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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

A theoretical study of Na(H2O)n(+) (n = 1-4)

The successive H2O binding energies of Na(H2O)n(+) are in excellent agreement with experiment and are rather insensitive to electron correlation since the bonding is predominantly electrostatic. A point-charge model shows that changes in the successive binding energies are due primarily to ligand-ligand repulsion. Vibrational frequencies and IR intensities are determined for Na(H2O)n(+) (n = 1-4) at the self-consistent-field and second-order Moller-Plesset levels of theory to facilitate experimental study of these ions.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1991

A study of Na(x)Pt3O4 as an O2 electrode bifunctional electrocatalyst

The present study suggests that polytetrafluoroethylene (PTFE) bonded Na(X)Pt3O4 gas porous diffusion electrodes may be a viable candidate for bifunctional O2 reduction and evolution activity. The electrodes exhibited Tafel slopes of about 0.06 V/decade for both O2 reduction an evolution. For O2 reduction, the 0.06 slope doubled to 0.12 V/decade at larger current densities. Preliminary stability testing at 24 C suggest that the Na(x)Pt3O4 electrodes were relatively stable at reducing and oxidizing potentials typically encountered at the O2 electrodes in a regenerative fuel cell.

Fielder, William L.↗
NASA NTRS1992

Silicon isotopic composition in large meteoritic SiC particles and Na-22 origin of Ne-22

Large SiC particles extracted from acid-insoluble residues of carbonaceous chondrites are isotopically anomalous in both silicon and carbon and contain isotopically extreme noble gases. These particles are thought to have originated in mass outflows from red giant stars and to have existed in the interstellar medium at the time the solar system formed from an interstellar cloud. Calculations show that the silicon isotope correlations in those large SiC particles can be generated only in the most massive carbon stars. Consequently, the almost pure Ne-22 in those particles must be interpreted as the condensation of radioactive Na-22 in the particles as they flowed away from the stars. The Na-22 is produced through proton capture by Ne-21 at the base of the surface convection zone. Ne-22 does not exist abundantly in helium shells hot enough to burn magnesium, which is necessary to establish the measured silicon isotopic composition.

Brown, Lawrence E.↗
NASA NTRS1994

Drink composition and cycle-ergometer endurance in men: Carbohydrate, Na(+), osmolality

Cycle-ergometer endurance performance was determined in 5 untrained men (22-39 yr, 62.4-100.5 kg, 29-55 mL x min(exp -1) x kg(exp -1) peak oxygen uptake) after consuming Nothing (N) or two fluid formulations (10 mL x kg(exp -1), 555-998 mL). Performance 1 (P1), a multi-ionic-glucose rehydration drink, contains 55 mEq/L Na(exp +), 416 mg/dL citrate, 2,049 mg/dL glucose, and 365 mOsm/kgH2O. HyperAde (HA), a sodium chloride-citrate hyperhydration drink, contains 164 mEq/L Na(exp +), 854 mg/dL citrate, less than 0.5 mg/dL glucose, and 253 mOsm/kgH2O. Endurance at a load of 87-91 percent of peak VO2 was 30.50 +/- SE 3.44 min with HA; 24.55 +/- 1.09 min with P1 (p greater than 0.10 from HA); and 24.68 +/- 1.50 min with N (p less than 0.05 from HA). The attenuated endurance performance with P1 and N could not be attributed to differences in exercise metabolism, change or absolute level of rectal and mean skin temperature, or change in perceived exertion. The greater increase in resting plasma volume with HA, compared with P1 or N, probably contributed to the greater endurance with HA.

Greenleaf, J. E.↗
NASA NTRS1995

Intensity oscillations in Na(I) D1 and D2 lines

The central intensities of Na(I) D1 and D2 linear profiles at the sites of the chromospheric bright points in the interior of the supergranulation cells were derived from photographic spectra. The observation scheme sampled spectra simultaneously in seven lines at a repetition rate of 12 sec. It is shown that the Na(I) D1 and D2 lines exhibit a four minute periodicity in their intensity oscillations. It is seen that the period of intensity oscillations decreases outwardly from the photosphere to the corona. It is surmised that the spatial and temporal relationships between intensity and/or velocity in the photosphere and chromosphere may explain the physical mechanisms of the underlying oscillations.

Kariyappa, R.↗
NASA NTRS1999

Abundances and Distributions of Volatile Elements (Na, S, Cl, K) Within Lunar Volcanic Glass Spheres

This research developed and applied high-precision analytical methods (electron microprobe) to determine the major- and minor-element abundances (Si, Ti, A], Cr, Fe, Mn, Mg, Ca, Na, K) in three suites of Apollo 14 volcanic green glasses. Since the precision of these data was a factor of 5-10 better than previously published results, the data provided the strongest constraints yet achieved on the geochemical processes that operated at depths less than 400 kilometers inside the Moon. The results of this work were submitted to the 29th Lunar and Planetary Science Conference, formed the basis for a Master's Thesis, and were published in the top-tier geochemical journal. Additional high-precision data on the trace abundances of sodium (Na), sulfur (S), and potassium (K) in the Apollo 17 volcanic orange glasses (74220) were also acquired during this grant-period. These data show diffusion profiles within individual 200-micron diameter, glass spherules that were apparently generated during the fire-fountain eruption of this magma in the presence of a transient vapor phase. Although these results have not yet been published, publication is planned in 2001 after additional numerical modeling has been completed. This work has also catalyzed on-going collaborative work with Professor Timothy Grove (MIT) to analyze and understand the origin of the Apollo 15 volcanic green glasses. That work will be completed for publication in 2001.

Delano, John W.↗
NASA NTRS1990

Radiolysis of aqueous solutions of acetic acid in the presence of Na-montmorillonite

The gamma-irradiation of 0.8 mol dm-3 aqueous, oxygen-free acetic acid solutions was investigated in the presence or absence of Na-montmorillonite. H2, CH4, CO, CO2, and several polycarboxylic acids were formed in all systems. The primary characteristics observed in the latter system were: (1) Higher yield of the decomposition of acetic acid; (2) Lower yield of the formation of polycarboxylic acids; (3) No effect on the formation of methane; (4) Higher yield of the formation of carbon dioxide; and (5) The reduction of Fe3+ in the octahedral sites of Na-montmorillonite. A possible reaction scheme was proposed to account for the observed changes. The results are important in understanding heterogeneous processes in radiation catalysis and might be significant to prebiotic chemistry.

Non-NASA Center↗
NASA NTRS2012

Mercury's Na Exosphere from MESSENGER Data

MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UWS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft :0 infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The portion of the hot/cold source appears to be highly variable.

Killen, Rosemary M.↗
NASA NTRS2015

Evidence of Metasomatism in the Lowest Petrographic Types Inferred from A Na(-), K, Rich Rim Around A LEW 86018 (L3.1) Chondrule

Ordinary chondrites (OCs) represent the most abundant extraterrestrial materials and also record the widest range of alteration of primary, pristine minerals of early Solar system material available for study. Relatively few investigations, however, address: (1) the role of fluid alteration, and (2) the relationship between thermal metamorphism and metasomatism in OCs, issues that have been extensively studied in many other meteorite groups e.g., CV, CO, CR, and enstatite chondrites. Detailed elemental abundances profiles across individual chondrules, and mineralogical studies of Lewis Hills (LEW) 86018 (L3.1), an unequilibrated ordinary chondrite (UOC) of low petrographic type of 3.1 returned from Antarctica, provide evidence of extensive alteration of primary minerals. Some chondrules have Na(-), K(-), rich rims surrounded by nepheline, albite, and sodalite-like Na(-), Cl(-), Al-rich secondary minerals in the near vicinity within the matrices. Although, limited evidences of low temperature (approximately 250 C) fluid-assisted alteration of primary minerals to phyllosilicates, ferroanolivine, magnetite, and scapolite have been reported in the lowest grades (less than 3.2) Semarkona (LL3.00) and Bishunpur (LL3.10), alkali-rich secondary mineralization has previously only been seen in higher grade greater than 3.4 UOCs. This preliminary result suggests highly localized metamorphism in UOCs and widens the range of alteration in UOCs and complicates classification of petrographic type and extent of thermal metamorphism or metasomatism. The work in progress will document the micro-textures, geochemistry (Ba, Ca, REE), and isotopic composition (oxygen, Al(-)- 26 Mg-26) of mineral phases in chondrules and adjoining objects to help us understand the formation scenario and delineate possible modes of metamorphism in UOCs.

Mishra, Ritesh Kumar↗
DOE OSTI2020

Materials Data on Na(FeSb3)4 by Materials Project

NaFe4Sb12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Na1+ is bonded to twelve equivalent Sb1- atoms to form NaSb12 cuboctahedra that share faces with eight equivalent FeSb6 octahedra. All Na–Sb bond lengths are 3.41 Å. Fe+2.75+ is bonded to six equivalent Sb1- atoms to form FeSb6 octahedra that share corners with six equivalent FeSb6 octahedra and faces with two equivalent NaSb12 cuboctahedra. The corner-sharing octahedral tilt angles are 52°. All Fe–Sb bond lengths are 2.56 Å. Sb1- is bonded in a 2-coordinate geometry to one Na1+, two equivalent Fe+2.75+, and two equivalent Sb1- atoms. There are one shorter (2.97 Å) and one longer (3.06 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(CuO)2 by Materials Project

NaCu2O2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded to five O2- atoms to form distorted edge-sharing NaO5 square pyramids. There are two shorter (2.32 Å) and three longer (2.39 Å) Na–O bond lengths. There are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (1.99 Å) and two longer (2.02 Å) Cu–O bond lengths. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.85 Å) and one longer (1.87 Å) Cu–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and three Cu+1.50+ atoms to form ONa3Cu3 octahedra that share corners with seven equivalent ONa2Cu3 square pyramids, edges with four equivalent ONa3Cu3 octahedra, and edges with two equivalent ONa2Cu3 square pyramids. In the second O2- site, O2- is bonded to two equivalent Na1+ and three Cu+1.50+ atoms to form ONa2Cu3 square pyramids that share corners with seven equivalent ONa3Cu3 octahedra, edges with two equivalent ONa3Cu3 octahedra, and edges with two equivalent ONa2Cu3 square pyramids. The corner-sharing octahedra tilt angles range from 0–76°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(RhO2)2 by Materials Project

NaRh2O4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.42–2.55 Å. There are two inequivalent Rh+3.50+ sites. In the first Rh+3.50+ site, Rh+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing RhO6 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are a spread of Rh–O bond distances ranging from 2.02–2.07 Å. In the second Rh+3.50+ site, Rh+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing RhO6 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are two shorter (2.04 Å) and four longer (2.06 Å) Rh–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Rh+3.50+ atoms. In the second O2- site, O2- is bonded to two equivalent Na1+ and three equivalent Rh+3.50+ atoms to form a mixture of distorted edge and corner-sharing ONa2Rh3 square pyramids. In the third O2- site, O2- is bonded to two equivalent Na1+ and three Rh+3.50+ atoms to form a mixture of distorted edge and corner-sharing ONa2Rh3 trigonal bipyramids. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three equivalent Rh+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(CuO)2 by Materials Project

NaCu2O2 crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. Na1+ is bonded to five O2- atoms to form edge-sharing NaO5 square pyramids. There are a spread of Na–O bond distances ranging from 2.31–2.40 Å. There are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.00 Å) and two longer (2.03 Å) Cu–O bond lengths. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.85 Å) and one longer (1.86 Å) Cu–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and three Cu+1.50+ atoms to form ONa3Cu3 octahedra that share corners with seven equivalent ONa2Cu3 square pyramids, edges with four equivalent ONa3Cu3 octahedra, and edges with two equivalent ONa2Cu3 square pyramids. In the second O2- site, O2- is bonded to two equivalent Na1+ and three Cu+1.50+ atoms to form distorted ONa2Cu3 square pyramids that share corners with seven equivalent ONa3Cu3 octahedra, edges with two equivalent ONa3Cu3 octahedra, and edges with two equivalent ONa2Cu3 square pyramids. The corner-sharing octahedra tilt angles range from 0–80°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(Cu2Sb)2 by Materials Project

NaCu4Sb2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Na1+ is bonded to six equivalent Sb3- atoms to form edge-sharing NaSb6 octahedra. All Na–Sb bond lengths are 3.26 Å. There are two inequivalent Cu+1.25+ sites. In the first Cu+1.25+ site, Cu+1.25+ is bonded in a 1-coordinate geometry to three equivalent Cu+1.25+ and four equivalent Sb3- atoms. All Cu–Cu bond lengths are 2.56 Å. There are one shorter (2.70 Å) and three longer (2.88 Å) Cu–Sb bond lengths. In the second Cu+1.25+ site, Cu+1.25+ is bonded in a trigonal non-coplanar geometry to three equivalent Cu+1.25+ and three equivalent Sb3- atoms. All Cu–Sb bond lengths are 2.60 Å. Sb3- is bonded in a 10-coordinate geometry to three equivalent Na1+ and seven Cu+1.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(Mo3Se4)2 by Materials Project

Na1Mo6Se8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight Se2- atoms. There are two shorter (2.80 Å) and six longer (3.25 Å) Na–Se bond lengths. Mo+2.50+ is bonded to five Se2- atoms to form a mixture of corner and edge-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.53–2.74 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to one Na1+ and three equivalent Mo+2.50+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one Na1+ and four equivalent Mo+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(CoO2)2 by Materials Project

NaCo2O4 crystallizes in the orthorhombic Amm2 space group. The structure is two-dimensional and consists of one NaCo2O4 sheet oriented in the (0, 0, 1) direction. Na1+ is bonded to six equivalent O2- atoms to form distorted NaO6 pentagonal pyramids that share corners with six equivalent CoO6 octahedra, edges with six equivalent CoO6 octahedra, and edges with six equivalent NaO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 9–12°. There are two shorter (2.36 Å) and four longer (2.38 Å) Na–O bond lengths. Co+3.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent NaO6 pentagonal pyramids, edges with six equivalent CoO6 octahedra, and edges with three equivalent NaO6 pentagonal pyramids. There are a spread of Co–O bond distances ranging from 1.88–2.16 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Co+3.50+ atoms to form a mixture of edge, corner, and face-sharing ONa3Co3 octahedra. The corner-sharing octahedra tilt angles range from 41–47°. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Co+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(Mo2O3)2 by Materials Project

NaMo4O6 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Na–O bond lengths are 3.05 Å. There are two inequivalent Mo+2.75+ sites. In the first Mo+2.75+ site, Mo+2.75+ is bonded in a see-saw-like geometry to four O2- atoms. There are two shorter (2.05 Å) and two longer (2.12 Å) Mo–O bond lengths. In the second Mo+2.75+ site, Mo+2.75+ is bonded to five O2- atoms to form edge-sharing MoO5 square pyramids. There are one shorter (2.03 Å) and four longer (2.15 Å) Mo–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Mo+2.75+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Mo+2.75+ atoms.

36 MATERIALS SCIENCE↗