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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Experimental and theoretical study of the formation of the 2AB, 3AB, and 9A meteorite chemical groups from the parent liquid

Segregation of solute elements was measured in plane front solidified Fe-Ni-S-P alloys of meteoritic composition containing Ir, Ge and/or Cu. The Ni and P contents reach maximum values of 10.5 wt% and 1.1 wt%, respectively, in austenite (taenite) at the end of primary solidification. Distribution coefficients of Ni, P, Ir, Ge and Cu were determined from the solidified alloys. The distribution coefficients vary with the S and P content of the liquid. In addition the distribution coefficients of Ni, P, Ir and Ge increase and the distribution coefficient of Cu decreases with the S to P ratio. Equations that describe the concentration dependence of the distribution coefficients were developed and used to calculate solute redistribution during the solidification of IIAB, IIIAB and IVA parent bodies. The calculated P vs Ni, Ir vs Ni and Ge vs Ni trends are in good agreement with the observed meteoritic data. Since the calculated value of the maximum solid solubility of P agrees well with the observed maximum P composition data for IIAB and IIIAB irons, it is concluded that complete crystallization of the parent liquids of IIAB and IIIAB had occurred before any fragmentation of the solidified body.

Sellamuthu, R.↗
DOE OSTI2016

Picoliter Drop-On-Demand Dispensing for Multiplex Liquid Cell Transmission Electron Microscopy

Abstract Liquid cell transmission electron microscopy (LCTEM) provides a unique insight into the dynamics of nanomaterials in solution. Controlling the addition of multiple solutions to the liquid cell remains a key hurdle in our ability to increase throughput and to study processes dependent on solution mixing including chemical reactions. Here, we report that a piezo dispensing technique allows for mixing of multiple solutions directly within the viewing area. This technique permits deposition of 50 pL droplets of various aqueous solutions onto the liquid cell window, before assembly of the cell in a fully controlled manner. This proof-of-concept study highlights the great potential of picoliter dispensing in combination with LCTEM for observing nanoparticle mixing in the solution phase and the creation of chemical gradients.

Environmental Molecular Sciences Laboratory↗
NASA NTRS1982

Investigation of compositional segregation during unidirectional solidification of solid solution semiconducting alloys

Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.

Wang, J. C.↗
DOE OSTI2024

A bicarbonate-rich liquid condensed phase in non-saturated solutions in the absence of divalent cations

Bicarbonate (HCO 3 - ) and sodium (Na + )-containing solutions contain droplets of a separate, bicarbonate-rich liquid condensed phase (LCP) that have higher concentrations of HCO 3 - relative to the bulk solution in which they reside. The existence and composition of the LCP droplets has been investigated by nanoparticle tracking analysis, nuclear magnetic resonance spectroscopy, refractive index measurements and X-ray pair distribution function analysis. The bicarbonate-rich LCP species is a previously unaccounted-for, ionic phenomenon which occurs even in solutions with solely monovalent cations. Its existence requires re-evaluation of models used to describe and model aqueous solution physicochemistry, especially those used to describe and model carbonate mineral formation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Liquid-phase diffusion bonding: Temperature effects and solute redistribution in high temperature lead-free composite solders

Liquid-phase diffusion bonding (LPDB) is being studied as the primary phenomena occurring in the development of a high temperature lead-free composite solder paste composed of gas-atomized Cu-10Ni, wt.% (Cu-11Ni, at.%) powder blended with Sn-0.7Cu-0.05Ni-0.01Ge (Sn-1.3Cu-0.1Ni-0.02Ge, at.%) Nihon-Superior SN100C solder powder. Powder compacts were used as a model system. LPDB promotes enhanced interdiffusion of the low-melting alloy matrix with the solid Cu-10Ni reinforcement powder above the matrix liquidus temperature. The initial study involved the effective intermetallic compound (IMC) compositions and microstructures that occur at varying reflow temperatures and times between 250-300°C and 30-60s, respectively. Certain reflow temperatures encourage adequate interdiffusion to form a continuous highly-conductive network throughout the composite solder joints. The diffusion of nickel, in particular, has a disperse pattern that foreshadows the possibility of a highly-conductive low-melting solder that can be successfully utilized at high temperatures.

42 ENGINEERING↗
DOE OSTI2022

Self-organized patterns at the plasma–liquid anode interface in a helium glow discharge: temporal development and mechanisms

Self-organization at the plasma–liquid anode interface is a commonly observed phenomenon for atmospheric pressure glow plasmas, resulting in patterns with distinctive shapes such as circular ring, star-shaped, and gear-like structures, depending primarily on the discharge current and solution conductivity. Recent studies have shown that the electrode gap distance, solute used for liquid anode solution, and gas composition can also significantly impact pattern formation. Nonetheless, an overarching model or explanation of the key underlying mechanisms consistent with all experimentally observed trends is not yet reported. We propose a key underlying mechanism enabling pattern formation motivated by a detailed parametric study of pattern formation complemented by the temporal development of patterns and consistent with all observed trends. Pattern formation was observed to be on a time scale of 100 μs, similar to the time scales of gas heating and evaporation. It was found that a minimum water evaporation rate of (3.5 ± 0.5) × 10 –6 kg s –1 and reduced electric field in the positive column of 16.6 ± 0.4 Td is required for pattern formation in the investigated cases irrespective of solution conductivity and gas composition for NaCl solutions. Nonetheless, the presence of cations for which the corresponding metal atom has a low ionization energy was identified as a necessary condition for pattern formation. Furthermore, the reported results suggest that the presence of a small amount of metal atoms in the gas phase with low ionization energy enhances the overall ionization rate in the near anode region which triggers pattern formation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Exact solutions to the problem on the shape of an uncharged conducting liquid jet in a transverse electric field

Exact solutions are obtained for the problem of an equilibrium configuration of an uncharged cylindrical jet of a conducting liquid in a transverse electric field. The transverse cross section of the jet moving between two planar electrodes is deformed under the action of electrostatic forces (capillary forces play a stabilizing role). According to the solutions obtained, the initially circular cross section of the jet may be significantly (formally, unboundedly) stretched along the lines of forces of the field, and the boundaries of the jet asymptotically approach the electrodes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

WOW Technology's Innovative Radioactive Liquid Waste Treatment - 16128

WOW presents its revolutionary technology and equipment for liquid radioactive waste treatment: outperforming ultimate water decontamination and purification process, enhanced sludge concentration, no secondary waste nor consumables, fully automated, remote controlled and self-decontaminating device. The WOW's technology is based upon a never before observed discovery of fluid dynamics science: the possibility of performing a molecular separation between solute and suspended elements and the solvent. The combination of such a molecular separation process with a standard vacuum evaporation improves the abatement performances by thousands of times, with respect to those of the state of the art vacuum evaporators. In addition to this, no secondary waste is produced during the process, as no filters, membranes, resins or additives are used. WOW equipment, automated and remote controlled, self decontaminates after use and can be designed and constructed either tailored to the application needs or with a modular approach for enhanced transportability and application flexibility. After the preliminary verification by CNR, the Italian National Research Center, WOW Technology's decontamination device was tested c/o LENA, the Laboratory of Applied Nuclear Energy of the University of Pavia, Italy with a simulated solution 6000 times more contaminated than the nuclear reactor's cooling water of Fukushima-Daiichi NPP. In addition to that, WOW's technology was also used in a real case at the Radiochemistry laboratory of the Pavia's University Chemistry department. Both the above mentioned contaminated fluids have been successfully decontaminated without production of additional or secondary waste. WOW's technology has already performed on industrial scale c/o the Nuclear Repository of S.S.M. in Saluggia, Italy: 45000 liters of acid radioactive solution have been successfully decontaminated to a Decontamination Factor (DF) of 335000 for Cs-137 by one single evaporation step and without using any additional tool to control steam. [Performances independently certified by: National Physics Laboratory (UK) and Pavia University Radiochemistry Laboratory, Chemistry Department (Italy)]. The high decontamination factors and the high volume reduction of the sludge make this technology suitable for the ultimate treatment of highly contaminated liquid waste such as the Fukushima-Daiichi nuclear reactor's cooling water. The WOW's technology addresses as well to interventions in both, operating and decommissioning nuclear power plants and any other nuclear and radioactive facility whose produced and/or stored radioactive liquid solutions, including acid liquid solutions, can be successfully treated, the waste volume reduced and no secondary waste produced. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Kinetic study of the hydrogen charging reaction on the graphite e in aqueous solution and in room temperature ionic liquid (RTIL)

Electrochemical impedance spectroscopy and other electrochemical methods were used to study the kinetics of hydrogen entry into porous, isotropic graphite and a single crystal graphite surfaces upon cathodic hydrogen charging and to calculate the hydrogen adsorption efficiencies. This model was first applied to graphite in an aqueous, alkaline solution, then in a room-temperature ionic liquid (RTIL), and, ultimately will be applied to FliNaK molten salt systems in future work. The results demonstrate that our model accurately describes the entry of hydrogen into graphite in harsh environments, which are important for the development of molten salt reactors (MSRs).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Particle migration in rotating liquids

An analytical solution predicting the behavior of particles in the presence of both gravitational and rotational fields is obtained at the limit of quasi-steady creeping flow. The experiments performed in the present work using fluid particles, as well as the experiments already reported on solid particles, agree satisfactorily with the theory.

Annamalai, P.↗
DOE OSTI2021

Solution and Interface Structure and Dynamics in Geochemistry: Gateway to Link Elementary Processes to Mineral Nucleation and Growth

Our understanding of the process of mineral nucleation is starting to evolve from the solely thermodynamical aspects in classical nucleation theory toward a mechanistic study of reactions influenced by solvation structures of ions and their dynamics. A knowledge of how these atomic and molecular interactions respond to changing solution composition and/or the nature of an interface will form a fundamental foundation to understand rate-limiting reactions and processes for nucleation and growth. Here, we review recent advances from multidisciplinary experimental and computational approaches of the structure and dynamics of aqueous solutions and mineral–liquid interfaces that will influence rates of nucleation (and growth behavior) both homogeneously in aqueous solutions and heterogeneously at mineral–liquid interfaces. Furthermore, these processes include structure (and extent) of solute clustering, solvent degrees of freedom, and the presence of noninnocent charge-balancing ions, all of which can drive the selectivity and exert control over nucleation mechanisms. Similar controlling reactions can also occur at interfaces with the added complexities of how solute ions interact with and assemble on surface sites and use different mechanisms from bulk solutes, such as lateral solvent exchanges between distinct surface sites. To gain a predictive understanding of nucleation chemistry, we emphasize several key knowledge gaps that will need to be addressed in this field and highlight the importance of combining computations and experiments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Producing radiometals in liquid targets: Proof of feasibility with {sup 94m}Tc

{sup 94m}Tc was produced in a liquid target loaded with a molybdenum-salt solution. This novel technique allows for the irradiation of metals dissolved in a liquid solution, normally only available in metal powder or foil form. By using this approach, the existing liquid targets and transfer infrastructure of many PET cyclotrons can be used to produce radiometals, avoiding the need, expense and challenges of operating solid targets. Such an approach allows for rapid testing of new isotopes for proof of feasibility studies. Different concentrations of Mo solution and their effect on the target performance were tested. Sufficient quantities to allow for preclinical studies were produced.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Dynamics of Emim + in [Emim][TFSI]/LiTFSI Solutions as Bulk and under Confinement in a Quasi-liquid Solid Electrolyte

Quasi-liquid solid electrolytes are a promising alternative for next-generation Li batteries. Furthermore, these systems combine the safety of solid electrolytes with the desired properties of liquids and are typically formed by solutions of Li salts in ionic liquids incorporated into solid matrices. Here, we present a fundamental understanding of the transport properties in solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]), either in bulk form or incorporated in a boron nitride (BN) matrix. We performed a series of quasi-elastic neutron scattering experiments that, given the high incoherent neutron scattering cross section of hydrogen, allowed us to focus on the Emim + dynamics. First, [Emim][TFSI]/LiTFSI solutions (0.5 and 2.5 mol·kg –1 ) were investigated and we show how the increase in the concentration reduces the Emim+ mobility and increases the activation energy of their long-range motions. Then, the 0.5 mol·kg –1 solution was incorporated into the BN matrix and we report that the diffusivities of the Emim + cations that remain mobile under confinement are highly accelerated in comparison with the bulk sample and the activation energy of these motions is drastically reduced. We present the experimental evidence that this effect is related to the content of the Emim+ cations immobilized near the surfaces of the BN pores.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1999

Effects of G-Jitter on Directional Solidification of a Binary Alloy

A study of directional solidification of a weak binary alloy (specifically, Bi - 1 at% Sn) based on the fixed grid single domain approach is being undertaken. The enthalpy method is used to solve for the temperature field over the computational domain including both the solid and liquid phases; latent heat evolution is treated with the aid of an effective specific heat coefficient. A source term accounting for the release of solute into the liquid during solidification has been incorporated into the solute transport equation. The vorticity-stream function formulation is used to describe thermo-solutal convection in the liquid region. In this paper we present a numerical simulation of g-jitter. A background gravity of 1 microgram has been assumed, and new results for the effects of periodic disturbances over a range of amplitudes and frequencies on solute field and segregation have been presented.

Benjapiyaporn, C.↗
DOE OSTI2013

SOLIEX: A Novel Solid-Liquid Method of Radionuclides Extraction from Radioactive Waste Solutions - 13486

This paper describes recent developments in new solid-liquid extraction method, called SOLIEX, to remove cesium from alkaline solutions. SOLIEX relies on the use of a reversible complexing system comprising a carbon felt bearing molecular traps (calixarenes). This complexing system exhibits a high selectivity for Cs, and is thus expected to be helpful for the treatment of highly diluted cesium wastes even with a high concentration of competing alkali metal cations. As additional advantage, this complexing system can be adapted by molecular engineering to capture other radionuclides, such as Sr, Eu, Am. Finally, this complexing system can be easily and efficiently regenerated by using a cost effective stripping procedure, which limits further generation of waste to meet 'zero liquid' discharge requirements for nuclear facilities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Synthesis of silicon containing materials using liquid hydrosilane compositions through direct injection

An apparatus and a non-vapor-pressure dependent method of chemical vapor deposition of Si based materials using direct injection of liquid hydrosilane(s) are presented. Liquid silane precursor solutions may also include metal, non-metal or metalloid dopants, nanomaterials and solvents. An illustrative apparatus has a precursor solution and carrier gas system, atomizer and deposit head with interior chamber and a hot plate supporting the substrate. Atomized liquid silane precursor solutions and carrier gas moves through a confined reaction zone that may be heated and the aerosol and vapor are deposited on a substrate to form a thin film. The substrate may be heated prior to deposition. The deposited film may be processed further with thermal or laser processing.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microsegregation Measurement: Methods and Applications

Microsegregation is chemical variation at the microstructural level in a solidified ingot, which can cause undesirable effects on material properties. Its formation is driven by different levels of solute elemental solubility between solid and liquid phases, resulting in solute buildup or depletion in the liquid phase during solidification. Characterization of microsegregation can be essential for understanding its formation and removing it through heat treatment. Measurement is frequently carried out via scanning electron microscope (SEM), though metallographic analysis, mechanical testing and optical radiography have been used. SEM analysis can consist of point measurements on single dendrites, line scans across or along dendrites, elemental maps, and extended line-based or grid-based analyses extending over many dendrites, which can generate large amounts of data. Line-based or grid-based data can be analyzed using scatterplots of element concentrations to visualize segregation behavior and sorting/ranking of data by a single element or a combination of elements, to give compositional profiles as a function of extent of solidification. For both qualitative and quantitative analyses, effects of phase transformations and secondary phases need to be considered as well as sorting of measurement errors when generating compositional profiles. Applications of analysis include determination of partition ratios, examination of solute–element interactions, determination of effects of cooling rate and back diffusion, applications to freckling studies, validations of modeling, and development of heat-treatment profiles.

36 MATERIALS SCIENCE↗