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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Experimental study of thermal conductivity at high pressures: Implications for the deep Earth’s interior

Lattice thermal conductivity of ferropericlase and radiative thermal conductivity of iron bearing magnesium silicate perovskite (bridgmanite) – the major mineral of Earth’s lower mantle– has been measured at room temperature up to 30 and 46 GPa, respectively, using time domain thermoreflectance and optical spectroscopy techniques in diamond anvil cells. The results provide new constraints for the pressure dependencies of the thermal conductivities of Fe bearing minerals. The lattice thermal conductivity of ferropericlase (Mg 0.9 Fe 0.1 )O is 5.7(6) W/(m*K) at ambient conditions, which is almost 10 times smaller than that of pure MgO; however, it increases with pressure much faster (6.1(7)%/GPa vs 3.6%/GPa). The radiative conductivity of Mg 0.94 Fe 0.06 SiO 3 bridgmanite single crystal agrees with previously determined values at ambient pressure; it is almost pressure-independent in the investigated pressure range. Furthermore, our results confirm the reduced radiative conductivity scenario for the Earth’s lower mantle, while the assessment of the heat flow through the core-mantle boundary still requires in situ measurements at the relevant pressure-temperature conditions.

58 GEOSCIENCES↗
DOE OSTI2018

Liberation and release of rare earth minerals from Middle Kittanning, Fire Clay, and West Kentucky No. 13 coal sources

Here, a laboratory REE release test procedure was designed to better understand the association and liberation characteristics of rare earth elements (REEs) from coal-based material, such as coal middlings and refuse. For this particular study, three samples of mixed-phase, middling material was collected from three coal preparation plants operating in three different coal basins and coal seams, namely Fire Clay, Middle Kittanning, and West Kentucky #13. In these release tests, the mixed-phase material was first ground in a laboratory ball mill for a designated amount of time and subsequently decarbonized using staged flotation. The REE content of the high ash tailings and low ash concentrate was determined, and the process was repeated for various target grind sizes down to the micron range. The results indicate that smaller grind sizes produce increased REE concentrations in the high ash tailings, and this result is predominantly driven by the increased ash content in the decarbonized tailings. The grinding characteristics of the Fire Clay coal source showed that more energy is needed to achieve the desired particle size reduction; however further size reduction of this sample resulted in a significantly higher ash and REE content in the tailings material due to improved liberation. For the Middle Kittanning and West Kentucky #13 sources, the grinding and release data indicates that the mineral matter is liberated at a coarser particle size, and micronizing the coals only produces marginal improvements in rare earth mineral liberation and recovery.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

“Straining” to Separate the Rare Earths: How the Lanthanide Contraction Impacts Chelation by Diglycolamide Ligands

The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid–liquid extraction experiments with solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the lanthanide series. The homoleptic [(DGA)3Ln]3+ complex was confirmed in the organic extractive solution by XAS, and this was modeled using DFT. An interplay between steric strain and coordination energies apparently gives rise to a nonlinear trend in discriminatory lanthanide ion complexation across the series. Our results highlight the importance of optimizing chelate molecular geometry to account for both coordination interactions and strain energies when designing new ligands for efficient adjacent lanthanide separation for rare-earth refining.

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

High temperature hydrothermal synthesis of rare-earth titanates: synthesis and structure of RE 5 Ti 4 O 15 (OH) (RE = La, Er), Sm 3 TiO 5 (OH) 3 , RE 5 Ti 2 O 11 (OH) (RE = Tm–Lu) and Ce 2 Ti 4 O 11

Reactions of rare-earth oxides with TiO 2 were performed in high temperature (650–700 °C) hydrothermal fluids. Two different mineralizer fluids were examined, 20 M KOH and 30 M CsF, and their respective products analyzed. When concentrated KOH fluids were used, single crystals of a variety of new OH - containing species were isolated and structurally characterized: RE 5 Ti 4 O 15 (OH) (RE = La, Er) I, Sm 3 TiO 5 (OH) 3 II and RE 5 Ti 2 O 11 (OH) (RE = Tm–Lu) III. La 5 Ti 4 O 15 (OH) I crystallizes in the orthorhombic space group Pnnm with unit cell dimensions of a = 30.5152(12) Å, b = 5.5832(2) Å, c = 7.7590(3) Å and V = 1321.92(9) Å 3 , Z = 4. Sm 3 TiO 5 (OH) 3 II crystallizes in the monoclinic space group P21/m with unit cell parameters of a = 5.6066(2) Å, b = 10.4622(4) Å, c = 6.1258(2) Å and β = 104.7390(10)°, V = 347.50(2) Å3, Z = 2. Lu5Ti2O11(OH) III crystallizes in the monoclinic space group C2/m with unit cell dimensions of a = 12.1252(9) Å, b = 5.8243(4) Å, c = 7.0407(5) Å, β = 106.939(3)° and V = 475.65(6) Å3, Z = 2. When concentrated fluoride solutions are used, mostly RE 2 Ti 2 O 7 type compounds were isolated in either cubic or monoclinic phases. In the case of cerium, Ce2Ti4O11IV was isolated that crystallizes in the monoclinic space group C2/c with unit cell parameters of a = 13.6875(7) Å, b = 5.0955(3) Å, c = 12.8592(7) Å, β = 108.964(2)° and V = 848.18(8) Å 3 , Z = 4. The synthesis, structural characterization, and supporting characterization are reported for all compounds. The work highlights the complementary nature of hydroxide and fluoride fluids in studying the reactivity of refractory oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Small hole polarons in rare-earth titanates

In this study, we investigate the behavior of hole polarons in rare-earth titanates by combining optical conductivity measurements with first-principles hybrid density functional calculations. Sr-doped GdTiO 3 (Gd 1-x Sr x TiO 3 ) was grown by molecular beam epitaxy. We show that a feature in the optical conductivity that was previously identified with the Mott-Hubbard gap is actually associated with the excitation of a small polaron. The assignment is based on an excellent match between the experimental spectra and first-principles calculations for polaron excitation mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Precision Mass Measurements of Neutron-Rich Neodymium and Samarium Isotopes and Their Role in Understanding Rare-Earth Peak Formation

The Canadian Penning Trap mass spectrometer at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility was used to measure the masses of eight neutron-rich isotopes of Nd and Sm. These measurements are the first to push into the region of nuclear masses relevant to the formation of the rare-earth abundance peak at A similar to 165 by the rapid neutron-capture process. We compare our results with theoretical predictions obtained from "reverse engineering" the mass surface that best reproduces the observed solar abundances in this region through a Markov chain Monte Carlo technique. Our measured masses are consistent with the reverse-engineering predictions for a neutron star merger wind scenario.

Orford, R.↗
NASA NTRS2023

NASA Earth Science Technology Office (ESTO) Advanced Information Systems Technology (AIST) Program: Earth Systems Digital Twins (ESDT) Standards for Interoperable Digital Twins Workshop Presentations

On September 18, 2023, NASA Earth Science Technology Office (ESTO) Advanced Information Systems Technology (AIST) Program conducted a mini-workshop that brought together seven experts to survey and discuss "Standards for Interoperable Digital Twins". Since three years, the AIST Program has been developing technologies and prototypes for Earth System Digital Twins (ESDT). During those developments and after the ESDT Workshop held in October 2022, it became clear that standard for ESDT interoperability were needed and should be defined as soon as possible. To address this challenge, the AIST program will survey ongoing development for Digital Twins standards in various domains and the September 18, 2023 Workshop represented the first step towards this understanding. Speakers during this event included: Michael Grieves (Digital Twin Institute), Siri Jodha Singh Khalsa (IEEE GRSS Standards), Trent Tinker (OGC), Ryan Berkheimer (NOAA), John Stone (NVIDIA), Thomas Geenen (ECMWF-DestinE) and Arne Berre (SINTEF-Iliad DTO and EDITO). This presentation regroups all the speakers' presentations.

Earth Science Remote Sensing; Information Systems↗
DOE OSTI2024

Opportunities for Earth Observation to Inform Risk Management for Ocean Tipping Points

Abstract As climate change continues, the likelihood of passing critical thresholds or tipping points increases. Hence, there is a need to advance the science for detecting such thresholds. In this paper, we assess the needs and opportunities for Earth Observation (EO, here understood to refer to satellite observations) to inform society in responding to the risks associated with ten potential large-scale ocean tipping elements: Atlantic Meridional Overturning Circulation; Atlantic Subpolar Gyre; Beaufort Gyre; Arctic halocline; Kuroshio Large Meander; deoxygenation; phytoplankton; zooplankton; higher level ecosystems (including fisheries); and marine biodiversity. We review current scientific understanding and identify specific EO and related modelling needs for each of these tipping elements. We draw out some generic points that apply across several of the elements. These common points include the importance of maintaining long-term, consistent time series; the need to combine EO data consistently with in situ data types (including subsurface), for example through data assimilation; and the need to reduce or work with current mismatches in resolution (in both directions) between climate models and EO datasets. Our analysis shows that developing EO, modelling and prediction systems together, with understanding of the strengths and limitations of each, provides many promising paths towards monitoring and early warning systems for tipping, and towards the development of the next generation of climate models.

Wood, Richard A. (ORCID:0000000239609513)↗