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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Framework Short-Range Order Observed in a Spinel-Type Li Superionic Conductor

Solid-state superionic conductors are characterized by rich structural disorders. Though structural complexities are central to their functionalities, they often give rise to short-range order that eludes detection by conventional diffraction-based techniques and is thus overlooked in establishing precise structure-property relationships. In this work, we synthesized single crystals of a recently discovered lithium (Li) superionic conductor Li16.2(1)In9.00(2)Sn1.10(1)O23.8 (LISO) for in-depth characterizations of structural subtleties. LISO exhibits an unusual spinel-like phase with significant Li overstoichiometry and a face-sharing Li network. Single-crystal neutron diffraction confirms significant Li disorder, as manifested in Li site splitting and partial occupancy. More importantly, synchrotron diffuse scattering combined with 3D-ΔPDF analysis and Monte Carlo simulations reveal short-range order in the nonalkali framework that might contribute to the phase stability and ionic conductivity. This work showcases an example in which subtle local energetics can be directly visualized in structurally disordered ionic conductors.

Chen, Yu↗
DOE OSTI2018

Suppression of atom motion and metal deposition in mixed ionic electronic conductors

Many superionic mixed ionic–electronic conductors with a liquid-like sublattice have been identified as high efficiency thermoelectric materials, but their applications are limited due to the possibility of decomposition when subjected to high electronic currents and large temperature gradients. Here, through systematically investigating electromigration in copper sulfide/selenide thermoelectric materials, we reveal the mechanism for atom migration and deposition based on a critical chemical potential difference. Then, a strategy for stable use is proposed: constructing a series of electronically conducting, but ion-blocking barriers to reset the chemical potential of such conductors to keep it below the threshold for decomposition, even if it is used with high electric currents and/or large temperature differences. This strategy not only opens the possibility of using such conductors in thermoelectric applications, but may also provide approaches to engineer perovskite photovoltaic materials and the experimental methods may be applicable to understanding dendrite growth in lithium ion batteries.

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

Recycling lead and transparent conductors from perovskite solar modules

Abstract Perovskite photovoltaics are gaining increasing common ground to partner with or compete with silicon photovoltaics to reduce cost of solar energy. However, a cost-effective waste management for toxic lead (Pb), which might determine the fate of this technology, has not been developed yet. Here, we report an end-of-life material management for perovskite solar modules to recycle toxic lead and valuable transparent conductors to protect the environment and create dramatic economic benefits from recycled materials. Lead is separated from decommissioned modules by weakly acidic cation exchange resin, which could be released as soluble Pb(NO 3 ) 2 followed by precipitation as PbI 2 for reuse, with a recycling efficiency of 99.2%. Thermal delamination disassembles the encapsulated modules with intact transparent conductors and cover glasses. The refabricated devices based on recycled lead iodide and recycled transparent conductors show comparable performance as devices based on fresh raw materials. Cost analysis shows this recycling technology is economically attractive.

14 SOLAR ENERGY↗
DOE OSTI2022

Argyrodite-type advanced lithium conductors and transport mechanisms beyond paddle-wheel effect

Abstract Development of next-generation solid-state Li-ion batteries requires not only electrolytes with high room-temperature (RT) ionic conductivities but also a fundamental understanding of the ionic transport in solids. In spite of considerable work, only a few lithium conductors are known with the highest RT ionic conductivities ~ 0.01 S/cm and the lowest activation energies ~0.2 eV. New design strategy and novel ionic conduction mechanism are needed to expand the pool of high-performance lithium conductors as well as achieve even higher RT ionic conductivities. Here, we theoretically show that lithium conductors with RT ionic conductivity over 0.1 S/cm and low activation energies ~ 0.1 eV can be achieved by incorporating cluster-dynamics into an argyrodite structure. The extraordinary superionic metrics are supported by conduction mechanism characterized as a relay between local and long-range ionic diffusions, as well as correlational dynamics beyond the paddle-wheel effect.

25 ENERGY STORAGE↗
DOE OSTI2023

Layered metals as polarized transparent conductors

The quest to improve transparent conductors balances two key goals: increasing electrical conductivity and increasing optical transparency. To improve both simultaneously is hindered by the physical limitation that good metals with high electrical conductivity have large carrier densities that push the plasma edge into the ultra-violet range. Technological solutions reflect this trade-off, achieving the desired transparencies only by reducing the conductor thickness or carrier density at the expense of a lower conductance. Here we demonstrate that highly anisotropic crystalline conductors offer an alternative solution, avoiding this compromise by separating the directions of conduction and transmission. We demonstrate that slabs of the layered oxides Sr 2 RuO 4 and Tl 2 Ba 2 CuO 6+δ are optically transparent even at macroscopic thicknesses >2 μm for c-axis polarized light. Underlying this observation is the fabrication of out-of-plane slabs by focused ion beam milling. This work provides a glimpse into future technologies, such as highly polarized and addressable optical screens.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Design principles for NASICON super-ionic conductors

Na Super Ionic Conductor (NASICON) materials are an important class of solid-state electrolytes owing to their high ionic conductivity and superior chemical and electrochemical stability. In this paper, we combine first-principles calculations, experimental synthesis and testing, and natural language-driven text-mined historical data on NASICON ionic conductivity to achieve clear insights into how chemical composition influences the Na-ion conductivity. These insights, together with a high-throughput first-principles analysis of the compositional space over which NASICONs are expected to be stable, lead to the successful synthesis and electrochemical investigation of several new NASICONs solid-state conductors. Among these, a high ionic conductivity of 1.2 mS cm ₋1 could be achieved at 25 °C. We find that the ionic conductivity increases with average metal size up to a certain value and that the substitution of PO 4 polyanions by SiO 4 also enhances the ionic conductivity. While optimal ionic conductivity is found near a Na content of 3 per formula unit, the exact optimum depends on other compositional variables. Surprisingly, the Na content enhances the ionic conductivity mostly through its effect on the activation barrier, rather than through the carrier concentration. These deconvoluted design criteria may provide guidelines for the design of optimized NASICON conductors.

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

Bridging length scales in organic mixed ionic–electronic conductors through internal strain and mesoscale dynamics

Understanding the structural and dynamic properties of disordered systems at the mesoscale is crucial. This is particularly important in organic mixed ionic-electronic conductors (OMIECs), which undergo significant and complex structural changes when operated in an electrolyte. Here, in this study, we investigate the mesoscale strain, reversibility and dynamics of a model OMIEC material under external electrochemical potential using operando X-ray photon correlation spectroscopy. Our results reveal that strain and structural hysteresis depend on the sample's cycling history, establishing a comprehensive kinetic sequence bridging the macroscopic and microscopic behaviours of OMIECs. Furthermore, we uncover the equilibrium and non-equilibrium dynamics of charge carriers and material-doping states, highlighting the unexpected coupling between charge carrier dynamics and mesoscale order. These findings advance our understanding of the structure-dynamics-function relationships in OMIECs, opening pathways for designing and engineering materials with improved performance and functionality in non-equilibrium states during device operation. Understanding mesoscale structure and dynamics in organic mixed ionic-electronic conductors is crucial. Mesoscale strain kinetics and structural hysteresis have been studied, and they uncover the coupling between charge carrier dynamics and mesoscale order in organic mixed ionic-electronic conductors.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The hierarchical structure of organic mixed ionic–electronic conductors and its evolution in water

Polymeric organic mixed ionic–electronic conductors underpin several technologies in which their electrochemical properties are desirable. These properties, however, depend on the microstructure that develops in their aqueous operational environment. We investigated the structure of a model organic mixed ionic–electronic conductor across multiple length scales using cryogenic four-dimensional scanning transmission electron microscopy in both its dry and hydrated states. Four-dimensional scanning transmission electron microscopy allows us to identify the prevalent defects in the polymer crystalline regions and to analyse the liquid crystalline nature of the polymer. The orientation maps of the dry and hydrated polymers show that swelling-induced disorder is mostly localized in discrete regions, thereby largely preserving the liquid crystalline order. Therefore, the liquid crystalline mesostructure makes electronic transport robust to electrolyte ingress. Furthermore, this study demonstrates that cryogenic four-dimensional scanning transmission electron microscopy provides multiscale structural insights into complex, hierarchical structures such as polymeric organic mixed ionic–electronic conductors, even in their hydrated operating state.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Uncovering fast solid-acid proton conductors based on dynamics of polyanion groups and proton bonding strength

Achieving high proton conductivity in inorganic solids is key for advancing many electrochemical technologies, including low-energy nano-electronics and energy-efficient fuel cells and electrolyzers. A quantitative understanding of the physical traits of a material that regulate proton diffusion is necessary for accelerating the discovery of fast proton conductors. In this work, we have mapped the structural, chemical and dynamic properties of solid acids to the elementary steps of the Grotthuss mechanism of proton diffusion. Our approach combines ab initio molecular dynamics simulations, analysis of phonon spectra and atomic structure calculations. We have identified the donor–hydrogen bond lengths and the acidity of polyanion groups as key descriptors of local proton transfer and the vibrational frequencies of the cation framework as the key descriptor of lattice flexibility. The latter facilitates rotations of polyanion groups and long-range proton migration in solid acid proton conductors. The calculated lattice flexibility also correlates with the experimentally reported superprotonic transition temperatures. Using these descriptors, we have screened the Materials Project database and identified potential solid acid proton conductors with monovalent, divalent and trivalent cations, including Ag + , Sr 2+ , Ba 2+ and Er 3+ cations, which go beyond the traditionally considered monovalent alkali cations (Cs + , Rb + , K + , and NH 4 + ) in solid acids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

High current carrying and thermal conductive copper-carbon conductors

The surging demand for miniaturized compact devices has generated the need for new metal conductors with high current carrying ampacity, electric and thermal conductivity. Herein, we report carbon-metal conductors that exhibit a high breakdown current density (39% higher than copper) and electrical conductivity (e.g. 63% higher than that of copper at 363 K) in a broad temperature range. The mechanistic studies of thermal conductivity through first-principle modeling show that the multilayer graphene percolation networks efficiently decrease the electron-phonon coupling in the copper-graphene composites, even if phonon modes are activated at a high temperature. These results imply that the copper-based composites have the potential to be the next generation metal conductor with high electrical and thermal conductivity, as well as excellent current-carrying ampacity. More importantly, the developed composite can be deployed in the ink form, making it possible to be utilized by the microelectronic fabrication process.

Zhang, Wei↗
DOE OSTI2021

Light-driven permanent transition from insulator to conductor

The transition from insulator to conductor can be realized in some materials but requires modification of both the arrangement of atoms and their electronic configurations. This is often achieved by doping. Here we reveal a different mechanism the lattice may adopt to induce such a transition. Experiments showed the surprising finding that limited exposure to subband-gap light caused a permanent transition from an insulator state to a conductor state in the insulating oxide Ga 2 O 3 , with a nine orders of magnitude increase in electronic conduction. Furthermore, annealing up to 400 °C did not suppress or decrease the induced conductivity. Photoexcitation by light-induced modification in the charge state of defects and subsequent lattice distortion around them was suggested to be the underlying mechanism behind this transition. Density functional theory calculations confirmed that modifying the charge state of defects leads to redistribution of the localized electrons and massive structural distortion in the surrounding lattice, causing large shifts in the density of states and introducing new states with shallower energy levels. Both experimental and theoretical results revealed the introduction of stable shallow energy levels, explaining the mechanism behind the transition from an insulator to a conductor state by light. We suggest that this mechanism may occur in other wide band-gap metal oxides leading to drastic modification in their electronic properties.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Sensitivity of magnetohydrodynamic simulations of Joule-heated conductors to the vaporization curve in equations of state

Magnetohydrodynamic (MHD) simulations of electrically exploded aluminum and copper rods demonstrate a technique to validate equations of state (EOS) for rapidly Joule-heated conductors. The balance of internal and magnetic forces at the conductor-insulator interface drives the metal there along the vaporization phase boundary. Variations between critical points and vaporization curves in existing models predict differing densities and temperatures in MHD simulations for these models. Here, the inclusion of Maxwell constructs in the liquid-vapor biphase region of the EOS caused the rod surface to vaporize earlier in time than unmodified tables with van der Waals loops. Velocimetry of recent experiments is used to validate the location of the vaporization curve in existing EOS models and differentiate between the vapor dome treatments. Dielectric coatings applied to the metal surface restricted the conductor’s expansion and diverted the metal into the warm dense matter regime.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Boron phosphide as a p-type transparent conductor: Optical absorption and transport through electron-phonon coupling

Boron phosphide has recently been identified as a potential high-hole-mobility transparent conducting material. This promise arises from its low hole effective masses. However, boron phosphide has a relatively small, 2 eV, indirect bandgap which will affect its transparency. In this study, we computationally study both optical absorption across the indirect gap and phonon-limited electronic transport to quantify the potential of boron phosphide as a p-type transparent conductor. We find that phonon-mediated indirect optical absorption is weak in the visible spectrum and that the phonon-limited hole mobility is very high (around 900 cm 2 /Vs) at room temperature. This exceptional mobility comes from the combination of a low hole effective mass and very weak scattering by polar phonon modes. We rationalize the weak scattering by the less ionic bonding in boron phosphide compared to oxides. We suggest that this could be a general advantage of nonoxides for p-type transparent conducting applications. Using our computed properties, we assess the transparent conductor figure of merit of boron phosphide and show that it exceeds by one order of magnitude that of established p-type transparent conductors, confirming the potential of this material.

36 MATERIALS SCIENCE↗
DOE OSTI2022

HTS Cable Conductor for Compact Fusion Tokamak Solenoids

Significant progress has been made recently in the US fusion community to develop a strategic plan to enable engineering design and construction of a fusion pilot plant (FPP). Princeton Plasma Physics Laboratory (PPPL) is working on developing high current density HTS conductors for next fusion experiments. Partnering with the US industry, we are evaluating feasibility and affordability of Conductor on Round Core (CORC ® ) developed by Advanced Conductor Technologies (ACT) for the next compact fusion tokamak facility. High current density achieved by a CORC ® cable based on a four-layer model coil recently tested at National High Magnetic Field Laboratory (NHMFL) motivated its consideration for low cost, reduced size fusion magnet application. This is of interest to PPPL because of its scalability to tokamak central solenoid (CS) coils in terms of required flux swings for plasma startup operations. Furthermore, partnering with ACT, we designed and built a two-layer model coil solenoid directly wound with CORC to demonstrate its applicability for compact solenoids such as that used in the national spherical torus experiment (NSTX), NSTX-upgrade (NSTX-U) and the US sustained high-power density test facility (SHPD). The ~160 mm diameter solenoid wound by a two-layer CORC is being tested in early 2022 under electromagnetic cyclic loading at NHMFL in a unique 160 mm bore, 14 T background field magnet facility.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Shubnikov–de Haas Thermoelectric Field Oscillations in Layered Conductors in the Vicinity of a Topological Lifshits Transition

We have studied the response of a layered conductor with a quasi-two-dimensional electron spectrum and a multisheet Fermi surface (FS) formed by two weakly corrugated cylinders and two planar sheets adjoining these cylinders to nonuniform heating. As a result of action of pressure on the conductor or its doping with impurity atoms, distance Δ{sub p} between the FS cylinder and planar sheets can be reduced to such an extent that conduction electrons begin roaming over these sheets, tunneling from one FS sheet (cavity) to the other. If a conduction electron can visit several times all FS sheets during its mean free time, its motion in the plane orthogonal to the magnetic field becomes finite. In this case, Shubnikov–de Haas oscillations are excited with a period determined by the closed area circumscribed by the electron during its motion in the magnetic-breakdown trajectory in the momentum space. We have calculated the dependence of the thermoelectric field on the magnitude and orientation of a quite strong quantizing magnetic field. In a magnetic field normal to the layers, the cross sections of the cylindrical part of the FS are equidistant from both FS planar sheets. However, this equidistance is violated even for a small deviation of the field from the normal to the layers by angle ϑ, and, at a certain value ϑ{sub k} of this angle, the probability of magnetic breakdown to one of the FS planar sheets can be so low that the electron cannot close the magnetic-breakdown trajectory, and its motion over the other planar sheet with a visit to the FS cylindrical part becomes infinite. In this case, the magnetic-breakdown quantum oscillations of magnetization and all kinetic characteristics of the conductor disappear, and their disappearance is repeated periodically with a change in the slope of the magnetic field to the layers as a function of tanϑ.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1972

Slitting flat conductor cables with the single cutting edge slitter

Manually operated slitter can cut single slit in flat conductor cable to any desired length. Lateral position of flat conductor cable is adjusted with aid of optical magnifier and cursor glass to ensure that slit is accurately placed between conductors. Multiple slits may be made by repeating procedure for single slit.

Angele, W.↗
NASA NTRS1972

Batch fabrication process development for ferrite logic conductors

A process for fabricating ultrareliable magnetic ferrite logic circuits is described in which the conductors are formed by a combination of two batch type processes - photolithography and electroplating - and a mechanized writing process for completing conductors in the third dimension. Up to 4 turns, through an aperture 1 mm in diameter, are formed by the described process. The number of joints in the conductors is reduced by use of this process to only those which are required for input, output and power connections of a logic block. To demonstrate feasibility, 8-stage magnetic ring counter circuits have been fabricated.

Heckler, C. H., Jr.↗
NASA NTRS1976

New solid conductors of Na/+/ and K/+/ ions

About 40 structure types for solid conductors of Na(+) and K(+) ions are surveyed. Five compounds in three structure types are discovered to be good solid conductors of alkali metal ions, capable of ion transport with conductivities in the vicinity of 0.00001/ohm-cm at 25 C. These compounds are a bcc form of NaSbO3, an orthorhombic layer structure of the composition 2M2O.3Nb2O5 with M equal to Na or K, and the Na pyrochlores NaTa2O5F and NaTaWO6. Ion exchange is required to produce each of these Na compounds. Only the 2K2O.3Nb2O5 can so far be synthesized directly from the oxides and thus is the only one which can be sintered readily. The niobate is about as good a conductor of K(+) ion as is K-beta alumina. The NaSbO3 compares well with Na beta at 280 C. A number of phase diagrams are developed.

Singer, J.↗