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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Nature-Inspired Hierarchical Steels

Materials can be made strong, but as such they are often brittle and prone to fracture when under stress. Inspired by the exceptionally strong and ductile structure of byssal threads found in certain mussels, we have thus designed and manufactured a multi-hierarchical steel, based on an inexpensive austenitic stainless steel, which defeats this "conflict" by possessing both superior strength and ductility. These excellent mechanical properties are realized by structurally introducing sandwich structures at both the macro- and nano-scales, the latter via an isometric, alternating, dual-phase crystal phases comprising nano-band austenite and nano-lamellar martensite, without change in chemical composition. Our experiments (transmission and scanning electron microscopy, electron back-scattered diffraction, nano-indentation and tensile tests) and micromechanics simulation results reveal a synergy of mechanisms underlying such exceptional properties. This synergy is key to the development of vastly superior mechanical properties, and may provide a unique strategy for the future development of new super strong and tough (damage-tolerant), lightweight and inexpensive structural materials.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Photocatalytic properties of h-WO{sub 3} nanoparticles obtained by annealing and h-WO{sub 3} nanorods prepared by hydrothermal method

In the present study, two different methods for preparing hexagonal WO{sub 3} (h-WO{sub 3}) photocatalysts were used - controlled thermal decomposition and hydrothermal synthesis. WO{sub 3} nanoparticles with hexagonal structure were obtained by annealing (NH{sub 4}){sub x}WO{sub 3-y} at 500 °C in air. WO{sub 3} nanorods were prepared by a hydrothermal method using sodium tungstate Na{sub 2}WO{sub 4}, HCl, (COOH){sub 2} and NaSO{sub 4} precursors at 200 °C. The formation, morphology, structure and composition of the as-prepared nanoparticles and nanorods were studied by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX). The photocatalytic activity of the h-WO{sub 3} nanoparticles and nanorods was studied by decomposing methyl orange in aqueous solution under UV light irradiation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A strain-driven thermotropic phase boundary in BaTiO 3 at room temperature by cycling compression

In BaTiO 3 single crystals, we observed a strain-driven phase transition from the tetragonal phase to the tetragonal-orthorhombic phase boundary which can be introduced by slow cycling compressions (a loading of up to 0.5 GPa, strain rate of 10 -4 s -1 , and 100 cycles) at room temperature. Different from the well-known tetragonal to cubic phase transition under stress (~2 GPa), it only takes place locally around bent 90° domain walls. The inhomogeneous local stress and electrical fields as well as the mobile point defect pinning effect contribute to the phase re-entrance. Through comparison experiments by in situ synchrotron x-ray diffraction, Raman scattering, and (scanning) transmission electron microscopy, we explored the phase transition mechanism. Based on that, we developed a mechanical method to obtain well-stabilized high-density thermotropic phase boundary structures (with tetragonal, orthorhombic, and bridging monoclinic phases) in BaTiO 3 for potential applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Designing Nuclear Fuels with a Multi-Principal Element Alloying Approach

Previous research has shown that multi-principal element alloys (MPEAs) using chromium, molybdenum, niobium, tantalum, titanium, vanadium, and zirconium can form stable body-centered-cubic (BCC) structures across a large temperature region (25°C to 1000°C). This is the same crystal structure as γ-uranium (U), which has shown desirable thermal and irradiation behavior in previous alloy fuel research. It is hypothesized then that the MPEA alloying approach can be used to produce a stable BCC uranium-bearing alloy and to retain its stability throughout anticipated operating regimes of power-producing reactors. Candidate elements were assessed using Monte Carlo N-Particle (MCNP) analysis to determine uranium densities necessary to make the alloy an economically viable fuel compared to conventional fuel forms. Following neutronic considerations, materials property databases and empirical predictors were used to determine the compositions with a high potential to form a BCC solid solution alloy. The final four alloys were MoNbTaU 2 , MoNbTiU 2 , NbTaTiU 2 , and NbTaVU 2 , which were cast using arc melting of raw elemental foils and chunks. Characterization of the fabricated alloys included scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The results showed a two-phase system with a U-rich matrix phase surrounding the refractory precipitates. The U phase was found to contain varying concentrations of the alloying elements and was a BCC γ-U phase. These results warrant further research to identify ideal compositions for use as an advanced alloy fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Freestanding crystalline YB a 2 C u 3 O 7 – x heterostructure membranes

We report the synthesis of millimeter-sized freestanding single-crystal YBa 2 Cu 3 O 7–x heterostructure membranes with nanoscale thickness. On a SrTiO 3 substrate, a heteroepitaxial water-soluble sacrificial layer of Sr 3 Al 2 O 6 followed by an encapsulated YBa 2 Cu 3 O 7–x film is grown by pulsed laser deposition. A freestanding YBa 2 Cu 3 O 7–x heterostructure membrane is obtained by etching the sacrificial layer. As a result, its high crystalline quality is demonstrated via x-ray diffraction, electrical measurements, and scanning transmission electron microscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Impact of the Stack Order in Cu-Zn-Sn Metal Precursors on the Properties of Cu2ZnSnS4 Thin Films

Cu2ZnSnS4 (CZTS) thin films were grown by the annealing of metallic precursors with different stack orders in sulfur atmosphere. The sequential deposition of the metal layers from single Cu, Zn, and Sn targets on Mo-coated soda-lime glass substrates was carried out using radio-frequency magnetron sputtering. In this work, we investigated the effect of the sequence of metal layers on the chemical, structural, and morphological properties of the final CZTS films using X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman scattering spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The realized stack sequences were Mo/Sn/Zn/Cu, Mo/Sn/Cu/Zn, Mo/Cu/Zn/Sn, Mo/Cu/Sn/Zn, and Mo/Zn/Cu/Sn. XRF measurements revealed notable impact of the metal layers' stacking order in the precursor on the chemical composition. It also showed Sn loss and high Zn concentration in all sulfurized films; however, having Cu on the Sn or Zn/Sn layer showed some minimization of the Sn loss. XRD showed CZTS films with good crystallinity and no evidence of the presence of secondary phases. Changing the precursor stack order did not show any influence on the films' crystallinity or texture. Raman spectroscopy, in contrast, indicated the presence of ZnS phase beside the main CZTS phase. The morphology study showed significant effect on the structure of the final CZTS films depending on the used stack order. Generally, the films that originated from precursors having a Zn layer deposited directly on Mo or as the second layer exhibited better adhesion to the Mo layer and showed fewer or even no voids compared to the other films.

14 SOLAR ENERGY↗
DOE OSTI2025

On Stability and Electrochemical Performance of 316 Stainless Steel in Wastewater: Implications for Resource Recovery

Electrochemical nutrient recovery systems rely on stable electrode materials capable of operating in chemically complex wastewater environments. We investigated corrosion resistance and interfacial electrochemical behavior of 316 stainless steel (SS316) in a synthetic wastewater matrix representative of centrate streams, a key knowledge gap in electrochemical phosphorus recovery. A comprehensive suite of electrochemical techniques (chronoamperometry, cyclic voltammetry, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS)) and surface characterization methods (scanning electron microscopy, X-ray diffraction) were employed. Results revealed that wastewater containing typical ionic constituents (such as PO 4 3- , NH 4 + , and divalent cations) exhibited enhanced cathodic activity and the formation of a more stable, protective surface film on SS316 that mitigated chloride-induced corrosion. In contrast, SS316 in the NaCl solution showed significant susceptibility to passive layer breakdown and localized corrosion. Time-resolved EIS further confirmed improved interfacial stability and restricted charge transfer in WW over time, in stark contrast to the progressive passive layer degradation in NaCl. Surface analyses corroborated these findings, showing limited surface attack in WW compared to distinct localized corrosion features in NaCl. These findings indicate that competing ionic species in WW effectively mitigate chloride aggressiveness, enhance SS316 stability, and demonstrate improved electrode longevity and reliability for sustainable wastewater-based electrochemical phosphorus recovery applications.

36 MATERIALS SCIENCE↗
DOE OSTI2016

In Situ Stress Evolution in Li 1+x Mn 2 O 4 Thin Films during Electrochemical Cycling in Li-Ion Cells

Real time monitoring of stress evolution in electrodes during electrochemical cycling can help quantify the driving forces that dictate their mechanical degradation. In the present work, in-situ stress evolution in thin films of spinel Li 1+x Mn 2 O 4 (LMO) was measured by monitoring the change in the elastic substrate curvature during electrochemical cycling in a specially designed beaker cell in the 3.5–4.3 V (vs. Li/Li+) voltage range. The LMO thin films were prepared using a solution deposition technique and their structures and morphologies were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The stress evolution in the early part of the first delithiation cycle (<4.05 V) was consistent with the XRD data. However, stress evolution during later stages of the first delithiation cycle (>4.05 V) was not consistent with the XRD results, and showed irreversible behavior, suggesting irreversible changes in the electrode. Beyond the first delithiation cycle, the stress evolution was reversible, with a steady buildup of compressive and tensile stress during lithium insertion and extraction, respectively. Measurements on LMO films of varying thicknesses suggest that the first cycle irreversibility in stress response arises primarily from the electrode bulk.

25 ENERGY STORAGE↗
DOE OSTI2016

pyCroscopy

Suite of Python Libraries that implement structure data format processing, multivariate analysis, and interactive visualization of microscopy data and other spectral imaging modalities, including scanning probe microscopy, electron microscopy, Bragg diffraction microscopy, and chemical imaging.

Jesse, Stephen↗
DOE OSTI2015

Characterization and corrosion behavior test of glass ceramic waste form

The research conducted in this work package is to collect data in support of future development of glass ceramic waste forms and to help develop the next generation high performance waste management technologies. This work package collaborates closely with the work conducted under “Glass Ceramic – Pacific Northwest National Laboratory (PNNL) - (FT-15PN030704)” and “CCIM Test with Glass Ceramic – Idaho National Laboratory (INL) – (FT-15IN030707)”. The Los Alamos National Laboratory (LANL) is focusing on characterization, testing procedures on glass ceramics from the test matrix and melter testing to further develop and mature the glass ceramic waste form for immobilization of high level waste (HLW) raffinate stream. In Fiscal Year 2015, we are mainly working on multi-phase glass ceramic waste forms. Various characterization and testing techniques (including X-ray diffraction, transmission electron microscopy/scanning transmission electron microscopy, scanning electron microscopy, synchrotron X-ray, nano-indentation) were used to characterize and investigate the corrosion behavior of glass ceramics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Effect of Silicon in U-10Mo Alloy

This document details a method for evaluating the effect of silicon impurity content on U-10Mo alloys. Silicon concentration in U-10Mo alloys has been shown to impact the following: volume fraction of precipitate phases, effective density of the final alloy, and 235-U enrichment in the gamma-UMo matrix. This report presents a model for calculating these quantities as a function of Silicon concentration, which along with fuel foil characterization data, will serve as a reference for quality control of the U-10Mo final alloy Si content. Additionally, detailed characterization using scanning electron microscope imaging, transmission electron microscope diffraction, and atom probe tomography showed that Silicon impurities present in U-10Mo alloys form a Si-rich precipitate phase.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAl alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed the non-welded specimens to exhibit strain-induced softening (decrease in the true stress level) with increasing plastic strain during tensile testing. Fracture for the weldments was found to occur exclusively within the fusion zone. The mechanical performance of the weldment was speculated to be directly linked to variances in the radiation-induced microstructure including the formation of dislocation loops and precipitation of the Cr-rich α' phase. The localized microstructural variation within the weldments, including grain size, was determined to play a significant role in the radiation-induced microstructure. The results summarized within highlight the need for additional data on the radiation tolerance of weldments as the mechanical performance of the fusion zone was shown to be the limiting factor in the overall performance of the weldments.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The Role of Metal Oxides in Li-S Batteries: A High-Areal-Capacity Sulfur Composite Cathode Investigation

Compared to lithium-ion batteries (LIB), lithium-sulfur (Li-S) batteries have low cost and high theoretical specific energy (2510 Wh/kg or about 10 times of the LIB). However, Li-S batteries have several challenges, including large volume expansion, poor utilization of the end products, sluggish kinetics of polysulfides, and crossover, so-called the "shuttle effect". To address these issues, we have introduced metal oxides to the Li-S electrode to develop a metal-oxide-sulfur composite electrode. We aim to use metal oxides to assist the Li-S formation (dissociation) during discharge (charge) cycles. We elect to focus on LIB-based metal oxides to ensure that the added material can contribute storage capacity to the battery. Our cathodes are fabricated by both the conventional slurry casting and air-controlled electrospray. LIB electrode materials, such as Li(Ni 0.6 Mn 0.6 Co 0.2 )O 2 , LiMn 2 O 4 , Li 2 TiO 3 , etc, were incorporated with the sulfur-carbon composite and their charge-discharge performances are compared. We found that the presence of metal oxides increased sulfur utilization with stable cycling performance, even in cells with high areal capacities. To unveil the interactions between lithium metal oxides and sulfur, the cathodes were analyzed by various characterization techniques, including scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and electrochemistry. The analysis of the role of the oxides will be presented along with the reaction mechanism.

25 ENERGY STORAGE↗
DOE OSTI2022

High Efficiency InGaN LEDs Emitting in Green, Amber and Beyond (Final Report)

This project focuses on developing high efficiency light emitting diodes (LEDs) with green, amber, and longer wavelengths using two compatible material systems based on III-nitride and II-IV-nitride semiconductor heterostructures. The proposed approach uses low-indium-content InGaN and ZnGeN 2 or ZnSnN 2 heterostructure quantum wells (QWs) as the active regions for high efficiency green and amber LEDs, and therefore to advance high efficiency color-mixed white LED technology. This approach takes advantage of the increased flexibility, afforded by the incorporation of the II-IV-nitrides into the III-nitride layers, to tune the QW active region to lower the emission wavelengths and to increase the electron-hole wave function overlap. This strategy paves a new way to extend the InGaN QW LED emission wavelength without using high-indium-content InGaN. An industrially preferable metalorganic chemical vapor deposition (MOCVD) method was used to develop the growth of ZnGeN 2 and ZnSnN 2 that are compatible with the InGaN growth. The unique dual chamber MOCVD instrument at OSU was used in this project. This program created an opportunity for the two institutions (The Ohio State University and Case Western Reserve University) with complementary expertise to perform this work. Two graduate students (Md Rezaul Karim (OSU) and Benthara Hewage Dinushi Jayatunga (CWRU)) gained experience in MOCVD growth and various characterization methods including scanning electron microscopy, x-ray diffraction spectroscopy, x-ray photoemission spectroscopy, Hall measurements, cathodoluminescence and photoluminescence. Both students successfully defended their PhD dissertations in April/May 2021. Both Karim and Jayatunga have joined Intel as engineers in June/July 2021. Another two graduate students Kaitian Zhang (OSU) and Chenxi Hu (CWRU) joined the project team since spring 2021 to continue on this project. They were trained on MOCVD epitaxy of InGaN QWs and materials characterization including SEM, AFM, PL, CL, XRD, Hall measurements and electroluminescence. A third student, Vijay Gopal Thirupakuzi Vangipuram (OSU), who joined the group in fall 2021 to perform LED fabrication and characterization. The key research accomplishments of the project include: (1) Successful development of MOCVD epitaxy of single crystalline ZnGeN 2 and ZnSnN 2 . MOCVD growth parameters that determine the stoichiometry of ZnGeN 2 and ZnSnN 2 films were identified. (2) Experimentally determined the band offsets between GaN/ZnGeN 2 and GaN/ZnGaSnN 2 hetero-interfaces, which agree very well with the theoretical predictions. (3) Demonstrated the incorporation of thin ZnGeN 2 layer in InGaN QWs. Proof-of-concept of the InGaN-ZnGeN 2 QW design demonstrated as much as 80 nm of red shift without increasing In composition or QW thickness. (4) InGaN/ZnGeN 2 QWs emitting at 480 nm achieved IQE of 47%. Resulted from this project, 7 journal articles were published, and 9 conference papers were presented.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Embedded High-Temperature Sensors: Enhancing Thermoelectrical Performance with Refractory Composites Gradient Layers

To monitor the stability of various energy and manufacturing systems, sensors capable of operating at temperatures exceeding 1000 °C in diverse environments for extended durations are essential. However, under harsh conditions, degradation of sensing materials is a concern that can be controlled by embedding the sensors into refractory oxides. Doped-LaCrO3 based composites are excellent candidates for high-temperature sensing applications due to their good thermoelectrical properties. However, chemical reactivity between the conductive phase and the refractory oxides can decrease the performance of the sensors. In this work, it was devised gradient-type protective layers safeguarding conductive phases within embedded thermocouples, which were fabricated and characterized by X-Ray Diffraction for phase development analysis, Scanning Electron Microscopy and Energy-dispersive X-ray spectroscopy for microstructure and cationic interdiffusion kinetics, long-term thermoelectric testing was completed up to 1400 °C. The enhanced performance of these novel sensors addresses a critical limitation, rendering them viable for long-term high-temperature applications.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Shear Assisted Processing and Extrusion of Magnesium Alloy Machining Chips

The Pacific Northwest National Laboratory (PNNL) utilized Shear Assisted Processing and Extrusion (ShAPE) to convert magnesium alloy machining chips directly into wrought material. PNNL fabricated 0.25” and 0.50” round rod from cold compacted briquettes pressed from dry-machined chips by Loukus Technologies. The alloy composition is proprietary and protected by a Materials Transfer Agreement (MTA) between PNNL and Loukus. Extrusions were fabricated using the ShAPE 2.0 machine, tooling, and process. PNNL is evaluating tensile properties per ASTM E8 and microstructure for grain size, texture, and porosity using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD). Tensile properties and microstructure results were not available at the time of writing this document. Extruded rods have also been sent to Loukus for evaluation.

36 MATERIALS SCIENCE↗
DOE OSTI2025

SEM/EBSD Characterization of Baffle-Former Bolts Designated for High Energy X-ray Microscopy Studies at the Advanced Photon Source

This report documents the microstructural and surface characterization of two high-fluence baffle-former bolts (BFBs) harvested from a commercial pressurized water reactor (PWR) after nearly four decades of service. These bolts experienced extreme conditions including high neutron fluence, elevated temperatures, corrosive primary water, and sustained mechanical loads, all of which contribute to degradation mechanisms such as irradiation-assisted stress corrosion cracking (IASCC). Using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), the study assessed bulk and near-surface microstructures, grain boundary characteristics, and in-service oxide layers. The results revealed significant differences between bolts exposed to 41 dpa and 29 dpa, including differences in recrystallization extent, deformation structures, and oxidation morphology. These findings establish critical baseline data for integration with advanced synchrotron-based high-energy X-ray microscopy (HEXM) and computational crystal plasticity models. Ultimately, the work supports improved mechanistic understanding and predictive capability regarding the long-term performance of reactor core internal components.

Lach, Tim [Oak Ridge National Laboratory (ORNL), O↗