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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Effect of short-range order on microstructure, texture and strain hardening of cold drawn Cu-10 at.%Mn alloy

Highlights: • Excluding the effect of stacking fault energy, short-range order effect is discussed solely. • Short-range order is beneficial for twinning and slip planarity. • Short-range order promotes the formation of <111> fiber texture. • Strain hardening improving by short-range order. - Abstract: The aim of the present study is to investigate the effect of short-range order (SRO) on the microstructural evolution and mechanical property of Cu-10 at.%Mn alloy during cold drawing deformation. Characterization of the cold drawn Cu-10 at.%Mn alloy samples were performed using transmission electron microscope (TEM) and electron back scattering diffraction (EBSD), and their hardness were also tested. The results show that SRO is beneficial for both twinning and the transition of dislocation glide from wavy slip to planar slip at the low strains. At the high strains, the wavy slip generates due to the destruction of SRO. SRO increases the volume fraction of <111> texture component and the critical strain threshold. Moreover, the presence of SRO significantly improves strain hardening by combining the effects of dislocation, deformation twinning and texture hardening, which results in a significant increase of hardness.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM 2 Sb 2 (A = Ba, Sr; M = Zn, Cd)

Five novel Zintl phase solid solutions in the Ba 1–x Sr x Zn 2–y Cd y Sb 2 (0 ≤ x ≤ 0.13(1); 0 ≤ y ≤ 0.32(2)) system were successfully synthesized by the molten Pb metal-flux method, and the powder X-ray diffraction and single-crystal X-ray diffraction analyses proved that all five title compounds adopted the BaCu 2 S 2 -type phase having the orthorhombic Pnma space group (Z = 4, Pearson code oP20) with five crystallographically independent atomic sites. The previously studied BaCu 2 S 2 -type antimonides demonstrated a limited tolerance for doping in contrast to the CaAl 2 Si 2 -type antimonides. To understand the relatively narrower phase width and limited dopability of the title BaCu 2 S 2 -type phase than the CaAl 2 Si 2 -type phase in the overall Ba 1–x Sr x Zn 2–y Cd y Sb 2 system, the radius ratio of cations and anionic elements r + /r – for two structure types were thoroughly investigated. For the first time, the r + /r – ratio was identified as a critical factor for the phase selectivity: (1) r + /r – > 1 favored the BaCu 2 S 2 -type phase, and (2) r + /r – < 1 favored the CaAl 2 Si 2 -type phase. Further, we also revealed the structural transformation mechanism from the more widely observed CaAl 2 Si 2 -type phase to the title BaCu 2 S 2 -type phase as the relatively larger cationic elements were introduced to the system. A series of DFT calculations using the three hypothetical models indicated that a resonance peak near EF in the density of states curves was descended from the relatively flat band structure at several special symmetry points rationalizing the enhanced Seebeck coefficients of Ba 0.94(1) Sr 0.06 Zn 1.86(3) Cd 0.14 Sb 2 and Ba 0.96(1) Sr 0.04 Zn 1.68(2) Cd 0.32 Sb 2 . Electron localization function analysis rationalized the correlation between the polarity change of anionic Zn/Cd–Sb bonds and the charge carrier mobility on the anionic frameworks. Temperature-dependent thermoelectric properties were studied for the four title compounds, and the results proved that the Sr and Cd doping in the title Ba 1–x Sr x Zn 2–y Cd y Sb 2 system successfully enhanced the ZT values through the increased Seebeck coefficients and the reduced total thermal conductivities.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Rapidity gap cross sections measured with the ATLAS detector in pp collisions at $\sqrt{s} = 7 \mbox{~TeV}$

Pseudorapidity gap distributions in proton-proton collisions at s√=7 ~TeVs=7 ~TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 μb -1 . Cross sections are measured differentially in terms of Δη F , the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at η= ±4.9, in which no final state particles are produced above a transverse momentum threshold p$cut\atop{T}$ . The measurements span the region 0<Δη F < 8 for 200~MeV< p$cut\atop{T}$ <800~MeV200~MeV F , the data test the reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process (pp→Xp), enhanced by double dissociation (pp→XY) where the invariant mass of the lighter of the two dissociation systems satisfies M Y ≲7 GeV. The resulting cross section is dσ/dΔη F ≈1 mb for Δη F ≳3. The large rapidity gap data are used to constrain the value of the Pomeron intercept appropriate to triple Regge models of soft diffraction. Finally, the cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Femtosecond X-ray Fourier holography imaging of free-flying nanoparticles

Ultrafast X-ray imaging on individual fragile specimens such as aerosols, metastable particles, superfluid quantum systems and live biospecimens provides high-resolution information that is inaccessible with conventional imaging techniques. Coherent X-ray diffractive imaging, however, suffers from intrinsic loss of phase, and therefore structure recovery is often complicated and not always uniquely defined. Here in this paper, we introduce the method of in-flight holography, where we use nanoclusters as reference X-ray scatterers to encode relative phase information into diffraction patterns of a virus. The resulting hologram contains an unambiguous three-dimensional map of a virus and two nanoclusters with the highest lateral resolution so far achieved via single shot X-ray holography. Our approach unlocks the benefits of holography for ultrafast X-ray imaging of nanoscale, non-periodic systems and paves the way to direct observation of complex electron dynamics down to the attosecond timescale.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

The fluorite related modulated structures of the Gd{sub 2}(Zr{sub 2-x}Ce{sub x})O{sub 7} solid solution: An analogue for Pu disposition

We present an overview of the Gd{sub 2}(Zr{sub 2-x}Ce{sub x})O{sub 7} phase diagram, of interest as a model system for ceramic disposition of Pu (with Ce as a Pu surrogate). The fluorite related structures of this solid solution were determined using a modulated structure approach, to identify the underlying cation and vacancy ordering mechanisms from analysis of key satellite reflections in selected zone axis electron diffraction patterns. This revealed the formation of four structure types: pyrochlore for x<0.25, defect fluorite for 0.5 1.50. X-ray absorption (XAS) and electron energy loss (EELS) spectra confirmed the presence of Ce{sup 4+} as the dominant species in compositions across this system, remaining analogous to Pu{sup 4+}. - Graphical abstract: Electron diffraction reveals the cation vacancy ordering mechanisms leading to fluorite related superstructures in the Gd{sub 2}(Zr{sub 2-x}Ce{sub x})O{sub 7} solid solution. Highlights: Black-Right-Pointing-Pointer The fluorite related solid solution Gd{sub 2}(Zr{sub 1-x}Ce{sub x})O{sub 7} was prepared by solid state synthesis. Black-Right-Pointing-Pointer Ce L{sub 3} edge XAS and Ce M{sub 4,5} EELS measurements show Ce substitutes as Ce{sup 4+}. Black-Right-Pointing-Pointer Cation and oxygen vacancy ordering results in four fluorite related structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Temperature gradients for thermophysical and thermochemical property measurements to 3000 °C for an aerodynamically levitated spheroid

This study examines thermal gradients in ceramic oxide spheroids being aerodynamically levitated in a conical nozzle levitator (CNL) system equipped with a CO 2 laser (10.6 μm wavelength). The CNL system is a versatile piece of equipment that can easily be coupled with advanced thermophysical and thermochemical measuring devices, such as diffraction/scattering (X-ray and neutron), nuclear magnetic resonance, and calorimetry, for the analysis of bulk spheroidal solids and liquids. The thermal gradients of a series of single crystal, polycrystalline solids, and liquid spheroids have been measured spatially in the CNL system, by means of a disappearing filament pyrometer (800-3000 °C) and by X-ray diffraction with reference to an internal standard (Pt: 800-1600 °C). The thermal gradient in a levitated sample being heated by a laser from the top can be minimized by: (i) maximizing the sphericity, (ii) maximizing the density, and (iii) minimizing microstructural features. A spheroid with these properties can be manufactured via machining a perfect sphere from a highly dense, chemically and phase pure pellet. These properties promote rotation of the sample about multiple axes in the air stream, enabling homogeneous heating. This homogeneous heating is the dominant factor in reducing thermal gradients in solid state samples. It was found that the thermal gradient in an similar to 3 mm diameter solid sample could be reduced from 1000 °C to 30 °C, by having a perfectly spherical shape that could rotate on multiple axes in a high velocity gas stream (similar to 1500-2000 cm 3 /min). As a result, these findings will allow accurate thermophysical and thermochemical property measurements of solids in situ at high temperatures, using the CNL system.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Diffraction properties of multilayer Laue lenses with an aperture of 102 µm and WSi 2 /Al bilayers

We report on the characterization of a multilayer Laue lens (MLL) with large acceptance, made of a novel WSi 2 /Al bilayer system. Fabrication of multilayers with large deposition thickness is required to obtain MLL structures with sufficient apertures capable of accepting the full lateral coherence length of x-rays at typical nanofocusing beamlines. To date, the total deposition thickness has been limited by stress-buildup in the multilayer. We were able to grow WSi2/Al with low grown-in stress, and asses the degree of stress reduction. X-ray diffraction experiments were conducted at beamline 1-BM at the Advanced Photon Source. We used monochromatic x-rays with a photon energy of 12 keV and a bandwidth of $ΔE/\atop {E}$ = 5.4 • 10 -4 . The MLL was grown with parallel layer interfaces, and was designed to have a large focal length of 9.6 mm. The mounted lens was 2.7 mm in width. We found and quantified kinks and bending of sections of the MLL. Sections with bending were found to partly have a systematic progression in the interface angles. We observed kinking in some, but not all, areas. The measurements are compared with dynamic diffraction calculations made with Coupled Wave Theory. Data are plotted showing the diffraction efficiency as a function of the external tilting angle of the entire mounted lens. This way of plotting the data was found to provide an overview into the diffraction properties of the whole lens, and enabled the following layer tilt analyses.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

A terahertz pump mega-electron-volt ultrafast electron diffraction probe apparatus at the SLAC Accelerator Structure Test Area facility

Here, we describe a new experimental setup capable of measuring structural dynamics following intense terahertz excitation. This system, developed at the SLAC Accelerator Structure Test Area facility, uses a high-energy ultrafast laser to produce intense terahertz pulses and femtosecond electron bunches that are accelerated to mega-electron-volt kinetic energies. The focused terahertz pulses have electric fields in excess of 600 kV/cm, and the resulting structural dynamics can be followed by electron diffraction. We also present some examples demonstrating its implementation where interactions between the THz pulses and the electron bunch are used to characterize the spatial and temporal characteristics of the THz field.

42 ENGINEERING↗
DOE OSTI2017

Determining the strengths of HCP slip systems using harmonic analyses of lattice strain distributions

A robust methodology is presented to extract slip system strengths from lattice strain distributions for polycrystalline samples obtained from high-energy x-ray diffraction (HEXD) experiments with in situ loading. The methodology consists of matching the evolution of coefficients of a harmonic expansion of the distributions from simulation to the coefficients derived from measurements. Simulation results are generated via finite element simulations of virtual polycrystals that are subjected to the loading history applied in the HEXD experiments. Advantages of the methodology include: (1) its ability to utilize extensive data sets generated by HEXD experiments; (2) its ability to capture trends in distributions that may be noisy (both measured and simulated); and (3) its sensitivity to the ratios of the family strengths. The approach is used to evaluate the slip system strengths of Ti-6Al-4V using samples having relatively equiaxed grains. These strength estimates are compared to values in the literature.

42 ENGINEERING↗
DOE OSTI2013

A Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}–Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3} ternary ferroelectric system with high T{sub C} and high piezoelectric properties

Graphical abstract: Display Omitted Highlights: ► (0.79 − x)Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}–0.21Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}–xPbTiO{sub 3} ceramics were prepared by two-step method. ► A morphotropic phase boundary region has been determined in the composition range of 0.28 < x < 0.32. ► The compositions within MPB region exhibit excellent piezoelectric properties. -- Abstract: (0.79 − x)Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}–0.21Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}–xPbTiO{sub 3} (x = 0.23–0.35) ternary ferroelectric system in the form of ceramics have been synthesized. Its structure and properties have been studied by X-ray powder diffraction and electric measurements. A morphotropic phase boundary region has been determined in the composition range of 0.28 < x < 0.32, where the Curie temperature T{sub C} and the rhombohedral–tetragonal phase transition temperature T{sub RT} were found to vary from 243 °C to 295 °C and 145 °C to 191 °C, respectively, much higher than PMNT and PZNT systems. The compositions within MPB region exhibit excellent piezoelectric properties such as piezoelectric coefficient d{sub 33} > 646 pC/N, T{sub RT} > 145 °C, T{sub C} > 273 °C and E{sub C} > 13 kV/cm for 0.5PIN–0.21PZN–0.29PT and 0.49PIN–0.21PZN–0.30PT, making the ceramics of this system a promising material for high power and high temperature application.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Effects of MnO doping on the electronic properties of zinc oxide: 406 GHz electron paramagnetic resonance spectroscopy and Newman superposition model analysis

MnO-doped ZnO ceramics have been synthesized through the conventional ceramic processing route. Mn{sup 2+} ions have been incorporated into the ZnO lattice within the limits of solid solubility. By using X-band-frequency and high-field electron paramagnetic resonance (EPR), we have resolved some of the main electronic transitions for the S = 5/2, I = 5/2 high-spin system and have determined accurately the EPR spin-Hamiltonian parameters. By combining data from crystallographic X-ray diffraction and EPR with the semi-empirical Newman superposition model, we have found the local configurational position of Mn{sup 2+} and have confirmed the symmetry of the lattice. The results presented in this contribution indicate that Mn ions substitute at Zn sites in ZnO. The effect of Mn{sup 2+} ions on the intrinsic defects becomes remarkable, thus the vacancy related intrinsic defect signals cannot be visible in the EPR spectrum. MnO doping affects the band gap energy of ZnO system which was confirmed via UV-Vis spectroscopy.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

Solid-state mechanochemical synthesis of alane (AlH 3 ) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3 ) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction, which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.

36 MATERIALS SCIENCE↗
DOE OSTI2015

A simple and wide-range refractive index measuring approach by using a sub-micron grating

This paper presents the design and simulation results of a high-precision low-cost refractometer that demonstrates the main advantage of a wide measurement range (1 ≤ n ≤ 2). The proposed design is based on the diffractive properties of sub-micron gratings and Snell's Law. The precision and uncertainty factors of the proposed system were tested and analyzed, revealing that the proposed refractometer demonstrates a wide measurement range with sensitivity of 10{sup −4}.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

The Grism Lens-Amplified Survey from space (GLASS). II. gas-phase metallicity and radial gradients in an interacting system at Z ≃ 2

We present spatially resolved gas-phase metallicity for a system of three galaxies at z = 1.85 detected in the Grism Lens-Amplified Survey from Space (GLASS). The combination of Hubble Space Telescope (HST’s) diffraction limit and strong gravitational lensing by the cluster MACS J0717+3745 results in a spatial resolution of ≃200–300 pc, enabling good spatial sampling despite the intrinsically small galaxy sizes. The galaxies in this system are separated by ≃50–200 kpc in projection and are likely in an early stage of interaction, evidenced by relatively high specific star formation rates. Their gas-phase metallicities are consistent with larger samples at similar redshift, star formation rate (SFR), and stellar mass. We obtain a precise measurement of the metallicity gradient for one galaxy and find a shallow slope compared to isolated galaxies at high redshift, consistent with a flattening of the gradient due to gravitational interaction. An alternative explanation for the shallow metallicity gradient and elevated SFR is rapid recycling of metal-enriched gas, but we find no evidence for enhanced gas-phase metallicities which should result from this effect. Notably, the measured stellar masses logM{sub ∗}/M = 7.2–9.1 probe to an order of magnitude below previous mass–metallicity studies at this redshift. The lowest mass galaxy has properties similar to those expected for Fornax at this redshift, indicating that GLASS is able to directly study the progenitors of local group dwarf galaxies on spatially resolved scales. Larger samples from the full GLASS survey will be ideal for studying the effects of feedback, and the time evolution of metallicity gradients. These initial results demonstrate the utility of HST spectroscopy combined with gravitational lensing for characterizing resolved physical properties of galaxies at high redshift.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A biosensor system using nickel ferrite nanoparticles

NiFe{sub 2}O{sub 4} ferrite nanoparticles were synthesized by chemical co-precipitation method and the structural characteristics were investigated using X-ray diffraction technique, where single cubic phase formation of nanoparticles was confirmed. The average particle size of NiFe{sub 2}O{sub 4} was found to be 4.9 nm. Nanoscale magnetic materials are an important source of labels for biosensing due to their strong magnetic properties which are not found in biological systems. This property of the material was exploited and the fabrication of the NiFe{sub 2}O{sub 4} nanoparticle based biosensor was done in the form of a capacitor system, with NiFe{sub 2}O{sub 4} as the dielectric material. The biosensor system was tested towards different biological materials with the help of electrochemical workstation and the same was analysed through Cole-Cole plot of NiFe{sub 2}O{sub 4}. The performance of the sensor was determined based on its sensitivity, response time and recovery time.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Structure and Anharmonicity of α- and β -Sb 2 O 3 at Low Temperature

Antimony oxides are important materials for catalysis and flame-retardant applications. The two most common phases, α-Sb 2 O 3 (senarmontite) and β-Sb 2 O 3 (valentinite), have been studied extensively. Specific focus has been placed recently on their lattice dynamics properties and how they relate to the α-β phase transformation and their potential anharmonicity. However, there has not been any direct investigation of anharmonicity in these systems, and a surprising lack of low-temperature structural information has prevented further study. Here, we report the powder neutron diffraction data of both phases of Sb 2 O 3 , as well as structural information. α-Sb 2 O 3 behaved as expected, but β-Sb 2 O 3 revealed a small region of zero thermal expansion along the c axis. Additionally, while the β phase matched well with reported atomic displacement parameters, the α phase displayed a marked deviation. This data will enable further investigations into these systems.

36 MATERIALS SCIENCE↗