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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

In situ molecular imaging of ion clusters reveals the acid gas capture capacity and mechanism of water-lean ionic liquids

Water-lean solvents are a promising technology for capturing acid gases like carbon dioxide (CO 2 ). In situ liquid time-of-flight secondary ionization mass spectroscopy (ToF-SIMS) is used to study a representative solvent N-(2-ethoxyethyl)-3-morpholinopropan-1-amine (2-EEMPA) with different CO 2 loadings to reveal the complex solvent structure upon CO 2 capture. Characteristic peaks of 2-EEMPA, such as m/z – 215 C 11 H 23 N 2 O 2 – (deprotonated 2-EEMPA) and m/z + 217 C 11 H 25 N 2 O 2 + (protonated 2-EEMPA), are detected due to acid gas uptake. Also, solvent molecules and carboxylate ion pairs, such as m/z – 259 C 12 H 23 N 2 O 4 – [(deprotonated 2-EEMPA∙∙∙CO 2 )] and m/z + 261 C 12 H 25 N 2 O 4 + (protonated 2-EEMPA∙∙∙CO 2 ), are observed. Interestingly, more than one CO 2 molecule can be captured per each solvent molecule as evidenced in SIMS mass spectra, for example, m/z – 321 C 13 H 25 N 2 O 7 – [(deprotonated 2-EEMPA)∙∙∙2CO 2 ∙∙∙H 2 O], m/z + 305 C 13 H 25 N 2 O 4 + [(protonated 2-EEMPA)∙∙∙2CO 2 ], m/z – 389 C 17 H 29 N 2 O 8 – [(deprotonated 2-EEMPA)∙∙∙3CO 2 ∙∙∙3CH 2 ], and m/z + 373 C 16 H 25 N 2 O 8 + [(protonated 2-EEMPA)∙∙∙3CO 2 ∙∙∙2C]. However, the monomer of 2-EEMPA and CO 2 seems to be most prevalent. Furthermore, solvent clusters are detected in loaded solvents, for instance m/z + 433 C 22 H 49 N 4 O 4 + [(2-EEMPA)2∙∙∙H] and m/z + 646 [(2-EEMPA) 3 -2H], while capturing CO 2 at different amounts. Relative abundance of cluster ions provides a semi-qualitative venue to assess the free energies of gas capture energetics, indicating the relative stability trend within the same solvent system, previously impossible. These observed ion clusters are verified with molecular modeling, where dimer, trimer, and cluster ions are validated for their presence either due to weak molecular interactions or hydrogen bonds. In situ molecular imaging of ionic liquids and molecular modeling reveals that the acid gas capture mechanism by ionic liquids includes both physical adsorption and chemical bonding with multiple reaction pathways, engaging cluster formation and alteration of solvent structures.

Acid gas capture↗
DOE OSTI2019

Surface evolution of synthetic bilgewater emulsion

Bilgewater is oil-in-water emulsion emitted from shipboard and it is a source of pollution to the ocean. Wastewater treatment needs fundamental knowledge of the bilgewater surface changes; however, limited information is available. We have reported the first surface characterization of synthetic bilgewater emulsion using time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with optical microscopy. A NAVY synthetic bilgewater emulsion consisting of three oils and a detergent mixture is used as the synthetic bilgewater model. Both fresh and aged emulsion samples are analyzed to determine their droplet size distributions (DSDs) and surface chemical compositions. Our results show that fresh emulsions are largely mono-modal with hydrocarbon fragments as the main surface composition. Aged emulsions are also monomodal with slightly larger size. Both SIMS spectral comparison and Principal Component Analysis (PCA) show that some surfactant components appear on the fresh emulsion surface immediately while larger molecular weight components appear at the aged bilge droplet surface. Our results indicate that the oil-water interface evolves after emulsion droplet forms. More importantly, surface evolution not only changes the bilgewater DSD but also surface chemical composition and reactivity.

bilgewater, droplet size distribution, ToF-SIMS, s↗
DOE OSTI2021

Photooxidative decomposition and defluorination of perfluorooctanoic acid (PFOA) using an innovative technology of UV–vis/Zn x Cu 1-x Fe 2 O 4 /oxalic acid

Per- and polyfluoroalkyl substances (PFAS) are a large group of perfluorinated organic molecules that have been in use since the 1940s for industrial, commercial, and consumer applications. PFAS are a growing concern because some of them have shown persistent, bioaccumulative and toxic effects. In this work, we demonstrate an innovative technology of UV–vis/Zn x Cu 1-x Fe 2 O 4 /oxalic acid for the degradation of perfluorooctanoic acid (PFOA) in water. The magnetically retrievable nanocrystalline heterogeneous ferrite catalysts, Zn x Cu 1-x Fe 2 O 4 were synthesized using a sol-gel auto-combustion process followed by calcination at 400 °C. The combination of Zn x Cu 1-x Fe 2 O 4 and oxalic acid generate reactive species under UV light irradiation. These reactive species are then shown to be capable of the photodegradation of PFOA. The degree of degradation is tracked by identifying transformation products using liquid chromatography coupled with quadrupole time-of-flight mass spectroscopy (LC-QTOF-MS).

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

Use of Fisher's Ratio assisted multivariate curve resolution- alternating least squares for discovery-based analysis using ultrahigh pressure liquid chromatography-high resolution mass spectrometry

Non-targeted analysis of complex chemical mixtures can be difficult considering the convoluted nature of the matrix and the potential unknown chemical differences between samples or classes of samples. Ultrahigh pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF) is an ideal technique to probe chemical differences for a wide variety of samples. While UHPLC-QTOF can discover minute chemical differences down to low part per billion (ppb) concentrations with a high degree of confidence, the application of high-resolution mass spectrometry can yield massive amounts of information (∼ 10 gb per sample) that cannot be analyzed manually. Therefore, the application of chemometric techniques is mandatory for the interrogation of complex samples. Fisher's ratio (FR) assisted multivariate curve resolution-alternating least squares (MCR-ALS) was used to the discover and identify the chemical differences between two classes of materials: 1) a pond water matrix and 2) the matrix spiked with a pharmaceutical standard mix containing 17 compounds. Thirteen of the seventeen spiked compounds were discovered using FR analysis, and then five were successfully deconvoluted using MCR-ALS wherein the number of curves chosen were automatically determined using singular value decomposition (SVD). In conclusion, the use of an automated FR assisted MCR-ALS will aid in discovering trace levels of chemical components without the need for the researcher to provide potentially biased input which will aid in non-targeted workflow.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Optimization of battery swapping infrastructure for e-commerce drone delivery

Drone delivery is widely-researched to alter the current e-commerce delivery convention for providing short delivery lead times. Yet, flight range of drones, constrained by the available battery technology, sets a milestone toward realizing the sole-drone delivery. To tackle with the flight range limitation, locating automated battery swapping machines (ABSM) have been proposed and a few studies modeled the problem. Using the ABSMs, drones can be loaded with fully-charged batteries along the route to a demand location. Here, we introduce a mixed-integer nonlinear program to model the problem. The objective of the program is to optimally select ABSM locations, determine the delivery-mode choices (drone-only, truck-only, and mixed delivery) of demand locations, find drone delivery routes, and approximate the baseline requirements for the number of drones and batteries needed. The program minimizes the overall delivery system costs including: ABSM, delivery, drone ownership, battery inventory, and service congestion. A cutting-plane method is developed to find exact solutions in finite iterations. Computational experiments showed that the method quickly yields the optimal solution to instances with less than 60 ABSM candidates and 20 demand locations. A case study shows that the optimal drone delivery infrastructure can save almost 20% cost compared to the conventional truck-only delivery. Sensitivity analyses were conducted to reveal the impact of key parameters in the decision-making and found that a decrease in the ABSM and drone costs highly affect the system cost.

25 ENERGY STORAGE↗
DOE OSTI2023

Microstructure and corrosion of CrFeMnV multi-principal element alloy

In this study, a multi-principal element alloy consisting of equiatomic concentrations of Cr, Fe, Mn, and V was produced by arc melting. The combination of X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy indicated that the CrFeMnV MPEA was comprised of a BCC matrix with a dispersion of a secondary phase. Cyclic potentiodynamic polarization tests in 0.6M NaCl revealed high corrosion resistance – superior to that of stainless steel 304L, as evident from high breakdown and repassivation potentials. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry provided insight into the formed multi-layer surface film after constant immersion and potentiostatic conditioning.

36 MATERIALS SCIENCE↗
DOE OSTI2022

In situ characterization of phase transformations in petroleum pitch by high temperature X-ray diffraction

The phase transformation from isotropic to mesophase of a petroleum-derived pitch was monitored by in situ X-ray diffraction at 410 °C. The kinetics of the transformation were characterized by monitoring the growth of a broad peak at 2θ~24° and could be described by Avrami’s equation. The volatilization of low molecular weight components originally present in the pitch, or produced during the condensation reaction, was assessed by thermal gravimetry analysis, following the same thermal history. Ex situ characterizations of the pitch precursor before and after thermal treatment provided insight into the evolution of the molecular structure associated with mesophase generation (optical polarized microscopy, molecular weight distribution by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, X-ray photoelectron spectroscopy, Auger spectroscopy, and thermal stability). Here, this investigation demonstrates the value of using complementary in situ and ex situ experimental techniques to characterize complex mechanisms during the processing of organic materials.

02 PETROLEUM↗
DOE OSTI2026

Comparative Dissolution of Iron-Bearing Minerals by Catecholate and Hydroxamate Siderophores under Oxic and Anoxic Conditions

Siderophores play a crucial role in biological iron (Fe) acquisition and mobilization by promoting Fe mineral and rock weathering. While the effects of the hydroxamate siderophore desferrioxamine B (DFOB) have been extensively studied, the role of catecholates in the dissolution of Fe mineral and rock under varying redox conditions remain limited. Moreover, despite Fe being one of the most redox-active metals, the siderophore-mediated redox transformations of solid-phase Fe and their impact on mineral dissolution are not well understood. Herein, this study systematically investigated dissolution behavior of both Fe(II) and Fe(III)-bearing minerals and rocks (Fe(II)- bearing basalt and olivine, and Fe(III)- bearing nontronite and goethite), by two structurally distinct biological siderophores, catecholate protochelin and hydroxamate DFOB, under both oxic and anoxic conditions. Batch experiments quantified Fe and transition metals (Mn, Ni, Zn, Mo) released from the tested minerals in the presence of siderophores. Throughout the dissolution experiments, siderophore concentrations and Fe-siderophore complexation in solutions were measured using UV-vis spectrometry. Fe redox changes under oxic and anoxic conditions by siderophores were determined, and mineral surface alterations following siderophore treatments were characterized through scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Results revealed distinct interplays of dissolution mechanisms, including ligand-exchange promoted dissolution and reductive dissolution, along with Fe(III) reduction and Fe(II) oxidation, contributing to the Fe(II)- and Fe(III)-rich mineral weathering under varying redox conditions. Under oxic conditions, both protochelin and DFOB enhanced Fe release from Fe(II)-rich basalt and olivine more effectively than from Fe(III)-rich minerals. DFOB induced greater Fe(II)-mineral dissolution than protochelin. This difference was attributed to a higher level of Fe(II) oxidation by DFOB in contrast to protochelin, as well as the protochelin oxidation with the loss of Fe binding groups (catechols). Under anoxic conditions, both siderophores significantly reduced Fe(III) in nontronite and goethite, with protochelin demonstrating substantially stronger Fe(III) reduction capacity than DFOB. However, Fe(III) reduction negatively impacted Fe release from Fe(III)-rich minerals. Instead, Fe release from Fe(II)-rich minerals was enhanced under anoxic conditions due to the absence of Fe(II) oxidation and labile Fe(II). Variations in siderophore adsorption also contributed to dissolution differences. Beyond iron, the release of transition metals from tested minerals was influenced by elemental contents, mineral compositions, and siderophore types, revealing distinct metal- and siderophore-dependent patterns. This systematic investigation highlights the roles of siderophores in Fe redox cycling and metal mobilization, enhancing our understanding of different siderophore behaviors in siderophore-mediated microbial metal acquisition within redox-dynamic environments, with implications for bioleaching industries and applications in agriculture and climate change mitigation.

Guo, Dongyi↗
DOE OSTI2020

H-Mat Hydrogen Compatibility of Polymers and Elastomers

The H2@Scale program of the U.S. Department of Energy (DOE) Fuel Cell Technologies Office is supporting work on the hydrogen compatibility of polymers to improve the durability and reliability of materials for hydrogen infrastructure. The hydrogen compatibility program (H-Mat) seeks “to address the challenges of hydrogen degradation by elucidating the mechanisms of hydrogen-materials interactions with the goal of providing science-based strategies to design materials, (micro)structures, and morphology with improved resistance to hydrogen degradation.” This research has observed interactions of hydrogen and pressure with model rubber-material compounds resulting in volume change and compression-set differences in the materials. The materials were investigated using helium-ion microscopy (HeIM), which revealed significant morphological changes in the plasticizer-incorporating compounds after exposure, as evidenced by time-of-flight secondary ion mass spectrometry. Additional studies using transmission electron microscopy and nuclear magnetic resonance were performed to correlate morphological change to potential chemical change in the materials.

08 HYDROGEN↗
DOE OSTI2022

Vertical gradient freeze growth of detector grade CdZnTeSe single crystals

Here, we report the growth of detector grade Cd 0.9 Zn 0.1 Te 0.97 Se 0.03 (CZTS) single crystals, a recently discovered quaternary semiconductor for room temperature radiation detection, by a vertical gradient freeze (VGF) method. VGF is a comparatively low-temperature growth method and avoids relative motion between the heater and the ampoule containing the precursor materials which minimizes any thermal drift or temperature fluctuations. As a result, CZTS single crystals with superior charge transport properties has been obtained. Growth of detector-grade CZTS single crystals using VGF method has not been reported yet. X-ray spectroscopy based elemental analysis showed that the grown crystals demonstrated the desired stoichiometry required for high resolution radiation detection. Planar detectors fabricated by deposition of gold contacts (~0.07 cm 2 ) demonstrated high bulk resistivity ~10 10 Ω-cm and a very low leakage current density of 2.8 × 10 –8 A/cm 2 at a bias of 100 V when measured at room temperature. The detectors showed excellent radiation response with 100 % charge collection efficiency when exposed to 5486 keV alpha particles. The electron mobility-lifetime (μτ) product was measured to be 3 × 10 –3 cm 2 /V using a single polarity Hecht analysis which is at par with the recently reported values measured in CZTS grown using conventional Bridgman or travelling heater method. The electron mobility has been calculated to be 964 cm 2 V –1 s –1 using a time-of-flight (TOF) method, a substantial improvement over that obtained from conventionally grown CZTS single crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Evidence of lithium mobility under neutron irradiation

Understanding the evolution of intermetallic materials in high-radiation environments is of great importance for fusion science and national security. Tritium ( 3 H) and lithium ( 6 Li, 7 Li) transport within neutron irradiated claddings coated with aluminide (FeAl3) has been investigated using state-of-the-art multimodal imaging. Specifically, scanning electron microscopy – focused ion beam (SEM-FIB) was used to prepare irradiated coating lift-out samples for follow-on microanalysis. Here, scanning transmission electron microscopy (STEM) was used to acquire atomic-scale information on the carbonaceous structure and elemental mapping. Atomic force microscopy (AFM) was used to determine lift-out dimensions nondestructively. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectral and depth profiling show unexpected lithium isotopic distributions in the irradiated cladding, raising an important evidence of possible light isotope mobility within the cladding under elevated temperature and irradiation. ToF-SIMS three-dimensional chemical mappings of mid- and bottom-cladding coatings show light isotopic (e.g., 3 H, 6 Li, 7 Li) distributions in the irradiated coating and give new insights into the fundamental mechanism related to transport mechanisms within the cladding. Multimodal imaging is power to link microstructure, chemistry, and nanoscale defects that impact reliability of these materials. Furthermore, chemical mapping offers observations of the microstructural evolution due to irradiation and provides insights into unexpected material transport under extreme conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Neutron diffraction discriminates between models for the nanoarchitecture of graphene sheets in glassy carbon

Glassy carbon is a chemically inert, biocompatible, disordered material with the graphene sheet as its basic building block. Structural characterisation techniques have so far been unable to provide definitive distinction between the many proposed models for its structure. Computer based simulation methods have made a step forward by predicting structure from interaction potentials, but the results are sensitive to the choice of the potential. Here we use the white neutron beam of the Spallation Neutron Source at Oak Ridge National Laboratory coupled with the SNAP time-of-flight diffractometer to sample the reciprocal space of glassy carbon and calculate accurate radial distribution functions. From the radial distribution information, we determine graphene sheet dimensions, registration, curvature, and assess defect content to rank the proposed structures in terms of their agreement with experimental data. In this work, we find that the recent models derived from empirical potentials give the best agreement.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A quantitative study of retention and release of deuterium and tritium during irradiation of y-LiAlO2 pellets

This study reports on the quantification of deuterium in ion-irradiated gamma-LiAlO2 pellets as a function of dose and temperature. The gamma-LiAlO2 pellets were sequentially irradiated with He+ and D2+ ions to the same fluences of 5E16, 1E17 and 2E17 He++D+/cm2 at 188 K. Additional irradiation was performed to 1E17, 2E17 and 4E17 He++D+/cm2 at 573 K. A set of the pellets irradiated at 188 K was shipped and stored at low temperatures from 80 to 132 K and characterized using time-of-flight secondary ion mass spectrometry at ~173 K. The deuterium depth profiles show a Gaussian-like distribution in the low-temperature pellets. The total deuterium retention is found to be directly proportional to the ion fluence. About 27 at.% of the implanted deuterium atoms were released from the pellet irradiated to 2E17 He++D+/cm2 at 188 K during storage at room temperature for ~1 month. Retention of the trapped or bound deuterium during ion irradiation at 573 K increases initially with ion fluence and tends to saturate at a high fluence. The amount of the released deuterium is observed to be quantitatively consistent with that of the released tritium from similar standard pellets during neutron irradiation at 573 K.

Deuterium retention and release, ion irradiation, ↗
DOE OSTI2022

Phase evolution of U-Zr system in a thermal cycling neutron diffraction experiment: as-cast U-35Zr and U-50Zr

Here, phase evolution of as-cast U-35 wt% Zr and U-50 wt% Zr alloys during thermal cycling (303–1073 K) was investigated using in-situ neutron diffraction. Analysis was performed using Rietveld crystal and microstructure refinements from time-of-flight neutron diffraction data, with a focus on evolution of lattice parameter, atom ordering, unit cell volume, and weight fractions during the thermal cycling. Disordered δ-UZr 2 and residual γ-(U,Zr) phase are retained in the field of δ of the U-Zr equilibrium phase diagram for the U-50Zr sample, and in the field between δ and α-U for the U-35Zr sample. The α phase that is present in the reported phase diagrams of U-Zr was not observed in the diffraction patterns. The evolutions of lattice parameter and unit cell volume of δ and γ are affected by both thermal expansion and chemistry.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Phase transformations and thermal expansion coefficients of unirradiated U-X wt.% Zr (X = 6, 10, 20, 30) measured via neutron diffraction

This work characterizes the crystallographic evolution of unirradiated U-X wt.% Zr (X = 6, 10, 20, 30) while cooling from equilibration, single phase γ-U-Zr, at 900 °C to ambient temperature using time-of-flight neutron diffraction. The β-U phase was unobserved during cooling at 1 °C/min in all alloys. All alloys followed the phase transformation pathway of γ-U-Zr→γ-U-Zr+α-U→α-U +δ-UZr2 with an observed miscibility gap in γ-U-Zr. The α-U and δ-UZr2 transformation took place simultaneously in the U-30 wt.% Zr sample. These findings strengthen the need to re-approach the U-Zr phase diagram in entirety. Bulk volumetric CTEs agree well with published data, strengthening the quantification of lattice-specific CTEs reported in this study. A compositionally dependent discontinuity in thermal expansion, increasing in magnitude with decreasing U content, occurs during the γ-U-Zr→α-U+δ-UZr2 transformation. The γ-U-Zr lattice parameter was measured to have a compositional dependency.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Microstructural features and deuterium diffusion in lithium penta-aluminate pellets under He + and D + ion irradiation

Lithium (Li) penta-aluminate (LiAl 5 O 8 ) is investigated as a potential tritium (T) breeding material, with a focus on microstructural response to ion irradiation and deuterium (D) diffusion behavior. Under high-fluence ion irradiation (2 x 10 17 (He + +D + )/cm 2 ) at 773 K, LiAl 5 O 8 exhibits significant disorder on the Li sublattice, as revealed by atomic-resolution scanning transmission electron microscopy, while the Al and O sublattices remain stable, demonstrating strong resistance to structural amorphization. Irradiation induces the formation of platelet-shaped antiphase boundaries (APBs), which may serve as effective D trapping sites. Atom probe tomography suggests the presence of 6 LiD clusters in the mass spectra, though definite conclusions regarding APB composition are hindered by signal overlap and limited data statistics. Time-of-flight secondary ion mass spectrometry reveals that D retention approaches to saturation at 3 x 10 17 (He + +D + )/cm 2 . Isothermal and isochronal annealing studies determine an average diffusivity of 1.6 x 10 -13 at 773 K and an effective activation energy of 0.8 ± 0.1 eV for D migration. Compared to γ-LiAlO 2 , LiAl 5 O 8 demonstrates superior irradiation resistance, minimal Li loss, and enhanced D retention, underscoring its potential as a durable breeder material for T production. In conclusion, these findings provide key insights into the microstructural evolution, defect dynamics, and D retention mechanisms in LiAl 5 O 8 under reactor-relevant conditions.

42 ENGINEERING↗
DOE OSTI2026

FIB-ToF-SIMS characterization of irradiated U-10Zr

Post-irradiation examination (PIE) is critical for the performance assessment and qualification of nuclear fuels. Secondary ion mass spectrometry (SIMS) is a powerful materials characterization technique that allows for elemental and isotopic mapping with a depth resolution greater than EDS and EPMA. However, it has not yet been applied to PIE of metallic nuclear fuel. Here, in this work, we characterize an fast neutron spectrum irradiated U-10Zr fuel sample using a time-of-flight SIMS (ToF-SIMS) system connected to a FIB/SEM system, which allows for flexible sample analysis compared to a dedicated ToF-SIMS instrument. Analysis of the resulting hyperspectral micrograph data was aided by the development of an unsupervised machine learning (ML) algorithm that iterates on existing methods to segment the 3D micrographic datasets based on the similarity of mass spectra. The results showed that the FIB-ToF-SIMS instrument was potentially capable of spatially resolving closed fission gas bubbles in 3D by continued ion sputtering of the analyzed volume. Additionally, the ML algorithm proved useful in revealing the chemical segregation of light fission products (those with an atomic mass between approximately 85–105 amu, such as ruthenium and rhodium) plus matrix zirconium, heavy fission products (those with an atomic mass between approximately 135–150 amu, such as the lanthanides) and uranium. Future studies are planned to conduct FIB-ToF-SIMS analysis on more irradiated U-Zr samples to study the constituent redistribution.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗