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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

The joined wing - An overview

The joined wing is a new type of aircraft configuration which employs tandem wings arranged to form diamond shapes in plan view and front view. Wind-tunnel tests and finite-element structural analyses have shown that the joined wing provides the following advantages over a comparable wing-plus-tail system; lighter weight and higher stiffness, higher span-efficiency factor, higher trimmed maximum lift coefficient, lower wave drag, plus built-in direct lift and direct sideforce control capability. A summary is given of research performed on the joined wing. Calculated joined wing weights are correlated with geometric parameters to provide simple weight estimation methods. The results of low-speed and transonic wind-tunnel tests are summarized, and guidelines for design of joined-wing aircraft are given. Some example joined-wing designs are presented and related configurations having connected wings are reviewed.

Wolkovitch, J.↗
DOE OSTI2021

High‐Pressure Phase Stability and Thermoelastic Properties of Iron Carbonitrides and Nitrogen in the Deep Earth

Abstract Iron‐dominant metallic phases are likely the primary hosts for nitrogen in the reduced deep Earth, hence the storage of nitrogen in the lower mantle and the core is governed by the behavior of the Fe‐N‐C system at high temperatures and pressures. In this study, phase transitions and thermoelastic properties of iron carbonitrides were investigated at high pressure‐temperature conditions by diamond anvil cell experiments and first‐principles calculations. Experimental data revealed no phase transition in ε ‐type Fe 4 (N 0.6 C 0.4 ) or Fe 7 (N 0.75 C 0.25 ) 3 up to 60 GPa at room temperature. At high temperature, Fe 7 (N 0.75 C 0.25 ) 3 transforms into the Fe 3 C‐type phase at ∼27 GPa, and then into the Fe 7 C 3 ‐type phase at ∼45 GPa, which is also corroborated by our theoretical calculations. We found that the phase stability of iron carbonitrides mainly depends on the N/C ratio, and the elastic properties of iron carbonitrides are dominantly affected by the Fe/(N+C) ratio. Iron carbonitrides with diverse structures may be the main host for nitrogen in the deep mantle. Some iron carbonitride inclusions in lower mantle diamonds could be the residue of the primordial mantle or originate from subducted nitrogen‐bearing materials, rather than iron‐enriched phases of the outer core. In addition, our experiments confirmed the existence of Fe 7 C 3 ‐type Fe 7 C 3 ‐Fe 7 N 3 solid solutions above 40 GPa. Fe 7 C 3 ‐type Fe 7 (C, N) 3 has comparable density and thermoelastic properties to its isostructural endmembers and may be a promising candidate constituent of the Earth's inner core.

Huang, Shengxuan↗
DOE OSTI2024

Thermally frustrated phase transition at high pressure in B 2-ordered FeV

X-ray diffraction measurements of equiatomic B2-ordered FeV were performed in a diamond-anvil cell at room temperature at several pressure points up to 80 GPa that showed the cubic phase to be stable with no indication of structural phase transitions. Density functional theory at 0 K predicts Fermi surface nesting, an electronic topological transition, and a phonon dynamical instability within the experimentally investigated pressure range. Nevertheless, the instability is absent in phonon dispersion curves extracted from ab initio molecular dynamics simulations below the critical volume at temperatures as low as 10 K, indicating that thermal atomic displacements can frustrate the phase transition by renormalizing the phonon dispersion curves. Ferrimagnetism is critical for the stability of the cubic phase at low temperature, but thermal atomic displacements are enough to support the structure at and above the Néel temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electric current paths in a Si:P delta-doped device imaged by nitrogen-vacancy diamond magnetic microscopy

The recently-developed ability to control phosphorous-doping of silicon at an atomic level using scanning tunneling microscopy, a technique known as atomic precision advanced manufacturing (APAM), has allowed us to tailor electronic devices with atomic precision, and thus has emerged as a way to explore new possibilities in Si electronics. In these applications, critical questions include where current flow is actually occurring in or near APAM structures as well as whether leakage currents are present. In general, detection and mapping of current flow in APAM structures are valuable diagnostic tools to obtain reliable devices in digital-enhanced applications. In this report, we used nitrogen-vacancy (NV) centers in diamond for wide-field magnetic imaging (with a few-mm field of view and micron-scale resolution) of magnetic fields from surface currents flowing in an APAM test device made of a P delta-doped layer on a Si substrate, a standard APAM witness material. We integrated a diamond having a surface NV ensemble with the device (patterned in two parallel mm-sized ribbons), then mapped the magnetic field from the DC current injected in the APAM device in a home-built NV wide-field microscope. The 2D magnetic field maps were used to reconstruct the surface current densities, allowing us to obtain information on current paths, device failures such as choke points where current flow is impeded, and current leakages outside the APAM-defined P-doped regions. Analysis on the current density reconstructed map showed a projected sensitivity of ~0.03 A m -1 , corresponding to a smallest-detectable current in the 200 μm wide APAM ribbon of ~6 μA. These results demonstrate the failure analysis capability of NV wide-field magnetometry for APAM materials, opening the possibility to investigate other cutting-edge microelectronic devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Kohn anomaly and elastic softening in body-centered cubic molybdenum at high pressure

Transition metals in body-centered cubic (bcc) structures under compression can display several novel physical properties because of their complex electronic structures and electron-phonon interactions. Here, we used inelastic x-ray scattering experiments in a diamond-anvil cell up to ∼45 GPa and density-functional theory calculations up to 210 GPa to investigate the phonon dispersions, and electronic and elastic properties of single-crystal molybdenum (Mo). Our results show a pressure-induced Kohn anomaly at 𝑞∼0.5 along the [ξ00] direction in the longitudinal acoustic mode at ∼45 GPa; this anomaly is triggered by the pressure-enhanced Fermi-surface nesting effect. Theoretical calculations show that electron redistributions in the 𝑠-to-𝑑 orbitals of bcc-Mo contribute to the shear modulus anomaly at ∼50 GPa. In contrast, the Young's modulus anomaly in bcc-Mo at ∼210 GPa results from a Lifshitz-type electronic topological transition. In conclusion, our results shed light on the complex electronic behaviors that are associated with macroscopic elastic properties in typical bcc 𝑑-block transition metals under compression.

3-dimensional systems↗
NASA NTRS1988

Growth of diamond by RF plasma-assisted chemical vapor deposition

A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

Meyer, Duane E.↗
NASA NTRS1985

Extensional tectonics and collapse structures in the Suez Rift (Egypt)

The Suez Rift is a 300 km long and 50 to 80 km wide basin which cuts a granitic and metamorphic shield of Precambrian age, covered by sediments of Paleozoic to Paleogene age. The rift structure is dominated by tilted blocks bounded by NW-SE normal faults. The reconstruction of the paleostresses indicates a N 050 extension during the whole stage of rifting. Rifting began 24 My ago with dikes intrusions; main faulting and subsidence occurred during Early Miocene producing a 80 km wide basin (Clysmic Gulf). During Pliocene and Quaternary times, faulting is still active but subsidence is restricted to a narrower area (Present Gulf). On the Eastern margin of the gulf, two sets of fault trends are predominant: (1) N 140 to 150 E faults parallel to the gulf trend with pure dip-slip displacement; and (2) cross faults, oriented NOO to N 30 E that have a strike-slip component consistent with the N 050 E distensive stress regime. The mean dip cross fault is steeper (70 to 80 deg) than the dip of the faults parallel to the Gulf (30 to 70 deg). These two sets of fault define diamond shaped tilted block. The difference of mechanical behavior between the basement rocks and the overlying sedimentary cover caused structural disharmony and distinct fault geometries.

Chenet, P. Y.↗
DOE OSTI2023

POWTEX visits POWGEN

The high-intensity time-of-flight (TOF) neutron diffractometer POWTEX for powder and texture analysis is currently being built prior to operation in the eastern guide hall of the research reactor FRM II at Garching close to Munich, Germany. Because of the world-wide 3 He crisis in 2009, the authors promptly initiated the development of 3 He-free detector alternatives that are tailor-made for the requirements of large-area diffractometers. Herein is reported the 2017 enterprise to operate one mounting unit of the final POWTEX detector on the neutron powder diffractometer POWGEN at the Spallation Neutron Source located at Oak Ridge National Laboratory, USA. As a result, presented here are the first angular- and wavelength-dependent data from the POWTEX detector, unfortunately damaged by a 50 g shock but still operating, as well as the efforts made both to characterize the transport damage and to successfully recalibrate the voxel positions in order to yield nonetheless reliable measurements. Also described is the current data reduction process using the PowderReduceP2D algorithm implemented in Mantid [Arnold et al. (2014). Nucl. Instrum. Methods Phys. Res. A , 764 , 156–166]. The final part of the data treatment chain, namely a novel multi-dimensional refinement using a modified version of the GSAS-II software suite [Toby & Von Dreele (2013). J. Appl. Cryst. 46 , 544–549], is compared with a standard data treatment of the same event data conventionally reduced as TOF diffraction patterns and refined with the unmodified version of GSAS-II . This involves both determining the instrumental resolution parameters using POWGEN's powdered diamond standard sample and the refinement of a friendly-user sample, BaZn(NCN) 2 . Although each structural parameter on its own looks similar upon comparing the conventional (1D) and multi-dimensional (2D) treatments, also in terms of precision, a closer view shows small but possibly significant differences. For example, the somewhat suspicious proximity of the a and b lattice parameters of BaZn(NCN) 2 crystallizing in Pbca as resulting from the 1D refinement (0.008 Å) is five times less pronounced in the 2D refinement (0.038 Å). Similar features are found when comparing bond lengths and bond angles, e.g. the two N—C—N units are less differently bent in the 1D results (173 and 175°) than in the 2D results (167 and 173°). The results are of importance not only for POWTEX but also for other neutron TOF diffractometers with large-area detectors, like POWGEN at the SNS or the future DREAM beamline at the European Spallation Source.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Phase transition in solid molecular hydrogen at ultrahigh pressures

Solid normal hydrogen was compressed in a diamond-anvil cell to pressures above 200 GPa. Spontaneous Raman spectra demonstrate that the solid undergoes a structural phase transformation beginning at 145 GPa at 77 K, as evidenced by an abrupt discontinuity in the intramolecular vibron frequency as a function of pressure. The magnitude of the vibron-frequency shift and the pressure-temperature conditions of the phase transformation are consistent with its identification as the theoretically predicted pressure-induced orientational ordering of the molecular solid.

Hemley, R. J.↗
NASA NTRS1999

Lightweight Aluminum Mirrors Using Foam Core Sandwich Construction

The possible use of all aluminum mirrors made from thin faceplates supported by aluminum foam is explored from an optomechanical design and fabrication perspective. Foam mirrors can be relatively cheaply and easily made using conventional foam fabrication and diamond turning; such a mirror recently flew for the first time on the Stardust mission. The proposed structural concept is highly weight efficient and should not be prone to quilting. The weight and structural stability of such mirrors is presented, along with plans underway at GSFC for developing this concept.

Content, D.↗
NASA NTRS1983

A mobile work station concept for mechanically aided astronaut assembly of large space trusses

This report presents results of a series of truss assembly tests conducted to evaluate a mobile work station concept intended to mechanically assist astronaut manual assembly of erectable space trusses. The tests involved assembly of a tetrahedral truss beam by a pair of test subjects with and without pressure (space) suits, both in Earth gravity and in simulated zero gravity (neutral buoyancy in water). The beam was assembled from 38 identical graphite-epoxy nestable struts, 5.4 m in length with aluminum quick-attachment structural joints. Struts and joints were designed to closely simulate flight hardware. The assembled beam was approximately 16.5 m long and 4.5 m on each of the four sides of its diamond-shaped cross section. The results show that average in-space assembly rates of approximately 38 seconds per strut can be expected for struts of comparable size. This result is virtually independent of the overall size of the structure being assembled. The mobile work station concept would improve astronaut efficiency for on-orbit manual assembly of truss structures, and also this assembly-line method is highly competitive with other construction methods being considered for large space structures.

Heard, W. L., Jr.↗
DOE OSTI2021

Magnetic and structural properties of the solid solution CuAl 2(1–x) Ga 2x O 4

CuAl 2 O 4 is a ternary oxide spinel with Cu 2+ ions (s = 1/2) primarily populating the A-site diamond sublattice. The compound is reported to display evidence of spin glass behavior but possess a non-frozen magnetic ground state below the transition temperature. On the other hand, the spinel CuGa 2 O 4 displays spin glass behavior at ~ 2.5 K with Cu 2+ ions more readily tending to the B-site pyrochlore sublattice. Therefore, we investigate the magnetic and structural properties of the solid solution CuAl 2(1-x) Ga 2x O 4 examining the evolution of the magnetic behavior as Al 3+ is replaced with a much larger Ga 3+ ion. Our results show that the Cu 2+ ions tend to migrate from tetrahedral to octahedral sites as the Ga 3+ ion concentration increases, resulting in a concomitant change in the glassy magnetic properties of the solution. Results indicate glassy behavior for much of the solution with a general trend towards decreasing magnetic frustration as the Cu 2+ ion shifts to the B-site. However, the x = 0.1 and 0.2 members of the system do not show glassy behavior down to our measurement limit (1.9 K) suggesting a delayed spin glass transition. We suggest that these two members are additional candidates for investigation to access highly frustrated exotic quantum states.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Phase Transitions in Amorphous Germanium under Non-Hydrostatic Compression

As the pioneer semiconductor in transistor, germanium (Ge) has been widely applied in information technology for over half a century. Although many phase transitions in Ge have been reported, the complicated phenomena of the phase structures in amorphous Ge under extreme conditions are still not fully investigated. Here, we report the different routes of phase transition in amorphous Ge under different compression conditions utilizing diamond anvil cell (DAC) combined with synchrotron-based X-ray diffraction (XRD) and Raman spectroscopy techniques. Upon non-hydrostatic compression of amorphous Ge, we observed that shear stress facilitates a reversible pressure-induced phase transformation, in contrast to the pressure-quenchable structure under a hydrostatic compression. These findings afford better understanding of the structural behaviors of Ge under extreme conditions, which contributes to more potential applications in the semiconductor field.

Xu, Jianing (ORCID:0000000325474344)↗
DOE OSTI2024

Comparison of Americium(III) and Neodymium(III) Monothiophosphate Complexes

Mixed-donor ligands, such as those containing a combination of O/N or O/S, have been studied extensively for the selective extraction of trivalent actinides, especially Am 3+ and Cm3+, from lanthanides during the recycling of used nuclear fuel. Oxygen/sulfur donor ligand combinations also result from the hydrolytic and/or radiolytic degradation of dithiophosphates, such as the Cyanex® class of extractants, that are initially converted to monothiophosphates. To understand potential differences between the binding of such degraded ligands to Nd 3+ and Am 3+ , the monothiophosphate complexes [M(OPS(OEt) 2 ) 5 (H 2 O) 2 ] 2- (M 3+ = Nd 3+ , Am 3+ ) were prepared and characterized by single crystal X-ray diffraction and optical spectroscopy and studied as a function of pressure up ca. 14 GPa using diamond-anvil techniques. Although Nd 3+ and Am 3+ have nearly identical eight-coordinated ionic radii, these structures reveal that while the M-O bond distances in these complexes are nearly equal that the M-S distances are statistically different. Moreover, for [Nd(OPS(OEt) 2 ) 5 (H 2 O) 2 ] 2- , the hypersensitive 4 I 9/2 → 4 G 5 / 2 transition shifts as a function of pressure by -11 cm -1 /GPa. Whereas for [Am(OPS(OEt) 2 ) 5 (H 2 O) 2 ] 2- , the 7 F 0 → 7 F 6 transition shows a slightly stronger pressure dependence with a shift of -13 cm -1 /GPa and also exhibits broadening of the 5f →5f transitions at high pressures. This data likely indicates an increased involvement of the 5f orbitals in bonding to Am 3+ relative to that of Nd 3+ in these complexes.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Water‐Induced Diamond Formation at Earth's Core‐Mantle Boundary

Abstract The carbon and water cycles in the Earth's interior are linked to key planetary processes, such as mantle melting, degassing, chemical differentiation, and advection. However, the role of water in the carbon exchange between the mantle and core is not well known. Here, we show experimental results of a reaction between Fe 3 C and H 2 O at pressures and temperatures of the deep mantle and core‐mantle boundary (CMB). The reaction produces diamond, FeO, and FeH x , suggesting that water can liberate carbon from the core in the form of diamond (“core carbon extraction”) while the core gains hydrogen, if subducted water reaches to the CMB. Therefore, Earth's deep water and carbon cycles can be linked. The extracted core carbon can explain a significant amount of the present‐day mantle carbon. Also, if diamond can be collected by mantle flow in the region, it can result in unusually high seismic‐velocity structures.

Ko, Byeongkwan↗
NASA NTRS1987

Laser techniques in high-pressure geophysics

Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

Hemley, R. J.↗
DOE OSTI2024

Equation of state and structural evolution of manganese dolomite (kutnohorite) under high pressures

Abstract Understanding the structural evolution of carbonate minerals with increasing pressure is essential to decoding the role of Earth’s mantle in the global carbon cycle and long-term climate change. Here, we carried out synchrotron single-crystal X-ray diffraction measurements on a natural sample of manganese dolomite [kutnohorite, Ca1.11Mn0.89(CO3)2] in a diamond-anvil cell up to 51.2 GPa at room temperature with neon as the pressure-transmitting medium. The manganese dolomite sample remains stable in the rhombohedral structure from 1 bar to ~13.3 GPa. The equation of state of Ca1.11Mn0.89(CO3)2 was determined: V0 = 334.06 ± 0.29 Å3, K0 = 99.9 ± 4.7 GPa, and K0′ = 4.3 ± 0.9; when K0′ is fixed at 4.0, V0 = 334.04 ± 0.24 Å3, and K0 = 101.4 ± 1.5 GPa. Upon further compression at room temperature, the split and disappearance of diffraction spots were observed. That is, the rhombohedral structure of manganese dolomite becomes highly distorted to lose its long-range order at 13.3–51.2 GPa at room temperature. Moreover, our single-crystal X-ray diffraction results reveal the mechanisms of the reported lattice and internal Raman mode splits of the same manganese dolomite sample approximately at 13 and 24 GPa, respectively. These results suggest manganese-bearing carbonates may play a distinct role in the deep carbon cycle.

Geochemistry & Geophysics↗