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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Electrolyte compositions comprising ionic liquids and metal hydride batteries comprising same

Electrolyte compositions comprising a) an ionic liquid and b) a protic acid and/or an organic solvent are suitable for use in electrochemical cells, e.g. metal hydride batteries. The electrolyte compositions may replace the currently employed 30% by weight aqueous KOH. Suitable protic acids include carboxylic acids, mineral acids, sulfonic acids and the like. Suitable organic solvents include organic carbonates, ethers, glymes, ortho esters, polyalkylene glycols, esters, lactones, glycols, formates, sulfones, sulfoxides, amides, alcohols, ketones, nitro solvents, nitrile solvents and combinations thereof. Present batteries may achieve a nominal open-circuit voltage of >1.2 V (volts) and up to about 6 V. The electrolyte compositions allow enlargement of the electrochemical window, thus allowing the use of further cathode active materials. Further cathode active materials include transition metals and their oxides, hydroxides and fluorides; for example, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, Ta, W, Re, Os, Ir, Pt and Au and their oxides, hydroxides, oxide/hydroxides and fluorides.

25 ENERGY STORAGE↗
DOE OSTI2023

Intercalation And High-Pressure Effects On Structural Phase Transitions In Layered As x P 1-x Alloys

This project was aimed at understanding the role of composition, intercalation, and high pressure on the structural evolution of black phosphorous (BP) and layered arsenic phosphorous alloys, As y P 1-y . Under normal conditions, BP is the most stable phase of phosphorous, known as the α-phase, characterized by an orthorhombic honeycomb puckered crystal structure with the Cmca space group. On the other hand, the most stable phase of arsenic is its β-phase, known as gray arsenic (g-As), which has a rhombohedral buckled layered crystal structure with the R3m space group. In a wide range of compositions (y < 0.83), the arsenic phosphorous alloys form the α-phase, known as black arsenic phosphorous (b-As y P 1-y ) with a similar structure to BP. The project was aimed at the synthesis of BP and b-As y P 1-y with different compositions and at studying the structural evolution of these materials during intercalation with alkali metal (especially Li), and under high-pressure conditions. The main goals were to gain a better understanding of these processes and structural changes taking place under these conditions. In particular, the project was aimed at addressing whether such conditions could induce a structural transition between the α- and β-phases. For this, a series of systematic in-situ studies were conducted, including electrochemical lithium intercalation in an in-situ electrochemical cell, and high-pressure experiments in a diamond anvil cell (DAC). Overall, both types of experiments have shown that above a certain composition-dependent threshold level of intercalation or high pressure, the system undergoes phase segregation rather than phase transition. Specifically, the segregation of the excess arsenic was observed, and a single-phase system of b-As y P 1-y transformed into a two-phase system consisting of b-As y P 1-y and g-As, through the following process: 1∗(b-As y P 1-y ) → 1∗(b As y-δ P 1-y ) + δ∗(g-As). Also, the study showed that intercalation and high-pressure are two competing rather than synergistic processes causing at least a partial cancelation of these two factors

36 MATERIALS SCIENCE↗
DOE OSTI2022

Synthesis of bioproducts from lignin-derived aromatics by genetically modified microorganisms

The present invention provides for a method of converting a depolymerized lignin aromatic compound into a bioproduct, comprising: (a) providing a composition comprising a depolymerized lignin aromatic compound, optionally a depolymerized cellulose, and optionally a depolymerized hemicellulose, and (b) introducing a genetically modified microorganism to the composition, wherein the genetically modified microorganism is capable of converting the depolymerized lignin aromatic compound into a bioproduct; such that the depolymerized lignin aromatic compound is converted into a bioproduct.

Gladden, John M.↗
DOE OSTI2022

Lithium and boron isotopic compositions of olivine in chondrules from carbonaceous and ordinary chondrite meteorites: Implications for the origin of solar 11 B/ 10 B ratio

We report the origin of solar 11 B/ 10 B ratio ~4 remains an open question. It has been thought that a significant portion of boron in the Solar System was derived from continuous spallation nucleosynthesis during interactions between Galactic Cosmic Rays and C—N—O nuclei in the interstellar medium. However, because GCR-produced boron is characterized by 11 B/ 10 B ~2.5, an endmember with 11 B/ 10 B > 4 is required to account for the solar 11 B/ 10 B ratio. Two leading hypotheses for the sources of 11 B-rich components include low energy spallation in the Sun’s parental molecular cloud and the neutrino process during the supernova explosions. In this study, lithium and boron elemental and isotopic compositions of seven porphyritic olivine chondrules and one isolated olivine crystal from four meteorites (Allende, Yamato 81020, Asuka 12236, and QUE 97008) were determined in-situ to help constrain which of the two nucleosynthetic mechanisms has most likely supplied the forming Solar System with extra 11 B. Apparent isotopic variations in Li/Si, B/Si, δ 7 Li and δ 11 B were found in chondrule olivine crystals, but only three chondrules exhibit statistically resolved δ 11 B heterogeneities. Using these three chondrules as a basis for discussion, we evaluated the processes that could potentially cause elemental and isotopic variations of Li and B. We argue that the data can be best understood in the context of condensation of lithium-boron-rich material onto chondrule precursors in (an) initially heterogeneous gaseous reservoir(s), which could be realized if the Solar System derived 11 B-rich components from a supernova or supernovae.

58 GEOSCIENCES↗
DOE OSTI2026

Structural characterization of neutron irradiated hexagonal boron-10 nitride-15 single crystals

The negatively charged boron vacancy ($V$$^{–}_{⁠B}$⁠) in hexagonal boron nitride (hBN) is a promising quantum defect that can be used to sense pressure, temperature, and magnetic field with high spatial resolution. hBN enriched with the boron-10 and nitrogen-15 isotopes, denoted h 10 B 15 N, has good contrast and coherence for quantum sensing because nitrogen-15 has nuclear spin (1/2), reducing hyperfine interactions. Boron vacancies can be generated by neutron irradiation, which causes the transmutation of the boron-10 isotope to lithium-7. In this study, the ancillary structural, compositional, and mechanical properties of h 10 B 15 N crystals that have been subjected to neutron irradiation fluences from 1.4 × 10 16 to 8.4 × 10 17 n/cm 2 were thoroughly characterized. Besides creating $V$$^{–}_{⁠B}$⁠, the process also induces other defects that generate strain in the crystal lattice. In turn, the mechanical properties of these crystals change drastically. Investigated here are the visual changes, lattice integrity, composition, crystal strain, and elastic constants (C 33 and C 66 ) to assess how these characteristics change as a function of neutron fluence.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The hard x-ray nanotomography microscope at the advanced light source

Beamline 11.3.1 at the Advanced Light Source is a tender/hard (6–17 keV) x-ray bend magnet beamline recently re-purposed with a new full-field, nanoscale transmission x-ray microscope. The microscope is designed to image composite and porous materials possessing a submicrometer structure and compositional heterogeneity that determine materials’ performance and geologic behavior. The theoretical and achieved resolutions are 55 and <100 nm, respectively. The microscope is used in tandem with a <25 nm eccentricity rotation stage for high-resolution volume imaging using nanoscale computed tomography. The system also features a novel bipolar illumination condenser for the illumination of an ~100 μm spot of interest on the sample, followed by a phase-type zone plate magnifying objective of ~52 µm field of view and a phase detection ring. The zone plate serves as the system objective and magnifies the sample with projection onto an indirect x-ray detection system, consisting of a polished single crystal CsI(Tl) scintillator and a range of high-quality Plan Fluorite visible light objectives. The objectives project the final visible light image onto a water-cooled CMOS 2048 × 2048-pixel 2 detector. Here, in this paper, we will discuss the salient features of this instrument and describe early results from imaging the internal three-dimensional microstructure and nanostructure of target materials, including fiber-reinforced composites and geomaterials.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827

HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the planets’ ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multiyear high-cadence observing campaign with Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder Spectrograph, we improved the planets’ mass measurements in anticipation of Hubble Space Telescope transmission spectroscopy. For GJ 9827, we modeled activity-induced radial velocity signals with a Gaussian process informed by the Calcium II H&K lines in order to more accurately model the effect of stellar noise on our data. We measured planet masses of M {sub b} = 4.87 ± 0.37 M {sub ⊕}, M {sub c} = 1.92 ± 0.49 M {sub ⊕}, and M {sub d} = 3.42 ± 0.62 M {sub ⊕}. For HD 106315, we found that such activity radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well (T {sub eff} > 6200 K). We measured planet masses of M {sub b} = 10.5 ± 3.1 M {sub ⊕} and M {sub c} = 12.0 ± 3.8 M {sub ⊕}. We investigated all of the planets’ compositions through comparison of their masses and radii to a range of interior models. GJ 9827 b and GJ 9827 c are both consistent with a 50/50 rock-iron composition, GJ 9827 d and HD 106315 b both require additional volatiles and are consistent with moderate amounts of water or hydrogen/helium, and HD 106315 c is consistent with a ∼10% hydrogen/helium envelope surrounding an Earth-like rock and iron core.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

High hardness and oxidation-resistant Cr-containing medium entropy ZrTaW diboride

This study reports the successful synthesis of a Cr-containing (Zr 0.30 Ta 0.34 Cr 0.06 W 0.30 )B 2 medium-entropy boride (MEB) via an in-situ reactive borothermal reduction route from oxide precursors. High-energy ball milling was employed to homogenize the precursor mixture prior to reactive densification. X-ray diffraction confirmed the formation of a predominantly AlB₂-type hexagonal diboride structure together with a secondary (W X , M 1-X )B monoboride phase. Microstructural characterization revealed compositional heterogeneity and localized W-rich regions associated with the secondary phase. The synthesized medium-entropy boride exhibited enhanced mechanical properties, which are attributed to lattice distortion and solid-solution strengthening effects. Thermogravimetric analysis revealed complex multistage oxidation behavior, and the oxidation resistance was compared with conventional ultra-high-temperature diborides. The results demonstrate the strong relationship between oxide-derived processing, compositional complexity, phase evolution, and oxidation behavior, highlighting the potential of medium-entropy borides for high-temperature structural applications

36 MATERIALS SCIENCE↗
DOE OSTI2025

Shock compression of additively manufactured high solids loaded polymer composites with aligned porosity

The effects of aligned porosity on the shock-compression response of additively manufactured (AM) composite structures with collinear and log-cabin geometries are investigated. The composites contain two inorganic and two organic particle populations and a UV-curable polymer binder. X-ray phase contrast imaging (X-PCI) is used as an in-material diagnostic in plate-impact experiments performed at the Dynamic Compression Sector of the Advanced Photon Source at the Argonne National Laboratory. Macroscale shock and particle velocities and microscale pore collapse velocities are measured from X-PCI images obtained from samples impacted in various orientations relative to the AM build directions. The linear shock and particle velocity relation for the structures with collinear build geometry shows directional differences, with the build direction exhibiting the highest slope and the filament print direction having the shallowest slope. Composites with log-cabin geometry, due to their slightly lower porosity and smaller sized pores, show higher shock velocities than the collinear structures at the same particle velocity. Microscale directionality effects are also observed, with the pore collapse velocity dependent on the pore configuration. Specifically, the pore collapse velocity is highest for pores elongated along the impact direction which is the case for the colinear structures impacted in the filament print direction, which is consistent with the directionality trend observed in the data for the shock and particle velocity equation of state. The pore collapse velocity approaches ∼80 % of the shock velocity and is several times the average bulk particle velocity, suggesting a highly hydrodynamic mechanism of pore collapse. Overall, both the macroscale response as measured by the shock and particle velocity relationship, and the microscale response as measured by the pore collapse velocity, are found to be anisotropic and dependent on the AM composite structure.

Wagner, K. B. [Georgia Institute of Technology, At↗
DOE OSTI2024

Strain-Induced Shifts in Defective Graphite Phonon Modes Predicted by Density Functional Theory

Carbon fiber composites have gained attention as a structural material because of their high strength-to-weight ratio, and understanding the effect of defects on reactivity and mechanical properties is important for the longevity and safety of the composite. Although it is known that strain causes the underlying graphitic vibrational modes to redshift, it is not clear how strain may alter reactivity and defect-induced vibrational changes. To investigate the strain-induced phonon changes of defective carbon fiber composites, density functional theory calculations of graphite are used, including intercalated hydrogen and fluorine defects. By comparing changes in the bond lengths, formation energies, and phonon density of states for uniaxially and biaxially strained graphite, strain was found to generally make defect formation more favorable and the specific behavior changes are dependent on the strain direction and defect identity. Specifically, intercalated fluorine phonons are more sensitive to strain than hydrogen intercalation phonons, and strain applied along the zigzag direction alters the calculated properties more than strain along the armchair direction. Finally, these results highlight the importance of understanding the microstructural effect of deviations from the ideal material because small changes in strain or defect type can significantly alter the behavior of the carbon fiber composite core.

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

Fluoropolymer Composites from Partially Perfluoroalkylated Waste Polyethylene

Chemically modified plastics have emerged as practical solutions to plastic waste increases. Here, the inherent novelty of decorating polymer chains with chemical functionality results in distinct properties that expand the available application space. Nevertheless, developing designer materials for specific applications beyond compatibilization or mild property enhancement is difficult due to the synergistic effects of both the polar functionality imparted and the parent materials' intrinsic properties. By incorporating perfluoro-alkyl side-chains onto the backbone of dehydrogenated waste HDPE, unique surface properties intermediate between polytetrafluoroethylene (PTFE, the model fluoropolymer) and HDPE become apparent, while the overall material mechanical and thermal properties result in more LLDPE-like materials. This is demonstrated through moderate decreases in the surface free energy of the perfluoroalkylated polyolefin surface (increase in H 2 O contact angle of ~ 6°) and increased ordering under shear when blended with PTFE nanoparticles where the crossover point occurred at higher strains. Critically, perfluoroalkylated HDPE possesses improved rheological modification properties at elevated temperatures with PTFE nanoparticles, resulting in more thermally robust and stable composite materials.

fluoropolymer↗
DOE OSTI2020

Easy-Processable and Aging-Free All-Polymer Polysiloxane Composites

In this work, we report all-polymer polysiloxane composites that overcome the long-standing processing problems of silica-reinforced silicone rubbers. Polystyrene fillers are dispersed with styrene/dimethylsiloxane symmetric diblock and triblock copolymers that control the filler morphology, filler–matrix interactions, and filler–filler interactions. Surprisingly, the composites not only rival the traditional silica-reinforced polysiloxane in mechanical properties of cured materials but also have better processability and stability than the silica-filled compound before curing. Large amplitude oscillatory shear experiments demonstrate that the triblock copolymer addition strongly affects the rheological properties. We hypothesize that the bridges and entangled loops that were formed by the triblock copolymer can connect different PS domains to provide additional reinforcement. The aging effect that originates from PDMS chain adsorption on the filler particle surface is also avoided because of the thermodynamic repulsion between PS and PDMS phases.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Exploring Microphase Separation in Semi-Fluorinated Diblock Copolymers: A Combined Experimental and Modeling Investigation

We report the combined experimental and theoretical study of the bulk self-assembly behavior of polystyrene-blockpoly( 2,3,4,5,6-pentafluorostyrene) diblock copolymers. These block copolymers were designed to create highly antagonistic blocks (with a high Flory−Huggins interaction parameter, χ) with minimum disruption to the molecular construct (i.e., only replacing five hydrogen atoms with five fluorine atoms). A large library of diblock copolymers (41 samples) was synthesized by reversible addition− fragmentation chain transfer (RAFT) polymerization to map out a major portion of the phase space. All block copolymers exhibited narrow molecular weight distributions with dispersity (D) values between 1.07 and 1.32, and subsequent thermal annealing revealed phase separation into well-defined nanoscale morphologies depending on their molecular composition, as determined from small-angle X-ray scattering and transmission electron microscopy analyses, with an experimental phase diagram being constructed. The χ value at 25 °C for this block copolymer was estimated to be 0.2 using strong segregation theory, based on trends in phase-separated domain spacing and interfacial width. When applying theoretical approaches, the majority of the domain spacing data trends were captured by a coil−coil diblock copolymer model; however, a better fit to the data for samples with shorter fluorinated blocks was obtained with a rod−coil model, indicating that the chains in these fluorinated blocks likely have a higher inherent stiffness and were thus rod-like. This observation demonstrates that, due to the very high value of χ, a transition from coil−coil to rod−coil behavior can be obtained purely by reducing the length of the stiffer of the two blocks and without varying temperature or the chemical composition of the polymers. Here, this work showcases the presence of strong microphase separation within AB diblock copolymers despite the relatively similar chemical composition of the constituent “A” and “B” units, with a clear transition from rod−coil to coil−coil segregation behavior.

RAFT polymerization↗
DOE OSTI2023

Optical constants of polycrystalline Al 0.25 Ga 0.75 P and Al 0.9 Ga 0.1 As determined by variable-angle spectroscopic ellipsometry

The optical constants of single-crystal Al x Ga 1-x P and Al x Ga 1-x As have been widely studied at various Al compositions but have not yet been thoroughly investigated as polycrystalline materials. Using variable-angle spectroscopic ellipsometry, we estimate and analyze the optical constants of polycrystalline Al 0.25 Ga 0.75 P and Al 0.9 Ga 0.1 As that were non-epitaxially deposited at deposition temperatures of either 250 or 420 °C, and with various dopant species, dopant concentrations, and V/III flux ratios. Here, for wavelengths of 350–400 nm, decreasing the V/III ratio increases the refractive index of Be-doped polycrystalline Al 0.25 Ga 0.75 P. For wavelengths >500 nm, as the targeted Be dopant concentration increases for polycrystalline Al 0.25 Ga 0.75 P, the amount the extinction coefficient increases and the indirect bandgap decreases depends on the V/III ratio. Furthermore, Si-doped polycrystalline Al 0.25 Ga 0.75 P has significantly smaller extinction coefficient values than when it is Be-doped, for the same V/III ratio and targeted doping concentration, at wavelengths >500 nm. Based on our findings, we hypothesize that the dopant species, dopant concentration, and the V/III ratio dictate various types of defect concentrations, which then affect the optical constants and indirect bandgap of polycrystalline Al 0.25 Ga 0.75 P. Additionally, for wavelengths >500 nm, we find that polycrystalline Al 0.25 Ga 0.75 P and Al 0.9 Ga 0.1 As have the lowest extinction coefficient values when deposited at 420 °C, as opposed to 250 °C. Thus, we hypothesize that the deposition temperature is the most significant factor in dictating the optical constants of these polycrystalline III-Vs. Ultimately, this work demonstrates alternative methods to tune the optical constants of polycrystalline Al 0.25 Ga 0.75 P and Al 0.9 Ga 0.1 As, as opposed to tuning the Al composition.

42 ENGINEERING↗
DOE OSTI2024

Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime

Electron transport in complex fluids, biology, and soft matter is a valuable characteristic in processes ranging from redox reactions to electrochemical energy storage. These processes often employ conductor–insulator composites in which electron transport properties are fundamentally linked to the microstructure and dynamics of the conductive phase. While microstructure and dynamics are well recognized as key determinants of the electrical properties, a unified description of their effect has yet to be determined, especially under flowing conditions. In this work, the conductivity and shear viscosity are measured for conductive colloidal suspensions to build a unified description by exploiting both recent quantification of the effect of flow-induced dynamics on electron transport and well-established relationships between electrical properties, microstructure, and flow. These model suspensions consist of conductive carbon black (CB) particles dispersed in fluids of varying viscosities and dielectric constants. In a stable, well-characterized shear rate regime where all suspensions undergo self-similar agglomerate breakup, competing relationships between conductivity and shear rate were observed. To account for the role of variable agglomerate size, equivalent microstructural states were identified using a dimensionless fluid Mason number, Mn f , which allowed for isolation of the role of dynamics on the flow-induced electron transport rate. At equivalent microstructural states, shear-enhanced particle–particle collisions are found to dominate the electron transport rate. This work rationalizes seemingly contradictory experimental observations in literature concerning the shear-dependent electrical properties of CB suspensions and can be extended to other flowing composite systems.

Science & Technology - Other Topics↗
DOE OSTI2022

A Computational Framework to Accelerate the Discovery of Perovskites for Solar Thermochemical Hydrogen Production: Identification of Gd Perovskite Oxide Redox Mediators

A high-throughput computational framework to identify novel multinary perovskite redox mediators is presented, and this framework is applied to discover the Gd-containing perovskite oxide compositions Gd 2 BB'O 6 , GdA'B 2 O 6 , and GdA'BB'O 6 that split water. The computational scheme uses a sequence of empirical approaches to evaluate the stabilities, electronic properties, and oxygen vacancy thermodynamics of these materials, including contributions to the enthalpies and entropies of reduction, ΔH TR and ΔS TR . This scheme uses the machine-learned descriptor τ to identify compositions that are likely stable as perovskites, the bond valence method to estimate the magnitude and phase of BO 6 octahedral tilting and provide accurate initial estimates of perovskite geometries, and density functional theory including magnetic- and defect-sampling to predict STCH-relevant properties. Eighty-three promising STCH candidate perovskite oxides down-selected from 4392 Gd-containing compositions are reported, three of which are referred to experimental collaborators for characterization and exhibit STCH activity. Our results demonstrate that the high-throughput computational scheme described herein—which is used to evaluate Gd-containing compositions but can be applied to any multinary perovskite oxide compositional space(s) of interest—accelerates the discovery of novel STCH active redox mediators with reasonable computational expense.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Deep underground measurement of B 11 ( α , n ) N 14

The primordial elemental abundance composition of the first stars leads to questions about their modes of energy production and nucleosynthesis. The formation of 12 C has been thought to occur primarily through the 3α process, however, alternative reaction chains may contribute significantly, such as 7 Li (α, γ) 11 B (α,n) 14 N. This reaction sequence cannot only bypass the mass A = 8 stability gap, but could also be a source of neutrons in the first star environment. However, the efficiency of this reaction chain depends on the possible enhancement of its low energy cross section by α-cluster resonances near the reaction threshold. A new study of the reaction 11 B(α,n) 14 N has been undertaken at the CASPAR underground facility at beam energies from 300–700 keV. A 4π neutron detector in combination with pulse shape discrimination at low background conditions resulted in the ability to probe energies lower than previously measured. Further, resonance strengths were determined for both the resonance at a laboratory energy of 411 keV, which was measured for the second time, and for a new resonance at 337 keV that has been measured for the first time. This resonance, found to be significantly weaker than previous estimates, dominates the reaction rate at lower temperatures (T < 0.2 KG) and reduces the reaction rate in first star environments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗