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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

CENTAUR - The small- and wide-angle neutron scattering diffractometer/spectrometer for the Second Target Station of the Spallation Neutron Source

CENTAUR has been selected as one of the eight initial instruments to be built at the Second Target Station (STS) of the Spallation Neutron Source at Oak Ridge National Laboratory. It is a small-angle neutron scattering (SANS) and wide-angle neutron scattering (WANS) instrument with diffraction and spectroscopic capabilities. This instrument will maximally leverage the high brightness of the STS source, the state-of-the-art neutron optics, and a suite of detectors to deliver unprecedented capabilities that enable measurements over a wide range of length scales with excellent resolution, measurements on smaller samples, and time-resolved investigations of evolving structures. Notably, the simultaneous WANS and diffraction capability will be unique among neutron scattering instruments in the United States. This instrument will provide much needed capabilities for soft matter and polymer sciences, geology, biology, quantum condensed matter, and other materials sciences that need in situ and operando experiments for kinetic and/or out-of-equilibrium studies. Beam polarization and a high-resolution chopper will enable detailed structural and dynamical investigations of magnetic and quantum materials. CENTAUR’s excellent resolution makes it ideal for low-angle diffraction studies of highly ordered large-scale structures, such as skyrmions, shear-induced ordering in colloids, and biomembranes. Additionally, the spectroscopic mode of this instrument extends to lower momentum transfers than are currently possible with existing spectrometers, thereby providing a unique capability for inelastic SANS studies.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Optimization of neutron chopper and optics for CENTAUR, the SANS/WANS diffractometer at the spallation neutron source second target station

Herein this report presents the physics design and optimization of the neutron chopper and optics systems for the CENTAUR instrument, a multifunctional small-angle and wide-angle neutron scattering diffractometer for the Spallation Neutron Source Second Target Station. This instrument will offer a wide range of capabilities, including small-angle neutron scattering with wide Q coverage (e.g., 0.001–20 Å –1 ), providing a tool to investigate structures from atomic to mesoscopic scales simultaneously. To efficiently transport desired neutrons from the compact high-brightness cold source, several innovative designs are utilized: a time-zero chopper with a straight guide system for short-wavelength neutrons, octagonal guides for higher flux, and a correlation chopper to reduce inelastic scattering. The optimization process considers factors such as useable time-integrated flux, instrument resolution, brilliance transfer, divergence, and acceptance diagram uniformity. The overall design prioritizes flexibility to accommodate diverse user requirements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Conceptual Polarization Setup at CENTAUR, the SANS/WANS Instrument at the Second Target Station of SNS

CENTAUR is a multifunctional general purpose small-angle and wide-angle neutron scattering instrument with diffraction and spectroscopic capability in the future Second Target Station at the Spallation Neutron Source of the Oak Ridge National Laboratory. To fill a gap in neutron polarization capability, the instrument will be designed to provide polarization analysis. Here we present the conceptual polarization setup at CENTAUR, as well as the Spin Echo Modulated Small-Angle Neutron Scattering setup which will further expand the length scale covered by the instrument.

Qian, Shuo↗
DOE OSTI2024

Ectopic Production of 3,4-Dihydroxybenzoate in Planta Affects Cellulose Structure and Organization

Lignocellulosic biomass is a highly sustainable and largely carbon dioxide neutral feedstock for the production of biofuels and advanced biomaterials. Although thermochemical pretreatment is typically used to increase the efficiency of cell wall deconstruction, genetic engineering of the major plant cell wall polymers, especially lignin, has shown promise as an alternative approach to reduce biomass recalcitrance. Poplar trees with reduced lignin content and altered composition were previously developed by overexpressing bacterial 3-dehydroshikimate dehydratase (QsuB) enzyme to divert carbon flux from the shikimate pathway. In this work, three transgenic poplar lines with increasing QsuB expression levels and different lignin contents were studied using small-angle neutron scattering (SANS) and wide-angle X-ray scattering (WAXS). SANS showed that although the cellulose microfibril cross-sectional dimension remained unchanged, the ordered organization of the microfibrils progressively decreased with increased QsuB expression. This was correlated with decreasing total lignin content in the QsuB lines. WAXS showed that the crystallite dimensions of cellulose microfibrils transverse to the growth direction were not affected by the QsuB expression, but the crystallite dimensions parallel to the growth direction were decreased by ~20%. Cellulose crystallinity was also decreased with increased QsuB expression, which could be related to high levels of 3,4-dihydroxybenzoate, the product of QsuB expression, disrupting microfibril crystallization. In addition, the cellulose microfibril orientation angle showed a bimodal distribution at higher QsuB expression levels. Altogether, this study provides new structural insights into the impact of ectopic synthesis of small-molecule metabolites on cellulose organization and structure that can be used for future efforts aimed at reducing biomass recalcitrance.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

The evolution of coal porosity during pyrolysis

Gasification of coal, municipal waste, or other organic materials is a potential hydrogen source that entails complex thermal decomposition and transport processes. This study provides a multiscale analysis of these processes for sub-bituminous (Usibelli, Healy, Alaska) and lignite (Center, North Dakota) coals and provides data useful for process design. The chemistry, mineralogy, and pore structures of pyrolyzed coal and their evolution with thermal decomposition are discussed. Samples pyrolyzed at 200–1000 °C were analyzed by small-angle neutron scattering; ultra-small, small-, and wide-angle X-ray scattering; and other complementary techniques. Scanning electron microscopy showed new pores in the high-temperature-pyrolyzed material. Upon heating, the coals became progressively denser, and the concentration of hydrogen decreased. Changes in pore volume fell into three temperature ranges: an initial, low-temperature range that, for the Usibelli coal, involved an increase in overall porosity; a mid-temperature range associated with pore volume loss; and a high-temperature range associated with significant porosity increase and char formation. This transformation was paralleled by changes in fractal dimension and correlation length. The higher the pyrolysis temperature the greater the small-pore-volume fraction and overall surface area became. Pyrolysis increased the lateral size of coal crystallites, decreased the amorphous fraction, and increased the aromatics fraction and overall coal rank. Comparisons of neutron and X-ray scattering data and subsequent water uptake studies showed that pre-dried coals can re-hydrate relatively rapidly upon exposure to air, which can significantly affect the porosity calculated from small-angle-scattering data. Fits to the cumulative porosity curves provide a method for modeling the physical and chemical transformation of hydrogen-containing feedstock during gasification.

Anovitz, Lawrence {Larry} [ORNL] (ORCID:0000000226↗
DOE OSTI2023

Spatiotemporal Studies of Soluble Inorganic Nanostructures with X‐rays and Neutrons

Abstract This Review addresses the use of X‐ray and neutron scattering as well as X‐ray absorption to describe how inorganic nanostructured materials assemble, evolve, and function in solution. We first provide an overview of techniques and instrumentation (both large user facilities and benchtop). We review recent studies of soluble inorganic nanostructure assembly, covering the disciplines of materials synthesis, processes in nature, nuclear materials, and the widely applicable fundamental processes of hydrophobic interactions and ion pairing. Reviewed studies cover size regimes and length scales ranging from sub‐Ångström (coordination chemistry and ion pairing) to several nanometers (molecular clusters, i.e. polyoxometalates, polyoxocations, and metal‐organic polyhedra), to the mesoscale (supramolecular assembly processes). Reviewed studies predominantly exploit 1) SAXS/WAXS/SANS (small‐ and wide‐angle X‐ray or neutron scattering), 2) PDF (pair‐distribution function analysis of X‐ray total scattering), and 3) XANES and EXAFS (X‐ray absorption near‐edge structure and extended X‐ray absorption fine structure, respectively). While the scattering techniques provide structural information, X‐ray absorption yields the oxidation state in addition to the local coordination. Our goal for this Review is to provide information and inspiration for the inorganic/materials science communities that may benefit from elucidating the role of solution speciation in natural and synthetic processes.

Yin, Jia‐Fu↗
DOE OSTI2025

Observation of the spiral spin liquid in a triangular-lattice material

The spiral spin liquid (SSL) is a highly degenerate state characterized by a continuous contour or surface in reciprocal space spanned by a spiral propagation vector. Although the SSL state has been predicted in a number of various theoretical models, very few materials are so far experimentally identified to host such a state. Via combined single-crystal wide-angle and small-angle neutron scattering, we report observation of the SSL in the quasi-two-dimensional delafossite-like AgCrSe 2 . We show that it is a very close realization of the ideal Heisenberg J 1 –J 2 –J 3 frustrated model on the triangular lattice. By supplementing our experimental results with microscopic spin-dynamics simulations, we demonstrate how such exotic magnetic states are driven by thermal fluctuations and exchange frustration.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Spatiotemporal Studies of Soluble Inorganic Nanostructures with X‐rays and Neutrons

This Review addresses the use of X-ray and neutron scattering as well as X-ray absorption to describe how inorganic nanostructured materials assemble, evolve, and function in solution. We first provide an overview of techniques and instrumentation (both large user facilities and benchtop). We review recent studies of soluble inorganic nanostructure assembly, covering the disciplines of materials synthesis, processes in nature, nuclear materials, and the widely applicable fundamental processes of hydrophobic interactions and ion pairing. Reviewed studies cover size regimes and length scales ranging from sub-Ångström (coordination chemistry and ion pairing) to several nanometers (molecular clusters, i.e. polyoxometalates, polyoxocations, and metal-organic polyhedra), to the mesoscale (supramolecular assembly processes). Reviewed studies predominantly exploit 1) SAXS/WAXS/SANS (small- and wide-angle X-ray or neutron scattering), 2) PDF (pair-distribution function analysis of X-ray total scattering), and 3) XANES and EXAFS (X-ray absorption near-edge structure and extended X-ray absorption fine structure, respectively). While the scattering techniques provide structural information, X-ray absorption yields the oxidation state in addition to the local coordination. Our goal for this Review is to provide information and inspiration for the inorganic/materials science communities that may benefit from elucidating the role of solution speciation in natural and synthetic processes.

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

Linking Lattice Strain and Fractal Dimensions to Non‐monotonic Volume Changes in Irradiated Nuclear Graphite

Graphite's resilience to high temperatures and neutron damage makes it vital for nuclear reactors, yet irradiation alters its microstructure, degrading key properties. We used small- and wide-angle X-ray scattering to study neutron-irradiated fine-grain nuclear graphite (Grade G347A) across varied temperatures and fluences. Results show significant shifts in internal strain and porosity, correlating with radiation-induced volume changes. Notably, porosity volume distribution (fractal dimensions) follows non-monotonic volume changes, suggesting a link to the Weibull distribution of fracture stress.

X-ray scattering↗
DOE OSTI2025

Interpreting scattered neutron spectra on omega cryogenic implosions with measured backgrounds and higher-order scattering

Measurements of the areal density (⁠ρR⁠) of inertially confined implosions are critical to evaluate their performance. On OMEGA, ρR is inferred from measurements of the scattered neutron spectrum via neutron-time-of-flight (nTOF) and magnetic recoil spectrometer detectors. The nTOF measurements, in particular, have the ability to measure a wide range of neutron energies and thus scattering angles, with high precision. However, the neutrons that are backscattered into the detector must transit through the entire dense fuel assembly, and as a result are subject to rescattering effects, which have been heretofore neglected in the interpretation of OMEGA neutron spectra. At the backscatter edge, neglecting rescattering on OMEGA can lead to a ~10 to 20% reduction of the apparent areal density and therefore must be included in the analysis. The low ρR s on OMEGA also mean that backgrounds from non-target physics effects, such as scattering in the target chamber or slow scintillator decays, can significantly alter the measured signal. Here, we discuss how the Monte Carlo neutron spectrum postprocessor IRIS is used to include second-order scattering effects in the interpretation of the scattered neutron spectrum in OMEGA implosion experiments, and how dedicated implosion experiments are used to measure nTOF backgrounds in order to infer backscattered areal densities on OMEGA.

Deuterium↗
DOE OSTI2022

High pressure neutron diffraction on WAND 2 with a Paris-Edinburgh press

The Paris-Edinburgh press is a widely available, highly adaptable pressure cell commonly used while collecting neutron scattering data. Here, we detail the use of the VX3 and VX5 Paris-Edinburgh presses on the Wide-Angle Neutron Diffractometer (WAND 2 ) at the High Flux Isotope Reactor at Oak Ridge National Laboratory. We first give a detailed overview of the instrument setup and alignment capabilities used at WAND 2 . We then demonstrate the high pressure capabilities through three examples. In this work, the first example focuses on diffraction data obtained from a lithium-diamond mixture to 10 GPa with the use of single toroidal cubic boron nitride anvils. Other examples include the room temperature compressions of germanium (up to 16 GPa) and the mineral malachite with double toroidal sintered diamond anvils. This work thereby represents the first studies above 10 GPa at the High Flux Isotope Reactor and opens the door for future user experiments at these elevated pressures.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Design, calibration, and performance of a uniaxial pressure cell for neutron scattering studies of quantum magnetism

Here we provide an overview of a pressure cell designed to apply uniaxial pressure to single crystals for the study, by neutron scattering techniques, of strongly correlated magnetic systems and, in particular, quantum magnets. A detailed overview of the pressure cell components, their requirements, and links to the scientific and technical specifications are presented. The pressure cell is able to accommodate a 200 mm 3 single crystal that can be pressurized up to 2 GPa at cryogenic temperatures. The pressure cell is consistent with the requirements of inelastic neutron scattering and, importantly, neutron polarization analysis. A particular strength of the uniaxial pressure cell is the highly uniform and low background for a wide scattering angle of 360° horizontally and ±20° vertically. We show the performance of the uniaxial pressure cell using a relevant neutron scattering instrument, the polarized diffuse scattering instrument, D7. The experiments confirm that the cell complies with the scientific and technical requirements. This uniaxial pressure cell will provide a useful additional tool in the sample environment suite available for the study of quantum magnetism.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Q-dependent collective relaxation dynamics of glass-forming liquid Ca0.4K0.6(NO3)1.4 investigated by wide-angle neutron spin-echo

Abstract The relaxation behavior of glass formers exhibits spatial heterogeneity and dramatically changes upon cooling towards the glass transition. However, the underlying mechanisms of the dynamics at different microscopic length scales are not fully understood. Employing the recently developed wide-angle neutron spin-echo spectroscopy technique, we measured the Q -dependent coherent intermediate scattering function of a prototypical ionic glass former Ca 0.4 K 0.6 (NO 3 ) 1.4 , in the highly viscous liquid state. In contrast to the structure modulated dynamics for Q < 2.4 Å −1 , i.e., at and below the structure factor main peak, for Q > 2.4 Å −1 , beyond the first minimum above the structure factor main peak, the stretching exponent exhibits no temperature dependence and concomitantly the relaxation time shows smaller deviations from Arrhenius behavior. This finding indicates a change in the dominant relaxation mechanisms around a characteristic length of 2π/(2.4 Å −1 ) ≈ 2.6 Å, below which the relaxation process exhibits a temperature independent distribution and more Arrhenius-like behavior.

42 ENGINEERING↗
DOE OSTI2022

Broadband Wide-Angle VElocity Selector (BWAVES) neutron spectrometer designed for the SNS Second Target Station

A recently proposed wide-angle velocity selector (WAVES) device for choosing the velocity of detected neutrons after they have been scattered by the sample paves the way for inverted geometry neutron spectrometers with continuously adjustable final neutron wavelength. BWAVES broadband inverted geometry spectrometer proposed for the Second Target Station at the Spallation Neutron Source at Oak Ridge National Laboratory is designed using WAVES to simultaneously probe dynamic processes spanning 4.5 decades in time (energy transfer). This makes BWAVES a uniquely flexible instrument which can be viewed as either a quasielasitc neutron scattering (QENS) spectrometer with a practically unlimited (overlapping with the vibrational excitations) range of energy transfers, or a broadband inelastic vibrational neutron spectrometer with QENS capabilities, including a range of accessible momentum transfer (Q) and a sufficiently high energy resolution at the elastic line. The new capabilities offered by BWAVES will expand the application of neutron scattering in ways not possible with existing neutron spectrometers.

36 MATERIALS SCIENCE↗
DOE OSTI2024

GENESIS: Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering

Improved neutron inelastic scattering cross section data are needed to inform integral benchmark studies and advance applications in a wide variety of areas including nuclear energy, stockpile stewardship, nonproliferation, and space exploration. Neutron inelastic scattering also serves as a non-selective probe of low-lying nuclear structure. To help meet these needs, the Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering (GENESIS) was constructed at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. This array couples high-resolution γ-ray detectors and fast neutron detectors to achieve single and coincident n/γ detection over a broad energy range. The current configuration of the array includes 26 organic liquid scintillators and four high-purity germanium detectors (two single-crystal and two four-crystal CLOVER detectors with two-fold segmentation). The array was constructed with minimal supporting material and designed to cover a wide range of secondary particle angles and energies with limited inter-element scattering. Data acquisition is accomplished using Mesytec MDPP-16 multi-channel high-resolution digital pulse processing modules. The array characteristics, including γ-ray and neutron energy resolution, timing resolution, and detection efficiency were measured and used to validate a Geant4 model of the array. Furthermore, the primary sources of neutron background and the uncertainties in the determination of incident and secondary neutron energy were assessed. GENESIS provides a new capability to address nuclear data needs and facilitates the advancement of a wide range of nuclear applications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Revealing the Correlation between the Solvation Structures and the Transport Properties of Water-in-Salt Electrolytes

Water-in-salt (WIS) electrolytes containing 21 m lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) have been considered as a safe and environment-friendly alternative to common organic electrolytes used in lithium-ion batteries. However, the relation between the solvation structures and transport properties of these materials remains elusive. Here, for this paper, we performed small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), and X-ray pair distribution function (PDF) measurements of LiTFSI aqueous solutions at a wide range of concentrations. Combined with molecular dynamics simulations, the detailed solvation structures from long to short length scale were resolved. We found that the TFSI– solvation structures consist of TFSI– solvated structures and TFSI– networks; the former corresponds to solvent separated ion pairs, while the latter corresponds to contact ion pairs and cation–anion aggregates. In addition, we found that the relaxation time in the q range associated with the anion network structure exhibits the same concentration dependence as the viscosity. By combining the results from the experiments and simulations, this study revealed a correlation between the solvation structures of LiTFSI and the transport properties of the solutions, which is critical to understand the relation between the transport properties and the dynamics of the ions for imide-based lithium-ion salt aqueous electrolytes.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Unveiling mesoscopic structures in distorted lamellar phases through deep learning-based small angle neutron scattering analysis

Hypothesis: The formation of distorted lamellar phases, distinguished by their arrangement of crumpled, stacked layers, is frequently accompanied by the disruption of long-range order, leading to the formation of interconnected network structures commonly observed in the sponge phase. Nevertheless, traditional scattering functions grounded in deterministic modeling fall short of fully representing these intricate structural characteristics. Our hypothesis posits that a deep learning method, in conjunction with the generalized leveled wave approach used for describing structural features of distorted lamellar phases, can quantitatively unveil the inherent spatial correlations within these phases. Experiments and Simulations: This report outlines a novel strategy that integrates convolutional neural networks and variational autoencoders, supported by stochastically generated density fluctuations, into a regression analysis framework for extracting structural features of distorted lamellar phases from small angle neutron scattering data. To evaluate the efficacy of our proposed approach, we conducted computational accuracy assessments and applied it to the analysis of experimentally measured small angle neutron scattering spectra of AOT surfactant solutions, a frequently studied lamellar system. Findings: The findings unambiguously demonstrate that deep learning provides a dependable and quantitative approach for investigating the morphology of wide variations of distorted lamellar phases. It is adaptable for deciphering structures from the lamellar to sponge phase including intermediate structures exhibiting fused topological features. In conclusion, this research highlights the effectiveness of deep learning methods in tackling complex issues in the field of soft matter structural analysis and beyond.

36 MATERIALS SCIENCE↗