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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

A new design of a non-magnetic high-pressure anvil cell for nuclear magnetic resonance (NMR) experiments at Giga-Pascal pressures is presented, which uses a micro-coil inside the pressurized region for high-sensitivity NMR. The comparably small cell has a length of 22 mm and a diameter of 18 mm, so it can be used with most NMR magnets. The performance of the cell is demonstrated with external-force vs. internal-pressure experiments, and the cell is shown to perform well at pressures up to 23.5 GPa using 800 μm 6H-SiC large cone Boehler-type anvils. {sup 1}H, {sup 23}Na, {sup 27}Al, {sup 69}Ga, and {sup 71}Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

A reactor for high-throughput high-pressure nuclear magnetic resonance spectroscopy

The design of a reactor for operando nuclear magnetic resonance (NMR) monitoring of high-pressure gas-liquid reactions is described. The Wisconsin High Pressure NMR Reactor (WiHP-NMRR) design comprises four modules: a sapphire NMR tube with titanium tube holder rated for pressures as high as 1000 psig (68 atm) and temperatures ranging from −90 to 90 °C, a gas circulation system that maintains equilibrium concentrations of dissolved gases during gas-consuming or gas-releasing reactions, a liquid injection apparatus that is capable of adding measured amounts of solutions to the reactor under high pressure conditions, and a rapid wash system that enables the reactor to be cleaned without removal from the NMR instrument. The WiHP-NMRR is compatible with commercial 10 mm NMR probes. Reactions performed in the WiHP-NMRR yield high quality, information-rich, and multinuclear NMR data over the entire reaction time course with rapid experimental turnaround.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Magnetic properties of the itinerant A- type antiferromagnet CaCo 2 P 2 studied by Co 59 and P 31 nuclear magnetic resonance

59 Co and 31 P nuclear magnetic resonance (NMR) measurements in external magnetic and zero magnetic fields have been performed to investigate the magnetic properties of the A-type antiferromagnetic (AFM) CaCo 2 P 2 . NMR data, especially the nuclear spin lattice relaxation rates 1/T 1 exhibiting a clear peak, provide clear evidence for the AFM transition at a Néel temperature of T N ~ 110 K. The magnetic fluctuations in the paramagnetic state were found to be three-dimensional ferromagnetic, suggesting ferromagnetic interaction between Co spins in the ab plane characterizes the spin correlations in the paramagnetic state. In the AFM state below TN, we have observed 59 Co and 31 P NMR signals under zero magnetic field. From 59 Co NMR data, the ordered magnetic moments of Co are found to be in ab plane and are estimated to be 0.35 μ B at 4.2 K. Furthermore, the external field dependence of 59 Co NMR spectrum in the AFM state suggests a very weak magnetic anisotropy of the Co ions and also provides microscopic evidence of canting the Co-ordered moments along the external magnetic field directions. The magnetic state of the Co ions in CaCo 2 P 2 is well explained by the local-moment picture in the AFM state, although the system is metallic, as seen by 1/T 1 T = constant behavior.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

Measurement of conductivity and permittivity on samples sealed in nuclear magnetic resonance tubes

We present a broadband impedance spectroscopy instrument designed to measure conductivity and/or permittivity for samples that are sealed in glass tubes, such as the standard 5 mm tubes used for nuclear magnetic resonance experiments. The calibrations and corrections required to extract the dielectric properties of the sample itself are outlined. It is demonstrated that good estimates of the value of dc-conductivity can be obtained even without correcting for the effects of glass or air on the overall impedance. The approach is validated by comparing data obtained from samples sealed in nuclear magnetic resonance tubes with those from standard dielectric cells, using glycerol and butylmethylimidazolium-hexafluorophosphate as respective examples of a molecular and an ionic liquid. This instrument and approach may prove useful for other studies of permittivity and conductivity where contact to the metal electrodes or to the ambient atmosphere needs to be avoided.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Water dynamics on ice and hydrate lattices studied by second-order central-line stimulated-echo oxygen-17 nuclear magnetic resonance

Oxygen-17 stimulated-echo spectroscopy is a novel nuclear magnetic resonance (NMR) technique that allows one to investigate the time scale and geometry of ultraslow molecular motions in materials containing oxygen. The method is based on detecting orientationally encoded frequency changes within oxygen’s central-transition NMR line that are caused by second-order quadrupolar interactions. In addition to the latter, the present theoretical analysis of various two-pulse echo and stimulated-echo pulse sequences takes also heteronuclear dipolar interactions into account. As an experimental example, the ultraslow water motion in polycrystals of tetrahydrofuran clathrate hydrate is studied via two-time oxygen-17 stimulated-echo correlation functions. The resulting correlation times and those of hexagonal ice are similar to those from previous deuteron NMR measurements. Calculations of the echo functions’ final-state correlations for various motional models are compared with the experimental data of the clathrate hydrate. It is found that a six-site model including the oxygen-proton dipolar interaction describes the present results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1998

Investigation of the Possibility of Using Nuclear Magnetic Spin Alignment

The goal of the program to investigate a "Gasdynamic fusion propulsion system for space exploration" is to develop a fusion propulsion system for a manned mission to the planet mars. A study using Deuterium and Tritium atoms are currently in progress. When these atoms under-go fusion, the resulting neutrons and alpha particles are emitted in random directions (isotropically). The probable direction of emission is equal for all directions, thus resulting in wasted energy, massive shielding and cooling requirements, and serious problems with the physics of achieving fusion. If the nuclear magnetic spin moments of the deuterium and tritium nuclei could be precisely aligned at the moment of fusion, the stream of emitted neutrons could be directed out the rear of the spacecraft for thrust and the alpha particles directed forward into an electromagnet ot produce electricity to continue operating the fusion engine. The following supporting topics are discussed: nuclear magnetic moments and spin precession in magnetic field, nuclear spin quantum mechanics, kinematics of nuclear reactions, and angular distribution of particles.

Dent, William V., Jr.↗
DOE OSTI2014

Dynamics of asymmetric binary glass formers. II. Results from nuclear magnetic resonance spectroscopy

Various {sup 2}H and {sup 31}P nuclear magnetic resonance (NMR) spectroscopy techniques are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene-d{sub 3} (PS) over the full concentration range. The results are quantitatively compared to those of a dielectric spectroscopy (DS) study on the same system previously published [R. Kahlau, D. Bock, B. Schmidtke, and E. A. Rössler, J. Chem. Phys. 140, 044509 (2014)]. While the PS dynamics does not significantly change in the mixtures compared to that of neat PS, two fractions of TPP molecules are identified, one joining the glass transition of PS in the mixture (α{sub 1}-process), the second reorienting isotropically (α{sub 2}-process) even in the rigid matrix of PS, although at low concentration resembling a secondary process regarding its manifestation in the DS spectra. Pronounced dynamical heterogeneities are found for the TPP α{sub 2}-process, showing up in extremely stretched, quasi-logarithmic stimulated echo decays. While the time window of NMR is insufficient for recording the full correlation functions, DS results, covering a larger dynamical range, provide a satisfactory interpolation of the NMR data. Two-dimensional {sup 31}P NMR spectra prove exchange within the broadly distributed α{sub 2}-process. As demonstrated by {sup 2}H NMR, the PS matrix reflects the faster α{sub 2}-process of TPP by performing a spatially highly hindered motion on the same timescale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

An in-silico NMR laboratory for nuclear magnetic shieldings computed via finite fields: Exploring nucleus-specific renormalizations of MP2 and MP3

Here we developed and implemented a method-independent, fully numerical, finite difference approach to calculating nuclear magnetic resonance shieldings, using gauge-including atomic orbitals. The resulting capability can be used to explore non-standard methods, given only the energy as a function of finite-applied magnetic fields and nuclear spins. For example, standard second-order Møller-Plesset theory (MP2) has well-known efficacy for 1H and 13C shieldings and known limitations for other nuclei such as 15N and 17O. It is, therefore, interesting to seek methods that offer good accuracy for 15N and 17O shieldings without greatly increased compute costs, as well as exploring whether such methods can further improve 1H and 13C shieldings. Using a small molecule test set of 28 species, we assessed two alternatives: κ regularized MP2 (κ-MP2), which provides energy-dependent damping of large amplitudes, and MP2.X, which includes a variable fraction, X, of third-order correlation (MP3). The aug-cc-pVTZ basis was used, and coupled cluster with singles and doubles and perturbative triples [CCSD(T)] results were taken as reference values. Our κ-MP2 results reveal significant improvements over MP2 for 13C and 15N, with the optimal κ value being element-specific. κ-MP2 with κ = 2 offers a 30% rms error reduction over MP2. For 15N, κ-MP2 with κ = 1.1 provides a 90% error reduction vs MP2 and a 60% error reduction vs CCSD. On the other hand, MP2.X with a scaling factor of 0.6 outperformed CCSD for all heavy nuclei. These results can be understood as providing renormalization of doubles amplitudes to partially account for neglected triple and higher substitutions and offer promising opportunities for future applications.

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

Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR) and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements were collected on columns of Rifle sediments during acetate amendment. The laboratory experiments were designed to simulate the field experiments; changes in geophysical signals were expected to correlate with changes in redox conditions and iron speciation. Field MS logging measurements revealed vertically stratified magnetic mineralization, likely the result of detrital magnetic fraction within the bulk alluvium. Little to no change was observed in the MS data suggesting negligible production of magnetic phases (e.g. magnetite, pyrrhotite) as a result of sulfidogenesis. Borehole NMR measurements contained high levels of noise contamination requiring significant signal processing, and analysis suggests that any changes may be difficult to differentiate from simultaneous changes in water content. Laboratory MS and NMR measurements remained relatively stable throughout the course of the acetate amendment experiment, consistent with field measurements. However, SIP measurements changed during the acetate amendment associated with the formation of iron-sulfide mineral phases; a finding that is consistent with chemical analysis of the solid phase materials in the columns.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Nuclear magnetic resonance investigation of the heavy fermion system Ce 2 CoAl 7 Ge 4

We present here nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements performed on single crystalline ${\mathrm{Ce}}_{2}{\mathrm{CoAl}}_{7}{\mathrm{Ge}}_{4}$, a member of a recently discovered family of heavy fermion materials ${\mathrm{Ce}}_{2}M{\mathrm{Al}}_{7}{\mathrm{Ge}}_{4}$ ($M=\mathrm{Co}$, Ir, Ni, or Pd). Previous measurements indicated a strong Kondo interaction as well as magnetic order below ${T}_{M}=1.8\mathrm{K}$. Our NMR spectral measurements show that the Knight shift $K$ is proportional to the bulk magnetic susceptibility ${\chi}$ at high temperatures. A clear Knight shift anomaly ($K\neg{}{\propto}{\chi}$) is observed at coherence temperatures ${T}^{*}{\sim}17.5\mathrm{K}$ for ${H}_{0}{\parallel}\stackrel{\hat{}{}{}}{c}$ and 10 K for ${H}_{0}{\parallel}\stackrel{\hat{}{}{}}{a}$ at the $^{59}\mathrm{Co}$ site, and ${T}^{*}{\sim}12.5\mathrm{K}$ at the $^{27}\mathrm{Al}$(3) site for ${H}_{0}{\parallel}\stackrel{\hat{}{}{}}{a}$ characteristic of the heavy fermion nature of this compound. At high temperatures, the $^{59}\mathrm{Co}$ NMR spin-lattice relaxation rate ${T}_{1}^{{-}1}$ is dominated by spin fluctuations of the $4f$ local moments with a weak metallic background. The spin fluctuations probed by $^{59}\mathrm{Co}$ NMR are anisotropic and larger in the basal plane than in the $c$ direction. Furthermore, we find ${({T}_{1}TK)}^{{-}1}{\propto}{T}^{{-}1/2}$ at the $^{59}\mathrm{Co}$ site as expected for a Kondo system for $T>{T}^{*}$ and $T>{T}_{K}$. $^{59}\mathrm{Co}$ NQR ${T}_{1}^{{-}1}$ measurements at low temperatures indicate slowing down of spin fluctuations above the magnetic ordering temperature ${T}_{M}{\sim}1.8\mathrm{K}$. A weak ferromagnetic character of fluctuations around $\mathbf{q}=0$ is evidenced by an increase of ${\chi}T$ versus $T$ above the magnetic ordering temperature. We also find good agreement between the observed and calculated electric field gradients at all observed sites.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Low-field nuclear magnetic resonance for the in vivo study of water content in trees

Nuclear magnetic resonance (NMR) and magnetic resonance imaging have long been used to study water content in plants. Approaches have been primarily based on systems using large magnetic fields (∼1 T) to obtain NMR signals with good signal-to-noise. This is because the NMR signal scales approximately with the magnetic field strength squared. However, there are also limits to this approach in terms of realistic physiological configuration or those imposed by the size and cost of the magnet. Here we have taken a different approach – keeping the magnetic field low to produce a very light and inexpensive system, suitable for bulk water measurements on trees less than 5 cm in diameter, which could easily be duplicated to measure on many trees or from multiple parts of the same tree. Using this system we have shown sensitivity to water content in trees and their cuttings and observed a diurnal signal variation in tree water content in a greenhouse. We also demonstrate that, with calibration and modeling of the thermal polarization, the system is reliable under significant temperature variation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Low-Field Nuclear Magnetic Resonance Characterization of Carbonate and Sandstone Reservoirs From Rock Spring Uplift of Wyoming

Laboratory measurements including gas (N 2 ) porosity and permeability, time-domain nuclear magnetic resonance, thin section, and scanning electron microscopy analysis were conducted to obtain petrographical and petrophysical descriptions of the Weber Sandstone and Madison Limestone at the Rock Spring Uplift, a potential carbon dioxide storage site in Southwestern Wyoming. The relationships between pore structures, such as pore geometry, pore-size distribution, pore network, and porosity/permeability are investigated. First, using thin sections combined with scanning electron microscopy for pore structures description, all samples are described in detail from the geological, petrographysical, and diagenetic viewpoint. Results show that within the Madison Limestone, pore types include intercrystalline, vuggy, moldic, or mixed (combination of all other pore types). Both moldic and vuggy pore types are associated with samples of high porosity and permeability. Nuclear magnetic resonance relaxation time distributions show either bimodal or multimodal distributions. Large relaxation time components are associated with samples with large pores, whereas small components are dominated by small pores. The T 2 geometric mean correlates well with gas permeability. Additionally, short-time diffusion coefficients (D) were measured by pulsed field gradient method using a series of gradient strengths. We found that diffusion coefficient distributions correlate with the corresponding T 2 distributions for macropores. By comparing the dominant peak position of T 2 distributions and their corresponding diffusion coefficient distributions, we predicted the surface relaxivity of different rock types. We found that surface relaxivities of Weber Sandstone samples can be well predicted, while for Madison Limestone samples, surface relaxivities are overestimated due to diffusive pore coupling effect.

58 GEOSCIENCES↗
DOE OSTI2015

Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe 1-x Co x ) 2 As 2 studied by 75 As nuclear magnetic resonance and anisotropic resistivity

We report 75 As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe 1–x Co x ) 2 As 2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350°C for 7 days. From the observation of a characteristic shape of 75 As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (T N =170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (T N =106 K) and x=0.028 (T N =53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T 1 ), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as in the case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ρ c (T), but not with the in-plane resistivity ρ a (T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T 1 data measured under magnetic fields parallel and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe 1–x Co x ) 2 As 2 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Nuclear Magnetic Resonance Relaxation Pathways in Electrolytes for Energy Storage

Nuclear Magnetic Resonance (NMR) spin relaxation times have been an instrumental tool in deciphering the local environment of ionic species, the various interactions they engender and the effect of these interactions on their dynamics in conducting media. Of particular importance has been their application in studying the wide range of electrolytes for energy storage, on which this review is based. Here we highlight some of the research carried out on electrolytes in recent years using NMR relaxometry techniques. Specifically, we highlight studies on liquid electrolytes, such as ionic liquids and organic solvents; on semi-solid-state electrolytes, such as ionogels and polymer gels; and on solid electrolytes such as glasses, glass ceramics and polymers. Although this review focuses on a small selection of materials, we believe they demonstrate the breadth of application and the invaluable nature of NMR relaxometry.

25 ENERGY STORAGE↗