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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Extending the capillary wave model to include the effect of bending rigidity: X-ray reflectivity and diffuse scattering

The surface roughness of a thin film at a liquid interface exhibits contributions of thermally excited fluctuations. This thermal roughness depends on temperature (𝑇), surface tension (𝛾), and elastic material properties, specifically the bending modulus (𝜅) of the film. A nonzero 𝜅 suppresses the thermal roughness at small length scales compared to an interface with zero 𝜅, as expressed by the power spectral density of the thermal roughness. The description of the x-ray scattering of the standard capillary wave model (CWM), which is valid for zero 𝜅, is extended to include the effect of 𝜅. The extended CWM (eCWM) provides a single analytical form for both the specular x-ray reflectivity (XRR) and the diffuse scattering around the specular reflection, and recovers the expression of the CWM at its zero 𝜅 limit. This theoretical approach enables the use of single-shot grazing incidence x-ray off-specular scattering (GIXOS) measurements for characterizing the structure of thin films on a liquid surface. The eCWM analysis approach decouples the thermal roughness factor from the surface scattering signal, providing direct access to the intrinsic surface-normal structure of the film and its bending modulus. Moreover, the eCWM facilitates the calculation of reflectivity at any desired resolution (pseudo-XRR approach). The transformation into pseudo-XRR provides the benefit of using widely available XRR software to perform GIXOS analysis. The extended range of the vertical scattering vector (𝑄 𝑧 ) available with the GIXOS pseudo-XRR approach allows for a higher spatial resolution than with conventional XRR. Experimental results are presented for various lipid systems, showing strong agreement between conventional specular XRR and pseudo-XRR methods. This agreement validates the proposed approach and highlights its utility for analyzing soft, thin films.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Revealing a Pathway for Low-Temperature Recrystallization in Germanium

Thermally activated annealing in semiconductors faces inherent limitations, such as dopant diffusion. Here, a nonthermal pathway is demonstrated for a complete structural restoration in predamaged germanium via ionization-induced recovery. By combining experiments and modeling, this study reveals that the energy transfer of only 2.4 keV nm −1 from incident ions to target electrons can effectively annihilate pre-existing defects and restore the original crystalline structure at room temperature. Moreover, it is revealed that the irradiation-induced crystalline-to-amorphous (c/a) transformation in Ge is reversible, a phenomenon previously considered unattainable without additional thermal energy imposed during irradiation. For partially damaged Ge, the overall damage fraction decreases exponentially with increasing fluence. Surprisingly, the recovery process in preamorphized Ge starts with defect recovery outside the amorphous layer and a shrinkage of the amorphous thickness. After this initial stage, the remaining damage decreases slowly with increasing fluence, but full restoration of the pristine state is not achieved. These differences in recovery are interpreted in the framework of structural differences in the initial defective layers that affect recovery kinetics. This study provides new insights on reversing the c/a transformation in Ge using highly-ionizing irradiation and has broad implications across materials science, radiation damage mitigation, and fabrication of Ge-based devices.

athermal recovery↗
NASA NTRS1984

Transformation toughened ceramics for the heavy duty diesel engine technology program

The objective of this program is to develop an advanced high temperature oxide structural ceramic for application to the heavy duty diesel engine. The approach is to employ transformation toughening by additions of ZrO.5HfO.5O2 solid solution to the oxide ceramics, mullite (2Al2O3S2SiO2) and alumina (Al2O3). The study is planned for three phases, each 12 months in duration. This report covers Phase 1. During this period, processing techniques were developed to incorporate the ZrO.5HfO.5O2 solid solution in the matrices while retaining the necessary metastable tetragonal phase. Modulus of rupture and of elasticity, coefficient of thermal expansion, fracture toughness by indent technique and thermal diffusivity of representative specimens were measured. In Phase 2, the process will be improved to provide higher mechanical strength and to define the techniques for scale up to component size. In Phase 3, full scale component prototypes will be fabri-]cated.

Musikant, S.↗
NASA NTRS2022

Laser Patterning Assisted Devitrification and Domain Engineering of Amorphous and Nanocrystalline Alloys

We have investigated laser-patterning and devitrification as a novel method to realize emergent properties in modified regions at the ribbon surface consisting of periodic localized laser spots thermally treated under rapid heating and cooling conditions. Fe-based amorphous ribbons were annealed for systematically varied laser power. Extremely high heating and cooling rates on the order of 10(exp 8)-10(exp 10)K/s have been estimated by finite element analysis simulations. Observations suggest surface melting followed by rapid solidification fast enough to quench and form an amorphous structure upon cooling. Diffusion of heat occurs from the laser irradiated surface region so that a finite volume of material surrounding this region rises in temperature above the crystallization temperature relevant for conventional isothermal annealing experiments. The underlying mechanism of laser annealing and consequences of heat transients involved are discussed in terms of impacts upon micro/nanostructure, residual stresses, and magnetic domain structure surrounding the laser irradiated region. The study illustrates the potential to exploit spatially optimized phase transformations in a scalable manufacturing process of amorphous and nanocrystalline alloys to locally access otherwise inaccessible extreme heating and cooling rates.

Amorphous ribbons↗
NASA NTRS1991

FTIR Spectroscopic Characterization Of II-VI Semiconductors

Combination of commercial Fourier-transform infrared (FTIR) spectrometer with computer and special-purpose software constitutes highly automated facility for acquisition and processing of infrared transmission or reflection spectral image data. Intended principally to acquire transmission spectra of some compounds of elements in groups II and VI of periodic table. System used to characterize specimens of II/VI alloy semiconductors grown by directional solidification and quenching. Transmission-edge maps helpful in studies of flows, gradients of temperature, and coefficients of diffusion in solidifying melts. Data acquired by system include optical characteristics, and they both verify and complement data obtained by such other techniques as measurements of density and x-ray-dispersion analysis.

Perry, G. L. E.↗
DOE OSTI2026

Low-Pressure Diffusion Bonding of Vanadium to Commercially Pure Titanium and Ti-6Al-4V

Modern technology increasingly requires components to be made from specific high-performance materials. To support complex multi-metal structures, a variety of techniques are required to join dissimilar metal parts with precise shapes. This study evaluates vacuum diffusion bonding as a method for joining titanium and vanadium, focusing on both pure titanium and the common alloy Ti-6Al-4V. We employ modest pressure provided by a weight and simple surface preparation to simulate the most commercially applicable process. Here, we show that Ti-6Al-4V alloy bonds readily to V, forming a continuous, clearly defined interdiffusion layer with predictable kinetics. Conversely, commercially pure Ti forms a crack-prone bond with V that fails to improve at higher bonding temperatures or longer times. We attribute this failure to the concentration of stress caused by the ß-to-α phase transformation in Ti. The contrasting bonding efficacy between pure Ti and the alloy provides insight into the crystallographic interactions that occur at the interface during bonding and cooling. These results provide surprising insight into a new method for bonding Ti alloys to V and possibly other metals that share the body-centered cubic crystal structure.

36 MATERIALS SCIENCE↗
DOE OSTI2026

D$e^+e^-$ffusion: Capturing the Beam-Beam Physics of $e^+e^-$ Collisions with Diffusion Models

Beam-induced backgrounds at high-luminosity $e^+e^-$ colliders, such as the FCC-ee, are dominated by incoherent pair creation (IPC), and require computationally expensive simulations with dedicated Monte Carlo (MC) event generators. Reliable detector and machine-detector interface studies necessitate event samples that are several orders of magnitude larger than what is practically attainable with existing MC. To alleviate this bottleneck, we present D$e^+e^-$ffusion, a denoising diffusion probabilistic model that operates as a permutation-equivariant, set-valued surrogate for fast IPC simulation. Trained on a small GuineaPig++ sample, D$e^+e^-$ffusion faithfully reproduces the marginal and joint kinematic, angular, and positional distributions of all three IPC production processes. In addition, we assess the fidelity at the detector level by propagating both Geant4 and D$e^+e^-$ffusion events through a Geant4 simulation of the CLD vertex detector and by training a transformer-based two-sample classifier; the classifier achieves an area under the ROC curve of $0.553 \pm 0.016$. The trained model generates events nearly four orders of magnitude faster than Geant4, paving the way for a fast-simulation surrogate for FCC-ee design studies.

Chahine, Antonio [Imperial Coll., London]↗
NASA NTRS1998

Evaluation of the Transient Liquid Phase (TLP) Bonding Process for Ti3Al-Based Honeycomb Core Sandwich Structure

The suitability of using transient liquid phase (TLP) bonding to fabricate honeycomb core sandwich panels with Ti-14Al-21Nb (wt%) titanium aluminide (T3Al) face sheets for high-temperature hypersonic vehicle applications was evaluated. Three titanium alloy honeycomb cores and one Ti3Al alloy honeycomb core were investigated. Edgewise compression (EWC) and flatwise tension (FWT) tests on honeycomb core sandwich specimens and tensile tests of the face sheet material were conducted at temperatures ranging from room temperature to 1500 F. EWC tests indicated that the honeycomb cores and diffusion bonded joints were able to stabilize the face sheets up to and beyond the face sheet compressive yield strength for all temperatures investigated. The specimens with the T3Al honeycomb core produced the highest FWT strengths at temperatures above 1000 F. Tensile tests indicated that TLP processing conditions resulted in decreases in ductility of the Ti-14Al-21Nb face sheets. Microstructural examination showed that the side of the face sheets to which the filler metals had been applied was transformed from equiaxed alpha2 grains to coarse plates of alpha2 with intergranular Beta. Fractographic examination of the tensile specimens showed that this transformed region was dominated by brittle fracture.

Bird, R. Keith↗
NASA NTRS1999

Crystal Growth Using MEPHISTO

The shuttle flight experiment "In Situ Monitoring of Crystal Growth Using MEPHISTO" was accomplished during STS-87 as part of the fourth flight of the United States Microgravity Payload (USMP-4), which was flown from November 19 to December 5, 1997. The data returned from that flight are just now beginning to yield quantitative results. This project is an international collaboration: the furnace system known as MEPHISTO was built in France by CNES (French National Space Agency) and CEA (French Atomic Energy Commission); the principal investigator, Prof. Reza Abbaschian, is from the University of Florida at Gainesville; and numerical and analytical modeling support includes collaborators from the University of New South Wales, Australia, the University of Wisconsin at Milwaukee, the National Institute of Standards and Technology, and the NASA Lewis Research Center. MEPHISTO is a French acronym that translates into English as Materials for the Study of Interesting Phenomena of Solidification on Earth and in Orbit. Since this was the fourth flight of the MEPHISTO furnace, the experiment is referred to as MEPHISTO-4. MEPHISTO-4 was a directional solidification experiment that studied the liquid-to-solid transformation of bismuth alloyed with tin. Directional solidification is a freezing technique common to the processing of the electronic materials used in integrated circuits and detectors, such as silicon and germanium. When liquids are frozen on Earth, they must be cooled. The cooling causes stirring because of density variations in the liquid. This stirring, known as natural convection, influences the quality of the resulting solid. During freezing, regions of high and low concentrations of tin are created. This introduces another important phenomenon: diffusion, or the movement by molecular action of matter from regions of high concentration to regions of lower concentration. In MEPHISTO-4, it is tin that diffuses from the high-concentration region in front of the solid-liquid interface to more distant low-concentration regions.

deGroh, Henry C., III↗
DOE OSTI2026

Generative AI in Supply Chain Management: Applications, Challenges, and Future Directions

Supply chain management (SCM) is undergoing rapid transformation due to increasing global complexity, demand volatility, and operational disruptions. Generative Artificial Intelligence (GenAI) has emerged as a powerful paradigm capable of synthesizing data, simulating operational scenarios, and enabling adaptive decision-making across supply chain networks. This paper presents a survey of GenAI’s role in SCM, focusing on its applications in predictive analytics, autonomous logistics, and fraud detection. Unlike traditional AI systems that rely primarily on predictive analytics, GenAI models, including large language models, generative adversarial networks, and diffusion-based architectures, enable the creation of synthetic supply chain scenarios and autonomous optimization strategies. This survey provides (1) a taxonomy of GenAI techniques for supply chain applications, (2) a comparative analysis of generative AI approaches with traditional machine learning, reinforcement learning, and blockchain-based methods, and (3) a discussion of key challenges such as data privacy, interpretability, and integration with legacy enterprise systems. Furthermore, we outline open research problems and propose directions for future research toward autonomous, resilient, and sustainable AI-driven supply chains.

15 - GEOTHERMAL ENERGY↗
NASA NTRS1992

The crystallization and crystalline properties of LARC-TPI

LARC-TPI, a thermoplastic polyimide, has been studied in order to develop an understanding of its crystalline phase transition. Our experiments suggest that samples synthesized in different laboratories apparently had different degrees of imidization and their thermal behaviors differed accordingly. When the most crystalline of these polyimides was studied in some detail, we found that it melted irreversibly in that once a sample was completely melted it would not recrystallize. A polymer that did not recrystallize displayed a glass transition, which increased in temperature upon subsequent cooling and reheating. Solubility experiments indicated that heating above the crystalline melting temperature led to network formation in the polymer, a conclusion that is consistent with other behavior just mentioned. Differential calorimetric studies revealed that annealing at slow heating rates or under isothermal conditions resulted in dual melting transitions. These studies, supported by X-ray diffraction results, strongly indicate that the annealing process involves a solid-liquid-solid transformation. From an existing phenomenological model for the kinetics of phase transitions, kinetic parameters for these crystallizations have been evaluated. The Avrami exponents n increased with the annealing temperature in the protocol used in this study. Their values were about 2 or lower, thus indicating that crystallization may have followed a mechanism that included heterogeneous nucleation of a low dimensional order in which all the embryonic crystallites formed at the beginning of the process. A positive temperature coefficient for these crystallizations indicated that diffusion may have had a rate controlling influence and affected the values of n.

Theil, Michael H.↗
NASA NTRS2003

Analysis of Radial Segregation in Directionally Solidified Hg(0.89)Mn(0.11)Te

Bridgman growth experiments were performed on Hg(0.89)Mn(0.11)Te (MMT) to determine the extent of radial Manganese segregation during directional solidification. MMT crystals were directionally solidified at rates of 0.09 and 0.18 p d s and in axial thermal gradients of 83 and 68"C/cm. Wavelength Dispersive Spectroscopy (WDS) and Fourier Transform Infra-Red (FTIR) analytical techniques were used to determine the radial homogeneity in all boules and the deflection of the solid-liquid interface (SLI) in two boules that were rapidly quenched after 5 to 6 cm of directional solidification. For all growth runs, the measured radial coinpositional variations were on the order of 0.01 molar percent MnTe in the steady state region of growth. Comparison of the measured radial compositional results of the crystals to predicted values in the diffusion-limited regime indicate a strong influence of convection near the solid-liquid interface. This conclusion is supported by the weak influence of the translation rates and axial thermal gradients utilized in this study upon radial compositional homogeneity.

Price, M. W.↗
NASA NTRS1985

Destabilization of yttria-stabilized zirconia induced by molten sodium vanadate-sodium sulfate melts

The extent of surface destabilization of ZrO2 - 8 wt percent Y2O3 ceramic disks was determined after exposure to molten salt mixtures of sodium sulfate containing up to 15 mole percent sodium metavanadate (NaVO3) at 1173 K. The ceramic surface was observed to transform from the cubic/tetragonal to monoclinic phase, concurrent with chemical changes in the molten salt layer in contact with the ceramic. Significant attack rates were observed in both pure sulfate and metavanadate sulfate melts. The rate of attack was found to be quite sensitive to the mole fraction of vanadate in the molten salt solution and the partial pressure of sulfur trioxide in equilibrium with the salt melt. The observed parabolic rate of attack is interpreted to be caused by a reaction controlled by diffusion in the salt that penetrates into the porous layer formed by the destabilization. The parabolic rate constant in mixed sodium metavanadate - sodium sulfate melts was found to be proportional to the SO3 partial pressure and the square of the metavanadate concentration. In-situ Raman spectroscopic measurements allowed simultaneous observations of the ceramic phases and salt chemistry during the attack process.

Nagelberg, A. S.↗
NASA NTRS1999

Pulse Phase Thermography for Defect Detection and Visualization

Pulse Phase Thermography (PPT) has been reported as a novel powerful technique of the thermal NDE. It employs application of the Discrete Fourier Transform (DFT) to thermal images obtained following flash heating of the front surface of a specimen. The computed phasegrams are excellent for defect visualization in a wide range of materials. This is in part due to their low sensitivity to uneven heating. This work is an attempt to analyze advantages and limitations of PPT. Results of application of the DFT to simulated temperature decays are presented. The temperature evolution on a surface has been simulated based on an analytical solution of the one-dimensional heat diffusion problem. A more sophisticated study has been done for different sizes of defects using numerical solution of the three-dimensional mathematical model. Capabilities of PPT for in-depth scanning and for monitoring of the material loss are discussed. The recommendations for the practical application of the PPT are presented. Experimental results obtained following these recommendations are reported.

Marinetti, Sergio↗
NASA NTRS2020

Shock Deformation in Zircon, a Comparison of Results from Shock-Reverberation and Single-Shock Experiments

The utility of the mineral zircon, ZrSiO4, as a shock-metamorphic geobarometer and geochronometer, has been steadily growing within the planetary science community. Zircon is an accessory phase found in many terrestrial rock types, lunar samples, lunar meteorites, martian meteorites and various other achondrites. Because zircon is refractory and has a high closure temperature for Pb diffusion, it has been used to determine the ages of some of the oldest material on Earth and elsewhere in the Solar System. Furthermore, major (O) and trace-element (REE, Ti, Hf) abundances and isotope compositions of zircon help characterize the petrogenetic environments and sources from which they crystallized. The response of zircon to impact-induced shock deformation is predominantly crystallographic, including dislocation creep and the formation of planar and sub-planar, low-angle grain boundaries; the formation of mechanical {112} twins; transformation to the high pressure polymorph reidite; the development of polycrystalline microtextures; and dissociation to the oxide constituents SiO2 and ZrO2. Shock microstructures can also variably affect the U- Pb isotope systematics of zircon and, in some instances, be used to constrain the impact age. While numerous studies have characterized shock deformation in zircon recovered from a variety of terrestrial impact craters and ejecta deposits and Apollo samples, experimental studies of shock deformation in zircon are limited to a handful of examples in the literature. In addition, the formation conditions (e.g., P, T) of various shock microstructures, such as planar-deformation bands, twins, and reidite lamellae, remain poorly con-strained. Furthermore, previous shocked-zircon experimental charges have not been analyzed using modern analytical equipment. This study will therefore under-take an new set of zircon shock experiments, which will then be microstructurally characterized using state-of-the-art instrumentation within the Astromaterials Research and Exploration Science Division (ARES), NASA Johnson Space Center.

Erickon, T. M.↗
NASA NTRS2006

Dynamic Theory of Relativistic Electrons Stochastic Heating by Whistler Mode Waves with Application to the Earth Magnetosphere

In the Hamiltonian approach an electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing a particle motion by group symmetries of the problem were transformed in to a closed pair of nonlinear difference equations. The solutions of these equations have shown there exists the energetic threshold below that the electron motion is regular, and when the initial energy is above the threshold an electron moves stochastically. It is proved that the upper boundary of particle stochastic heating is conditioned by intrinsic property of the particle chaotic motion. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV.

Khazanov, G. V.↗
DOE OSTI2025

Water Dynamics of Superacid Aromatic Proton Exchange Membranes for Fuel Cell Applications

Proton exchange membranes (PEMs) with high conductivity are of critical importance for the development of fuel cells, electrolyzers, and other electrochemical technologies. In this research, poly(1,1,2,2-tetrafluoro-2-phenoxyethane-1-sulfonic acid) (PTPS) with an aromatic polymer main chain and a perfluorinated superacidic polymer side chain was synthesized. The water dynamics of PTPS were characterized across various length scales using a combination of Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) and compared with Nafion, a standard perfluorinated PEM, and sulfonated poly(ether sulfone) (SPES 40), an aromatic PEM without perfluorinated superacid side chains. The T 1 and T 2 relaxation times of water in the samples probed by NMR increase from SPES 40 to PTPS to Nafion, indicating that the local motion of the water molecules becomes faster. This trend corresponds well with the relative fraction of bulk-like water determined using FTIR. At larger length scales, the diffusion coefficient of water was characterized using pulsed-field gradient NMR (PFG-NMR). At a longer diffusion time (Δ = 100 ms), PTPS has a smaller diffusion coefficient compared with both Nafion and SPES 40, due to restricted diffusion, and this effect is also evident in the proton conductivity of the hydrated membranes. From this comparison, it is apparent that the aromatic backbone and side chain type greatly influence the water dynamics in PEMs at various length scales and the water dynamics significantly impact the bulk proton conductivity. These insights will lead to new designs for aromatic PEMs and help to identify bottlenecks in current materials.

25 ENERGY STORAGE↗
DOE OSTI2026

Toward a microscopic picture of hadronization and multi-parton processes

This project advanced the understanding of how quarks and gluons produced in high-energy collisions transform into the hadrons observed in particle detectors, a fundamental process known as quantum chromodynamics (QCD) hadronization. By combining theoretical calculations, quantum simulation methods, and modern AI techniques, the research developed new tools to study multi-parton dynamics and nonperturbative effects that are essential for interpreting data from current and future nuclear physics experiments. Key outcomes include new theoretical frameworks for jet and hadron measurements, pioneering quantum simulation algorithms for real-time dynamics in field theories, and the development of advanced machine-learning models, such as diffusion models and explainable classifiers, to simulate and analyze collider events. These results are directly relevant to experiments at Jefferson Lab, Brookhaven National Laboratory, and the future Electron-Ion Collider, and they also have a broader impact in areas such as quantum information science and data-driven modeling of complex systems. The project supported the training of graduate students and postdoctoral fellows and contributed to the broader scientific community through publications, workshops, and collaborative activities. Overall, this work provides new insights into the microscopic mechanisms of hadron formation and establishes a foundation for future studies at the intersection of nuclear physics, artificial intelligence, and quantum computing.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗