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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 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Deuterated polyethylene nanowire arrays for high-energy density physics

Abstract The interaction of intense, ultrashort laser pulses with ordered nanostructure arrays offers a path to the efficient creation of ultra-high-energy density (UHED) matter and the generation of high-energy particles with compact lasers. Irradiation of deuterated nanowires arrays results in a near-solid density environment with extremely high temperatures and large electromagnetic fields in which deuterons are accelerated to multi-megaelectronvolt energies, resulting in deuterium–deuterium (D–D) fusion. Here we focus on the method of fabrication and the characteristics of ordered arrays of deuterated polyethylene nanowires. The irradiation of these array targets with femtosecond pulses of relativistic intensity and joule-level energy creates a micro-scale fusion environment that produced $2\times {10}^6$ neutrons per joule, an increase of about 500 times with respect to flat solid CD 2 targets irradiated with the same laser pulses. Irradiation with 8 J laser pulses was measured to generate up to 1.2 × 10 7 D–D fusion neutrons per shot.

Optics↗
DOE OSTI2025

Pulse-length dependence of the laser-induced damage behavior of a fused-silica antireflective metasurface

A broadband, antireflective metasurface optic on a silica substrate is subjected to laser-induced damage-threshold measurements to quantify its performance under exposure to high-intensity/fluence laser pulses in the near-infrared at four pulse durations, ranging from 20 fs to 1.4 ns. The performance of the metasurface is benchmarked against that obtained from an equivalent bare fused-silica substrate that did not receive reactive-ion-etching metasurface treatment. Results showed that the damage threshold of the antireflective metasurface was always lower than the input-surface damage threshold of the untreated substrate. The damage initiations with nanosecond and picosecond pulses resulted in localized modification and removal of the nanostructures, whereas the onset of laser-induced modification with 20-fs pulses in a vacuum environment manifested as changes in the optical and electronic properties without significant material removal. The broader goal of this work is to develop a preliminary understanding of the laser-induced failure mechanisms of silica-based metasurface optics.

antireflection↗
DOE OSTI2022

A Three-Dimensional Reconstruction Algorithm for Scanning Transmission Electron Microscopy Data from a Single Sample Orientation

Abstract Increasing interest in three-dimensional nanostructures adds impetus to electron microscopy techniques capable of imaging at or below the nanoscale in three dimensions. We present a reconstruction algorithm that takes as input a focal series of four-dimensional scanning transmission electron microscopy (4D-STEM) data. We apply the approach to a lead iridate, PbIrO, and yttrium-stabilized zirconia, YZrO, heterostructure from data acquired with the specimen in a single plan-view orientation, with the epitaxial layers stacked along the beam direction. We demonstrate that Pb–Ir atomic columns are visible in the uppermost layers of the reconstructed volume. We compare this approach to the alternative techniques of depth sectioning using differential phase contrast scanning transmission electron microscopy (DPC-STEM) and multislice ptychographic reconstruction.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Mesoporous Thin Film Architectures: Addressing Material Demands through Molecular Self-Assembly

Mesoporous thin films spark interest across a wide range of disciplines due to their tunable nanostructures, large internal surface areas, and strong compatibility with planar optical, electronic, and microfluidic devices. While attention in the porous materials community has shifted toward macroporous or disordered nanoporous systems, a resurgence in mesoporous thin film research is underway, driven by new molecular self-assembly methods, advanced materials chemistry, and improved characterization techniques. The integration of high-χN block copolymer design, kinetically persistent micelle templating, and postdeposition processing protocols now allows control over structural parameters such as pore size, wall thickness, porosity, and connectivity. These advances have overcome many of the thermodynamic and processing constraints that previously limited widespread adoption. Rather than serving only as high-surface-area supports, mesoporous thin films are engineered as active interfaces where responsive chemistries and nanoscale confinement act in tandem. Embedding switchable ligands, thermoresponsive polymers, redox mediators, or ion-selective groups directly within the pore walls enables real-time control over transport, optical, and electrochemical properties. These capabilities open up new directions in adaptive coatings, gated membranes, and fast-response biosensors. To further expand their functional scope, mesoporous films are integrated into hierarchical and multicomponent architectures. Techniques such as triblock terpolymer templating, crack-directed assembly, and nanoimprint lithography allow for control over spatial organization on the micron and submicron scale and pore system orientation. This enables programmable anisotropy, enhanced molecular diffusion, and wavelength-selective photonic behavior, essential for next-generation sensing, catalysis, and energy applications. Such structural and functional complexity requires equally sophisticated characterization. Multimodal and in situ techniques can track material dynamics under operational conditions. Recent progress includes extended-range ellipsometric porosimetry (EP) for hierarchical architectures, vacuum EP for interface energetics, time-resolved EP for diffusion kinetics, and correlative AFM-SAXS mapping. The introduction of advanced neutron-based spectroscopies, particularly quasielastic neutron scattering (QENS), promises to provide real-time access to ion transport dynamics and segmental motion under nanoscale confinement, offering a path toward deeper mechanistic understanding of structure-performance correlations in mesoporous systems. This Account reflects the technical advances made and the interdisciplinary collaborations that have shaped our collective vision. The particular dimensions of mesopores enable us to subtly tune interactions at the molecular, interfacial, and mesoscopic levels that permit us to harness nanoconfinement. What emerges is a versatile, modular platform capable of chemical gating, energy transduction, and sensing with a level of tunability unmatched by other porous materials. We highlight critical challenges including the need for more robust large-area processing, a deeper understanding of dynamic behavior under cycling, and better integration with device-level architectures. Our strategies support the transition of mesoporous thin films into active high-performance components in next-generation energy, environmental, and biomedical systems.

oxides↗
DOE OSTI2025

Tuning 3-D Nanomaterial Architectures Using Atomic Layer Deposition to Direct Solution Synthesis

The ability to synthesize nanoarchitected materials with tunable geometries provides a means to control their functional properties, with applications in biological, environmental, and energy fields. To this end, various bottom-up and top-down synthesis processes have been developed. However, many of these processes require prepatterning or etching steps, making them challenging to scale-up to complex, nonplanar substrates. Furthermore, the ability to integrate nanomaterials into hierarchical arrays with precise control of feature spacing and orientation remains a challenge. One approach to overcome these patterning challenges is the use of surface modification layers to guide the resulting geometry of nanomaterial architectures grown from the substrate. A powerful strategy to accomplish this is what we will refer to as “surface-directed assembly,” where the resulting geometric parameters (feature size, shape, orientation) are predetermined by the initial surface layer. In particular, the use of Atomic Layer Deposition (ALD) to form a surface layer, followed by solution-based growth processes, has the ability to synthesize architected structures with tunable geometries on complex, nonplanar surfaces. Over the past decade, we have reported a series of studies where surface-directed assembly is used to synthesize ZnO nanowires (NWs) on top of a variety of substrates. In this case, a thin film of ZnO is deposited onto the substrate using ALD, which can guide the NW diameter, spacing, and angular orientation with respect to the substrate by controlling epitaxial relationships. Furthermore, we have shown that by depositing a submonolayer overcoat of a secondary material (e.g., amorphous TiO 2 ), nucleation sites are partially blocked, which can further tune the spacing between nanowires while minimizing changes to their other geometric properties. This approach can be used to generate multilevel hierarchical structures, such as hyperbranched NW arrays with tunable control of each level of hierarchy using ALD. Finally, we have demonstrated that the tunable control of geometric parameters can be scaled-up to curved, nonplanar substrates. This highlights the power of ALD to conformally and uniformly deposit the seed layers on complex substrates with subnanometer precision. To complement these seeded hydrothermal approaches, we expanded this strategy to include conversion chemistry of the initial ALD seed layers. For example, by replacing ZnO with Al 2 O 3 as the seed layer without changing the hydrothermal growth conditions, Al–Zn layered-double hydroxide nanosheets can be formed instead of nanowires. In another example of conversion chemistry, a solution anion-exchange process was used to incorporate sulfur into ALD metal oxide films. In both of these conversion processes, the properties of the initial ALD film enabled tuning of the resulting nanostructure geometry. In this Account, we describe the use of ALD to guide the growth of diverse nanomaterial systems, with tunable control over their geometry and composition. We further show how these approaches can be used to tune functional properties for a range of applications, including superomniphobic surfaces, antibiofouling coatings, and photocatalysis. In conclusion, we conclude with an outlook on how the combination of ALD and solution synthesis can enable future directions in scalable nanomanufacturing to overcome the limitations of traditional top-down and bottom-up approaches.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Electron Tomography and Machine Learning for Understanding the Highly Ordered Structure of Leafhopper Brochosomes

Insects known as leafhoppers (Hemiptera: Cicadellidae) produce hierarchically structured nanoparticles known as brochosomes that are exuded and applied to the insect cuticle, thereby providing camouflage and anti-wetting properties to aid insect survival. Although the physical properties of brochosomes are thought to depend on the leafhopper species, the structure–function relationships governing brochosome behavior are not fully understood. Brochosomes have complex hierarchical structures and morphological heterogeneity across species, due to which a multimodal characterization approach is required to effectively elucidate their nanoscale structure and properties. In this work, we study the structural and mechanical properties of brochosomes using a combination of atomic force microscopy (AFM), electron microscopy (EM), electron tomography, and machine learning (ML)-based quantification of large and complex scanning electron microscopy (SEM) image data sets. This suite of techniques allows for the characterization of internal and external brochosome structures, and ML-based image analysis methods of large data sets reveal correlations in the structure across several leafhopper species. Our results show that brochosomes are relatively rigid hollow spheres with characteristic dimensions and morphologies that depend on leafhopper species. Nanomechanical mapping AFM is used to determine a characteristic compression modulus for brochosomes on the order of 1–3 GPa, which is consistent with crystalline proteins. Altogether, this work provides an improved understanding of the structural and mechanical properties of leafhopper brochosomes using a new set of ML-based image classification tools that can be broadly applied to nanostructured biological materials.

Chemical structure↗
DOE OSTI2022

Short-Range Mechanisms in the Creation of a ZnO/InGaAs Interface

Here we perform quantitative analysis of the X-ray absorption data taken in situ during the earliest cycles of the ZnO atomic layer deposition on atomically flat InGaAs (001) surfaces. As deposition progresses, we observe a transition from an amorphous structure to a nanocrystalline one. The former retains much of the characteristics of a ZnO crystal in the Zn coordination shell, while the latter shows atomic ordering up to at least the third neighbor shell of Zn atoms, despite the absence of Bragg X-ray diffraction peaks. We show that the different chemical preparation of the substrate surface affects the ZnO local structure and that, counterintuitively, a stronger short-range order is obtained in the nanostructures characterized by lower local order at the interface. We propose a model that accounts for these findings.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Target Configuration Effect on Microstructures and Properties of Vertically Aligned Nanocomposites

Vertically aligned nanocomposites (VANs) are unique thin films with vertical nanostructures embedded in a matrix material, allowing for the integration of two distinct materials. These nanocomposites offer novel combined physical properties, such as nanocomposite-based multiferroics and strongly coupled physical properties, such as magneto-optic coupling. Much work has been conducted in exploring different two-phase combinations and various processing conditions to achieve novel tunable properties that cannot be obtained by any single-phase material alone. Here, in this work, the target configuration effects are explored for the growth of LaFeO 3 –CoNi 2 O 4 VANs. Both mixed and pie-shaped targets are utilized to compare the target configuration effects on the phase separation, morphology tuning, and their resulting physical properties, including optical and magnetic properties. This work suggests that the target configuration is another important parameter for achieving the desired VAN morphology and can be used to design different two-phase VANs with tailorable properties.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Direct Observation of Electron Beam-Induced Phase Transition in MgCrMnO 4

Irreversible structural transformation in intercalation-type cathode materials, which has been frequently observed, has been perceived as a principal cause of capacity fading and voltage decay in (uni) multivalent batteries. Herein, we explored the electron beam-induced spinel to defective rocksalt phase transitions in MgCrMnO 4 , a potential multivalent cation intercalation cathode, using atomic-resolution imaging and spectroscopy in an aberration-corrected scanning transmission electron microscope. This dynamic electron beam irradiation study of specific structural transformations provides an atomistic understanding of the structural evolution observed in transition-metal oxide spinels during electrochemical cycling using multivalent cations, such as Mg 2+ . By combining an imaging study with first-principles modeling, we demonstrate that the mechanism of the spinel to defective rocksalt transformation in MgCrMnO 4 nanostructures is enabled by the presence of oxygen vacancies and is, therefore, very similar to that observed in transition-metal oxide spinels upon Li intercalation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

On the Origin of Room-Temperature Amplified Spontaneous Emission in CsPbBr 3 Single Crystals

CsPbBr 3 is an all-inorganic halide perovskite with excellent photoluminescence (PL) properties for laser applications. Amplified spontaneous emission (ASE) is a prerequisite for lasing and typically observed from low-dimensional CsPbBr3 nanostructures, where quantum confinement enhances ASE. However, a gain medium for lasing should be prepared into a robust bulk form that works under intense light illumination. Here, we demonstrate that bulk CsPbBr 3 single crystals exhibit highly efficient ASE with a threshold of 46 MWcm -2 at 520 nm, if PL reabsorption via the indirect Rashba gap is properly suppressed by thickness control. Based on a series of spectroscopic and microscopic measurements, we show that this below-the-gap absorption can significantly alter the PL feature and even the apparent color of the crystal depending on the crystal size. Our results show that a thin CsPbBr 3 single crystal can be utilized for lasing applications when engineered into a submillimeter thickness for effective light–matter interaction.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Nanotubes from the Misfit Layered Compound (SmS) 1.19 TaS 2 : Atomic Structure, Charge Transfer, and Electrical Properties

Misfit layered compounds (MLCs) MX-TX 2 , where M, T = metal atoms and X = S, Se, or Te, and their nanotubes are of significant interest due to their rich chemistry and unique quasi-1D structure. In particular, LnX-TX 2 (Ln = rare-earth atom) constitute a relatively large family of MLCs, from which nanotubes have been synthesized. The properties of MLCs can be tuned by the chemical and structural interplay between LnX and TX 2 sublayers and alloying of each of the Ln, T, and X elements. In order to engineer them to gain desirable performance, a detailed understanding of their complex structure is indispensable. MLC nanotubes are a relative newcomer and offer new opportunities. In particular, like WS 2 nanotubes before, the confinement of the free carriers in these quasi-1D nanostructures and their chiral nature offer intriguing physical behavior. High-resolution transmission electron microscopy in conjunction with a focused ion beam are engaged to study SmS-TaS 2 nanotubes and their cross-sections at the atomic scale. The atomic resolution images distinctly reveal that Ta is in trigonal prismatic coordination with S atoms in a hexagonal structure. Furthermore, the position of the sulfur atoms in both the SmS and the TaS 2 sublattices is revealed. X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and X-ray absorption spectroscopy are carried out. These analyses conclude that charge transfer from the Sm to the Ta atoms leads to filling of the Ta 5d z 2 level, which is confirmed by density functional theory (DFT) calculations. Transport measurements show that the nanotubes are semimetallic with resistivities in the range of 10 –4 Ω·cm at room temperature, and magnetic susceptibility measurements show a superconducting transition at 4 K.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation

The ability to assemble nanoparticles (NPs) into functional nanostructures is critical for the advancement of nanoscience. However, common assembling techniques utilize organic ligands or biomolecules, which are detrimental for charge transport and interparticle coupling, which impede the efficient integration of low-dimensional properties. Herein, we report a methodology for the self-supported assembly of ultra-small (3-6 nm) Au/Ag/Pt alloy NPs into large, free-standing alloy superstructures (aerogels) that exhibit direct NP connectivity, high surface area (125 ± 0.43 to142 ± 0.93 m 2 /g) and mesoporosity (21.6 ± 2.2 nm), and superior electrocatalytic activity for methanol oxidation reaction (MOR). Precursor Au/Ag/Pt alloy NPs and hydrogels were synthesized via stepwise galvanic replacement reaction (GRR) of the glutathione (GSH)-coated Ag NPs, followed by oxidative removal of the surfactant ligands. The composition of alloy aerogels was tuned by varying the oxidant/GSH molar ratio, which governs the extent of Ag dealloying with in-situ generated HNO 3 and increases the exposure of Au and Pt on the aerogel surface. The alloy aerogels exhibit superior MOR mass activity, which is 21.4 and 2.5 times higher than those of the precursor NPs and commercial Pt (40 wt.%)/C electrocatalysts, respectively. The MOR surface-specific activity (MOR-SSA) of the aerogels was improved by >17% when the Pt content was increased from 22.4% to 31.2%. The aerogels exhibit improved electronic conductivity, enhanced tolerance for carbonaceous byproducts, and maintained ~94% of the initial MOR activity at -0.3 V for 24 h in an alkaline medium. In conclusion, the interconnected porous superstructure of the aerogel provides a facile conduit for molecules to reach the pristine active surface whereas the presence of oxophilic Au promotes the dissociative adsorption of methanol, enabling the Au/Ag/Pt alloy aerogel a high efficiency, durable electrocatalyst for next generation of energy conversion studies.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Tin Metal Improves the Lithiation Kinetics of High-Capacity Silicon Anodes

Si-based anodes present a great promise for high energy density lithium-ion batteries. However, its commercialization is largely hindered by a grand challenge of a rapid capacity fade. Here, we demonstrate excellent cycling stability on a Si-Sn thin film electrode that outperforms pure Si or Sn counterpart under the similar conditions. Combined with the first-principles calculations, in situ transmission electron microscopy studies reveal a reduced volume expansion, increased conductivity, as well as dynamic rearrangement upon lithiation of the Si-Sn film. Here we attribute the improved lithiation kinetics to the formation of a conductive matrix that comprises a mosaic of nanostructured Sn, Li y Sn (specifically, Li 7 Sn 2 develops around the lithiation potential of Si), and Li x Si. This work provides an important advance in understanding the lithiation mechanism of Si-based anodes for next-generation lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Modeling Analysis of Ball-Milling Process for Battery-Electrode Synthesis

The mechanical alloying process is a promising method for synthesizing electrode materials for batteries owing to its benefits such as the ability to produce nanostructured, high-performing electrode alloys, no adverse effects on the solid electrolyte for solid-state batteries, stable production of thick electrodes, simple processing steps, and low processing costs. It is gaining intensive attention in the battery industry as one of the best methods to replace the conventional wet-slurry-solvent method, and its application is rapidly increasing these days. However, the operation is currently conducted purely based on trial-and-error methods without fully utilizing the features of its functions. Here, this may be attributed to a lack of understanding of the effect of operating parameters on the alloying process and final products. Surprisingly, there is a scarcity of the literature conducting fundamental research to comprehend the underlying physics of the entire mechanical alloying process, resulting in a significant knowledge gap. To address this knowledge gap, extensive research was conducted. The existing literature on mechanical alloying was reviewed to comprehend the current state of understanding and to discuss the direction for future research. Mathematical expressions were developed to create physics-based models capable of capturing the entire mechanical alloying process, including milling kinetics and defect-enhanced phase evolution. These methods were then applied to investigate the impact of operating parameters such as milling frequency, initial mole ratio of the alloyed materials, density of grinding balls, and energy required for the powders to become amorphous (i.e., the amorphization energy threshold). This research aimed not only to comprehend the direct effects of these operating parameters but also to unveil the physics underlying the ball-milling process. The results of our study can serve as crucial information for the battery industry in designing or operating the ball-milling process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

A critical review of different prominent nanotechnologies adapted to catalysis is provided, with focus on how they contribute to the improvement of selectivity in heterogeneous catalysis. Ways to modify catalytic sites range from the use of the reversible or irreversible adsorption of molecular modifiers to the immobilization or tethering of homogeneous catalysts and the development of well-defined catalytic sites on solid surfaces. The latter covers methods for the dispersion of single-atom sites within solid supports as well as the use of complex nanostructures, and it includes the post-modification of materials via processes such as silylation and atomic layer deposition. All these methodologies exhibit both advantages and limitations, but all offer new avenues for the design of catalysts for specific applications. Because of the high cost of most nanotechnologies and the fact that the resulting materials may exhibit limited thermal or chemical stability, they may be best aimed at improving the selective synthesis of high value-added chemicals, to be incorporated in organic synthesis schemes, but other applications are being explored as well to address problems in energy production, for instance, and to design greener chemical processes. Finally, the details of each of these approaches are discussed, and representative examples are provided. We conclude with some general remarks on the future of this field.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Garnet-Type Solid-State Electrolytes: Materials, Interfaces, and Batteries

Solid-state batteries with desirable advantages, including high-energy density, wide temperature tolerance, and fewer safety-concerns, have been considered as a promising energy storage technology to replace organic liquid electrolyte-dominated Li-ion batteries. Solid-state electrolytes (SSEs) as the most vital component in solid-state batteries largely lead the future battery development. Among different types of solid-state electrolytes, garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolytes have particularly high ionic conductivity (10 –3 to 10 –4 S/cm) and good chemical stability against Li metal, offering a great opportunity for solid-state Li-metal batteries. Since the discovery of garnet-type LLZO in 2007, there has been an increasing interest in the development of garnet-type solid-state electrolytes and all solid-state batteries. Garnet-type electrolyte has been considered one of the most promising and important solid-state electrolytes for batteries with potential benefits in energy density, electrochemical stability, high temperature stability, and safety. In this Review, we will survey recent development of garnet-type LLZO electrolytes with discussions of experimental studies and theoretical results in parallel, LLZO electrolyte synthesis strategies and modifications, stability of garnet solid electrolytes/electrodes, emerging nanostructure designs, degradation mechanisms and mitigations, and battery architectures and integrations. We will also provide a target-oriented research overview of garnet-type LLZO electrolyte and its application in various types of solid-state battery concepts (e.g., Li-ion, Li–S, and Li–air), and we will demonstrate opportunities and perspectives as guides for future development of solid electrolytes and solid-state batteries.

25 ENERGY STORAGE↗