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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Gas-solid reaction pathway for chlorination of rare earth and actinide metals using hydrogen and chlorine gas

Hydriding and chlorination of buttons of metallic cerium have been tested as a head-end step to separating metal impurities from actinides. The objective here was to achieve complete conversion to chlorides while maintaining high surface area via small particles and open porosity. Hydriding by reaction with 100% H 2 gas at 573 K was successful at reducing cm-scale metal buttons into small particles/fragments. This step was followed by reaction with flowing 99.5% anhydrous Cl 2 gas at temperatures ranging from 423 to 573 K for 60 min. In experiments reported here, up to 92% conversion to cerium chloride was achieved from reacting with the anhydrous chlorine gas. The final chloride product has high porosity coupled with small particle sizes (microns to 1600 μm), which makes it suitable for subsequent purification processes. Higher chlorine concentrations in the gas favor higher conversion to chloride. The optimal temperature to achieve high chlorination is 523 K. Oxygen is a minor impurity in the chlorine gas which appears to prevent complete chlorination from being achieved.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1993

Research on Earth's rotation and the effect of atmospheric pressure on vertical deformation and sea level variability

The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.

Wahr, John↗
DOE OSTI2023

Chemical durability and corrosion-induced microstructure evolution of compositionally complex titanate pyrochlore waste forms with uranium incorporation

Chemical durability of compositionally-complex rare-earth titanate pyrochlore solid solutions with or without uranium incorporation was investigated by semi-dynamic leaching testing. A Ti-enriched amorphous passivation film formed on the surface due to the surface alteration-reorganization mechanism with preferential release of the weakly oxygen-bonded rare earth elements. Elemental release was found to be strongly correlated with chemical disorder, with a negligible correlation with entropy. The release rate of the uranium gradually decreased with increasing numbers of components, implying a possibility of designing and optimizing waste form performance with enhanced chemical durability by controlling composition complexity and chemical disorder for effective nuclear waste management.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2002

Defining Top-of-Atmosphere Flux Reference Level for Earth Radiation Budget Studies

To estimate the earth's radiation budget at the top of the atmosphere (TOA) from satellite-measured radiances, it is necessary to account for the finite geometry of the earth and recognize that the earth is a solid body surrounded by a translucent atmosphere of finite thickness that attenuates solar radiation differently at different heights. As a result, in order to account for all of the reflected solar and emitted thermal radiation from the planet by direct integration of satellite-measured radiances, the measurement viewing geometry must be defined at a reference level well above the earth s surface (e.g., 100 km). This ensures that all radiation contributions, including radiation escaping the planet along slant paths above the earth s tangent point, are accounted for. By using a field-of- view (FOV) reference level that is too low (such as the surface reference level), TOA fluxes for most scene types are systematically underestimated by 1-2 W/sq m. In addition, since TOA flux represents a flow of radiant energy per unit area, and varies with distance from the earth according to the inverse-square law, a reference level is also needed to define satellite-based TOA fluxes. From theoretical radiative transfer calculations using a model that accounts for spherical geometry, the optimal reference level for defining TOA fluxes in radiation budget studies for the earth is estimated to be approximately 20 km. At this reference level, there is no need to explicitly account for horizontal transmission of solar radiation through the atmosphere in the earth radiation budget calculation. In this context, therefore, the 20-km reference level corresponds to the effective radiative top of atmosphere for the planet. Although the optimal flux reference level depends slightly on scene type due to differences in effective transmission of solar radiation with cloud height, the difference in flux caused by neglecting the scene-type dependence is less than 0.1%. If an inappropriate TOA flux reference level is used to define satellite TOA fluxes, and horizontal transmission of solar radiation through the planet is not accounted for in the radiation budget equation, systematic errors in net flux of up to 8 W/sq m can result. Since climate models generally use a plane-parallel model approximation to estimate TOA fluxes and the earth radiation budget, they implicitly assume zero horizontal transmission of solar radiation in the radiation budget equation, and do not need to specify a flux reference level. By defining satellite-based TOA flux estimates at a 20-km flux reference level, comparisons with plane-parallel climate model calculations are simplified since there is no need to explicitly correct plane-parallel climate model fluxes for horizontal transmission of solar radiation through a finite earth.

Loeb, N. G.↗
NASA NTRS1995

Radiative and Nonradiative Transitions of the Rare-Earth Ions Tm(3+) and Ho(3+) in Y3AI5O12 and LiYF4

The optical spectra of rare earth ions in solids arise primarily from electric and magnetic dipole transitions between stark split multiplets of the 4f(sup N) electronic configuration. Electric dipole transitions are parity forbidden between levels of the 4f(sup N) configuration, while those of magnetic dipole origin are allowed. It is known from experiment, however, that the significant contributions to the intensities of most transitions are electric dipole in nature. Judd and Ofelt developed the theory of forced electric dipole transitions of rare-earth ions. This study is devoted to determining electric dipole transition probabilities and branching ratios for Tm(3+) and Ho(3+) ions in Yttrium Aluminum Garnet (YAG) and Yttrium Lithium Fluoride (YLF) using the theory of Judd and Ofelt. The radiative rates determined from the Judd-Ofelt analysis are used with measured lifetimes to find nonradiative rates of relaxation.

Walsh, Brian M.↗
DOE OSTI2025

Quantum Transduction with Abundant Elements for Cleaner Energy

This three-year project established a new approach to calculating crystal field coefficients for rare-earth elements in solids, especially for quantum applications such as transduction. Crystal field values of erbium doping several oxide hosts were presented. In addition stoichiometric materials, erbium oxide and cerium vanadate and phosphate, were simulated to understand their properties for quantum information. A fundamental enhancement to transduction enabled by magnon interaction was presented, along with magnon calculations in several oxide hosts and 2D materials.

36 MATERIALS SCIENCE↗
NASA NTRS1993

The Sub-bureau for Atmospheric Angular Momentum of the International Earth Rotation Service - A meteorological data center with geodetic applications

By exchanging angular momentum with the solid portion of the earth, the atmosphere plays a vital role in exciting small but measurable changes in the rotation of our planet. Recognizing this relationship, the International Earth Rotation Service invited the U.S. National Meteorological Center to organize a Sub-bureau for Atmospheric Angular Momentum (SBAAM) for the purpose of collecting, distributing, archiving, and analyzing atmospheric parameters relevant to earth rotation/polar motion. These functions of wind and surface pressure are being computed with data from several of the world's weather services, and they are being widely applied to the research and operations of the geodetic community. The SBAAM began operating formally in October 1989, and this article highlights its development, operations, and significance.

Salstein, David A.↗
DOE OSTI2020

Continuous-Flow Centrifugal Solid/Liquid Separation for the Recovery of Rare-Earth Elements Containing Particles from Phosphoric Acid Sludge

Phosphoric acid sludge contains acid (~54% P 2 O 5 ) and solid precipitates including rare earth elements (REEs) at concentrations of ~2200 ppm. Low-cost recovery of valuable P 2 O 5 and simultaneous solid separation could be an economically feasible approach to recovering REEs while increasing the production of phosphoric acid. The sludge, however, is a complicated stream that cannot be separated by traditional technologies because of high viscosity and a large solid content (30–40%). Guided by a force balance model, an efficient solid/liquid separation method is demonstrated, using a continuous-flow centrifugal contactor. Additionally, the shear regime is bypassed by introducing the sludge directly into the rotor where a centrifugal force is exerted on the fluid, inducing phase separation. Solid particles are trapped in the contactor. High liquid recovery is demonstrated and the effects of process parameters on solid capture are investigated. Three contactors in series yield 94% recovery of solids containing 1500–2895 ppm of REEs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Characterization of Precipitate Reactor Feed Tank (PRFT) Batches 44 and 49 from the Defense Waste Processing Facility (DWPF)

The Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) processes a Monosodium Titanate/Sludge Solids (MST/SS) waste stream received from the Salt Waste Processing Facility (SWPF) via the Precipitate Reactor Feed Tank (PRFT). During processing, DWPF is required to provide evidence of compliance with the Waste Acceptance Product Specifications (WAPS). Savannah River Mission Completion (SRMC) has requested Savannah River National Laboratory (SRNL) to analyze PRFT samples representing each SWPF salt batch for thirty-two radionuclides. Additionally, elemental analysis of PRFT slurry and MST/SS solids was performed to aid SRMC in further refinement of the inputs and assumptions used in future frit development and Material Tracking Program calculations. The analyses of PRFT Batches 44 and 49, which correspond to material from the processing of Salt Batches (StB) 12 and 11, respectively, are reported herein. The unwashed dried solids of the PRFT Batches 44 and 49 are predominately MST, ~63-59% MST. The two batches have a much higher amount of Fe, Mn, and Ni compared to all previous batches. For Batch 44 this appears to be due to the use of a sludge simulant filter aid during processing of StB 12 and for Batch 49, it is possibly due to the larger amount of insoluble solids for StB 11 in comparison to all previous salt batches. Like previous PRFT batches, a significant amount of the unwashed dried solids are alkaline earth metals. The total sulfate, in mg/kg of slurry, for PRFT Batches 44 and 49 is 119 and 139, respectively, which is well below the current sulfate concentration used in Material Tracking Program calculations and is in agreement with DWPF laboratory sulfate measurements.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1992

High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

Chubb, Donald L.↗
NASA NTRS1993

High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

Chubb, Donald L.↗
DOE OSTI2024

Microbial Reduction of Manganese Oxides From AMD Solids for the Biomining of Critical Minerals / Rare Earth Elements

Abandoned Coal-Mine Drainage (AMD) is a source of critical minerals (CMs) that can be biomined to increase domestic CM production for the growing tech industry while mitigating current AMD hazardous waste. Pennsylvania has ~11,000 abandoned mines, ~500 of which are currently being treated with passive remediation systems (PRS), designed to increase the pH and precipitate AMD waste onsite. Manganese (Mn) that precipitates from AMD waste can co-precipitate with CMs, and the Mn and CMs will accumulate on the PRS solids over the treatment period. This results in high Mn/CM solids that could produce a valuable leachate if resolubilized. Mn reduction and solubilization can occur through microbial driven geochemical changes such as the acidification of the environment, and it is expected that Mn resolubilization will lead to a co-resolubilization of the CMs. Investigation and stimulation of this microbial resolubilization could result in an affordable CM release process that does not require chemical additives into the environment. However the microbial mechanisms that contribute to Mn resolubilization are poorly understood. Here, we have isolated bacteria capable of resolubilizing Mn from AMD PRS. Five of the bacteria isolates have been identified as Bacillus spp. and two as Corynebacterium spp. that ferment glucose to reduce/solubilize Mn MnO2 by acidogenesis. The bacterial isolates are also capable of solubilizing Mn and CMs (Y, Zr, Sb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) from AMD PRS precipitated solids through their production of organic acids. Determining the microbial metabolism and genes involved in the resolubilization of manganese is crucial to optimize the biomining of CMs from AMD solid precipitants. This work addresses the growing need to develop novel CM recovery methods from domestic sources.

critical minerals↗
NASA NTRS1981

Technologies for the multispectral mapping of earth resources

The application of solid-state detector array imaging to the remote sensing of the earth as a follow-on to currently planned Landsat missions provides the opportunity to achieve significantly increased performance. First-order advantages to be anticipated are higher sensitivity resulting in greater radiometric accuracies and improved geometric fidelity. The Multispectral Mapper design concept is responsive to a broad range of user needs by incorporating in-flight selection of spectral bands, instantaneous fields of view, and swath width. This versatility is achieved by the use of an imaging spectrometer which permits both spatial and spectral sampling in the image plane using area array detectors. Other improvements over the current Landsat multispectral scanner and Thematic Mapper include higher spatial resolution and inherently precise registration of the spectral bands. The key technologies required in order to realize these improvements include short-wavelength infrared detectors, wide field of view, broad spectral coverage optics, focal plane cooling, and high-speed onboard signal processing. Significant development activities will be required if an advanced remote sensing capability is to be implemented.

Wellman, J. B.↗
DOE OSTI2025

Coherent control of strongly interacting spins in the solid-state

The major goal of this project is to develop coherent interacting spin systems in the solid state, based on rare earth ions. By leveraging the ability to controllably incorporate rare earth ions such as Er into a solid-state host, and maintain individual-ion addressability below the diffraction limit based on inhomogeneous broadening, we aim to create strongly interacting electron spin clusters with individual-site control. Performing spectroscopy of these strongly interacting systems will shed light on their fundamental properties, as well as enable applications to quantum information science, in particular quantum networks that are also enabled by a telecom-band spin-photon interface in Er.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Trace Metal Uptake and Mercury Methylation by Sediments from a Stream in Tennessee

The formation and transport of methylmercury (MeHg), a neurotoxin, in aquatic environments is a global concern for human health as MeHg can bioaccumulate and biomagnify to high concentrations in aquatic food webs. MeHg is formed by conversion from inorganic mercury through microbial mediated methylation. Sulfate-reducing bacteria have been identified as the primary organisms responsible for MeHg production. Pure-culture studies suggest that low availability of cobalt and copper may inhibit mercury methylation, but whether such limitations occur in the environment is unclear. To explore the possible interaction between trace metal availability and mercury methylation, sediments from the East Fork Poplar Creek in Oak Ridge, Tennessee were sampled and then incubated in the presence and absence of added dissolved cobalt and copper. Three types of data are provided in this package. The first reports the uptake of dissolved cobalt and copper by these stream sediments on short time scales (24 hours) in the form of final dissolved and adsorbed concentrations. The second data component consists of a time series of dissolved concentrations and pH values for stream sediments incubated with artificial stream water containing different addition levels of dissolved cobalt or copper. The dissolved concentrations reported include total iron, manganese, sulfur, phosphorus, nickel, zinc and cobalt, dissolved concentrations of sulfate and orthophosphate, and the amount of cobalt or copper adsorbed by the sediment. The third data component reports data at 0 and 72 hours of incubation time for stream sediments to which cobalt was added. These data include concentrations of methylmercury with isotope labeling to enable determination of methylation and demethylation rates as well as dissolved concentrations of sulfate, phosphate, chloride, iron, cobalt, and organic carbon. All data are provided in text-based CSV format with header sections indicating the data contained in each file and the corresponding units. Note that "u" is used in place of Greek lower-case mu to indicate the micro prefix on units. A Table of Contents file (Data_package_TableofContents.txt) provides an index for the data contained in the individual files.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy

Density functional theory (DFT) and its extensions, such as DFT+U and DFT+dynamical mean-field theory, are invaluable for studying magnetic properties in solids. However, rare-earth (R) materials remain challenging due to self-interaction errors and the lack of proper orbital polarization. We show how the orbital dependence of self-interaction error contradicts Hund’s rules and plagues magnetocrystalline anisotropy (MA) calculations, and how analyzing DFT states that respect Hund’s rules can mitigate this issue. We benchmark MA in RCo 5 , R 2 Fe 14 B, and RFe 12 , extending prior work on RMn 6 Sn 6 , achieving excellent agreement with experiments. Additionally, we illustrate a semi-analytical perturbation approach that treats crystal fields as a perturbation in the large spin-orbit coupling limit. Using Gd-4f crystal-field splitting, this method provides a microscopic understanding of MA and enables rapid screening of high-MA materials.

36 MATERIALS SCIENCE↗