Mechanical behavior of a continuous filament carbon composite.
Mechanical properties of continuous filament- graphite matrix composite in 0.50 inch diameter rod form, discussing limitation of binder phase and interface
FILAMENT↗
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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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Oak Ridge Wang-Landau (OWL)
The code is a set of first-principles based thermodynamic properties calculations for materials properties at finite temperature. It provides a collection of commonly used Monte Carlo algorithms, interfaced with a few external codes that carry out density functional theory calculations, such as Quantum Espresso and Local Self-consistent Multiple Scattering. The code provides high accuracy thermodynamic calculations that are comparable to real-world materials properties.
Li, YingWai↗
Solid-state polymer-particle hybrid electrolytes: Structure and electrochemical properties
Solid-state electrolytes (SSEs) are challenged by complex interfacial chemistry and poor ion transport through the interfaces they form with battery electrodes. Here, we investigate a class of SSE composed of micrometer-sized lithium oxide (Li 2 O) particles dispersed in a polymerizable 1,3-dioxolane (DOL) liquid. Ring-opening polymerization (ROP) of the DOL by Lewis acid salts inside a battery cell produces polymer-inorganic hybrid electrolytes with gradient properties on both the particle and battery cell length scales. These electrolytes sustain stable charge-discharge behavior in Li||NCM811 and anode-free Cu||NCM811 electrochemical cells. On the particle length scale, Li 2 O retards ROP, facilitating efficient ion transport in a fluid-like region near the particle surface. On battery cell length scales, gravity-assisted settling creates physical and electrochemical gradients in the hybrid electrolytes. By means of electrochemical and spectroscopic analyses, we find that Li 2 O particles participate in a reversible redox reaction that increases the effective CE in anode-free cells to values approaching 100%, enhancing battery cycle life.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
The complexity of { 11 2 ¯ 1 } twin interface structure and energetics in HCP materials
Here, the quest for a deeper understanding of the mechanical properties of HCP alloys has been an ongoing effort. Due to the lack of a sufficient number of slip systems, twin nucleation and migration originate as a substantial plastic deformation mechanism in HCP metals. The paper uncovers the energetics and atomistic mechanism of the {$11\overline{2}1$} < $11\overline{2}6$ > which is one of the most prominent twin modes in HCP materials that has not been fully understood. In view of corrugated {$11\overline{2}1$} interfaces, the positioning of lattice/motif atoms needs to be clarified. First, we establish the initial twin boundary (TB) structure unambiguously via the lattice offsets resulting in volume invariancy and correct relative positioning of the twin variants. Secondly, the TB migration mechanism is determined from a crystallographic (zero net shuffle, $Σ\vec{s}$ = 0) and energetic standpoints (minimum energy path). The Generalized Planar Fault Energy (GPFE) curves are calculated for Ti, Hf, Mg, and Zr. Such GPFE curves for this twin mode are calculated for the first time, and point to unusually high unstable energies (300-850 mJ/m 2 ), and low migration barriers (<60 mJ/m 2 ) for twinning accompanied with large shuffle magnitudes, |$\vec{s}$|, comparable to the Burger’s vector (|$\vec{s}$| ≅ $b_e$ > 0.44Å)
36 MATERIALS SCIENCE↗
Mesoporous CuFe 2 O 4 Photoanodes for Solar Water Oxidation: Impact of Surface Morphology on the Photoelectrochemical Properties**
Abstract Metal oxide‐based photoelectrodes for solar water splitting often utilize nanostructures to increase the solid‐liquid interface area. This reduces charge transport distances and increases the photocurrent for materials with short minority charge carrier diffusion lengths. While the merits of nanostructuring are well established, the effect of surface order on the photocurrent and carrier recombination has not yet received much attention in the literature. To evaluate the impact of pore ordering on the photoelectrochemical properties, mesoporous CuFe 2 O 4 (CFO) thin film photoanodes were prepared by dip‐coating and soft‐templating. Here, the pore order and geometry can be controlled by addition of copolymer surfactants poly(ethylene oxide)‐ block ‐poly(propylene oxide)‐ block ‐poly(ethylene oxide) (Pluronic® F‐127), polyisobutylene‐ block ‐poly(ethylene oxide) (PIB‐PEO) and poly(ethylene‐ co ‐butylene)‐ block ‐poly(ethylene oxide) (Kraton liquid™‐PEO, KLE). The non‐ordered CFO showed the highest photocurrent density of 0.2 mA/cm 2 at 1.3 V vs. RHE for sulfite oxidation, but the least photocurrent density for water oxidation. Conversely, the ordered CFO presented the best photoelectrochemical water oxidation performance. These differences can be understood on the basis of the high surface area, which promotes hole transfer to sulfite (a fast hole acceptor), but retards oxidation of water (a slow hole acceptor) due to electron‐hole recombination at the defective surface. This interpretation is confirmed by intensity‐modulated photocurrent (IMPS) and vibrating Kelvin probe surface photovoltage spectroscopy (VKP‐SPS). The lowest surface recombination rate was observed for the ordered KLE‐based mesoporous CFO, which retains spherical pore shapes at the surface resulting in fewer surface defects. Overall, this work shows that the photoelectrochemical energy conversion efficiency of copper ferrite thin films is not just controlled by the surface area, but also by surface order.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Charge-Transfer-to-Solvent Spectrum of Thiocyanate at the Air/Water Interface Measured by Broadband Deep Ultraviolet Electronic Sum Frequency Generation Spectroscopy
Measurement of interfacial electronic spectra is a powerful tool for characterizing the properties of ions in physical, biological, environmental, and industrial systems. Here, we describe measurement of the complete charge-transfer-to-solvent (CTTS) spectrum of thiocyanate at the air/water interface using our recently developed femtosecond broadband deep ultraviolet electronic sum frequency generation technique. Here, we find that the lower energy CTTS band characterized in bulk thiocyanate spectra is not observed in the |χ (2) | 2 -power spectrum of the air/water interface, likely reflecting the different solvation environments, altering of the charge distribution of the ion, and possible ion-ion effects, and that sodium and potassium salts yield identical spectra. Additional experiments and comparison with theoretical calculations are necessary to extract the interesting chemical details responsible for these salient spectral differences.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
On the Stability of Power Transmission Systems Under Persistent Inverter Attacks: A Bi-Linear Matrix Approach
We investigate the stability and robustness properties of a power transmission system under persistent deceiving attacks on inverter-interfaced energy resources. The attacks can corrupt the damping coefficients in the inverters' controllers and measurements of the frequency at the points of coupling. Leveraging tools from hybrid dynamical systems theory, we characterize a broad family of persistent (and not necessarily periodic) attacks acting on the inverters, under which the stability properties of the transmission system can be shown to not be compromised. To address potentially conservative conditions identified through conventional bounding techniques, sufficient conditions on the average activation time of the attacks are identified via Lyapunov theory, as well as the formulation and solution of a class of bilinear matrix inequalities (BMI). The results are obtained for constant and slowly time-varying loads via input-to-state stability (ISS) tools. Numerical simulations on the IEEE 39-bus test system are also presented.
24 POWER TRANSMISSION AND DISTRIBUTION↗
or-topas: Operations Research Toolkit for Pyomo Alternative Solutions
SAND2026-16702O OR-TOPAS: Operations Research Toolkit for Pyomo Alternative Solutions is a tool that enhances optimization applications defined by the Pyomo modeling library. It offers functions to generate optimal or near-optimal solutions, operating independently of Pyomo’s solver interface. Users can configure these functions with specific solver names and options, resulting in a custom solution object that returns a list of solutions. The OR-TOPAS library includes methods tailored to the properties of the model, such as binary integer programs versus linear programs, and specific solver interfaces like Gurobi. It does not provide models for specific applications, but it is applicable to a wide range of Pyomo optimization models. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Siirola, John [Sandia National Lab. (SNL-CA), Live↗
Effect of Functional and Electron Correlation on the Structure and Spectroscopy of the Al 2 O 3 (001)–H 2 O Interface
Oxide–water interfaces are ubiquitous, with many applications in industry and the environment, yet there is a great deal of controversy over their properties and microscopic structure. This controversy stems, in part, from the unique H-bond networks formed at different surface terminations and mineral compositions. Density functional theory simulations of these interfaces require an accurate description of both the oxide mineral and water in diverse H-bond environments. Thus, herein we simulate the Al 2 O 3 (001)–H 2 O interface using the PBE, PBE-TS, RPBE, SCAN, and HSE06-TS functionals to determine how calculated interfacial properties depend on the choice of functional. We find that the structure of the first few layers of water at the surface is determined by electron correlation in a way that cannot be approximated using semiemipirical van der Waals corrections. Of the functionals investigated, we find that SCAN yields the most accurate interfacial structure, dynamics, and sum frequency generation spectrum. Furthermore, SCAN leads to a reduction in the order of the 2D H-bond network of water at the alumina surface predicted by GGA functionals, leading to a significant decrease in the anisotropy of the diffusion coefficient at the surface. We emphasize the importance of using a functional which accurately describes electron correlation for more complex oxides, such as transition-metal oxides, where electron correlation may play an even greater role in determining the structure and dynamics of the oxide–water interface.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Electronic and Vibrational Coherence in Heterogeneous Electron Transfer (Final Report)
Interfacial electron transfer reactions constitute key physical phenomena central to a variety of energy related transport and conversion processes such as catalysis, photocatalysis, photovoltaics, energy storage, molecular electronics, etc. Heterogeneous material systems like organic/inorganic interfaces are of particular interest because they provide great potential to tailor properties according to application specific requirements. While electron transfer dynamics has been studied intensively in heterogeneous systems many questions remain unanswered. The significance of electronic-vibrational coupling and coherence is one aspect that has yet to be fully explored. The objective of this project is to develop and implement new ultrafast spectroscopic techniques based on pump four-wave mixing spectroscopy (pump-FWM) for studying the dynamics of vibrational coupling and coherence in heterogeneous electron transfer (HET) at molecule/semiconductor interfaces. The implementation of the spectroscopic setup allows to explore different four-wave mixing techniques and thus to identify a suitable approach to study the significance of vibrational as well as electronic coherence in HET.
14 SOLAR ENERGY↗
Optical Properties of Metal-Dielectric Structures Based on Photon-Crystal Opal Matrices
Optical properties of novel metal–dielectric nanocomposite materials based on opal matrices have been investigated. The position of optical resonances of nanocomposites, obtained by embedding of silver into the opal matrix by the electrothermodiffusion method, is explained by the Bragg diffraction, and an asymmetric form of resonance curves is attributed to the Fano resonance. An anomalous transmission and absorption of light by hybrid plasmon-photonic layered heterostructures, which is apparently associated with excitation of surface plasmon-polaritons, propagating along “metal–dielectric” interfaces, was revealed.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Development, Characterization, and Testing of Solid-State Electrolytes for Batteries
Traditional liquid electrolytes used in lithium (Li) metal batteries (LMBs) have severe safety issues, poor power density, as well as thermal and electrochemical instability that prevents their scaling to newer applications, such as electric vehicles. Using sulfide-based solid-state electrolytes (SSEs) is a viable method to address many of the issues that plague LMBs. However, the key issue preventing the expansion of sulfide-based SSEs is an interplay between poor interfacial stability with the electrodes and massive external stack pressure required to maintain electrode-electrolyte contact. The need for extensive pressure requires large system-level (i.e., battery pack used in an electric vehicle) housing that causes a disconnect between performance at a smaller scale and actual application. Secondary prevention to sulfide-based SSE adoption are difficulties in manufacturing, as toxic deterioration occurs when these materials are exposed to humidity, as well as drastic reduction in SSE performance at low temperature. This work hypothesizes that unique interfacial designs of electrodes and the modification of the sulfide-based SSE will enable reduction of necessary external cell pressure, and therefore support the design of practical LMBs. This will be done through collaboration within Idaho National Laboratory (INL), where manufacturing practices will be parameterized to produce low defect, low porosity SSEs with slight modifications. Next, artificial interfaces will be produced on electrodes to observe the conformality and mass transport properties between the modified SSE and pre-treated anode. External pressure on Li-metal cells will also be parameterized to reduce interfacial impedance while a reduction in the pressure will allot reasonable housing design for larger scale applications. Focus on novelty in this work occurs by modifications to the solid-solid interfaces between electrolyte and electrode, done through doping of the electrolyte and production of artificial interfaces on the Li-metal anode. The modifications at these interfaces, in addition to modified external pressure could identify and address the poor interfacial impedance that hinders high performance SSEs. Fundamental understanding on how to reduce the key hindrances of all-solid-state batteries (ASSBs) will support the advancement for larger scale production and performance, of which will be held in perspective for future works. Beyond battery development, the knowledge gained from process control and defect analysis is applicable to other ceramic systems, such as nuclear fuel coatings and high temperature electrolyzers.
25 ENERGY STORAGE↗
Development, Characterization, and Testing of Solid-State Electrolytes for Batteries
Traditional liquid electrolytes used in lithium (Li) metal batteries (LMBs) have severe safety issues, poor power density, as well as thermal and electrochemical instability that prevents their scaling to newer applications, such as electric vehicles. Using sulfide-based solid-state electrolytes (SSEs) is a viable method to address many of the issues that plague LMBs. However, the key issue preventing the expansion of sulfide-based SSEs is an interplay between poor interfacial stability with the electrodes and massive external stack pressure required to maintain electrode-electrolyte contact. The need for extensive pressure requires large system-level (i.e., battery pack used in an electric vehicle) housing that causes a disconnect between performance at a smaller scale and actual application. Secondary prevention to sulfide-based SSE adoption are difficulties in manufacturing, as toxic deterioration occurs when these materials are exposed to humidity, as well as drastic reduction in SSE performance at low temperature. This work hypothesizes that unique interfacial designs of electrodes and the modification of the sulfide-based SSE will enable reduction of necessary external cell pressure, and therefore support the design of practical LMBs. This will be done through collaboration within Idaho National Laboratory (INL), where manufacturing practices will be parameterized to produce low defect, low porosity SSEs with slight modifications. Next, artificial interfaces will be produced on electrodes to observe the conformality and mass transport properties between the modified SSE and pre-treated anode. External pressure on Li-metal cells will also be parameterized to reduce interfacial impedance while a reduction in the pressure will allot reasonable housing design for larger scale applications. Focus on novelty in this work occurs by modifications to the solid-solid interfaces between electrolyte and electrode, done through doping of the electrolyte and production of artificial interfaces on the Li-metal anode. The modifications at these interfaces, in addition to modified external pressure could identify and address the poor interfacial impedance that hinders high performance SSEs. Fundamental understanding on how to reduce the key hindrances of all-solid-state batteries (ASSBs) will support the advancement for larger scale production and performance, of which will be held in perspective for future works. Beyond battery development, the knowledge gained from process control and defect analysis is applicable to other ceramic systems, such as nuclear fuel coatings and high temperature electrolyzers.
25 ENERGY STORAGE↗
Hydrogen Annealing Effect on the Magnetic Properties of ZnCoO/MoS{sub 2} Hybrid
The ZnCoO/MoS{sub 2} hybrid is successfully synthesized through a general and facile process. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectra reveal that the hybrid consists of wurtzite ZnCoO and few layers of MoS{sub 2}, which shows a paramagnetic property. In contrast, the hybrid presents clear magnetic hysteresis at room temperature with a H{sub 2} post-annealing process. No Co metal nanoclusters can be identified by XRD and HRTEM. The red shift of E{sub 2g}{sup 1} and A{sub 1g} peak indicates the strain effect induced by H{sub 2} annealing. On the other hand, the disappeared peak at 477 cm{sup −1} can be ascribed to the modification of the interface and surface state of the ZnCoO. Temperature-dependent Raman spectroscopies demonstrate the significant H{sub 2} annealing effect on the structural properties of ZnCoO/MoS{sub 2} hybrid. The interplay between the electron interaction at the interface and oxygen vacancies of ZnCoO can be responsible for the magnetic properties of the ZnCoO/MoS{sub 2} hybrid. The tunable magnetic properties have a promising application in multifunctional MoS{sub 2}-based semiconductor and spintronic devices.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Enhancement of SOFC Cathode Electrochemical Performance Using Multi-Phase Interfaces
This work explored the use of oxide heterostructures for enhancing the catalytic and degradation properties of solid oxide fuel cell (SOFC) cathode electrodes. We focused on heterostructures of Ruddlesden-Popper and perovskite phases. Building on previous work showing enhancement of the Ruddlesden-Popper (La,Sr) 2 CoO 4 / perovskite (La,Sr)CoO 3 heterostructure compared to pure (La,Sr)CoO 3 we explored the application of related heterostructures of Ruddlesden-Popper phases on perovskite (La,Sr)(Co,Fe)O 3 . Our approaches included thin-film electrodes, physical and electrochemical characterization, elementary reaction kinetics modeling, and ab initio simulations. We demonstrated that Sr segregation to surfaces is likely playing a critical role in the performance of (La,Sr)CoO 3 and (La,Sr)(Co,Fe)O 3 and that modification of this Sr segregation may be the mechanism by which Ruddlesden-Popper coatings enhance performances. We determined that (La,Sr)(Co,Fe)O 3 could be enhanced in thin films by about 10× by forming a heterostructure simultaneously with (La,Sr) 2 CoO 4 and (La,Sr)CoO 3 . We hope that future work will develop this heterostructure for use as a bulk porous electrode.
25 ENERGY STORAGE↗
Mechanical Characterization of Composites and Foams for Aerospace Applications
Experimental studies to investigate the mechanical properties of ultra-lightweight polyimide foams for space applications, compression after impact (CAI) properties for low velocity impact of sandwich composites, and aspen fiber/polypropylene composites containing an interface adhesive additive, Maleic Anhydride Grafted Polypropylene (MAPP), were performed at Clark Atlanta University. Tensile, compression, flexural, and shear modulus tests were performed on TEEK foams categorized by their densities and relative cost according to ASTM specifications. Results showed that the mechanical properties of the foams increased as a function of higher price and increasing density. The CAI properties of Nomex/phenolic honeycomb core, fiberglass/epoxy facesheet sandwich composites for two damage arrangements were compared using different levels of impact energy ranging from 0 - 452 Joules. Impact on the thin side showed slightly more retention of CAI strength at low impact levels, whereas higher residual compressive strength was observed from impact on the thick side at higher impact levels. The aspen fiber/polypropylene composites studied are composed of various percentages (by weight) of aspen fiber and polypropylene ranging from 30%-60% and 40%-100%, respectively. Results showed that the MAPP increases tensile and flexural strength, while having no significant influence on tensile and flexural modulus.
Veazie, D. R.↗
Molecular Dynamics of ULTEM 9085 for 3D Manufacturing: Spectra, Thermodynamic Properties, and Shear Viscosity.
We present results of a molecular dynamic analysis of welding at the polymer-polymer interface. The analysis is performed for polyetherimide/ polycarbonate polymer blends. The work is motivated by the applications to 3D manufacturing in space. In the first part of the report, we discuss bulk and spectral characteristics of the amorphous polymer blends. The vibrational and infra-red spectra obtained using auto-correlation functions calculations in molecular dynamics are compared with the experimental spectra. The mechanical and thermal properties of the samples including heat capacity, bulk modulus, and thermal expansion coefficients are estimated and compared with experimental values. In the second part of the report, we discuss the result of molecular dynamical modeling of shear viscosity in a fully atomistic model of amorphous polymer blends with flat interface. The key result of the research is the demonstration of shear thinning behavior of the shear viscosity as a function of shear rate which is in good agreement with experimental data.
Luchinsky, Dmitry G.↗
Interfacial Inversion of Stealth Surfactants
Amphiphilic macromolecular surfactants segregate to liquid–liquid interfaces, thereby reducing the interfacial tension and free energy. Here, we investigated “stealth surfactants” in the form of core–shell bottlebrush polymers comprised of pH-responsive diblock copolymer side chains forming a hydrophilic core and a hydrophobic shell, enabling solubility in oil. At liquid–liquid interfaces, these polymers undergo a structural “inversion”, with hydrophilic blocks segregating into the aqueous phase and hydrophobic blocks residing in the oil phase. The reconfiguration kinetics and surfactant properties are influenced by multiple factors, including the molecular weights of the backbone and side chain components, the hydrophilic-to-hydrophobic balance of the side chains, and the pH of the aqueous phase. An observed nonmonotonic dependence of interfacial tension with time is attributed to a progressive structural inversion, where the projected area of the macromolecule onto the interface decreases. To validate this inversion hypothesis, interfacial properties were characterized by sum-frequency generation vibrational spectroscopy, which revealed configurational changes of the core–shell bottlebrush polymers at the fluid interface and revealed a pH-dependent interfacial coverage. Coarse-grained molecular dynamics simulations supported these experimental findings, showing that the pH-responsive core and hydrophobic shell assume a time-averaged configuration with orientations parallel and perpendicular to the plane of the interface, respectively. These findings open routes to design multistimuli-responsive polymeric surfactants and compatibilizers, expanding their potential applications in advanced interfacial systems.
Stealth surfactants↗