Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “crystalline”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Preparation, Identification, and Low-Temperature Infrared Spectra of Two Elusive Crystalline Nitrile Ices

Infrared (IR) spectra of the alkyl nitrile ices CH3CN and CH3CH2CN are relevant to the study of the low-temperature chemistry of objects within and beyond the Solar System, but the thermodynamically favored low-temperature crystalline phases of these compounds have not been presented and identified in the planetary-sciences literature. Moreover, there is a large variation in the published IR spectra of these two icy solids, including spectra that are used for the analyses of spacecraft data from the Voyager and Cassini missions. Here the IR spectra of the low-temperature crystalline forms of CH3CN and CH3CH2CN, which are the thermodynamically stable phases at Titan temperatures, are presented for the first time with all samples being made by vapor-phase deposition. Conditions are described for producing these ice phases for both compounds, and new measurements are reported of ice density and refractive index, quantities needed to compute IR absorption coefficients, band strengths, optical constants, and, ultimately, nitrile abundances in extraterrestrial environments. Comparisons are drawn between CH3CN and CH3CH2CN, an earlier prediction on their similar crystallization behaviors is verified, and previous work is examined in light of these new results, including a counter-intuitive observation in which the low-temperature phase of an ice is made by heating a high-temperature phase. Applications and extensions are described.

Reggie L Hudson↗
NASA NTRS2019

Preparation, Identification, and Low-Temperature Infrared Spectra of Two Elusive Crystalline Nitrile Ices

Infrared (IR) spectra of the alkyl nitrile ices CH3CN and CH3CH2CN are relevant to the study of the low- temperature chemistry of objects within and beyond the Solar System, but the thermodynamically favored low-temperature crystalline phases of these compounds have not been presented and identified in the planetary- sciences literature. Moreover, there is a large variation in the published IR spectra of these two icy solids, including spectra that are used for the analyses of spacecraft data from the Voyager and Cassini missions. Here the IR spectra of the low-temperature crystalline forms of CH3CN and CH3CH2CN, which are the thermody-namically stable phases at Titan temperatures, are presented for the first time with all samples being made by vapor-phase deposition. Conditions are described for producing these ice phases for both compounds, and new measurements are reported of ice density and refractive index, quantities needed to compute IR absorption coefficients, band strengths, optical constants, and, ultimately, nitrile abundances in extraterrestrial environments. Comparisons are drawn between CH3CN and CH3CH2CN, an earlier prediction on their similar crystallization behaviors is verified, and previous work is examined in light of these new results, including a counter- intuitive observation in which the low-temperature phase of an ice is made by heating a high-temperature phase. Applications and extensions are described.

Hudson, Reggie L.↗
NASA NTRS2019

Preparation, Identification, and Low-Temperature Infrared Spectra of Two Elusive Crystalline Nitrile Ices

Infrared (IR) spectra of the alkyl nitrile ices CH3CN and CH3CH2CN are relevant to the study of the low-temperature chemistry of objects within and beyond the Solar System, but the thermodynamically favored low-temperature crystalline phases of these compounds have not been presented and identified in the planetary-sciences literature. Moreover, there is a large variation in the published IR spectra of these two icy solids, including spectra that are used for the analyses of spacecraft data from the Voyager and Cassini missions. Here the IR spectra of the low-temperature crystalline forms of CH3CN and CH3CH2CN, which are the thermodynamically stable phases at Titan temperatures, are presented for the first time with all samples being made by vapor-phase deposition. Conditions are described for producing these ice phases for both compounds, and new measurements are reported of ice density and refractive index, quantities needed to compute IR absorption coefficients, band strengths, optical constants, and, ultimately, nitrile abundances in extraterrestrial environments. Comparisons are drawn between CH3CN and CH3CH2CN, an earlier prediction on their similar crystallization behaviors is verified, and previous work is examined in light of these new results, including a counter-intuitive observation in which the low-temperature phase of an ice is made by heating a high-temperature phase. Applications and extensions are described.

Ices, IR spectroscopy, Titan, organic chemistry, i↗
NASA NTRS2022

Oxygen Isotopes in AMMS and IDPS: Universality of Oxygen Isotope Systematics Of Crystalline Silicates in Comets

It has been suggested that the major source of crystalline silicates in comets is CR chondrule-like materials along with minor sources including O, R, CH-CB chondrite chondrule-like materials based on the comparisons of oxygen isotope systematics between cometary silicates and chondrules from various types of primitive chondrites [1-3]. However, cometary silicates used for these studies are from only two comets: Wild2 and a parent comet of U2-20GCA. It is uncertain that the oxygen isotope systematics represent that of crystalline silicates in all comets.

D Nakashima↗
DOE OSTI2020

Crystalline Aluminosilicates for Radionuclide Remediation

Crystalline aluminosilicates have a wide range of applications such as media for the capture and/or immobilization of radionuclides. Several different types of metal-exchanged zeolites have been successfully demonstrated as effective sorbents for gaseous, aqueous, or solid-state capture and immobilization of radionuclides including iodine [e.g., I2(g), CH3I(g)], xenon, krypton, radium (e.g., 226Ra and 228Ra), selenium (e.g., 79Se6+), technetium (e.g., 99TcO4-), strontium (e.g., 90Sr2+), cesium (e.g., 135Cs+, 137Cs+), mixed alkali halide streams (i.e., iodide and chloride salts), and actinides (e.g., U6+, Th4+). These zeolites include sodalite (SOD), mordenite (MOR or Z-type), faujasite (FAU), Linde type-A (LTA), cancrinite (CAN), gismondine (GIS), and heulandite (or clinoptilolite) (HEU). The structural building blocks of these seven materials vary from cages (e.g., a-cages, ß-cages, e-cages) to channels linking various cage types and these are mostly comprised of aluminosilicates. This chapter will delve into the crystallographic differences between these framework materials and provide a brief overview of literature data where these seven crystalline aluminosilicates have been utilized for the capture and/or immobilization of radionuclides. Metal-exchanged zeolites (e.g., MOR, FAU, LTA) have often been the source of study for gaseous capture of iodine where the more promising compositions include Ag-exchanged sorbents; these types of materials can be made in a variety of robust forms including berl saddles and extrudates. Sodalite can be used as an immobilization strategy for halide waste streams (e.g., Cl, I), including those from electrochemical reprocessing of used nuclear fuel, as well as TcO4–. Cancrinite has been demonstrated to enhance sorption capacity of sediments for several problematic ionic radionuclides including Cs+, SeO42–, and TcO4–. Actinides such as U6+ and Th4+ have been successfully captured from solutions using MOR, FAU, LTA, and HEU-type aluminosilicates. Finally, mixtures of aluminosilicates have been included in a set of zeolite materials that show promise as sorbents for 226Ra and 228Ra removal from mine waters.

zeolites, aluminosilicates, radionuclide remediati↗
DOE OSTI2024

The EGS Collab project: Outcomes and lessons learned from hydraulic fracture stimulations in crystalline rock at 1.25 and 1.5 km depth

With the goal of better understanding stimulation in crystalline rock for improving enhanced geothermal systems (EGS), the EGS Collab Project performed a series of stimulations and flow tests at 1.25 and 1.5 km depths. The tests were performed in two well-instrumented testbeds in the Sanford Underground Research Facility in Lead, South Dakota, United States. The testbed for Experiment 1 at 1.5 km depth contained two open wells for injection and production and six instrumented monitoring wells surrounding the targeted stimulation zone. Four multi-step stimulation tests targeting hydraulic fracturing and nearly year-long ambient temperature and chilled water flow tests were performed in Experiment 1. The testbed for Experiments 2 and 3 was at 1.25 km depth and contained five open wells in an outwardly fanning five-spot pattern and two fans of well-instrumented monitoring wells surrounding the targeted stimulation zone. Experiment 2 targeted shear stimulation, and Experiment 3 targeted low-flow, high-flow, and oscillating pressure stimulation strategies. Hydraulic fracturing was successful in Experiments 1 and 3 in generating a connected system wherein injected water could be collected. However, the resulting flow was distributed dynamically, and not entirely collected at the anticipated production well. Thermal breakthrough was not observed in the production well, but that could have been masked by the Joule-Thomson effect. Shear stimulation in Experiment 2 did not occur - despite attempting to pressurize the fractures most likely to shear - because of the inability to inject water into a mostly-healed fracture, and the low shear-to-normal stress ratio. The EGS Collab experiments are described to provide a background for lessons learned on topics including induced seismicity, the correlation between seismicity and permeability, distributed and dynamic flow systems, thermoelastic and pressure effects, shear stimulation, local geology, thermal breakthrough, monitoring stimulation, grouting boreholes, modeling, and system management.

15 - GEOTHERMAL ENERGY↗
DOE OSTI2021

Early-Stage Aggregation and Crystalline Interactions of Peptoid Nanomembranes

Fully synthetic peptoid membranes are known to mimic important features of biological membranes, with several advantages over other biomimetic membranes. A fundamental understanding of how the individual peptoid amphiphiles assemble in solution to form the bilayer membrane is key to unlocking their versatility for application in a broad range of processes. Here, in this study, in situ X-ray scattering and molecular dynamics simulations are used to understand the early stages of assembly of three different peptoids that exhibit distinctly different crystallization kinetics. The in situ measurements reveal that the peptoids aggregate first into a nascent phase that is less crystalline than the assembled peptoid membrane. Anisotropic aromatic interactions are determined to be the dominant driving force in the early stages of membrane formation. These results provide key insights into how the peptoid assembly may be manipulated during the early stages of assembly and nucleation and growth.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Digital Light Process 3D Printing of Magnetically Aligned Liquid Crystalline Elastomer Free–forms

Liquid crystalline elastomers (LCEs) are anisotropic soft materials capable of large dimensional changes when subjected to a stimulus. The magnitude and directionality of the stimuli-induced thermomechanical response is associated with the alignment of the LCE. Recent reports detail the preparation of LCEs by additive manufacturing (AM) techniques, predominately using direct ink write printing. Another AM technique, digital light process (DLP) 3D printing, has generated significant interest as it affords LCE free-forms with high fidelity and resolution. However, one challenge of printing LCEs using vat polymerization methods such as DLP is enforcing alignment. Here, we document the preparation of aligned, main-chain LCEs via DLP 3D printing using a 100 mT magnetic field. Systematic examination isolates the contribution of magnetic field strength, alignment time, and build layer thickness on the degree of orientation in 3D printed LCEs. Informed by this fundamental understanding, DLP is used to print complex LCE free-forms with through-thickness variation in both spatial orientations. Further, the hierarchical variation in spatial orientation within LCE free-forms is used to produce objects that exhibit mechanical instabilities upon heating. DLP printing of aligned LCEs opens new opportunities to fabricate stimuli-responsive materials in form factors optimized for functional use in soft robotics and energy absorption.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Ultraviolet Laser Activation of Phosphorus-Doped Polysilicon Layers for Crystalline Silicon Solar Cells

In crystalline silicon photovoltaics (c-Si PV), a pulsed laser can be used as a substitute for a high-temperature furnace dopant diffusion/activation step. In contrast to furnace-based activation, lasers can be used to achieve highly localized doping with controlled dopant concentrations, useful in advanced architectures such as the interdigitated back contact (IBC) solar cell. In this study, a pulsed ultraviolet (UV) laser is utilized for phosphorus dopant activation within a low-pressure chemical vapor deposited (LPCVD) polycrystalline silicon (poly-Si) passivated contact layer. The highest implied open-circuit voltage iV oc values achieved using this approach reach 726 mV. However, this comes at the expense of high specific contact resistivities ρ c , which is attributed to a lower dopant concentration across the poly-Si(n + )/SiO x /c-Si interface. Regardless, the optimum iV oc , ρ c combination is measured at a laser fluence of 0.78 J cm -2 producing values of 712 mV and 89 mΩ-cm 2 , respectively. These values are still compatible with high-efficiency solar cell designs, underscoring the feasibility and effectiveness of this approach.

14 SOLAR ENERGY↗
DOE OSTI2023

Millimeter-Thick Liquid Crystalline Elastomer Actuators Prepared by-Surface-Enforced Alignment

Here, liquid crystalline elastomers (LCE) are thermally cyclable, compliant actuators with compelling mechanical properties. The large and programmable deformation of LCE has led to numerous functional examinations spanning optics, medical devices, and robotics. A well-established method to prepare complex LCE actuators is to utilize surface-enforced photoalignment. Herein, a facile and scalable approach is reported to circumvent the physical limits of surface-enforced alignment (e.g., samples that are 50 µm or less) to amplify the achievable force output in LCE. Applying an approach termed direct layering, the thermomechanical response of LCE elements prepared with +1 disclination patterns in a range of compositions and thicknesses is contrasted. The design and preparation of +1 disclination patterns and arrays is explored to assess the contribution of sample geometry and overlap to deformation and force output. The methodology detailed in this contribution allows for the preparation of elements ≈1 mm in thickness that are capable of actuating large objects. Furthermore, the fabrication of these elements uniquely enables the realization of mechanical instabilities to hasten the actuation rate in response to thermal change and to enable leaping.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A Solution-Processable High-Modulus Crystalline Artificial Solid Electrolyte Interphase for Practical Lithium Metal Batteries

The solid electrolyte interphase (SEI) has been identified as a key challenge for Li metal anodes. The brittle and inhomogeneous native SEI generated by parasitic reactions between Li and liquid electrolytes can devastate battery performance; therefore, artificial SEIs (ASEIs) have been proposed as an effective strategy to replace native SEIs. Herein, as a collaboration between academia and industrial R&D teams, a multifunctional (crystalline, high modulus, and robust, Li + ion conductive, electrolyte-blocking, and solution processable) ASEI material, LiAl-FBD (where “FBD” refers to 2,2,3,3-tetra-fluoro-1,4-butanediol), for improving Li metal battery performance is designed and synthesized. The LiAl-FBD crystal structure consists of Al 3+ ions bridged by FBD 2– ligands to form anion clusters while Li + ions are loosely bound at the periphery, enabling an Li + ion conductivity of 9.4 × 10 –6 S cm –1 . Further, the fluorinated, short ligands endow LiAl-FBD with electrolyte phobicity and high modulus. The ASEI is found to prevent side reactions and extend the cycle life of Li metal electrodes. Specifically, pairing LiAl-FBD coated 50 μm thick Li with industrial 3.5 mAh cm –2 NMC811 cathode and 2.8 μL mAh –1 lean elec-trolyte, the Li metal full cells show superior cycle life compared to bare ones, achieving 250 cycles at 1 mA cm –2 .

25 ENERGY STORAGE↗
DOE OSTI2020

Solvent-Free Self-Assembly for Scalable Preparation of Highly Crystalline Mesoporous Metal Oxides

Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic-organic self-assembly process. In this work, we develop a facile, general, and high throughput solvent-free self-assembly strategy to synthesize a series of MMOs including single-component MMOs and multi-component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self-assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications.

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

Highly crystalline, low-ash, graphite from coal using an Fe 2 O 3 -based catalytic process with recovery and reuse of catalyst and process acid

This study presents a sustainable process for producing highly crystalline, low-ash graphite from sub-bituminous coal using an Fe 2 O 3 -based catalytic method. The process integrates coal mineral removal, catalyst regeneration, and reagent recycling into a closed-loop system. Acid-soluble Fe-residue and mineral impurities are eliminated from the solid graphite through HCl treatment, followed by hydrolytic distillation to regenerate Fe 2 O 3 and recover HCl for reuse. Coal-derived silica is removed with a KOH rinse, yielding low-ash graphite suitable for high-performance applications. The closed-loop catalytic graphitization, where the recovered Fe 2 O 3 and HCl are used in subsequent graphitization runs, produces graphite with a degree of graphitization exceeding 95%. The L a and L c crystallite sizes reach 65–78 nm and 44–48 nm, respectively, with BET surface areas of 4–10 m 2 /g and an ash content below 0.1 wt.%. Lithium-ion battery testing reveals that anodes fabricated with this graphite deliver an initial discharge capacity between 384.5 and 421.2 mAh/g, averaging 395.0 ± 19.1 mAh/g, along with initial coulombic efficiencies of 85.0–89.1%. After 100 discharge–charge cycles at 0.25C, reversible capacities remain between 358.8 and 369.7 mAh/g, while coulombic efficiency stays above 99.9%. The findings highlight that coal can serve as a viable precursor for high-quality graphite production under relatively mild conditions, avoiding the need for extreme temperatures or aggressive reagents such as hydrofluoric acid, commonly employed in conventional processes. This work demonstrates both technical feasibility and environmental benefits, emphasizing its potential to support large-scale, sustainable graphite production for applications such as lithium-ion batteries.

Catalytic graphitization↗
DOE OSTI2021

The adsorption of As(V) on poorly crystalline Fe oxyhydroxides, revisited: Effect of the reaction media and the drying treatment

Arsenic (As) adsorbed on Fe oxyhydroxides (adsorbent) is widely occurring in many environmental settings such as in acid mine drainage systems or in the hydrometallurgical operations to form Fe-As coprecipitates. However, the influence of the reaction media and the drying treatment on the microstructure of the directly formed adsorbents at various pHs was still not fully understood. In this work, As adsorption behaviors on various forms of Fe oxyhydroxides were systematically investigated by using XRD, FTIR, Raman, XANES, and HRTEM. Overall, the results revealed that at weak acidic pH, more As could adsorbed on the suspension adsorbent formed in sulfate and chloride media than that in nitrate media, possibly due to the microstructure alteration of the adsorbent in the presence of sulfate and chloride. Besides, the increasing crystallinity of the Fe oxyhydroxides and the aggregation effect after drying were the major reasons why less As could be hold by the dried adsorbents than that of the corresponding suspension adsorbents. These findings could shed more light on the nature of the Fe oxyhydroxides which may be helpful for more precisely predicting the fate of some toxic metal(loid)s in the environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

The surface triple-coupling on single crystalline cathode for lithium ion batteries

Single crystalline (SC) cathode materials, which are less susceptible to micro/nano-cracks formation and offer better structure stability compared to the polycrystalline counterpart, have attained great attention. However, the parasitic side reactions at the cathode-electrolyte interface induces the loss of active species, which consequently leads to continual degradation of the electrochemical performances. Herein, a triple coupling of concentration-gradient Na+, F- co-doping and surface NaF coating are exploited for the first time on SC LiNi 0.5C o 0.2 Mn 0.3 O 2 cathode by the hydrolysis of NaPF 6 . This process regulates the external structure of materials by constructing a “sandwich” configuration from surface to bulk: rock salt - mixing zone - layered phase. The detailed interface transformation mechanism is revealed by Neutron powder diffraction (NPD), spherical aberration corrected high-resolution scanning transmission electron microscopy (HR-STEM), electron energy loss spectroscopy (EELS), and Ar+ sputtering assisted X-ray photoelectron spectroscopy (XPS). The synergistic effects endow the SC cathode with outstanding capacity retentions: 91.3% at 25 °C and 85% at 45 °C, after 500 cycles at 5 C between 3.0 and 4.5 V. In addition, a high full-cell reversible capacity of 168.9 mAh g -1 with a capacity retention of 92.4% is achieved after 300 cycles at 1 C. Multiple characterizations further indicate that these superior results are mainly ascribed to the overall structure integrity of SC material, the thin cathode electrolyte interface, high content of lithium fluoride, and the low solubility of transition metal ions. This work opens a new avenue to construct a benign interface towards high-performance lithium ion batteries.

lithium ion batteries↗
DOE OSTI2022

Technoeconomic Analysis of High-Value, Crystalline Silicon Photovoltaic Module Recycling Processes

Recycling is an important circular economy strategy, and for photovoltaics (PV), the one that has received the greatest research attention. Recycling of PV modules is required in Europe; everywhere else it competes in the market of end-of-life options, where cost is a primary decision factor. The vast majority of PV modules sold globally are crystalline-silicon (c-Si); most of the rest of the market are cadmium telluride thin film modules whose primary manufacturer runs its own commercial-scale recycling program. While many different c-Si recycling approaches and technologies have been proposed, they generally lack accompanying cost estimates or enough process information to model costs. Herein we develop detailed estimates of seven categories of capital and operating costs along with estimates of revenue from recovered materials for each step in two proposed recycling processes for c-Si PV modules. Using these results, we develop a hypothetical third recycling process merging process steps from the original two, estimate surcharges required to achieve minimum sustainable prices for each recycling process, as well as consider how economies of scale could reduce costs. Increasing the purity of and identifying higher-value markets for recovered materials are approaches to reducing costs and increasing recycling rates in voluntary markets.

crystalline silicon↗
DOE OSTI2023

Achieving High Permittivity Paraelectric Behavior in Mesogen-Free Sulfonylated Chiral Polyethers with Smectic C Liquid Crystalline Self-Assembly

Ferroelectric liquid crystalline polymers (LCPs) with a high spontaneous polarization (P s ) are of great interest for the fabrication of advanced electronic devices. However, conventional ferroelectric LCPs typically exhibit low spontaneous polarization, only around 1 mC/m 2 . To increase the orientational polarization for ferroelectric LCPs, in this work, we designed mesogen-free comb-shaped LCPs based on isotactic polyepichlorohydrin, which contained highly dipolar sulfonyl groups (dipole moment of 4.5 Debye) in the side chains. The goal was to increase dipole density and induce ferroelectric switching. In this new series of mesogen-free LCPs, the sulfonyl groups were first moved away from the main chain to mitigate strong dipole–dipole interactions. Second, methyl-branched alkyl side chains were implemented to decrease the crystallizability and induce the Smectic C (SmC) self-assembly. Intriguingly, these SmC samples, for the first time, exhibited typical paraelectric behavior (i.e., slim S-shaped single hysteresis loops) with a high dielectric constant in the range of 20–30. Finally, learning from the knowledge obtained from this study, we will be able to design new mesogen-free LCPs with tailor-made dipole–dipole interactions and realize ferroelectricity.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Resonant ultrasound spectroscopy for crystalline samples containing initial strain

Resonant ultrasound spectroscopy (RUS) is a mature and robust technique for the nondestructive characterization of the elastic properties of solids capable of providing the elastic constants of anisotropic crystalline solids. The traditional method is based on assuming that the solid is linear elastic and, therefore, obeys a linearized Hookean constitutive relationship (Hooke’s law). In this work, an alternative constitutive law is provided that allows for an initial strain or prestrain to be present stemming from residual stress. Then, the constitutive relationship is integrated into the RUS framework. The model is demonstrated using a realistic prestrain field obtained by simulating shot-peening processing of a polycrystalline Cu sample. The sensitivity of the resonances to the developed prestrain is established and discussed. This work allows researchers to consider the influence of initial strain or residual stress in their samples and the potential influence on accurate elastic constant estimates. The model also supports the potential of RUS for the nondestructive characterization of prestrain in materials.

42 ENGINEERING↗