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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

X-ray and neutron diffraction study of the defect crystal structure of the as-grown nonstoichiometric phase Y{sub 0.715}Ca{sub 0.285}F{sub 2.715}

This work begins a series of papers aimed at studying the defect structure of nonstoichiometric phases R{sub 1-y}Ca{sub y}F{sub 3-y} with a tysonite-type (LaF{sub 3}) structure. In the single-crystal structure of Y{sub 0.715}Ca{sub 0.285}F{sub 2.715} with a tysonite-type small unit cell (sp. gr. P6{sub 3}/mmc, a = 3.9095(2) A, c = 6.9829(2) A; Z = 2; R{sub w} = 2.16%), the displacements of Y{sup 3+} cations and F{sup 2-} anions from 6{sub 3} symmetry axes were observed for the first time. The X-ray diffraction pattern shows weak satellites insufficient for structural calculations. The LaF{sub 3} structure type is stabilized up and down on the temperature scale due to anion vacancies and the symmetrizing effect of Ca{sup 2+} cations lying on 6{sub 3} symmetry axes. At 120 Degree-Sign C the fluoride-ion conductivity in the nonstoichiometric phase Y{sub 0.715}Ca{sub 0.285}F{sub 2.715} is five orders of magnitude higher than that in the stoichiometric phase {beta}-YF{sub 3}. The transition to a superionic state is caused by a deviation from stoichiometry and is not associated with reconstructive phase transformation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

On the ability of resonant diffraction gratings to differentiate a pulsed optical signal

The passage of an optical pulse through a resonant grating is considered. The conditions under which the resonant grating differentiates the envelope of the incident pulse are determined. It is shown that the necessary condition for computing the k-order derivative is the presence of k resonances in the transmission spectrum of the grating in the vicinity of the central frequency of the incident pulse. A method is described for constructing the stacked structure for computing the kth derivative on the basis of repetition of the structure for computing the first derivative. The results of numerical simulation of diffraction of the pulse from the analyzed structure for computing the first, second, and third derivative are presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Study of Kinetics of Solid Phase Transition in Tetracosane С{sub 24}Н{sub 50} by High-Resolution Synchrotron X-Ray Powder Diffraction

Using the small-angle synchrotron X-ray diffraction method at the research facility “BELOK” of the Kurchatov synchrotron radiation source at the NRC Kurchatov Institute, it was shown that the first-order solid phase transition in tetracosane C{sub 24}H{sub 50} passes according to a heterogeneous mechanism in a narrow temperature range ΔT ~ 1 K in accordance with the theory of diffuse phase transitions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Measurement of Residual Stresses by X-ray Diffraction Near Simulated Heat Affected Zones in Austenitic Stainless Steels

Simulated heat-affected zones (HAZs) were made in austenitic stainless steel specimens using a Gleeble. The samples were heated to temperatures as high as 1100°C by computer controlled resistance heating. By controlling the heating rate, maximum temperature, and cooling rate, a wide range of residual stresses were introduced in the specimens. Stress measurements were made using X-ray diffraction. It was found that significant stress gradients were produced in the simulated HAZs, and that all stresses were compressive in nature, both in the longitudinal and transverse directions. These results are not representative of the residual stresses determined in the HAZs of real welds, thus calling into question some aspects of the role of the Gleeble in such simulations.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Spectroscopic and X-ray Diffraction Study of Structural Disorder in Cryomilled and Amorphous Griseofulvin

Structural disorder induced by cryogenic milling and by heating to the amorphous phase in the active pharmaceutical ingredient Griseofulvin has been studied using Raman spectroscopy, X-ray powder diffraction (XRPD), and fluorescence spectroscopy. A broad, exciting-frequency-independent scattering background in the Raman spectra and changes in intensities and splitting of some of the Raman lines due to lattice and molecular modes have been observed. In the cryomilled samples this strong background is deconvoluted into two components: one due to lattice disorder induced by cryomilling and the other due to Mie scattering from nanosized crystallites. A single-component background scattering attributed to lattice disorder is seen in the Raman spectrum of the amorphous sample. Fluorescence measurements showed an intrinsic fluorescence signal in as-received Griseofulvin that does not correspond to the inelastic background in the Raman spectra and, moreover, decreases in intensity upon cryomilling, thus excluding an assignment of the Raman background intensity to impurity- or molecular-defect-induced fluorescence. Wide-angle XRPD measurements on cryomilled Griseofulvin shows a broad two-component background consistent with the background-scattering component in the Raman data associated with lattice disorder, but at longer correlation lengths. Persistence of this disorder to even longer lengths is evident in small-angle synchrotron XRPD data on micronized Griseofulvin taken as a function of temperature from the crystalline to the amorphous phase.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

Utah FORGE: Powder X-ray Diffraction Data from Well 16A(78)-32 Core

This dataset from Lawrence Livermore National Laboratory (LLNL) consists of four raw X-ray diffraction (XRD) scans and preliminary results of quantitative XRD analysis. The scanned samples were prepared from four subcores, which came from various depths of the FORGE well 16A(78)-32 core. Desired core lengths were selected from available core photos (on GDR), provided by FORGE personnel, and subcored at LLNL. The XRD scans were collected in May 2023 at LLNL as pre-experimental characterization data for these subcores, which will be used in core-flooding experiments at LLNL and in triaxial direct shear experiments at Los Alamos National Laboratory as part of DOE Project 5-2428. XRD scans are in RAW file format (e.g., FORGE-5477-full.raw) and are suitable for viewing and analysis using open-source quantitative XRD software (e.g., Profex; www.profex-xrd.org ) and/or other proprietary instrument software.

15 GEOTHERMAL ENERGY↗
DOE OSTI2021

Ultrafast X-ray Diffraction Study of a Shock-Compressed Iron Meteorite above 100 GPa

Natural kamacite samples (Fe92.5Ni7.5) from a fragment of the Gibeon meteorite were studied as a proxy material for terrestrial cores to examine phase transition kinetics under shock compression for a range of different pressures up to 140 GPa. In situ time-resolved X-ray diffraction (XRD) data were collected of a body-centered cubic (bcc) kamacite section that transforms to the high-pressure hexagonal close-packed (hcp) phase with sub-nanosecond temporal resolution. The coarse-grained crystal of kamacite rapidly transformed to highly oriented crystallites of the hcp phase at maximum compression. The hcp phase persisted for as long as 9.5 ns following shock release. Comparing the c/a ratio with previous static and dynamic work on Fe and Fe-rich Fe-Ni alloys, it was found that some shots exhibit a larger than ideal c/a ratio, up to nearly 1.65. This work represents the first time-resolved laser shock compression structural study of a natural iron meteorite, relevant for understanding the dynamic material properties of metallic planetary bodies during impact events and Earth’s core elasticity.

36 MATERIALS SCIENCE↗
DOE OSTI2011

The Crystal Structures of two Anhydrous Magnesium Hydroxychloride Phases from in situ Synchrotron Powder Diffraction Data

The crystal structures of two members of the solid solution series Mg(OH){sub x}Cl{sub y}x+y = 2, Mg(OH){sub 1.7}Cl{sub 0.3} (P{sup {bar 3}}m1, a = 3.169(2) {angstrom}, c = 5.530(12), V = 48.1(1) {angstrom}{sup 3} at T = 365 C) and MgOHCl (R{sup {bar 3}}m, a = 3.3877(4) {angstrom}, c = 17.534(4) {angstrom}, V = 174.27(6) {angstrom}{sup 3} at T = 625 C) were determined from in situ synchrotron powder diffraction data at high temperature upon dehydration of 3Mg(OH){sub 2} {center_dot} MgCl{sub 2} {center_dot} 8H{sub 2}O (F3) and 5Mg(OH){sub 2} {center_dot} MgCl{sub 2} {center_dot} 8H{sub 2}O (F5) phases. The crystal structures of Mg(OH){sub 1.7}Cl{sub 0.3} (example of ss-type-OH) and MgOHCl (example of ss-type-Cl) can be related to the C19 (CdCl{sub 2}) and C6 (CdI{sub 2}) structure type, respectively, with the disordered chloride and hydroxide anions occupying the same crystallographic site in layers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Mineralogy, provenance, and diagenesis of a potassic basaltic sandstone on Mars: CheMin X-ray diffraction of the Windjana sample (Kimberley area, Gale Crater)

The Windjana drill sample, a sandstone of the Dillinger member (Kimberley formation, Gale Crater, Mars), was analyzed by CheMin X-ray diffraction (XRD) in the MSL Curiosity rover. From Rietveld refinements of its XRD pattern, Windjana contains the following: sanidine (21% weight, ~Or 95 ); augite (20%); magnetite (12%); pigeonite; olivine; plagioclase; amorphous and smectitic material (~25%); and percent levels of others including ilmenite, fluorapatite, and bassanite. From mass balance on the Alpha Proton X-ray Spectrometer (APXS) chemical analysis, the amorphous material is Fe rich with nearly no other cations—like ferrihydrite. The Windjana sample shows little alteration and was likely cemented by its magnetite and ferrihydrite. From ChemCam Laser-Induced Breakdown Spectrometer (LIBS) chemical analyses, Windjana is representative of the Dillinger and Mount Remarkable members of the Kimberley formation. LIBS data suggest that the Kimberley sediments include at least three chemical components. The most K-rich targets have 5.6% K 2 O, ~1.8 times that of Windjana, implying a sediment component with >40% sanidine, e.g., a trachyte. A second component is rich in mafic minerals, with little feldspar (like a shergottite). A third component is richer in plagioclase and in Na 2 O, and is likely to be basaltic. The K-rich sediment component is consistent with APXS and ChemCam observations of K-rich rocks elsewhere in Gale Crater. The source of this sediment component was likely volcanic. Finally, the presence of sediment from many igneous sources, in concert with Curiosity's identifications of other igneous materials (e.g., mugearite), implies that the northern rim of Gale Crater exposes a diverse igneous complex, at least as diverse as that found in similar-age terranes on Earth.

58 GEOSCIENCES↗
DOE OSTI2022

Nanoscale Antiferromagnetic Domain Imaging using Full-Field Resonant X-ray Magnetic Diffraction Microscopy

The physical properties of magnetic materials frequently depend not only on the microscopic spin and electronic structures, but also on the structures of mesoscopic length scales that emerge, for instance, from domain formations, or chemical and/or electronic phase separations. However, experimental access to such mesoscopic structures is currently limited, especially for antiferromagnets with net zero magnetization. Here, full-field microscopy and resonant magnetic X-ray diffraction are combined to visualize antiferromagnetic (AF) domains of the spin–orbit Mott insulator Sr 2 IrO 4 with area over ≈0.1 mm 2 and with spatial resolution as high as ≈150 nm. With the unprecedented wide field of views and high spatial resolution, an intertwining of two AF domains on a length comparable to the measured average AF domain wall width of 545 nm is revealed. This mesoscopic structure comprises a substantial portion of the sample surface, and thus can result in a macroscopic response unexpected from its microscopic magnetic structure. In particular, the symmetry analysis presented in this work shows that the inversion symmetry, which is preserved by the microscopic AF order, becomes ill-defined at the mesoscopic length scale. We report this result underscores the importance of this novel technique for a thorough understanding of the physical properties of antiferromagnets.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Structural Evolution and Transition Dynamics in Lithium Ion Battery under Fast Charging: An Operando Neutron Diffraction Investigation

Abstract Fast charging (<15 min) of lithium‐ion batteries (LIBs) for electrical vehicles (EVs) is widely seen as the key factor that will greatly stimulate the EV markets, and its realization is mainly hindered by the sluggish diffusion of Li + . To have a mechanistic understanding of Li + diffusion within LIBs, in this study, structural evolutions of electrodes for a Ni‐rich LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) || graphite cylindrical cell with high areal loading (2.78 mAh cm −2 ) are developed for operando neutron powder diffraction study at different charging rates. Via sequential Rietveld refinements, changes in structures of NMC622 and Li x C 6 are obtained during moderate and fast charging (from 0.27 C to 4.4 C). NMC622 exhibits the same structural evolution regardless of C‐rates. For phase transitions of Li x C 6 , the stage I (LiC 6 ) phase emerges earlier during the stepwise intercalation at a lower state of charge when charging rate is increased. It is also found that the stage II (LiC 12 ) → stage I (LiC 6 ) transition is the rate‐limiting step during fast charging. The LiC 12 → LiC 6 transition mechanism is further analyzed using the Johnson–Mehl–Avrami–Kolmogorov model. It is concluded as a diffusion‐controlled, 1D phase transition with decreasing nucleation kinetics under increasing chargingrates.

25 ENERGY STORAGE↗
DOE OSTI2021

Visualizing Intrinsic 3D-Strain Distribution in Gold Coated ZnO Microstructures by Bragg Coherent X-Ray Diffraction Imaging and Transmission Electron Microscopy with Respect to Piezotronic Applications

Novel devices ranging from bio magnetic field sensors to energy harvesting nano machines utilize the piezotronic effect. For optimal function, understanding the interaction of electrical and strain phenomena within the semiconductor crystal is necessary. Here, studies of a model piezotronic system are presented, consisting of a ZnO microrod coated by a thin layer of gold, which forms a Schottky contact with the piezoelectric ZnO material. Coherent X-ray diffraction imaging (CXDI) and transmission electron microscopy (TEM) are used to visualize the structure and strain distribution, showing that the ZnO microrod exhibits strains of multiple origins in the bulk and at the interface. Strain values of -6 × 10 -4 have been measured by CXDI at the ZnO/Au interface. The origin is shown to be a combination of an interface strain, possibly caused by the Schottky contact formation, and distinct, localized electrical fields inside the crystal which are assigned to electron depletion and screening in a bent ZnO/Au piezotronic rod. These findings will contribute to sensor development and to a better understanding of piezotronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Disorder Dynamics in Battery Nanoparticles During Phase Transitions Revealed by Operando Single-Particle Diffraction

Structural and ion-ordering phase transitions limit the viability of sodium-ion intercalation materials in grid scale battery storage by reducing their lifetime. However, the combination of phenomena in nanoparticulate electrodes creates complex behavior that is difficult to investigate, especially on the single-nanoparticle scale under operating conditions. In this work, operando single-particle X-ray diffraction (oSP-XRD) is used to observe single-particle rotation, interlayer spacing, and layer misorientation in a functional sodium-ion battery. oSP-XRD is applied to Na 2/3 [Ni 1/3 Mn 2/3 ]O 2 , an archetypal P2-type sodium-ion-positive electrode material with the notorious P2-O2 phase transition induced by sodium (de)intercalation. Here, it is found that during sodium extraction, the misorientation of crystalline layers inside individual particles increases before the layers suddenly align just prior to the P2-O2 transition. The increase in the long-range order coincides with an additional voltage plateau signifying a phase transition prior to the P2-O2 transition. To explain the layer alignment, a model for the phase evolution is proposed that includes a transition from localized to correlated Jahn-Teller distortions. The model is anticipated to guide further characterization and engineering of sodium-ion intercalation materials with P2-O2 type transitions. oSP-XRD, therefore, opens a powerful avenue for revealing complex phase behavior in heterogeneous nanoparticulate systems.

25 ENERGY STORAGE↗
DOE OSTI2025

In Situ Diffraction and Ex Situ Transmission X‐Ray Microscopy Studies of Solid‐State Upcycling for NMC Cathodes

Upcycling of recycled LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) cathodes offers an economical route to produce cathode materials with increased energy density (i.e., LiNi 0.8 Mn 0.1 Co 0.1 O 2 , NMC811) that meet the performance needs of present-day electric vehicles. In this work, solid-state upcycling of NMC622 via calcination with Ni(OH) 2 and LiOH was monitored using in situ synchrotron powder X-ray diffraction measurements. Sequential Rietveld refinements indicate that the calcination proceeds by initially converting Ni(OH) 2 to a rocksalt NiO phase followed by lithiation of NiO to form LiNiO 2 (LNO), with both NMC and LNO phases present in nearly equal proportions at the calcination endpoint. Variable-energy transmission X-ray microscopy tomograms of upcycled samples reveal that the NMC and LNO domains are intermixed at sub-micron length scales. Depth-dependent analysis of multi-elemental fitting maps matches the expected NMC811 composition at the secondary particle level and indicates that transition metal diffusion is not limited by the secondary particle size.

cathode upcycling↗
DOE OSTI2024

Accurate and Data‐Efficient Micro X‐ray Diffraction Phase Identification Using Multitask Learning: Application to Hydrothermal Fluids

Traditional analysis of highly distorted micro X‐ray diffraction (μ‐XRD) patterns from hydrothermal fluid environments is a time‐consuming process, often requiring substantial data preprocessing and labeled experimental data. Herein, the potential of deep learning with a multitask learning (MTL) architecture to overcome these limitations is demonstrated. MTL models are trained to identify phase information in μ‐XRD patterns, minimizing the need for labeled experimental data and masking preprocessing steps. Notably, MTL models show superior accuracy compared to binary classification convolutional neural networks. Additionally, introducing a tailored cross‐entropy loss function improves MTL model performance. Most significantly, MTL models tuned to analyze raw and unmasked XRD patterns achieve close performance to models analyzing preprocessed data, with minimal accuracy differences. This work indicates that advanced deep learning architectures like MTL can automate arduous data handling tasks, streamline the analysis of distorted XRD patterns, and reduce the reliance on labor‐intensive experimental datasets.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

[Cu 32 (H) 20 {S 2 P(O i Pr) 2 } 12 ]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction

An air- and moisture-stable nanoscale polyhydrido copper cluster [Cu 32 (H) 20 {S 2 P(O i Pr) 2 } 12 ] (1 H ) was synthesized and structurally characterized. The molecular structure of 1 H exhibits a hexacapped pseudo-rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2x9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu 32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high-resolution neutron diffraction to exhibit tri-, tetra-, and pentacoordinated hydrides in capping and interstitial modes. We conclude that this result was further supported by a density functional theory investigation on the simplified model [Cu 32 (H) 20 (S 2 PH 2 ) 12 ].

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Active-Phase Formation and Stability of Gd/Pt(111) Electrocatalysts for Oxygen Reduction: An In Situ Grazing Incidence X-Ray Diffraction Study

Alloys of platinum and gadolinium present significant activity enhancement over pure Pt for the oxygen reduction reaction (ORR), both in the form of extended electrode surfaces and nanoparticulate catalysts. The active phase consists of a compressed Pt overlayer formed on Pt 5 Gd electrodes upon exposure to the electrolyte by acid leaching. Here, we investigate the formation, strain and correlation lengths of the active Pt overlayer by using in situ synchrotron grazing incidence X–ray diffraction on Gd/Pt(111) single–crystalline electrodes. The overlayer forms upon exposure to electrolyte under open circuit conditions; the compressive strain relaxes slightly upon repeated electrochemical cycling in the potential range 0.6 to 1.0 V versus the reversible hydrogen electrode (RHE). Furthermore, the strain relaxes strongly when exposing the electrode to 1.2 V versus RHE, and the thickness of the crystalline portion of the overlayer increases with potential above 1.3 V versus RHE.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗