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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 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Microscopic description of diffractive deuteron breakup by {sup 3}He nuclei

A microscopic formalism for describing observed cross sections for deuteron breakup by threenucleon nuclei was developed on the basis of the diffraction nuclear model. A general formula that describes the amplitude for the reaction {sup 2}H({sup 3}He, {sup 3}Hep)n and which involves only one adjustable parameter was obtained by using expansions of the integrands involved in terms of a Gaussian basis. This formula was used to analyze experimental data on the exclusive cross sections for deuteron breakup by {sup 3}He nuclei at the projectile energy of 89.4MeV. The importance of employing, in calculations, a deuteron wave function that has a correct asymptotic behavior at large nucleon–nucleon distances was demonstrated.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Study of silicon strip waveguides with diffraction gratings and photonic crystals tuned to a wavelength of 1.5 µm

Single-mode submicrometer-thick strip waveguides on silicon-on-insulator substrates, fabricated by silicon-planar-technology methods are considered. To solve the problem of 1.5-µm wavelength radiation input-output and its frequency filtering, strip diffraction gratings and two-dimensional photonic crystals are integrated into waveguides. The reflection and transmission spectra of gratings and photonic crystals are calculated. The waveguide-mode-attenuation coefficient for a polycrystalline silicon waveguide is experimentally estimated.

36 MATERIALS SCIENCE↗
DOE OSTI2018

X-Ray Diffraction Analysis of Features of the Crystal Structure of GaN/Al{sub 0.32}Ga{sub 0.68}N HEMT-Heterostructures by the Williamson–Hall Method

The fitting of θ/2θ and ω peaks in X-ray diffraction curves is shown to be most accurate in the case of using an inverse fourth-degree polynomial or probability density function with Student’s distribution (Pearson type VII function). These functions describe well both the highest-intensity central part of the experimental peak and its low-intensity broadened base caused by X-ray diffuse scattering. The mean microdeformation ε and mean vertical domain size D are determined by the Williamson–Hall method for layers of GaN (ε ≈ 0.00006, D ≈ 200 nm) and Al{sub 0.32}Ga{sub 0.68}N (ε = 0.0032 ± 0.0005, D = 24 ± 7 nm). The D value obtained for the Al{sub 0.32}Ga{sub 0.68}N layer is most likely to result from the nominal thickness of this layer, which is 11 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Microstructure of Si Crystals Subjected to Irradiation with High-Energy H{sup +} Ions and Heat Treatment by High-Resolution Three-Crystal X-Ray Diffraction and Transmission Electron Microscopy

The structural features of the formation of radiation defects in proton-implanted layers of silicon plates during their heat treatment have been studied. New data on the nature, the characteristics, and the microdefect concentration in Si crystals irradiated with protons with energies 100 + 200 + 300 keV with the total dose 2 × 10{sup 16} cm{sup –2} and the evolution of the defect structure during heat treatment have been obtained by high-resolution three-crystal X-ray diffraction and transmission electron microscopy over wide temperature range from 200 to 1100°C.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Electron Diffraction Study of Epitaxial Graphene Structure Grown upon SiC (0001) Thermal Destruction in Ar Atmosphere and in High Vacuum

We have studied the structure of epitaxial graphene obtained as a result of thermal desorption of the silicon carbide surface under conditions of vacuum synthesis and in Ar medium by reflection electron diffraction. As a result of the study, a significantly more uniform buffer layer coating of the SiC surface by epitaxial graphene has been found when forming in inert medium on the surface of 4H- and 6H-SiC(0001) polytypes compared with the synthesis of graphene in high vacuum. The quality of the coating has been shown to depend on the degree of perfection of the original single crystal.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Measurement Error of Interferometers with Diffraction Reference Wave

An experimental setup and results on aberration of sources of a reference spherical wave (SRSW) based on a single-mode optical fiber with a subwavelength output aperture obtained with the aid of an optical part of recording system (OPRS) are presented. SRSW and OPRS are developed for referenceless interferometer with diffraction reference wave. Methods for minimization of the measurement error are proposed. The SRSW and OPRS provide subnanometer measurement accuracy for optics. An increase in the measurement accuracy of the interferometer to a picometer level is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Reciprocal-Space Maps of X-Ray Diffraction Intensity Distribution and Their Relation to the Dislocation Structure of Epitaxial Layers

X-ray diffraction (XRD) in asymmetric Bragg geometry was measured and XRD intensity distribution maps in the reciprocal space were constructed for GaN epitaxial layers with various degrees of structural perfection grown on c-sapphire substrates. It is established that equal-intensity lines (isolines) related to a regular system of perpendicular rectilinear threading dislocations are extended in a direction parallel to the surface. For a more chaotic distribution of dislocations with a large fraction of horizontal fragments, these isolines are rotated toward a direction perpendicular to the reciprocal lattice vector, although they still not attain a limiting position characteristic of the ideal mosaic crystal.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

A Crystal-Diffraction System Prototype for Measuring Neutron’s Charge: Thermal Protection Test and Vibration Measurements

A prototype system design for ultra-high-precision neutron spectrometry using diffraction in perfect crystals is described. Results of experimental verification of the temperature stability inside the setup are presented. Results of vibration spectrum measurements in working zone of the PF1b beam of ILL reactor (Grenoble, France), where the prototype setup will be arranged for experimental testing, are considered.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

Quantitative Scanning Transmission Electron Microscopy for Materials Science: Imaging, Diffraction, Spectroscopy, and Tomography

Scanning transmission electron microscopy (STEM) is one of the most powerful characterization tools in materials science research. Due to instrumentation developments such as highly coherent electron sources, aberration correctors, and direct electron detectors, STEM experiments can examine the structure and properties of materials at length scales of functional devices and materials down to single atoms. STEM encompasses a wide array of flexible operating modes, including imaging, diffraction, spectroscopy, and 3D tomography experiments. This review outlines many common STEM experimental methods with a focus on quantitative data analysis and simulation methods, especially those enabled by open source software. The hope is to introduce both classic and new experimental methods to materials scientists and summarize recent progress in STEM characterization. The review also discusses the strengths and weaknesses of the various STEM methodologies and briefly considers promising future directions for quantitative STEM research.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets

Time-resolved wide-angle coherent diffraction imaging of individual helium nanodroplets, doped with xenon and excited with an 800 nm NIR laser pulse. Raw and preprocessed pattern, together with useful metadata, are contained in HDF5 files. Every field in the H5 container comes with a description, under the field "description", and the actual data under the field "data". For further information about the dataset see the [ArXiv article](https://arxiv.org/abs/2205.04154 ) and Bruno Langbehn's [PhD thesis](https://depositonce.tu-berlin.de/handle/11303/13189).

FERMI FEL-1↗
DOE OSTI2022

Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets

Time-resolved wide-angle coherent diffraction imaging of individual helium nanodroplets, doped with xenon and excited with an 800 nm NIR laser pulse. Raw and preprocessed pattern, together with useful metadata, are contained in HDF5 files. Every field in the H5 container comes with a description, under the field "description", and the actual data under the field "data". For further information about the dataset see the [ArXiv article](https://arxiv.org/abs/2205.04154 ) and Bruno Langbehn's [PhD thesis](https://depositonce.tu-berlin.de/handle/11303/13189).

FERMI FEL-1↗
DOE OSTI2018

Utah FORGE: X-Ray Diffraction Data

This dataset contains X-ray diffraction (XRD) data taken from wells and outcrops as part of the DOE GTO supported Utah FORGE project located near Roosevelt Hot Springs. It contains an Excel spreadsheet with the XRD data, a text file with sample site names, types, and locations in UTM, Zone 12, NAD83 coordinates, and a GIS shapefile of the sample locations with attributes.

15 GEOTHERMAL ENERGY↗
DOE OSTI2018

Microstructure Evolution in Ion-Irradiated Oxidized Zircaloy-4 Studied with Synchrotron Radiation Microdiffraction and Transmission Electron Microscopy

The corrosion process (oxidation and hydriding) of zirconium alloy fuel cladding is one of the limiting factors on fuel rod lifetime, particularly for Zircaloy-4. The corrosion rate of this alloy shows indeed a great acceleration at high burnup in light water reactors (LWRs). Understanding the corrosion behavior under irradiation for this alloy is an important technological issue for the safety and efficiency of LWRs. In particular, understanding the effect of irradiation on the metal and oxide layers is a key parameter in the study of corrosion behavior of zirconium alloys. In this study, Zircaloy-4 samples underwent helium and proton ion irradiation up to 0.3 dpa, forming a uniform defect distribution up to 1 pm deep. Both as-received and precorroded samples were irradiated to compare the effect of metal irradiation to that of oxide layer irradiation. After irradiation, samples were corroded to study the impact of irradiation defects in the metal and in preexisting oxide layers on the formation of new oxide layers. Synchrotron X-ray microdiffraction and microfluorescence were used to follow the evolution of oxide crystallographic phases, texture, and stoichiometry both in the metal and in the oxide. In particular, the tetragonal oxide phase fraction, which has been known to play an important role in corrosion behavior, was mapped in both unirradiated and irradiated metals at the submicron scale and appeared to be significantly affected by irradiation. These observations, complemented with electron microscopy analyses on samples in carefully chosen areas of interest, were combined to fully characterize changes caused by irradiation in metal and oxide phases of both alloys.

ion-irradiation↗
DOE OSTI2019

Method Development for High Temperature In-Situ Neutron Diffraction Measurements of Glass Crystallization on Cooling from Melt

A glass-ceramic borosilicate waste form is being considered for immobilization of waste streams of alkali, alkaline-earth, lanthanide, and transition metals generated by transuranic extraction for reprocessing used nuclear fuel. Waste forms are created by partial crystallization on cooling, primarily of oxyapatite and powellite phases. In-situ neutron diffraction experiments were performed to obtain detailed information about crystallization upon cooling from 1200°C. The combination of high temperatures and reactivity of borosilicate glass with typical containers used in neutron experiments, such as vanadium and niobium, prevented their use here. Thus, methods using sealed thick-walled silica ampoules were developed for the in-situ studies. Unexpectedly, high neutron absorption, low crystal fraction, and high silica container background made quantification difficult for these high temperature measurements. As a follow-up, proof-of-concept measurements were performed on different potential high-temperature container materials, emphasizing crystalline materials so that residual glass in the waste form sample could be more easily analyzed. Room temperature measurements were conducted with a pre-crystallized sample in ‘ideal’ containers stable at low temperatures (i.e., vanadium and thin-wall silica capillaries) and compared to the same measurements in containers stable at high temperatures (i.e, platinum, single crystal sapphire, and thick-walled silica ampoules). Results indicated that Pt is probably the best choice if suitably sealed to prevent contamination from the sample after neutron activation.

36 MATERIALS SCIENCE↗