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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 OSTI2020

Electrochemically induced crystallization of amorphous materials in molten MgCl2: boron nitride and hard carbon

A novel and versatile strategy for the amorphous-to-crystalline transformation of boron nitride (BN) with the capability to control the degree of crystallization was developed through an electrochemical pathway using MgCl 2 at low temperature (750 °C). This procedure can be extended to the transformation of amorphous carbon to graphite, which significantly reduces the energy and cost, accelerates the synthesis process and could potentially replace industrial graphite synthesis globally. Therefore, the synthesized graphite exhibits much enhanced electrochemical performance at high charge–discharge rates (5C) compared to commercial synthetic graphite.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Nanocomposites from Solution-Synthesized PbTe-BiSbTe Nanoheterostructure with Unity Figure of Merit at Low-Medium Temperatures (500-600 K)

The large-scale implementation of thermoelectric devices is inhibited, in part, by the limited temperature range where each material can operate at its highest efficiency, as evaluated by the dimensionless figure of merit ( zT = S 2 σT/κ ). To date, Bi 2 Te 3 -based materials have been restricted to zT ≥ 1 between 300-500 K, before the onset of bipolar conduction reduces the zT significantly. Herein, we show that a scalable, low-temperature solution process method can be used to synthesize precursor material for Pb-doped Bi x Sb 2-x Te 3 bulk nanocomposites with a zT = 1 over the 500-600 K range, making this material suitable for low-grade waste heat recovery for the first time. Our success in increasing the efficiency of p-type Bi x Sb 2-x Te 3 at higher temperatures can be largely explained by the increase in the optical band gap, according to the Burstein-Moss shift, due to Pb doping, thus delaying the onset of bipolar conduction. Furthermore, the solution synthesis method enabled controlled nanostructuring of the bulk materials, which greatly reduced the thermal conductivity over the investigated temperature range. Lastly, our scalable synthesis processing method may be applicable to not only other thermoelectrics, but also in fields such as photocatalysis, electronics and optoelectronics.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Comparative Study of Differentially Private Data Synthesis Methods

When sharing data among researchers or releasing data for public use, there is a risk of exposing sensitive information of individuals in the data set. Data synthesis is a statistical disclosure limitation technique for releasing synthetic data sets with pseudo individual records. Traditional data synthesis techniques often rely on strong assumptions of a data intruder’s behaviors and background knowledge to assess disclosure risk. Differential privacy (DP) formulates a theoretical approach for a strong and robust privacy guarantee in data release without having to model intruders’ behaviors. Efforts have been made aiming to incorporate the DP concept in the data synthesis process. Here, we examine current DIfferentially Private Data Synthesis (DIPS) techniques for releasing individual-level surrogate data for the original data, compare the techniques conceptually and evaluate the statistical utility and inferential properties of the synthetic data via each DIPS technique through extensive simulation studies. Our work sheds light on the practical feasibility and utility of the various DIPS approaches, and suggests future research directions for DIPS.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Native lattice strain induced structural earthquake in sodium layered oxide cathodes

Abstract High-voltage operation is essential for the energy and power densities of battery cathode materials, but its stabilization remains a universal challenge. To date, the degradation origin has been mostly attributed to cycling-initiated structural deformation while the effect of native crystallographic defects induced during the sophisticated synthesis process has been significantly overlooked. Here, using in situ synchrotron X-ray probes and advanced transmission electron microscopy to probe the solid-state synthesis and charge/discharge process of sodium layered oxide cathodes, we reveal that quenching-induced native lattice strain plays an overwhelming role in the catastrophic capacity degradation of sodium layered cathodes, which runs counter to conventional perception—phase transition and cathode interfacial reactions. We observe that the spontaneous relaxation of native lattice strain is responsible for the structural earthquake (e.g., dislocation, stacking faults and fragmentation) of sodium layered cathodes during cycling, which is unexpectedly not regulated by the voltage window but is strongly coupled with charge/discharge temperature and rate. Our findings resolve the controversial understanding on the degradation origin of cathode materials and highlight the importance of eliminating intrinsic crystallographic defects to guarantee superior cycling stability at high voltages.

25 ENERGY STORAGE↗
DOE OSTI2024

Structure Development in Cross-Linked, Soybean Oil-based Waterborne Polyurethanes

Development of waterborne polyurethanes (WPU) using bio-based sources represents a step towards sustainable materials science and industry. We synthesized bio-based cationic water-dispersed crosslinked polyurethanes from high oleic soybean oil (HOSO) polyol, isophorone diisocyanate, and methyldiethanol amine, with varying ionic group contents after neutralization with acetic acid. Our primary objective was to analyze how crosslinking affects the dispersion process and film properties in multifunctional systems. The synthesis-structure-property relationship is elucidated through comprehensive analyses of the products at different stages of the synthesis. The dispersion of the WPU particles in water must occur prior to gelation during the final preparation, leading to incomplete conversion and the formation of imperfect networks. Insight into the synthesis process and polymer structure was gained by simulating polymer network parameters. Morphological analyses using synchrotron-based X-ray scattering and atomic force microscopy revealed a hierarchical structure within the WPU films. Importantly, all the films prepared in this study, without using coalescence agents, have low water absorption and high water contact angles, demonstrating their potential for textile and leather coatings and other applications.

bio-based polymers↗
DOE OSTI2013

Synthesis of flower-like Boehmite (γ-AlOOH) via a one-step ionic liquid-assisted hydrothermal route

A simple and novel synthesis process, one-step ionic liquid-assisted hydrothermal synthesis route, has been developed in the work to synthesize Bohemithe (γ-AlOOH) with flower-like structure. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscope (SEM). Ionic liquid [Omim]{sup +}Cl{sup −}, as a template, plays an important role in the morphology and pore structure of the products due to its strong interactions with reaction particles. With the increase in the dosage of ionic liquid [Omim]{sup +}Cl{sup −}, the morphology of the γ-AlOOH was changed from initial bundles of nanosheets (without ionic liquid) into final well-developed monodispersed 3D flower-like architectures ([Omim]{sup +}Cl{sup −}=72 mmol). The pore structure was also altered gradually from initial disordered slit-like pore into final relatively ordered ink-bottle pore. Furthermore, the proposed formation mechanism and other influencing factors such as reaction temperature and urea on formation and morphology of the γ-AlOOH have also been investigated. - Graphical abstract: The flower-like γ-AlOOH architectures composed by nanosheets with narrow size distribution (1.6–2.2 μm) and uniform pore size (6.92 nm) have been synthesized via a one-step ionic liquid-assisted hydrothermal route. - Highlights: • The γ-AlOOH microflowers were synthesized via an ionic liquid-assisted hydrothermal route. • Ionic liquid plays an important role on the morphology and porous structure of the products. • Ionic liquid can be easily removed from the products and reused in recycling experiments. • A “aggregation–recrystallization–Ostwald Ripening“formation mechanism may occur.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1992

Aqueous organic geochemistry at high temperature/high pressure

A description of the fate and chemical alterations of organic matter under hydrothermal conditions is given, with a brief overview of the geographic localities where these processes have been investigated to date. Two major aspects are examined: (1) alteration and degradation processes and reactions, both reductive and oxidative; and (2) synthesis processes and reactions which are primarily reductive. Examples of industrial applications of the related supercritical fluid technology are discussed.

Simoneit, Bernd R. T.↗
NASA NTRS2003

Flame Synthesis Of Single-Walled Carbon Nanotubes And Nanofibers

Carbon nanotubes are widely sought for a variety of applications including gas storage, intercalation media, catalyst support and composite reinforcing material [1]. Each of these applications will require large scale quantities of CNTs. A second consideration is that some of these applications may require redispersal of the collected CNTs and attachment to a support structure. If the CNTs could be synthesized directly upon the support to be used in the end application, a tremendous savings in post-synthesis processing could be realized. Therein we have pursued both aerosol and supported catalyst synthesis of CNTs. Given space limitations, only the aerosol portion of the work is outlined here though results from both thrusts will be presented during the talk. Aerosol methods of SWNT, MWNT or nanofiber synthesis hold promise of large-scale production to supply the tonnage quantities these applications will require. Aerosol methods may potentially permit control of the catalyst particle size, offer continuous processing, provide highest product purity and most importantly, are scaleable. Only via economy of scale will the cost of CNTs be sufficient to realize the large-scale structural and power applications on both earth and in space. Present aerosol methods for SWNT synthesis include laser ablation of composite metalgraphite targets or thermal decomposition/pyrolysis of a sublimed or vaporized organometallic [2]. Both approaches, conducted within a high temperature furnace, have produced single-walled nanotubes (SWNTs). The former method requires sophisticated hardware and is inherently limited by the energy deposition that can be realized using pulsed laser light. The latter method, using expensive organometallics is difficult to control for SWNT synthesis given a range of gasparticle mixing conditions along variable temperature gradients; multi-walled nanotubes (MWNTs) are a far more likely end products. Both approaches require large energy expenditures and produce CNTs at prohibitive costs, around $500 per gram. Moreover these approaches do not possess demonstrated scalability. In contrast to these approaches, flame synthesis can be a very energy efficient, low-cost process [3]; a portion of the fuel serves as the heating source while the remainder serves as reactant. Moreover, flame systems are geometrically versatile as illustrated by innumerable boiler and furnace designs. Addressing scalability, flame systems are commercially used for producing megatonnage quantities of carbon black [4]. Although it presents a complex chemically reacting flow, a flame also offers many variables for control, e.g. temperature, chemical environment and residence times [5]. Despite these advantages, there are challenges to scaling flame synthesis as well.

Wal, Randy L. Vander↗
DOE OSTI2014

Magnetic properties and scale-up of nanostructured cobalt carbide permanent magnetic powders

Co{sub x}C magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 45 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of surfactants, reaction temperature, and reaction duration on the crystallographic structure and magnetic properties of Co{sub x}C, while tetraethylene glycol was employed as a reducing agent. The role of the ratios of Co{sub 2}C and Co{sub 3}C phases in the admixture magnetic properties is discussed. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Selective synthesis of boron nitride nanotubes by self-propagation high-temperature synthesis and annealing process

Four types of BN nanotubes are selectively synthesized by annealing porous precursor in flowing NH{sub 3} and NH{sub 3}/H{sub 2} atmosphere at temperature ranging from 1000 to 1200 deg. C in a vertical furnace. The as-synthesized BN nanotubes, including cylinder, wave-like, bamboo-like and bubble-chain, are characterized by XRD, FTIR, Raman, SEM, TEM and HRTEM. Three phenomenological growth models are proposed to interpret growth scenario and structure features of the four types of BN nanotubes. Selectivity of nanotubes formation is estimated as approximately 80-95%. The precursor containing B, Mg, Fe and O prepared by self-propagation high-temperature synthesis (SHS) method plays a key role in selective synthesis of the as-synthesized BN nanotubes. Chemical reactions are also discussed. - Graphical Abstract: Four types of BN nanotubes are selectively synthesized by annealing porous precursor prepared by self-propagation high-temperature synthesis. Three phenomenological growth models are proposed to reveal growth scenario and characteristics of the as-synthesized BN nanotubes. Highlights: > Four types of BN nanotubes are selectively synthesized by annealing porous precursor. > Selectivity of BN nanotubes formation is estimated as approximately 80-95 wt%. > Three growth models are proposed to interpret growth of the as-synthesized BN nanotubes. > The precursor prepared by SHS method plays a key role in selective synthesis process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Correlation between processing conditions, microstructure and charge transport in half-Heusler alloys

Five bulk samples of n-type Zr₀.₂₅Hf₀.₇₅NiSn₀.₉₇₅Sb₀.₀₂₅ half-Heusler (HH) alloy were fabricated by reacting elemental powders via (1) high temperature solid state (SS) reaction and (2) mechanical alloying (MA), followed by densification using spark plasma sintering (SPS) and/or hot pressing (HP). A portion of the sample obtained by SS reaction was mechanically alloyed before consolidation by hot pressing (SS–MA–HP). X-ray powder diffraction and transmission electron microscopy studies revealed that all SS specimen (SS–SPS, SS–HP, SS–MA–HP) are single phase HH alloys, whereas the MA sample (MA–SPS) contains metallic nanoprecipitates. Electronic and thermal transport measurements showed that the embedded nanoprecipitates induce a drastic increase in the carrier concentration (n), a large decrease in the Seebeck coefficient (S) and a marginal decrease in the lattice thermal conductivity (κ l ) of the MA–SPS sample leading to lower ZT values when compared to the SS–HP samples. Constant values of S are observed for the SS series regardless of the processing method. However, a strong dependence of the carrier mobility (μ), electrical conductivity (σ) and κ l on the processing and consolidation method is observed. For instance, mechanical alloying introduces additional structural defects which enhance electron and phonon scattering leading to moderately low values of μ and large reduction in κ l . This results in a net 20% enhancement in the figure of merit (ZT=0.6 at 775 K). HH specimen of the same nominal composition with higher ZT is anticipated from a combination of SS reaction, MA and SPS (SS–MA–SPS). - Graphical abstract: In half-Heusler alloys, thermopower values are insensitive to processing method, whereas carrier mobility (μ), electrical conductivity (σ), and κ l strongly dependent on the microstructure which in turn is altered by the synthesis, processing and consolidation method. Highlights: • Phase composition of HH alloy strongly depends on the synthesis technique. • Mechanical alloying of elements yields bulk HH alloy with metallic impurity phases. • Thermopower, carrier density, and effective mass of HHs are insensitive to processing conditions. • Mechanical alloying decreases the carrier mobility and lattice thermal conductivity of bulk HH.

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

Text-mined dataset of inorganic materials synthesis recipes

Abstract Materials discovery has become significantly facilitated and accelerated by high-throughput ab-initio computations. This ability to rapidly design interesting novel compounds has displaced the materials innovation bottleneck to the development of synthesis routes for the desired material. As there is no a fundamental theory for materials synthesis, one might attempt a data-driven approach for predicting inorganic materials synthesis, but this is impeded by the lack of a comprehensive database containing synthesis processes. To overcome this limitation, we have generated a dataset of “codified recipes” for solid-state synthesis automatically extracted from scientific publications. The dataset consists of 19,488 synthesis entries retrieved from 53,538 solid-state synthesis paragraphs by using text mining and natural language processing approaches. Every entry contains information about target material, starting compounds, operations used and their conditions, as well as the balanced chemical equation of the synthesis reaction. The dataset is publicly available and can be used for data mining of various aspects of inorganic materials synthesis.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2019

Bis(1,2,4-oxadiazolyl) Furoxan: A Promising Melt-Castable Eutectic Material of Low Sensitivity

A scalable synthesis of bis(1,2,4-oxadiazoyl) furoxan, C 6 H 2 N 6 O 4 , its physical properties, and its theoretical performance values are described herein. Previous attempts to synthesize this compound required expensive reagents, and/or time-consuming synthesis processes and low overall yields. In addition to disclosing a streamlined synthesis of bis(1,2,4-oxadiazolyl) furoxan, we report its molecular configuration and crystal structure, as well as its correct melting point. Bis(1,2,4-oxadiazolyl) furoxan exhibits a very insensitive behavior to impact, friction, and electrostatic discharge, with a calculated detonation pressure 20 % higher than that of TNT. Given its physical properties and theoretical performance values, this material can be classified as a promising ingredient in the development of melt-castable eutectic technology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Room-Temperature Eutectic Synthesis for Upcycling of Cathode Materials

Ni-rich LiNixMnyCo1−x−yO2 (NMC) materials have been adopted in a range of applications, including electric vehicles. The recycled NMC material from a spent cell would be much more valuable if it could be upgraded to a Ni-rich, more energy-dense version of the material. This work demonstrates a simple, inexpensive, and facile method to upcycle LiNi1/3Mn1/3Co1/3O2 (NMC111, 160 mAh∙g−1), a cathode used in early generations of electric vehicle batteries, to LiNi0.8Mn0.1Co0.1O2 (NMC811, 190 mAh∙g−1), a more energy-dense cathode material. In this study, a preliminary investigation into a room-temperature eutectic synthesis of NMC811 is performed using NMC111, LiOH, and nickel nitrate as precursors. The synthesized material showed the desired crystal structure and stoichiometry, though the cycle life and Li diffusion coefficient need improvement when compared to commercially available NMC811. This study demonstrates an interesting proof of concept of the room-temperature eutectic synthesis process for LIB cathodes and could be improved by tuning the synthesis conditions.

lithium-ion battery↗
DOE OSTI2018

Low vacuum annealing of polymer at low temperatures towards direct and scalable growth of graphene

Highlights: • Low Temperature and pressure growth process. • Synthesis of transfer free single layer graphene in the absence of reducing gases. • Sandwich structure growth process. - Abstract: A transfer-free method is demonstrated for the synthesis of graphene flakes directly on insulating substrate (SiO{sub 2}/Si) by carbon decomposition and diffusion through a layer of nickel. The 100 nm nickel catalyst was deposited on the top of SiO{sub 2} (300 nm)/Si substrate. The sandwich structure was prepared wherein spin-coated polymer was used as a carbon source for the graphene formation. The carbon molecules decomposed and diffused into the nickel layer during annealing of sandwich structures in low vacuum (∼5 × 10{sup −1} Pa) at 600–750 °C for 10 min. When cooled to room temperature (25 °C), graphene is formed at the interface between Ni and SiO{sub 2}/Si, the nickel film was removed by chemical etching. The observed graphene on SiO{sub 2}/Si substrates is confirmed by optical microscopy, Raman spectroscopy and atomic force microscopy. The Raman spectroscopy mapping over a 55 × 55 μm{sup 2} area confirmed the good quality of graphene flakes obtained.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Terminator-free template-independent enzymatic DNA synthesis for digital information storage

Abstract DNA is an emerging medium for digital data and its adoption can be accelerated by synthesis processes specialized for storage applications. Here, we describe a de novo enzymatic synthesis strategy designed for data storage which harnesses the template-independent polymerase terminal deoxynucleotidyl transferase (TdT) in kinetically controlled conditions. Information is stored in transitions between non-identical nucleotides of DNA strands. To produce strands representing user-defined content, nucleotide substrates are added iteratively, yielding short homopolymeric extensions whose lengths are controlled by apyrase-mediated substrate degradation. With this scheme, we synthesize DNA strands carrying 144 bits, including addressing, and demonstrate retrieval with streaming nanopore sequencing. We further devise a digital codec to reduce requirements for synthesis accuracy and sequencing coverage, and experimentally show robust data retrieval from imperfectly synthesized strands. This work provides distributive enzymatic synthesis and information-theoretic approaches to advance digital information storage in DNA.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Identification of efficient and stable solid-solid electrochemical interfaces for Li-S batteries. Final Report

The objective of this work is to develop a better understanding of the interactions between battery components that drive the observed battery performance. Using computational tools at the atomistic level, we elucidate molecular, crystal, and amorphous structures, interfacial structures and reactions, and electrochemical behavior. We focus on Li metal anodes, liquid electrolytes, solid electrolytes, S cathodes, and metal-oxide cathodes, and their corresponding interfaces. Within liquid electrolytes, we study their bulk structure and dynamics, as a function of salt concentration. The analysis allows to understand the formation of localized high concentrated regions as the solvent is substituted by a weakly interacting diluent species. Analysis of the electron distribution yields the reactive behavior at interfaces. Moreover, we employ tools that allow the characterization of ion and electron transport at interfaces, during the processes of solvation and desolvation occurring while cycling. For Sulfur cathodes we elucidate synthesis processes and the role of carbon-sulfur and nitrogen-sulfur interactions not only to provide electronic conductivity but also to define alternative reaction pathways during discharge of Li-S batteries. Full-cell simulations offer new insights regarding the integration of all the battery components. Our studies also include solid electrolytes and their interfaces with Li metal, S-C, and metal-oxide electrodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Renewable Solvents to Replace Water in the Synthesis of Battery Materials

Our lab has been engaged in using glycerol to replace water in the synthesis of metal oxides, especially those for use in Li-ion battery. Glycerol is a byproduct from biodiesel production. The U.S. biodiesel manufacturers generate about 1 billion pounds of glycerol yearly, which needs to be utilized for producing value added products. By using glycerol as a solvent, we found that it can replace water to prepare many metal oxide powders. The materials synthesis processes have the potential to significantly reduce manufacturing cost and alleviate the environmental issues with aqueous processes. In this talk, I will present some of our work in materials synthesis using glycerol as a solvent. In particular, I will introduce the work on making active cathode materials for the Li-ion battery.

36 MATERIALS SCIENCE↗