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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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Novel isotopic labelling and imaging techniques are used to directly observe the autocatalytic reaction and facet-selective adsorption of Fe( ii ) onto individual hematite (Fe 2 O 3 ) crystallites.
Profound morphological and fluorogenic changes ensue upon binding of a zinc ion by two polymers, each of which bears a single dipyrrin at one terminus, forming the bis(dipyrrinato)Zn( ii ) complex.
Li-Intercalation in nano-rutile TiO 2 -anodes induces loss of long-range order with the formation of ∼5 nm layered Li x TiO 2 domains with ∼1 nm columbite-like grain boundaries.
This review summarizes the progress of pre-lithiation technologies involving the fundamental research and practical application of LICs.
The replacement of lithium metal by lithium intercalated graphite was crucial for developing safe lithium-ion batteries. Superoxide-based potassium–oxygen batteries represent an exciting metal–oxygen battery with the highest energy efficiencies. However, using potassium metal is a more serious safety threat than lithium. Herein, we explore the possibility of graphite-intercalation anodes for potassium-ion oxygen batteries (PIOBs) with enhanced safety. This work demonstrates for the first time that establishing an artificial potassium salt-rich solid electrolyte interphase (SEI) enables a reversible graphite-intercalation anode (249.6 mA h g -1 after 600 cycles) in a potassium bis(trifluoromethanesulfonyl)imide (KTFSI)-based localized high-concentration electrolyte. Such an electrolyte is stable with the superoxide cathode. The PIOB delivers energy efficiencies above 90% at a depth of discharge (DOD) of 25% for 80 cycles. A three-electrode measurement shows that its overpotential mainly comes from the anode. The lifespan is limited to the gradual degradation of the artificial SEI caused by oxygen crossover. This work represents a step towards achieving holistic anode–electrolyte–cathode compatibility in a PIOB and its realistic evaluation under a controlled DOD.
Iron( iii ) hydroxide phosphate hydrate Fe 1.13 (PO 4 )(OH) 0.39 (H 2 O) 0.61 is investigated for the first time as a Na-ion battery cathode. The material exhibits similar storage capacities for Na- and Li-ions at relatively low current rates ( i.e. C/10).
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Enabling the lithium metal anode has been the holy grail for improving the energy density for the next generation advanced batteries. Developing electrolytes that will suppress Li dendrite growth and provide sufficient ionic conductivity remains a major challenge in this field. In this study, we develop a polymer–ceramic composite electrolyte for lithium metal batteries. The polymer matrix is a vinyl ethylene carbonate (VEC) based single-ion-conducting polymer electrolyte. The ceramic filler is a Li 7 La 3 Zr 0.5 Nb 0.5 Ta 0.5 Hf 0.5 O 12 high-entropy Li-garnet (HE Li-garnet) ceramic, which is less prone to surface Li 2 CO 3 formation compared to Al-doped Li garnets. The addition of HE Li-garnet leads to a 7-fold increase in the ionic conductivity (8.6 × 10 −5 S cm −1 at 30 °C) compared to the pure polymer, while maintaining a high Li + transference of 0.73. Proton nuclear magnetic resonance and thermogravimetric analysis results suggest that the addition of HE Li-garnet results in a lower degree of polymerization of VEC, leaving more unpolymerized VEC monomers in the matrix, serving as the governing mechanism for conductivity enhancement. The favorable interactions between HE Li-garnet particles and the polymer matrix lead to a stable and well-mixed composite with 2-fold enhancement of storage modulus at 40 °C. The simultaneous ion transport and mechanical property enhancement significantly improves the composite electrolyte's dendrite resistance and cycle life in Li symmetric cells. This work highlights the positive role HE Li-garnet can play in improving polymer electrolytes to enable lithium metal anodes.
A new magnetic configuration is proposed for the suppression of co-extracted electrons in a negative-ion accelerator. This configuration is produced by an arrangement of permanent magnets embedded in one accelerator grid and creates an asymmetric local magnetic field on the upstream and downstream sides of this grid. Thanks to the “concentration” of the magnetic field on the upstream side of the grid, the resulting deflection of the ions due to magnetic field can be “intrinsically” cancelled by calibrating the configuration of permanent magnets. At the same time, the suppression of co-extracted electrons can be improved.
A 12 × 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions {sup 9}Be(α, nγ){sup 12}C, {sup 9}Be(d, nγ){sup 12}C, and {sup 12}C(d, pγ){sup 13}C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle.
Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range—indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs.
Here, a Particle X-ray Temporal Diagnostic (PXTD) has been implemented on OMEGA for simultaneous time-resolved measurements of several nuclear products as well as the x-ray continuum produced in High Energy Density Plasmas and Inertial Confinement Fusion implosions. The PXTD removes systematic timing uncertainties typically introduced by using multiple instruments, and it has been used to measure DD, DT, D 3 He, and T 3 He reaction histories and the emission history of the x-ray core continuum with relative timing uncertainties within ±10-20 ps. This enables, for the first time, accurate and simultaneous measurements of the x-ray emission histories, nuclear reaction histories, their time differences, and measurements of T i (t) and T e (t) from which an assessment of multiple-ion-fluid effects, kinetic effects during the shock-burn phase, and ion-electron equilibration rates can be made.
Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn3+. We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn3+ may be introduced into MnO2 by an electrochemically induced comproportionation reaction with Mn2+ and that Mn3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn3+-activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies show that Mn3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn3+(Td) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the d-MnO2 polymorph incorporating Mn3+ ions.
Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, 'freshly injected' PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ∼0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.
The Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) paused production of carbon-14 ion beams with the removal of the Tandem Van de Graaff in 2013. Installation of ECR3, an Electron Cyclotron Resonance Ion Source, returned that production capability to ATLAS, with the first C-14 beam delivered in December 2020. Information is presented on C-14 beam current, gas consumption and N-14 filtering techniques using stripping foils at different sections of ATLAS. ECR3 also fulfilled the operational goal of adding flexibility to ATLAS stable beam production capabilities. Beneficial impacts to ATLAS operation, beam development and experimental programs are discussed.
Phase transformations induced in the cubic C-type lanthanide sesquioxides, Ln 2 O 3 (Ln = Sm, Gd, Ho, Tm, and Lu), by dense electronic excitation are investigated. The structural modifications resulting from exposure to beams of 185 MeV Xe and 2246 MeV Au ions are characterized using synchrotron x-ray diffraction and Raman spectroscopy. The formation of a B-type polymorph, an X-type nonequilibrium phase, and an amorphous phase are observed. The specific phase formed and the transformation rate show dependence on the material composition, as well as the ion beam mass and energy. Atomistic mechanisms for these transformations are determined, indicating that formation of the B-type phase results from the production of anti-Frenkel defects and the aggregation of anion vacancies into planar clusters, whereas formation of the X-type and amorphous phases requires extensive displacement of both anions and cations. Here, the observed variations in phase behavior with changing lanthanide ionic radius and deposited electronic energy density are related to the energetics of these transformation mechanisms.
In the present study, a theoretical study of electron-phonon (electron-ion) coupling rates in semiconductors driven out of equilibrium is performed. Transient change of optical coefficients reflects the band gap shrinkage in covalently bonded materials, and thus, the heating of atomic lattice. Utilizing this dependence, we test various models of electron-ion coupling. The simulation technique is based on tight-binding molecular dynamics. Our simulations with the dedicated hybrid approach (XTANT) indicate that the widely used Fermi's golden rule can break down describing material excitation on femtosecond time scales. In contrast, dynamical coupling proposed in this work yields a reasonably good agreement of simulation results with available experimental data.
The magnetic ground state of the quasi-one-dimensional spin-1 antiferromagnetic chain is sensitive to the relative sizes of the single-ion anisotropy (D) and the intrachain (J) and interchain (J') exchange interactions. The ratios D/J and J' /J dictate the material's placement in one of three competing phases: a Haldane gapped phase, a quantum paramagnet, and an XY-ordered state, with a quantum critical point at their junction. We have identified [Ni(HF 2 )(pyz) 2 ] SbF 6 , where pyz = pyrazine, as a rare candidate in which this behavior can be explored in detail. Combining neutron scattering (elastic and inelastic) in applied magnetic fields of up to 10 tesla and magnetization measurements in fields of up to 60 tesla with numerical modeling of experimental observables, we are able to obtain accurate values of all of the parameters of the Hamiltonian [D = 13.3(1) K, J = 10.4(3) K, and J' = 1.4(2) K], despite the polycrystalline nature of the sample. Density-functional theory calculations result in similar couplings (J = 9.2 K, J' = 1.8 K) and predict that the majority of the total spin population resides on the Ni(II) ion, while the remaining spin density is delocalized over both ligand types. Finally, the general procedures outlined in this paper permit phase boundaries and quantum-critical points to be explored in anisotropic systems for which single crystals are as yet unavailable.