides material erosion and long-term durability concerns, thermal cycling of the particles could also introduce changes in particle thermal performance due to alterations in particle morphology. Current research on the issue of erosion has been limited to industrial applications and does not necessarily coincide with the operating conditions in CSP systems. We focus on attrition erosion resulting from particle-to-wall and particle-to-particle interactions. Research has shown that besides material hardness affecting how fast particles break down, attrition erosion increased as the size of the particles increased due to a higher chance of collision between the particles. Particle attrition is relevant to the CSP community as it may result in material loss, change the system's thermal performance, and generation of fines which could pose an environmental hazard. In this work, we focus on developing a test set up that can isolate and measure particle attrition when subjected to conditions relevant to Gen3 CSP systems.

14 SOLAR ENERGY↗
DOE OSTI2022

Three-dimensional microstructure of a friction stir welded magnesium/steel interface characterized via high-energy synchrotron X-rays

Here, the three-dimensional (3D) microstructure of a friction stir assisted scribe technique (FaST) weld interface consisting of AZ31 magnesium (Mg) alloy and zinc (Zn)-coated DP590 steel was analyzed via synchrotron micro-computed tomography (μ-CT), correlated to synchrotron x-ray diffraction, and electron microscopy. Diffraction assessment of the AZ31/Zn-coated DP590 steel interface revealed the presence of several complex Mg–Zn intermetallic phases and differences in crystalline orientation of the Mg phase at the weld interface. The 3D characterization of the synchrotron μ-CT images of the weld interface revealed: (1) the presence of AZ31 weld nugget material with iron (Fe)-rich particles; (2) the presence of a weld layer at the joining interface with Fe-rich particles; (3) the formation of a thin non-uniform layer between the weld layer and the interface of the scribed DP590 material; and (4) the presence of an Fe–Al-rich intermetallic layer and Fe-rich particles at the interface of the scribed DP590 material. This study also performed a detailed analysis of lump-like features seen in the Zn coating layer at the weld interface. A detailed 3D particle analysis of the Fe-rich particles in the AZ31 weld nugget and the weld layer at the weld interface revealed the presence of several types of particle morphologies (i.e., spherical and irregular).

36 MATERIALS SCIENCE↗
NASA NTRS2001

Studies of Ice Nucleating Aerosol Particles in Arctic Cloud Systems

The focus of this research is to improve the understanding of ice nucleating aerosol particles (IN) and the role they play in ice formation in Arctic clouds. IN are important for global climate issues in a variety of ways. The primary effect is their role in determining the phase (liquid or solid) of cloud particles. The microscale impact is on cloud particle size, growth rate, shape, fall speed, concentration, radiative properties, and scavenging of gases and aerosols. On a larger scale, ice formation affects the development of precipitation (rate, amount, type, and distribution), latent heat release (rate and altitude), ambient humidity, the persistence of clouds, and cloud albedo. The overall goals of our FIRE 3 research are to characterize the concentrations and variability of Arctic IN during the winter-spring transition, to compare IN measurements with ice concentrations in Arctic clouds, and to examine selected IN samples for particle morphology and chemical there are distinguishable chemical signatures. The results can be combined with other measurements of aerosols, gaseous species, and cloud characteristics in order to understand the processes that determine the phase and concentration of cloud particles.

Rogers, David C.↗
DOE OSTI2020

Tuning the Morphology and Electronic Properties of Single-Crystal LiNi 0.5 Mn 1.5 O 4-δ : Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature

Single-crystal materials have played a unique role in the development of high-performance cathode materials for Li batteries due to their favorable chemomechanical stability. The molten salt synthesis method has become one of the most prominent techniques used to synthesize single-crystal layered and spinel materials. In this work, the molten salt synthesis method is used as a technique to tune both the morphology and Mn 3+ content of high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes. The resulting materials are thoroughly characterized by a suite of analytical techniques, including synchrotron X-ray core-level spectroscopy, which are sensitive to the material properties on multiple length scales. Furthermore, the multidimensional characterization allows us to build a materials library according to the molten salt phase diagram as well as to establish the relationship among synthesis, material properties, and battery performance. The results of this work show that the Mn 3+ content is primarily dependent on the synthesis temperature and increases as the temperature is increased. Additionally, the particle morphology is mostly dependent on the composition of the molten salt flux, which can be tailored to obtain well-defined octahedrons enclosed by (111) facets, plates with predominant ($11\tilde{2}$) facets, irregularly shaped particles, or mixtures of these. The electrochemical measurements indicate that the Mn 3+ content has a larger contribution to the battery performance of LNMO than do morphological characteristics and that a significant amount of Mn 3+ could become detrimental to the battery performance. However, with similar Mn 3+ contents, morphology still plays a role in influencing the battery cycle life and rate performance. The insights of molten salt synthesis parameters on the formation of LNMO, with deconvolution of the roles of Mn 3+ and morphology, are crucial to continuing studies in the rational design of LNMO cathode materials for high-energy Li batteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Affordable Realtime Viral Detection: Demonstrated with SARS COV-2

The near real-time detection of airborne particles-of-interest is needed for avoiding current/future threats. The incorporation of imprinted particles into a micelle-based electrochemical cell produced a signal when brought into contact with particle analytes (such as SARS-COV-2), previously imprinted onto the structure. Nanoamp scales of signals were generated from what may’ve been individual virus-micelle interactions. The system showed selectivity when tested against similar size and morphology particles. The technology was compatible with airborne aerosol sampling techniques. Overall, the application of imprinted micelle technology could provide near real-time detection methods to a host of possible analytes of interest in the field.

47 OTHER INSTRUMENTATION↗
NASA NTRS2008

A Thermal Precipitator for Fire Characterization Research

Characterization of the smoke from pyrolysis of common spacecraft materials provides insight for the design of future smoke detectors and post-fire clean-up equipment on the International Space Station. A thermal precipitator was designed to collect smoke aerosol particles for microscopic analysis in fire characterization research. Information on particle morphology, size and agglomerate structure obtained from these tests supplements additional aerosol data collected. Initial modeling for the thermal precipitator design was performed with the finite element software COMSOL Multiphysics, and includes the flow field and heat transfer in the device. The COMSOL Particle Tracing Module was used to determine particle deposition on SEM stubs which include TEM grids. Modeling provided optimized design parameters such as geometry, flow rate and temperatures. Microscopy results from fire characterization research using the thermal precipitator are presented.

Meyer, Marit↗