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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Engineering Na‐Rich P2‐Type Layered Oxides Through Li/Ti Dual Doping for Oxygen Redox Activation and Superior Structural Stability

Sodium layered oxides Na x MO 2 (x ≤ 1 and M = transition metal ions) have gained significant interest as sodium-ion battery (NIB) cathodes owing to their high operating voltages and potential for higher energy density compared with polyanion and Prussian blue–type cathodes. However, their practical applications are often hindered by the irreversible structural transitions leading to capacity fading during cycling. The nature and substitution of transition metal ions define the material properties and electrochemical performance. In this study, through comprehensive electrochemical characterization combined with multi-scale structural and spectroscopical analyses, we demonstrate the synergistic impacts of Lithium and Titanium doping, which not only increases overall capacity by boosting cation and anion cooperative redox contributions but also improves the rate capability and cycling stability. Specifically, Li + doping enhances the available sodium inventory for extraction, while Ti 4+ disrupts Na + /vacancy ordering at lower voltages (< 4 V) and mitigates the detrimental P2→OP4/O2 phase transition during cycling. The combined effect of Lithium and Titanium doping promotes more charge localization on Oxygen, which activates reversible lattice oxygen redox reactions at elevated voltages, contributing additional capacity beyond conventional cationic redox. This work provides crucial insights into the design of high-performance, high-capacity P2-type layered cathode materials for sodium-ion batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Tailoring P2/P3‐Intergrowth in Manganese‐Based Layered Transition Metal Oxide Positive Electrodes via Sodium Content for Na‐Ion Batteries

High-manganese content sodium-ion positive electrodes have received heightened interest as an alternative to contemporary Li-ion chemistries due to their high abundance, low toxicity, and even geographical distribution. However, these materials typically suffer from poor capacity, unstable cycling performance, and sluggish Na + kinetics. Herein, we explore a manganese-based layered transition metal oxide (Na x N 0.25 Mn 0.75 O 2 ) and show by X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) that careful variation of the sodium content can instigate the formation of a biphasic intergrowth. This intergrown P2/P3 material offered a higher capacity than its monophasic P2 counterpart due to the P3 structure having greater low-voltage Mn 3+/4+ redox. Further, the intergrowth material offers greatly enhanced kinetics and cycling stability when compared to single-phase P3 material, due to the stabilizing nature of the P2 structure, elucidated by galvanostatic intermittent titration technique (GITT) and operando synchrotron X-ray diffraction. These results highlight the beneficial effect that the intergrowth structure has on the electrochemical performance of high-manganese content positive electrode for future sodium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

4 V Na Solid State Batteries Enabled by a Scalable Sodium Metal Oxyhalide Solid Electrolyte

All-solid-state sodium batteries (ASSSBs) are viable candidates for large scale energy storage that could vie with lithium. Ductile solid catholytes for such cells that can be prepared without extensive ball milling and directly paired with high voltage sodium cathodes are lacking, however. We report a new amorphous fast Na-ion conducting metal oxychloride that meets these criteria, synthesized through a scalable and low-cost route based on a spontaneous solid-state reaction with simple short mixing and 100 °C annealing. It has an ionic conductivity of 1.2 mS·cm–1 and low activation energy of 0.31 eV. Due to its dual O2–/Cl– framework, it exhibits a high anodic potential of 4 V vs Na+/Na and good chemical/electrochemical compatibility with high voltage sodium cathode materials. ASSSBs consisting of the oxychloride solid electrolyte paired with a high voltage P2–Na2/3Ni1/3Mn2/3O2 cathode showed stable long-term cycling with a 4.0 V vs Na3Sn cutoff potential and even to 4.3 V.

solid-state electrolyte, solid-state batteries, Nu↗
DOE OSTI2026

Mechanistic insight into the effects of A-site doping in perovskite nanorods on interfacial Li-ion and Na-ion transport in polymer–perovskite composite electrolytes

Composite polymer electrolytes (CPEs) offer a promising pathway to safer and higher energy density electrochemical energy storage yet optimizing interfacial ion transport remains a critical challenge due to high resistances and a lack of understanding of the complex interfacial electrostatic interactions. This work investigates the mechanistic origins of the interfacial ion transport enhancement in single-ion conducting (SIC) polymer electrolytes filled with A-site disordered perovskite LaxMyTiOz (LMTO) (M = Li, Na, K) nanorods. By integrating Density Functional Theory (DFT) with broadband dielectric spectroscopy (BDS) and pulsed-field-gradient NMR (PFG-NMR), we analyze the ion transport behavior in Li-based and Na-based SIC systems containing compositionally distinct LMTO fillers (LMTO800 and LMTO900). Specifically, we introduce the site-to-site energy difference (ΔE) descriptor, which extends beyond single-site descriptors such as adsorption energy and ion binding energies. We demonstrate that ΔE together with ion binding energies provide a more comprehensive picture of the energy landscape at the polymer–ceramic interface. The combined DFT and experimental results show that A-site doping in the ceramic filler can effectively modulate ΔE and ion binding energies, creating a favorable potential energy landscape that promotes enhanced ion transport along the interface. This comprehensive study illustrates the impact of ceramic compositional tuning on interfacial ion transport and provides materials design rules towards real-world applications.

B shepard, Lauren [Pennsylvania State University]↗
DOE OSTI2024

Unraveling the magnetic ground state in the alkali-metal lanthanide oxide Na 2 ⁢Pr⁡O 3

Here, a comprehensive set of muon spin spectroscopy and neutron scattering measurements supported by ab initio and model Hamiltonian simulations have been used to investigate the magnetic ground state of Na 2 ⁢PrO 3 . μSR reveals a Néel antiferromagnetic order below T N ~ 4.9K, with a small static magnetic moment m static ≤ 0.22 μ B /Pr collinearly aligned along the c axis. Inelastic neutron measurements reveal the full spectrum of crystal field excitations and confirm that the Pr 4+ ground-state wave function deviates significantly from the Γ 7 limit that is relevant to the Kitaev model. Single- and two-magnon excitations are observed in the ordered state below T N =4.6K and are well described by nonlinear spin wave theory from the Néel state using a magnetic Hamiltonian with Heisenberg exchange J=1 meV and symmetric anisotropic exchange Γ/J=0.1, corresponding to an XY model. Intense two magnon excitations are accounted for by g-factor anisotropy g z /g ± = 1.29. A fluctuating moment δm 2 = 0.57 ⁢(22) ⁢μ$^2_B$/Pr extracted from the energy and momentum integrated inelastic neutron signal is reduced from expectations for a local J = 1/2 moment with average g factor g avg ≈ 1.1. Together, the results demonstrate that the small moment in Na 2 ⁢PrO 3 arises from crystal field and covalency effects and the material does not exhibit significant quantum fluctuations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Structure of odd-mass Ne, Na, and Mg nuclei

The island of inversion is a region of neutron-rich nuclei around 31 Na that are deformed in their ground states. In this region, less is known about the energy levels of odd-mass nuclei, how they evolve with increasing neutron numbers, and how they can be organized into rotational bands. We perform ab initio coupled-cluster calculations of spectra in odd-mass Ne, Na, and Mg nuclei based on an interaction of chiral effective field theory. In conclusion, our results confirm some tentative spin and parity assignments, predict the structure of nuclei near the neutron dripline, and inform us about rotational bands in this region of the nuclear table.

20 ≤ A ≤ 38↗
DOE OSTI2024

Synthesis and structural characterization of a hydrated sodium–caesium tetracosatungstate(VI), Na 5 Cs 19 [W 24 O 84 ]·21H 2 O

Crystal formation of penta­sodium nona­deca­cesium tetra­cosa­tungstate(VI) heneikosahydrate, Na 5 Cs 19 [W 24 O 84 ]·21H 2 O, was successfully achieved by the conversion of [H 2 W 12 O 42 ] 10– through the addition of excess Cs + . The crystal structure comprising the toroidal isopolyoxidometalate is presented, as well as its Raman spectrum. Na 5 Cs 19 (H 2 O) 21 W 24 O 84 crystallizes in the rhombohedral space group R$\overline{3}$ with an obverse centering. The title compound represents the addition of a new member to the isopolytungstate family with mixed alkali counter-ions and contains rarely observed five-coordinate tungsten(VI) atoms in the [W 24 O 84 ] 24– anion (site symmetry C 3i ) arising from the conversion mediated by Cs + counter-ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Strain phase equilibria and phase‐field method of ferroelectric polydomain: A case study of monoclinic K x Na 1 − x NbO 3 thin films

Abstract Knowledge of the thermodynamic equilibria and domain structures of ferroelectrics is critical to establishing their structure–property relationships that underpin their applications from piezoelectric devices to nonlinear optics. Here, we establish the strain condition for strain phase separation and polydomain formation and analytically predict the corresponding domain volume fractions and wall orientations of, relatively low symmetry and theoretically more challenging, monoclinic ferroelectric thin films by integrating thermodynamics of ferroelectrics, strain phase equilibria theory, microelasticity, and phase‐field method. Using monoclinic K x Na 1 − x NbO 3 (0.5 < x < 1.0) thin films as a model system, we establish the polydomain strain–strain phase diagrams, from which we identify two types of monoclinic polydomain structures. The analytically predicted strain conditions of formation, domain volume fractions, and domain wall orientations for the two polydomain structures are consistent with phase‐field simulations and in good agreement with experimental results in the literature. The present study demonstrates a general, powerful analytical theoretical framework to predict the strain phase equilibria and domain wall orientations of polydomain structures applicable to both high‐ and low‐symmetry ferroelectrics and provide fundamental insights into the equilibrium domain structures of ferroelectric K x Na 1 − x NbO 3 thin films that are of technology relevance for lead‐free dielectric and piezoelectric applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Dual mechanism of the OXA-23 carbapenemase inhibition by the carbapenem NA-1-157

Carbapenem-resistant Acinetobacter baumannii continues to be a leading cause of life-threatening infections that result in high mortality rates. The major cause of carbapenem resistance in this pathogen is the production of class D carbapenemases, enzymes that inactivate the last resort carbapenem antibiotics, thus significantly diminishing the available therapeutic options. In this study, we evaluated the interaction of OXA-23, the most widely disseminated class D carbapenemase in A. baumannii clinical isolates, with the atypically modified carbapenem, NA-1-157. The MICs of this compound against strains producing OXA-23 were reduced from highly resistant levels observed for the commercial carbapenems meropenem and imipenem (16–128 µg/mL) to sensitive or intermediate levels (2–4 µg/mL). Kinetic studies showed that NA-1-157 inhibits the enzyme due to a significant decrease (>2,000-fold) in the deacylation rate relative to its closest structural analog, meropenem. Structural studies and molecular dynamics simulations demonstrated that inhibition is caused by both the inability of a water molecule to get close enough to the scissile bond to perform deacylation and by partial decarboxylation of the catalytic lysine residue upon formation of the acyl-enzyme intermediate.

Acinetobacter baumannii↗
DOE OSTI2025

Robust COTS objective for diffraction-limited, high-NA, long front working distance imaging

We present a robust objective lens optimized for applications requiring both high numerical aperture (NA) and long front working distance imaging, comprised of all commercial-off-the-shelf (COTS) spherical singlet lenses. Unlike traditional designs that require separate collimation and refocusing stages, our approach directly converges imaged light to the back focal plane using a single lens group. Our configuration corrects spherical aberrations and efficiently collects light to achieve diffraction-limited performance across a wide range of wavelengths while simplifying alignment and assembly. Using this approach, we design and construct an example objective lens that features a long front working distance of 61 mm and a clipped NA of 0.30 (limited by an aperture in our experimental setup). We experimentally verify that it achieves monochromatic diffraction-limited resolution at wavelengths from 375 nm to 866 nm without requiring replacement of the lenses or changing the inter-lens spacings, and its performance remains robust across a 46 mm range variation in total length (by adjusting mainly the back working distance). Additionally, we develop a quantitative method to measure the field of view (FOV) using an experimentally calibrated pinhole target. Under 397 nm illumination (i.e., from 40 Ca + ion fluorescence), the objective achieves a resolution of 0.87 μm with a 540 μm FOV. This robust, all-COTS, and versatile design is well-suited for a broad range of experiments, supporting high-precision measurements and exploring quantum phenomena.

Cui, Jiafeng [Oak Ridge National Laboratory (ORNL)↗
DOE OSTI2024

Metadynamics simulations reveal mechanisms of Na + and Ca 2+ transport in two open states of the channelrhodopsin chimera, C1C2

Cation conducting channelrhodopsins (ChRs) are a popular tool used in optogenetics to control the activity of excitable cells and tissues using light. ChRs with altered ion selectivity are in high demand for use in different cell types and for other specialized applications. However, a detailed mechanism of ion permeation in ChRs is not fully resolved. Here, we use complementary experimental and computational methods to uncover the mechanisms of cation transport and valence selectivity through the channelrhodopsin chimera, C1C2, in the high- and low-conducting open states. Electrophysiology measurements identified a single-residue substitution within the central gate, N297D, that increased Ca 2+ permeability vs. Na + by nearly two-fold at peak current, but less so at stationary current. We then developed molecular models of dimeric wild-type C1C2 and N297D mutant channels in both open states and calculated the PMF profiles for Na + and Ca 2+ permeation through each protein using well-tempered/multiple-walker metadynamics. Results of these studies agree well with experimental measurements and demonstrate that the pore entrance on the extracellular side differs from original predictions and is actually located in a gap between helices I and II. Cation transport occurs via a relay mechanism where cations are passed between flexible carboxylate sidechains lining the full length of the pore by sidechain swinging, like a monkey swinging on vines. In the mutant channel, residue D297 enhances Ca 2+ permeability by mediating the handoff between the central and cytosolic binding sites via direct coordination and sidechain swinging. We also found that altered cation binding affinities at both the extracellular entrance and central binding sites underly the distinct transport properties of the low-conducting open state. This work significantly advances our understanding of ion selectivity and permeation in cation channelrhodopsins and provides the insights needed for successful development of new ion-selective optogenetic tools.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

High-temperature Raman spectroscopy of K 2 Ca(CO 3 ) 2 bütschliite and Na 2 Ca 2 (CO 3 ) 3 shortite

Raman spectra of Na 2 Ca 2 (CO 3 ) 3 shortite and K 2 Ca(CO 3 ) 2 bütschliite were measured to 715°C and 740°C respectively, under vacuum. The vibrational spectra demonstrate that shortite converts to nyerereite (Na 2 Ca(CO 3 ) 2 ) and calcite at 535°C. This assemblage is stable to ~700°C, where nyerereite begins to decompose. Bütschliite converts to the isochemical phase fairchildite at 570°C, which is stable to 665°C, where it decomposes to an assemblage of K 2 CO 3 and CaO. The variation of anharmonicity between different vibrational modes of each of the low temperature phases is assessed, and these yield insights into inter-carbonate group couplings. In conclusion, both fairchildite and nyerereite exhibit spectral features consistent with extensive disordering.

58 GEOSCIENCES↗
NASA NTRS1974

On the velocity dependence of the interstellar Na I/Ca II ratio

The correlation noted by Routly and Spitzer (1952) between the ratio of the column densities of interstellar Na I and Ca II and radial velocity in the spectra of 21 early-type stars is reinvestigated on the basis of more recent data for 64 stars. The original result is confirmed, and it is further demonstrated that the low values of Na I/Ca II are associated with large peculiar velocities relative to the local standard of rest. It is proposed that the bulk of the high-velocity components can be interpreted as old supernova remnants. A statistical analysis of the distribution with velocity of interstellar Ca II K lines observed by Adams (1949) in the directions of some 300 early-type stars is found to be consistent with this hypothesis.

Siluk, R. S.↗
NASA NTRS1974

Cosmogenic Al-26 and Na-22 in Luna-16 lunar regolith

The activities of cosmogenic isotopes Al-26 and Na-22 in two samples taken from different depths of the lunar regolith core returned by the Luna 16 automatic station were measured by scintillation gamma spectrometer. The measured activities, when recalculated to the time of sampling of the lunar surface material, are: Al-26 - 62 + or - 8 and 54 + or - 9; Na-22 - 42 + or - 8 and 48 + or - 9. Depthwise distributions of the activities of these isotopes in lunar rocks of different types indicate the presence of a considerable depth gradient of activity near the surface caused by the fall off in the fluxes of primary and secondary cosmic radiation. The absence of this gradient in the measured samples, along with data on the tracks and content of inert gases, as well as the granulometric characteristics of the regolith indicate that the surficial layer of the regolith at the sampling site underwent mixing.

Vinogradov, A. P.↗
NASA NTRS1975

Interstellar K I and Na I absorption lines near rho Ophiuchi

Results are reported for photoelectric interferometric scans of the interstellar K I (7699 A) and Na I D1 absorption lines toward rho Oph AB and omicron Sco in the complex of dark clouds near rho Oph. The scans are found to reveal a well-marked line multiplicity toward both stars. It is shown that the resolved components of the line profiles can provide a natural explanation for the difference between the radial velocity of the strongest atomic lines of Na I and Ca II and that of the much weaker molecular lines of CH(+), CH, and CN that was previously observed toward rho Oph. The less saturated 7699-A lines toward both stars yield K I column densities roughly consistent with the calculated interstellar reddening.

Hobbs, L. M.↗
NASA NTRS1975

Interstellar Na I and Ca II absorption in intercloud regions

The weak interstellar absorption lines of Na I, Ca II, and H I formed in the intercloud medium toward eight nearly unreddened stars are analyzed. Compared with the corresponding column densities within a standard cloud, the Na I/H column-density ratio is smaller by a factor probably in excess of 17, while the Ca II/H column-density ratio is about normal. These results imply that the local intercloud medium extensively contains low-density H I regions in which the temperature is at least about 2500 K and the depletion of calcium is less severe than in the clouds, by a factor of 20.

Hobbs, L. M.↗
NASA NTRS1980

Na + Xe collisions in the presence of two nonresonant lasers

Na+Xe collisions in the presence of two distinct laser fields (rhodamine 110 and Nd:glass) are investigated with reference to the response to nonresonant radiation of alkali metals collisionally perturbed by a buffer gas. It is found that the excited Na-asterisk (4s)+Xe state is produced with a measurable cross section due to two-photon absorption with field intensities as low as 10 MW/sq cm.

De Vries, P. L.↗