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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Morphology-driven oxygen evolution performance of NiO x nanostructures and implications for hole transport in perovskite solar cells

Morphology-controlled nanostructures provide an effective strategy to modulate both oxygen evolution reaction (OER) activity and photovoltaic performance in perovskite solar cells (PSCs). However, achieving low OER overpotentials and high power conversion efficiency (PCE) simultaneously through morphology engineering remains challenging. In this work, nickel oxide (NiO x ) nanostructures with spindle-like (NiO x -NS) and plate-like (NiO x -NP) morphologies were synthesized and evaluated as bi-functional OER catalysts and hole transport layers (HTLs) in inverted PSCs. Structural and thermal analyses reveal that NiO x -NS crystallizes into a cubic phase at a lower temperature (300 °C), whereas NiO x -NP requires higher calcination temperatures, reflecting differences in precursor microstructure. Electrochemical measurements indicate that NiO x -NS calcined at 300 °C delivers the lowest OER overpotential (395 mV at 10 mA cm −2 ), outperforming NiO x -NP calcined at 400 °C (565 mV) and 500 °C (474 mV). This enhanced activity is ascribed to favorable surface strain, increased defect density, and advantageous facet exposure. When used as HTLs, NiO x -NS also delivers the highest PCE (13.25%) among all tested devices, exceeding those based on NiO x -NP and commercial NiO x , owing to improved hole extraction and interfacial contact. Overall, this study highlights the importance of morphology control and thermal processing in tailoring NiO x for multifunctional nanomaterials in electrocatalytic and photovoltaic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Growth of nanostructured molybdenum disulfide (MoS 2 ) thin films on a nanohole-patterned substrate using plasma-enhanced atomic layer deposition (ALD)

Nanostructured molybdenum disulfide (MoS 2 ) thin films were grown on a nanohole-patterned silicon substrate using plasma-enhanced atomic layer deposition. A nanoscale hole-patterned silicon substrate was fabricated for the growth of MoS 2 film using the self-assembly-based nanofabrication method. The nanoscale holes can significantly increase the surface area of the substrate while the formation and growth of nanostructures normally start at the surface of the substrate. Hydrogen sulfide (H 2 S) gas was used as the S source in the growth of molybdenum disulfide (MoS 2 ) while molybdenum (V) chloride (MoCl 5 ) powder was used as the Mo source. The MoS 2 film had a stoichiometric ratio of 1 (Mo) to 2 (S), and had peaks of E 1 2g and A 1g , which represent the in-plane and out-plane vibration modes of the Mo–S bond, respectively. It was found that the MoS 2 film grown in the nanoscale hole, especially at the wall of the hole, has more hexagonal-like structures due to the effects of nanoscale space confinement and the nanoscale interface although the film shows an amorphous structure. Post-growth high-temperature annealing ranging from 800 to 900 °C produced local crystalline structures in the film, which are compatible with those reported by other researchers.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Structural and optical characterization of dilute Bi-doped GaN nanostructures grown by molecular beam epitaxy

We have carried out detailed studies on the epitaxy and characterization of dilute Bi-doped GaN nanostructures. A comprehensive investigation of Bi-doped GaN nanowires and quasi-film epitaxial growth conditions has been performed. Scanning electron microscopy studies show that lowering the GaBiN growth temperature causes gradual changes in top c-plane nanowire morphology due to the incremental incorporation of foreign Bi atoms. This trend is further substantiated by the secondary ion mass spectroscopy analysis of a multi-layer Bi-doped GaN quasi-film. However, it is also found that the amount of Bi incorporation into the GaN lattice is relatively independent of the N2 flow rate variation under the growth conditions investigated. Furthermore, room-temperature micro-Raman spectra show that there are additional peaks near 530, 650, and 729 cm−1 wave numbers in the Bi-doped GaN samples, which can primarily be attributed to Bi local vibrational modes, indicative of a small amount of Bi incorporation in the GaN lattice. Moreover, phonon calculations with density functional theory indicate that Bi replacing the N sites is the likely origin of the experimentally measured Raman modes. X-ray photoelectron spectroscopy measurements have also been obtained to deduce the electronic interaction between the Bi dopant atom and the GaN nanostructure. Such one-dimensional nanowires permit the synthesis of dislocation-free highly mismatched alloys due to strain relaxation, allowing efficient light absorption and charge carrier extraction that is relevant for solar energy harvesting and artificial photosynthesis.

Materials Science↗
DOE OSTI2024

Versatile stochastic model for predictive KMC simulation of fcc metal nanostructure evolution with realistic kinetics

Stochastic lattice-gas models provide the natural framework for analysis of the surface diffusion-mediated evolution of crystalline metal nanostructures on the appropriate time scale (often 10 1 –10 4 s) and length scale. Model behavior can be precisely assessed by kinetic Monte Carlo simulation, typically incorporating a rejection-free algorithm to efficiently handle the broad range of Arrhenius rates for hopping of surface atoms. The model should realistically prescribe these rates, or the associated barriers, for a diversity of local surface environments. However, commonly used generic choices for barriers fail, even qualitatively, to simultaneously describe diffusion for different low-index facets, for terrace vs step edge diffusion, etc. We introduce an alternative Unconventional Interaction–Conventional Interaction formalism to prescribe these barriers, which, even with few parameters, can realistically capture most aspects of behavior. Here, the model is illustrated for single-component fcc metal systems, mainly for the case of Ag. It is quite versatile and can be applied to describe both the post-deposition evolution of 2D nanostructures in homoepitaxial thin films (e.g., reshaping and coalescence of 2D islands) and the post-synthesis evolution of 3D nanocrystals (e.g., reshaping of nanocrystals synthesized with various faceted non-equilibrium shapes back to 3D equilibrium Wulff shapes).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Temperature effects of ion irradiation on the nanostructural features in ductile-phase-toughened tungsten composites

Ductile-phase toughened tungsten (DPT W) composites have emerged as promising candidates for load-bearing components behind the plasma-facing tungsten armor in fusion reactors due to their enhanced thermomechanical properties. This study focuses on a composite consisting of W particles embedded in a ductile NiFeW solution matrix, hot-rolled to a thickness reduction of 87% (87R DPT W). Sequential irradiations with Ni2+ and He+ ions were performed to identical doses and helium concentrations at room temperature (RT) and 1273 K. Irradiation at RT produced no discernible nanostructural features due to the immobility of mono-vacancies, whereas cavity formation was observed at 973 K. At 1273 K, the W phase exhibited larger cavities, reduced cavity number density, and lower volumetric swelling compared to 973 K. Notably, nanosized NiFeW precipitates formed within the W phase at 1273 K, a phenomenon absent at 973 K. A new phase of cubic (NiFe)6W6C was also observed at the interphase boundary. In contrast, the NiFeW matrix showed no nanostructural changes at 1273 K, likely due to cavity dissociation. Separate irradiations at 1273 K indicated that Ni2+ ions induced precipitate formation in the W phase, while He+ ions exclusively caused cavity formation. The microstructure of 87R DPT W irradiated at RT and subsequently annealed at 1273 K closely resembled that of material irradiated directly at 1273 K. Like oxide-dispersion-strengthened steels, the observed nanoparticle-embedded W can inhibit dislocation propagation, potentially delaying the ductile-to-brittle transition temperature. These findings highlight the potential of NiFeW nanoparticle-reinforced W composites as irradiation-resistant materials for fusion reactors.

Jiang, Weilin (ORCID:0000000183028313)↗
DOE OSTI2021

MnSn 2 and MnSn 2 –TiO 2 nanostructured anode materials for lithium-ion batteries

The high theoretical lithium storage capacity of Sn makes it an enticing anode material for Li-ion batteries (LIBs); however, its large volumetric expansion during Li–Sn alloying must be addressed. Combining Sn with metals that are electrochemically inactive to lithium leads to intermetallics that can alleviate volumetric expansion issues and still enable high capacity. Here, we present the cycling behavior of a nanostructured MnSn 2 intermetallic used in LIBs. Nanostructured MnSn 2 is synthesized by reducing Sn and Mn salts using a hot injection method. The resulting MnSn 2 is characterized by x-ray diffraction and transmission electron microscopy and then is investigated as an anode for LIBs. The MnSn 2 electrode delivers a stable capacity of 514 mAh g -1 after 100 cycles at a C/10 current rate with a Coulombic efficiency >99%. Unlike other Sn-intermetallic anodes, an activation overpotential peak near 0.9 V versus Li is present from the second lithiation and in subsequent cycles. We hypothesize that this effect is likely due to electrolyte reactions with segregated Mn from MnSn 2 . To prevent these undesirable Mn reactions with the electrolyte, a 5 nm TiO 2 protection layer is applied onto the MnSn 2 electrode surface via atomic layer deposition. The TiO 2 -coated MnSn 2 electrodes do not exhibit the activation overpotential peak. The protection layer also increases the capacity to 612 mAh g -1 after 100 cycles at a C/10 current rate with a Coulombic efficiency >99%. This higher capacity is achieved by suppressing the parasitic reaction of Mn with the electrolyte, as is supported by x-ray photoelectron spectroscopy analysis.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Gradient nanostructured steel with superior tensile plasticity

Nanostructured metallic materials with abundant high-angle grain boundaries exhibit high strength and good radiation resistance. While the nanoscale grains induce high strength, they also degrade tensile ductility. We show that a gradient nanostructured ferritic steel exhibits simultaneous improvement in yield strength by 36% and uniform elongation by 50% compared to the homogenously structured counterpart. In situ tension studies coupled with electron backscattered diffraction analyses reveal intricate coordinated deformation mechanisms in the gradient structures. The outermost nanolaminate grains sustain a substantial plastic strain via a profound deformation mechanism involving prominent grain reorientation. This synergistic plastic co-deformation process alters the rupture mode in the post-necking regime, thus delaying the onset of fracture. The present discovery highlights the intrinsic plasticity of nanolaminate grains and their significance in simultaneous improvement of strength and tensile ductility of structural metallic materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Defect passivation in nanostructured silica for stable birefringence in polarization optics

Nanostructured materials with anisotropic microstructure exhibit direction-dependent refractive index, known as form birefringence. One of the main advantages of these nanostructured materials is that the ease of fabrication significantly reduces the cost of production. However, their birefringence is affected by humidity as well as time. The hypothesis is that defects, particularly silanols, are responsible. Here, in this work, we present the use of hexamethyldisilazane (HMDS) vapor as a passivation strategy. Using spectroscopic ellipsometry and Raman scattering, the data show that HMDS successfully passivates silanol groups and promotes O-Si-O bond formation, resulting in improved stability. The results demonstrate a simple method to enhance the reliability of all-silica polarization optics offering potential advancements for high-power laser components.

Mireles, Marcela [Univ. of Rochester, NY (United S↗
DOE OSTI2024

Ultra-intense femtosecond laser interactions with aligned nanostructures

The interaction of ultrafast laser pulses of relativistic intensity with high aspect ratio nanostructures can efficiently and volumetrically heat matter to an ultra-high-energy-density regime encountered in the center of stars and within the core of fusion capsules compressed by the world’s largest lasers. It also generates gigantic quasi-static electromagnetic fields that accelerate particles to very high energy. Here, we present an overview of the physics and applications of these dense relativistic plasmas that can be created with pulses of relatively modest energy from lasers that can operate at a high repetition rate. Recent nanowire array experiments produced near-solid density plasmas with an extreme degree of ionization (e.g., Au +72 ), converted ultrafast pulses of laser light into intense x-ray flashes with record efficiency, and accelerated ions to MeV energies, efficiently driving micro-scale fusion reactions that generate flashes of quasi-monoenergetic neutrons. These plasmas also serve as a platform for advancing the understanding of atomic processes in extreme environments and open a new pathway to laser-driven fusion energy. The irradiation of nanostructures at intensities of > 1 x 10 22 W cm –2 is predicted to lead to an extreme ultra-high energy density plasma regime characterized by terabar pressures that is virtually unexplored.

Optics↗
DOE OSTI2023

Theoretical Characterization of Correlated Redox Activity and Nanostructure in Hybrid Supercapacitors

Electrochemical energy storage devices such as supercapacitors, batteries, and fuel cells fundamentally rely on complex and correlated redox processes at electrode/electrolyte interfaces. Furthermore, the nanostructured morphology of high-surface area electrodes can significantly modulate this physics, and further complicates mechanistic understanding. Focusing on supercapacitor devices composed of carbon/polymer based electrodes and organic electrolytes, we will employ first-principles-based computer simulations to understand the coupling of these essential energy storage pathways occurring at the electrode/electrolyte interface. Of critical importance will be the development of theoretical methodologies to allow for the first-principles description of redox processes within electrochemical systems at fixed external voltage. Based on our hypothesis that redox activity and ion structuring is dramatically altered under nanoconfinement, we will then conduct a systematic study utilizing atomistic models of nanoporous carbon electrodes to understand the coupling of redox-activity, energy-storage, and nanostructuring for a variety of electrode morphologies.

25 ENERGY STORAGE↗
DOE OSTI2023

Polarized Resonant X-ray Scattering to Measure Molecular Orientation and Conformation in Organic Nanostructures

The ordering of organic (carbon-based) molecules into nanostructures drives useful materials properties for applications such as organic light emitting diodes, flexible batteries, and polymer nanocarriers. However, there is a current lack of techniques to measure this ordering. X-ray scattering techniques involving molecular resonances have shown promise in identifying molecular types, locations, and orientation. However, resonant soft X-ray scattering (RSoXS) techniques have not been developed even lacking basic optical models. The objectives achieved by this research were the development of methods, models, and analysis techniques that harness these resonant phenomena in X-ray scattering measurements to quantitatively probe ordering of organic molecules within devices and nanostructures. This award resulted in 11 peer reviewed publications with two others soon to be submitted. New physical models for X-ray scattering that accurately describe these complex molecular resonances enable measurements of how molecules assemble, orient and conform at the nanometer scale. These new techniques were applied to both organic electronic devices and aqueous nanoparticles being developed for hydrocarbon sequestration. This new measurement capability will enable characterization of structure-property relationships that lead to disruptive technologies of printable, stretchable, and biocompatible devices based on organic materials.

14 SOLAR ENERGY↗
DOE OSTI2024

Synthesis of Novel Hybrid Nanostructures Employing Advanced Structural Characterization Techniques

This proposal was for carrying out research on creating novel hybrid nanostructures with novel and interesting functional properties with the help of advanced structural on adding 0.001, 0.01 and 0.02 mg of Au nanoparticles. From the reflectivity measurements, and the intensities of the various order diffraction peaks from the multilayers, we were able to reconstruct the electron density profiles of the films normal to their surfaces. characterization techniques. There were 3 components to the research: (1) seeing if new hybrid nanostructures could be synthesized from Au nanoparticles and lipid multilayers (2) making artificial cells from Galactopyranose-Derived Single-Chain Amphiphiles and sponge phases of lipid/amphiphile mixtures, and (3) characterizing the pair distribution function for complex nanoparticles of melanin to understand/predict the structural colors seen in aggregates of such nanoparticles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Nanostructured Alumina Forming Austenitic Alloy (NAFA) Production Using Mechanical Alloying and High-Temperature Consolidation

Alumina-forming austenitic (AFA) alloys are a promising class of nuclear materials because of their high-temperature oxidation/corrosion resistance and mechanical properties. Unfortunately, these alloys are limited in use for core material applications, and they are specifically limited for use as nuclear fuel cladding because of their high Ni-transmutation and helium generation rate in-service. Improving these alloys through a fine dispersion of oxide precipitates and thus increasing the effective irradiation sink strength of the alloy system may mitigate many of the degradation phenomena expected during alloy deployment. These phenomena include high-temperature helium embrittlement and cavity swelling for lead-cooled fast reactor applications. This work effort uses combination of conventional and advanced manufacturing approaches are being used to fabricate nanostructured AFA (NAFA) materials. As the first objective of this initiative, a conventional AFA was modified using mechanical alloying and extrusion to alter the precipitation characteristics to include a fine dispersion of nanoscale oxides intended to serve as traps for irradiation-induced point defects and transmuted He within the lattice. This analysis compared the efficacy of the conventional mechanical alloying and extrusion approach with the unalloyed AFA consolidated approach using hot isostatic pressing (HIP). It was found that, although the mechanical alloying approach is successful in producing a fine distribution of oxides within the first nanostructured AFA (NAFA-1), the distribution is heterogeneous because of the mild milling parameters used to prevent cold welding of powder to the spherical milling media. The additional dispersion of oxides, coupled with a higher volume fraction of other secondary phases in the NAFA-1, produces higher alloy strengths that range up to 600°C in comparison to the unalloyed HIP AFA, thus exceeding the operating temperature of lead-cooled fast reactors. However, the strength of the NAFA-1 is lower than that of the HIP AFA at 800°C, which is presumed to be a function of increased secondary phases from the nonoptimized AFA chemistry. Future work is planned on a newly procured NAFA-2 chemistry that is more suitable for advanced reactor applications exploring new manufacturing routes.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nanostructured Alumina Forming Austenitic Alloy (NAFA) Production using Advanced Manufacturing

Alumina-forming austenitic (AFA) alloys are well known for their exceptional corrosion-resistant properties due to the formation of a dense oxide scale beneficial in their application as a nuclear material. However, use of the alloys in core material applications is limited due to the high nickel-transmutation and helium generation rate in service, leading to swelling and reduced lifetimes. Enhancing the sink strength to pin gas bubbles and increasing gas management of the material may mitigate many of the degradation phenomena expected during alloy deployment (such as high-temperature helium embrittlement and cavity swelling for lead-cooled fast-reactor applications). Nanostructured materials are usually produced using a time-consuming and expensive batch process like mechanical alloying to achieve the fine homogenous distribution of nanoprecipitates throughout the matrix material. Integrating the nanoprecipitates in modern additive manufacturing processes has proven difficult, as the required nano-sizes or number densities cannot be achieved simultaneously. Efforts to increase the number density of precipitates by adding more precipitate-forming rare-earth elements led to agglomeration of such elements, while the nano-sized precipitates did not form in sufficient quantity when not enough rare-earth element was use. In this work a novel approach to advanced manufacturing and the fabrication of Nanostructured AFA (NAFA) materials was chosen. A dual precipitate-forming NAFA steel with a chemistry more suitable for advanced reactor applications was produced to create an environmentally resistant, high-sink-strength austenitic alloy for advanced reactor cladding applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nanostructured Alumina-Forming Austenitic Alloy (NAFA) Production Using Advanced Manufacturing

Alumina-forming austenitic (AFA) alloys are well known for their exceptional corrosion-resistant properties due to the formation of a dense oxide scale beneficial in their application as a nuclear material. However, use of the alloys in core material applications is limited due to the high nickel-transmutation and helium generation rate in service, leading to swelling and reduced lifetimes. Enhancing the sink strength to pin gas bubbles and increasing gas management of the material may mitigate many of the degradation phenomena expected during alloy deployment (such as high-temperature helium embrittlement and cavity swelling for lead-cooled fast-reactor applications). Nanostructured materials are usually produced using a time-consuming and expensive batch process like mechanical alloying to achieve the fine homogenous distribution of nanoprecipitates throughout the matrix material. Integrating the nanoprecipitates in modern additive manufacturing processes has proven difficult, as the required nano-sizes or number densities cannot be achieved simultaneously. Efforts to increase the number density of precipitates by adding more precipitate-forming rare-earth elements led to agglomeration of such elements, while the nano-sized precipitates did not form in sufficient quantity when not enough rare-earth element was use. In this work a novel approach to advanced manufacturing and the fabrication of Nanostructured AFA (NAFA) materials was chosen. A dual precipitate-forming NAFA steel with a chemistry more suitable for advanced reactor applications was produced to create an environmentally resistant, high-sink-strength austenitic alloy for advanced reactor cladding applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nanostructured C@CuS Core–Shell Framework with High Lithium-Ion Storage Performance

In this study, we have synthesized a nanostructured core–shell framework of carbon-coated copper sulfide (C@CuS) through a one-step precipitation technique. The carbon sphere template facilitated the nucleation of CuS nanostructures. The synthesized nanocomposites have demonstrated remarkable lithium-ion storage capabilities when utilized as an anode in lithium-ion batteries. Notably, they exhibit an impressive rate capability of 314 mAh g -1 at a high current density of 5000 mA g -1 , along with excellent long-term cycle stability, maintaining 463 mAh g -1 at 1000 mA g -1 after 800 cycles. This superior performance is due to the core–shell architecture of the composite, where the carbon core enhances the conductivity of CuS nanoparticles and mitigates volume expansion, thus preventing capacity loss. Our study not only elucidates the significance of carbon in the construction of nano-heterojunctions or composite electrodes but also presents a practical approach to significantly boost the electrochemical performance of CuS and other metal sulfides.

25 ENERGY STORAGE↗
NASA NTRS1996

Temperature measurement involving nanostructured thermal barrier coating using a multiwavelength pyrometer

It has been reported that erroneous results were obtained when a conventional pyrometer was used to measure the surface temperature of turbine engine components. Temperatures discrepancies were observed in components which were identical, except that one had its measured surface covered by a nanostructured thermal barrier coating (TBC) whereas the other component's surface was not so coated. These components were placed in an identical environment, receiving identical heat fluxes. A pyrometer measured the TBC covered surface hundreds degrees lower. These coatings were about 25 (mu)m thick, consisting of hundreds of layers of finer structures. The TBC's had very low thermal conductivity, heat flux calculations indicated that the temperatures of the coated surface should exhibit much higher temperature than the uncoated surface. Because these coatings were transparent to radiation from the visible to the infrared region, the temperatures measured by the pyrometer should be the temperature of the covered surface. Turbo components' performance and service life depend critically on the temperatures that it would experience; it is therefore important to know accurately and confidently the real surface temperature. Out of these concerns, an investigation into the measurement of nanostructured material surface temperature was carried out.

Ng, Daniel↗
NASA NTRS1997

Fullerenes, PAH, Carbon Nanostructures, and Soot in Low Pressure Diffusion Flames

The formation of fullerenes C60 and C7O is known to occur in premixed laminar benzene/oxygen/argon flames operated at reduced pressures. High resolution transmission electron microscopy (HRTEM) images of material collected from these flames has identified a variety of multishelled nanotubes and fullerene 'onions' as well as some trigonous structures. These fullerenes and nanostructures resemble the material that results from commercial fullerene production systems using graphite vaporization. As a result, combustion is an interesting method for fullerenes synthesis. If commercial scale operation is to be considered, the use of diffusion flames might be safer and less cumbersome than premixed flames. However, it is not known whether diffusion flames produce the types and yields of fullerenes obtained from premixed benzene/oxygen flames. Therefore, the formation of fullerenes and carbon nanostructures, as well as polycyclic aromatic hydrocarbons (PAH) and soot, in acetylene and benzene diffusion flames is being studied using high performance liquid chromatography (HPLC) and high resolution transmission electron microscopy (HRTEM).

Grieco, William J.↗