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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Effects of interfacial ligand type on hybrid P3HT:CdSe quantum dot solar cell device parameters

In this work, a series of CdSe quantum dot acceptors possessing six different ligand frameworks (i.e., pivalic acid, pyridine, butylamine, tert-butylthiol, thiophenol, and tetrahydrothiophene) were used as platforms for investigating the influence of quantum dot surface chemistry on the performance of hybrid poly(3-hexythiophene-2,5-diyl) (P3HT):CdSe quantum dot bulk heterojunction (BHJ) solar cells. We confirm that the device parameters used to evaluate solar cell performance are significantly influenced by the nature of the quantum dot surface ligand. The dependence of short circuit current density ($J_{SC}$) on the CdSe ligand type was probed using ultrafast time-resolved photoluminescence (PL) measurements, and good correlations between the ligand-dependent trends in $J_{SC}$ and excited state lifetime were found, in which the P3HT:CdSe quantum dot BHJs with the shortest PL lifetimes possess the largest device current densities. The frontier energy levels of the quantum dot acceptors are significantly influenced by surface ligands, wherein the device open circuit potentials (VOC) were found to linearly correlate with the energy difference ($ΔE_{DA}$) between the HOMO of the P3HT donor and the electrochemically determined LUMO of the CdSe quantum dot acceptors over a range of 220 mV. This work demonstrates the versatility of quantum dot ligand engineering for tuning the device parameters and performance of hybrid solar cells.

14 SOLAR ENERGY↗
DOE OSTI2024

Influence of zwitterionic amphiphilic copolymers on heterogeneous gypsum formation: A promising approach for scaling resistance

Here, this study aims to investigate the influence of zwitterionic amphiphilic copolymers (ZACs) in the nucleation and growth of heterogeneous CaSO4 at the zwitterion-water interface, which is crucial for the prevention of mineral scaling and consequent downtime or suboptimal performance in industries like membrane desalination, heat exchangers, and pipeline transportation. In situ grazing incidence small angle X-ray Scattering (GISAXS), and quartz crystal microbalance with dissipation (QCM-D) techniques were used to analyze the evolution of CaSO 4 particles on two new ZAC coatings: poly-(trifluoroethyl methacrylate-random-sulfobetaine methacrylate) (PTFEMA-r-SBMA, or PT:SBMA) and poly(trifluoroethyl methacrylate-random-2-methacryloyloxyethyl phosphorylcholine) (PTFEMA-r-MPC, or PT:MPC). The results showed that PT:MPC coatings promoted nucleation but inhibited crystal growth, resulting in slower overall reaction kinetics on PT:MPC coatings compared to PT:SBMA coatings. Interfacial interactions involving the substrates, sulfate minerals, and ions were examined, revealing that calcium ion adsorption, primarily governed by electrostatic attraction, played a crucial role in the nucleation and growth processes on both ZAC coatings. The crystal characterization revealed a phase transition from bassanite to gypsum on both ZAC coatings, suggesting that these zwitterionic materials can influence the mineral phase of heterogeneously formed CaSO 4 crystals. These findings enhance our understanding of the fundamental mechanisms underlying heterogeneous CaSO 4 scaling in the presence of zwitterionic materials.

42 ENGINEERING↗
DOE OSTI2020

Effect of Molecular Structure of Quinones and Carbon Electrode Surfaces on the Interfacial Electron Transfer Process

Quinones can undergo thermodynamically reversible proton-coupled electron transfer reactions and are being applied as electroactive compounds in aqueous organic batteries. However, the electrochemical reversibility of these compounds is affected not only by their molecular structure but also by the properties of a carbon-based electrode surface. This study combines experimental and theoretical approaches to understand this dependence. Specifically, we study the electron transfer kinetics of two synthesized quinone derivatives and two commercially available ones with a glassy carbon, a highly ordered pyrolytic graphite, and a high-edge-density graphite electrode (HEDGE). The electrochemical reversibility is notably improved on the HEDGE, which shows a higher density of defects and presents oxygenated functional groups at its surface. The electron transfer kinetics are controlled by adsorbed species onto the HEDGE. Molecular dynamics simulation and quantum mechanics calculations suggest defects with oxygen-containing functional groups, such as C-O and C$=$O, on HEDGE surfaces drive the interaction with the functional groups of the molecules, during physisorption from van der Waals forces. The presence of sulfonic acid side groups and a greater number of aromatic rings in the molecular structure may contribute to a higher stabilization of quinone derivatives on HEDGEs. We propose that high-performance carbon-based electrodes can be obtained without catalysts for organic batteries, by the engineering of carbon-based surfaces with edge-like defects and oxygenated functional groups.

25 ENERGY STORAGE↗
DOE OSTI2018

A three-dimensional meso-scale approach to concrete fracture based on combined DEM with X-ray μCT images

Highlights: • We investigate fracture in concrete beams subjected to 3-point bending. • We use a discrete element method (DEM) to capture fracture. • Concrete is described as 4-phase material. • Evolution of micro-structural phenomena is investigated. • The 3D results are carefully compared with the 2D ones. - Abstract: The paper shows three-dimensional (3D) numerical mesoscopic results on progressive concrete fracture at aggregate level in a notched concrete beam under bending. A classical particle discrete element method was used to capture fracture in concrete. Heterogeneity was taken into account with a 4-phase concrete description: aggregate, cement matrix, macro-voids and interfacial transitional zones. Both the real shape and location of aggregate particles in concrete were assumed in DEM analyses based on X-ray μCT scans. A satisfactory agreement in terms of the vertical force versus crack mouth opening displacement evolution and crack geometry was achieved between DEM analyses and own laboratory tests. The evolution of broken contacts, contact normal forces, particle rotations, internal energies was studied at the aggregate level. The 3D results were also carefully compared with the 2D ones. The 3D model proved to be a promising simulation tool in predicting concrete fracture at the mesoscopic and macroscopic level.

36 MATERIALS SCIENCE↗
NASA NTRS1999

Materials Science Experiments on the International Space Station

The Performance Goal for NASA's Microgravity Materials Science Program reads "Use microgravity to establish and improve quantitative and predictive relationships between the structure, processing and properties of materials." The advent of the International Space Station will open up a new era in Materials Science Research including the ability to perform long term and frequent experiments in microgravity. As indicated the objective is to gain a greater understanding of issues of materials science in an environment in which the force of gravity can be effectively switched off. Thus gravity related issues of convection, buoyancy and hydrostatic forces can be reduced and the science behind the structure/processing/properties relationship can more easily be understood. The specific areas of research covered within the program are (1) the study of Nucleation and Metastable States, (2) Prediction and Control of Microstructure (including pattern formation and morphological stability), (3) Phase Separation and Interfacial Stability, (4) Transport Phenomena (including process modeling and thermophysical properties measurement), and (5) Crystal Growth, and Defect Generation and Control. All classes of materials, including metals and alloys, glasses and ceramics, polymers, electronic materials (including organic and inorganic single crystals), aerogels and nanostructures, are included in these areas. The principal experimental equipment available to the materials scientist on the International Space Station (ISS) will be the Materials Science Research Facility (MSRF). Each of these systems will be accommodated in a single ISS rack, which can operate autonomously, will accommodate telescience operations, and will provide real time data to the ground. Eventual plans call for three MSRF racks, the first of which will be shared with the European Space Agency (ESA). Under international agreements, ESA and other partners will provide some of the equipment, while NASA covers launch and integration costs. The MSRF facilities will include modular components, which can be exchanged to provide inserts specifically matched to the engineering requirements of the particular Principal Investigator. To defray costs and avoid duplication of engineering effort NASA is also pursuing the possibility of using facilities provided by international partners. By this means it is anticipated that all of the types of research outlined in the previous paragraph can be done on the ISS.

Gillies, Donald C.↗
DOE OSTI2021

Fiber/matrix debonding evaluation of SiCf/SiC composites using micropillar compression technique

Third-generation silicon carbide (SiC) composites reinforced by SiC fibers (Hi-Nicalon S [HNS] and Tyranno SA3 [SA3]) are attractive for use in next generation reactors owing to their high strength and chemical inertness at high temperatures, as well as enhanced radiation tolerance under neutron irradiation environments. To optimize composite performance, the interfacial mechanical properties of chemical vapor–infiltrated (CVI) SiC f /SiC composites are investigated in this effort by using a slant interface micropillar compression testing procedure. The micropillar test specimens, containing an inclined pyrolytic carbon (PyC) interphase, are prepared using a focused ion beam. The novel microcompression testing successfully quantifies the debond shear strength and internal friction coefficient of micropillar test samples by using the Mohr-Coulomb formulation. Furthermore, according to four types of SiCf/SiC composite microcompression test results, interfacial properties and debond mechanisms are significantly affected by the PyC layer thickness, the local bonding mechanism of the PyC interphase on the SiC fiber surface, and the surface roughness of fibers. Regardless of PyC thicknesses, SA3-reinforced CVI SiC f /SiC composites are found to have much higher debond shear strengths than HNS-reinforced SiC f /SiC CVI composites. By using this micropillar compression technique alongside analytical methods, we uncover new understandings of PyC interface properties. Additionally, the micropillar test results obtained are correlated with macroscopic mechanical properties of neutron-irradiated CVI SiCf/SiC composites.

42 ENGINEERING↗
DOE OSTI2019

Ignition thresholds of aluminized HMX-based polymer-bonded explosives

Here, the ignition of aluminized HMX-based polymer-bonded explosives (PBXs) under shock loading is studied via mesoscale simulations. The conditions analyzed concern loading pulses of 20 nanoseconds to 0.8 microseconds in duration and impact piston velocities on the order of 400-1000 m/s or loading stresses on the order of 3-14 GPa. The sets of samples studied have stochastically similar microstructures consisting of a bimodal distribution of HMX grains, an Estane binder, and aluminum particles 50-100 µm in diameter. The computational model accounts for constituent elasto-viscoplasticity, viscoelasticity, bulk compressibility, fracture, interfacial debonding, internal contact, bulk and frictional heating, and heat conduction. The analysis focuses on the development of hotspots under different material settings and loading conditions. In particular, the ignition thresholds in the forms of the James relation and the Walker-Wasley relation and the corresponding ignition probability are calculated and expressed as functions of the aluminum volume fraction for the PBXs analyzed. Lastly, it is found that the addition of aluminum raises the ignition thresholds, causing the materials to be less sensitive. Dissipation and heating mechanism changes responsible for this trend are delineated.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Delineating the Impact of Diluent on High-Concentration Electrolytes for Developing High-Voltage LiNi 0.5 Mn 1.5 O 4 Spinel Cathode

LiNi 0.5 Mn 1.5 O 4 (LNMO) is a high-voltage spinel cathode with low nickel content, making it an attractive candidate for next-generation lithium-ion batteries (LIBs). However, its application is limited by interfacial instability with conventional carbonate-based electrolytes at high voltages. In this work, a localized saturated electrolyte (LSE) capable of stably operating up to 4.85 V is investigated. Molecular dynamics simulations and Fourier transform infrared spectroscopy reveal that adding “non-solvating” 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether diluent in the saturated electrolyte, more PF 6 − anions are present in the first solvation shell of Li + , at the expense of solvent molecules. This tailored solvation environment promotes the formation of a robust, LiF-rich cathode-electrolyte interphase that mitigates transition metal dissolution and parasitic side reactions. The optimized LSE enables excellent cycling performance, with 95% capacity retention in Li|LNMO half-cells after 100 cycles and 94% retention in Li 4 Ti 5 O 12 |LNMO full cells after 250 cycles, even at a practically relevant LNMO cathode loading of ≈15 mg cm −2 . In conclusion, these results highlight the benefits of electrolyte engineering and solvation structure control in advancing high-voltage LIB technologies.

LNMO cathode↗
DOE OSTI2019

High-voltage regrown nonpolar m -plane vertical p-n diodes: A step toward future selective-area-doped power switches

Here, we report high-voltage regrown nonpolar m-plane p-n diodes on freestanding GaN substrates. Secondary-ion mass spectroscopy (SIMS) measurements indicate O and Si spikes at the regrowth interfaces with maximum concentration ~ 5×10 17 cm -3 , which is similar to previously published c-plane studies. A high blocking voltage of 540 V at ~ 1 mA/cm2 (corresponding to an electric field of E ~ 3.35 MV/cm), turn-on voltages between 2.9-3.1 V, specific on-resistance of 1.7 mΩ.cm 2 at 300 A/cm 2 , and a minimum ideality factor of 1.7 were obtained for the regrown diodes. Our results suggest that Si, O and C interfacial impurity levels up to 2×10 17 cm -3 , 8×10 17 cm -3 , and 1×10 19 cm -3 , respectively, at the metallurgical junction of m-plane p-n diodes do not result in very early breakdown in the reverse bias, although the off-state leakage current in forward bias is affected. The impact of growth interruption/regrowth on diode performance is also investigated.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2017

Interfacial and Alloying Effects on Activation of Ethanol from First-Principles

Here, we present a first-principles density-functional theory study of ethanol activation at oxide/Rh(111) interface and the alloying effect on mitigating carbon deposition, which are essential to direct ethanol fuel cell (DEFC) anode reaction and steam reforming of ethanol (SRE) reaction. Our calculated results show that charge can transfer from Rh(111) substrate to MO x chain (e.g., MoO 3 and MnO 2 ), or from MO x chain (e.g., MgO, SnO 2 , ZrO 2 , and TiO 2 ) to Rh(111) substrate. The OH-binding strength is increased exponentially with M δ+ charge ranging from 1.4 to 2.2, which renders MnO 2 /Rh(111) and MgO/Rh(111) interfaces weaker OH-binding, and thereby enhanced oxidizing functionality of OH* for promoting ethanol oxidation reaction (EOR) at DEFC anode. For efficient C–C bond breaking, a large number of Rh ensemble sizes are critically needed at the interface of MO x /Rh(111). We found that Rh 1 Au 3 near surface alloy has the weakest C* and CO* binding, followed by Rh 1 Cu 3 and Rh 1 Pd 3 near surface alloys, while Rh 1 Ir 3 and Rh 1 Ru 3 surface alloys have C* and CO* binding strength similar to that of pure Rh metal. The general implication of this study is that by engineering alloyed structure of weakened C* and CO* binding complemented with metal oxides of weakened OH-binding, high-performance DEFC anode or SRE catalysts can be identified.

36 MATERIALS SCIENCE↗
DOE OSTI2025

An Oxygen‐Scavenger Sulfide Coating Enabling Long‐Term Stable Nickel‐Rich Cathodes

Oxygen release is a major issue associated with layer-structured metal oxide cathodes in lithium batteries, which can further cause a series of problems, such as irreversible phase transition, microcracking, and electrolyte decomposition. Eventually, these issues jointly result in cell performance degradation and safety hazards. Thus, it is very significant to tackle oxygen release for achieving long-term stable cyclability, but very challenging. Although intensive efforts have been invested to date, there still lacks a feasible solution. In this study, nanoscale ZrS 2 coatings are applied on prefabricated LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes directly via atomic layer deposition (ALD). Very encouragingly, we reveal that this ALD-deposited conformal ZrS 2 nanocoating can serve as an exceptional oxygen scavenger and then convert into a stable sulfate (Zr(SO 4 ) 2 ) coating. Such an in situ conversion is very beneficial and effective for protecting the electrolyte from decomposition. In addition, the resultant Zr(SO 4 ) 2 coating further inhibits undesirable reactions, stabilizes the interface between NMC811 and the electrolyte, suppresses microcracking, mitigates transition metal dissolution, and maintains the structural stability of the NMC811 cathode. Consequently, the ZrS 2 -coated NMC811 cathode has demonstrated extraordinary performance. Thus, this study advances the understanding of interface engineering while paving a new technical pathway for commercializing NMC811 cathodes.

Nickel-rich cathodes↗
DOE OSTI2022

High temperature ceramic thermal insulation material

Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems. Ceramic aerogels promise high-temperature thermal insulation but lack mechanical robustness, while the fibrous materials with excellent mechanical elasticity display modest thermal insulation. Here we describe flexible hierarchical superhydrophobic ceramic insulation nanocomposites through the densified architectured hierarchical nanostructures, radiative insulation coating, and interfacial cross-linking among composites. The lightweight flexible ceramic nanocomposites exhibit a density of 0.13 g/cm 3 , high-temperature fire resistance with thermal conductivity of 0.024 W/(m·K), and super-hydrophobicity with the water contact angle of 152°. The mechanical robustness and high-temperature thermal insulation of ceramic nanocomposites, together with its soundproof performance, shed light on the low-cost flexible insulation materials manufacturing with scalability for high-temperature thermal insulation applications under high mechanical loading conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Orientation microscopy–assisted grain boundary analysis for protonic ceramic cell electrolytes

Abstract Grain boundaries in protonic ceramic cell (PCC) electrolytes hinder proton transport, reducing interfacial conductivity. In multicomponent PCC electrolytes, the inclusion of sintering aids further accentuates the complexity of grain boundaries. In this study, we synthesize nanocrystalline BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3− δ thin films via pulsed laser deposition and analyze their grain boundary character distributions using orientation data collected by precession electron diffraction technique. The results reveal an anisotropic distribution of grain boundary characters, with notably high populations of 180°‐tilt and twist grain boundaries. These findings provide critical insights into identifying the predominant grain boundaries in this PCC electrolyte material, assessing the vast five‐dimensional grain boundary space.

Patel, Sooraj [School of Aerospace and Mechanical ↗
DOE OSTI2024

03.02.02.45: Energy Efficiency Improvement Approaches in Ice Related Processes

The primary objective of this project was to facilitate the dislocation of the interfacial ice layer by employing advanced materials and ultrasonic vibration to reduce ice adhesion strength. This work employed two technical approaches that were thoroughly investigated and previously reported. The effectiveness of these approaches, both individually and in combination, has been quantified, demonstrating notable energy savings. The projected payback period for these enhancements is approximately 2.2 years or less, contingent upon specific energy costs. Furthermore, these advancements hold significant promise for reducing carbon emissions across various equipment scales. This study particularly focused on the ultrasonic deicing technique for diverse structures, utilizing numerical simulations to evaluate performance and potential benefits.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
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↗
NASA NTRS1991

Thermal barrier coating life prediction model development, phase 2

The objective of this program was to generate a life prediction model for electron-beam-physical vapor deposited (EB-PVD) zirconia thermal barrier coating (TBC) on gas turbine engine components. Specific activities involved in development of the EB-PVD life prediction model included measurement of EB-PVD ceramic physical and mechanical properties and adherence strength, measurement of the thermally grown oxide (TGO) growth kinetics, generation of quantitative cyclic thermal spallation life data, and development of a spallation life prediction model. Life data useful for model development was obtained by exposing instrumented, EB-PVD ceramic coated cylindrical specimens in a jet fueled burner rig. Monotonic compression and tensile mechanical tests and physical property tests were conducted to obtain the EB-PVD ceramic behavior required for burner rig specimen analysis. As part of that effort, a nonlinear constitutive model was developed for the EB-PVD ceramic. Spallation failure of the EB-PVD TBC system consistently occurred at the TGO-metal interface. Calculated out-of-plane stresses were a small fraction of that required to statically fail the TGO. Thus, EB-PVD spallation was attributed to the interfacial cracking caused by in-plane TGO strains. Since TGO mechanical properties were not measured in this program, calculation of the burner rig specimen TGO in-plane strains was performed by using alumina properties. A life model based on maximum in-plane TGO tensile mechanical strain and TGO thickness correlated the burner rig specimen EB-PVD ceramic spallation lives within a factor of about plus or minus 2X.

Meier, Susan Manning↗
DOE OSTI2017

Recordings and Analysis of Atomic Ledge and Dislocation Movements in InGaAs to Nickelide Nanowire Phase Transformation

The formation of low resistance and self‐aligned contacts with thermally stable alloyed phases is a prerequisite for realizing reliable functionality in ultrascaled semiconductor transistors. Detailed structural analysis of the phase transformation accompanying contact alloying can facilitate contact engineering as transistor channels approach a few atoms across. Original in situ heating transmission electron microscopy studies are carried out to record and analyze the atomic scale dynamics of contact alloy formation between Ni and In 0.53 Ga 0.47 As nanowire channels. It is observed that the nickelide reacts on the In 0.53 Ga 0.47 As (111) || Ni 2 In 0.53 Ga 0.47 As (0001) interface with atomic ledge propagation along the Ni 2 In 0.53 Ga 0.47 As direction. Ledges nucleate as a train of strained single‐bilayers and propagate in‐plane as double‐bilayers that are associated with a misfit dislocation of . The atomic structure is reconstructed to explain this phase transformation that involves collective gliding of three Shockley partials in In 0.53 Ga 0.47 As lattice to cancel out shear stress and the formation of misfit dislocations to compensate the large lattice mismatch in the newly formed nickelide phase and the In 0.53 Ga 0.47 As layers. This work demonstrates the applicability of interfacial disconnection (ledge + dislocation) theory in a nanowire channel during thermally induced phase transformation that is typical in metal/III–V semiconductor reactions.

Chen, Renjie↗