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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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45 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A redox-reversible A/B-site co-doped BaFeO 3 electrode for direct hydrocarbon solid oxide fuel cells

Solid oxide fuel cells (SOFCs) can directly convert the chemical energy in fuel to electrical energy with fuel flexibility; however, the conventional nickel-based anodes face great challenges due to coking upon direct oxidation of hydrocarbon fuels and redox instability. Thus, developing new anode materials which can provide high coking resistance as well as redox stability is crucial. In this work, Ba 0.6 La 0.4 Fe 0.8 Mo 0.1 Ni 0.1 O 3-δ (BLFMN) has been synthesized in air using a sol–gel combustion method, resulting in a dual phase consisting of a cubic BLFMN main phase and scheelite BaMoO 4 (BMO 4 ) secondary phase. By heat-treating the BLFMN dual phase in H 2 at 800 °C for 5 h, a metallic nanoparticle-decorated BLFMN triple phase compound comprising cubic BLFMN, cubic BaMoO 3 (BMO 3 ) and in situ exsolved FeNi 3 alloy was obtained. BLFMN was subsequently investigated as an electrode material for La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 3-δ (LSGM) electrolyte (300 μm) supported SOFCs. Symmetrical cells using BLFMN as electrodes with the cell configuration of BLFMN//LSGM//BLFMN showed excellent redox reversibility and a peak power density (PPD) of 1.32 W cm -2 at 850 °C when using H 2 as fuel. Single cell with the cell configuration of BLFMN//LSGM//LSCF (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ) reached PPD of 1.61 and 0.41 W cm -2 at 850 °C when operating with H 2 and CH 4 fuel, respectively. Moreover, the single cell exhibit excellent stability (over 300 h) upon direct oxidation of hydrocarbon fuels of CH 4 and C 3 H 8 . This study indicates that BLFMN is a promising redox reversible and coking resistant anode for SOFCs.

08 HYDROGEN↗
DOE OSTI2021

Effect of Pd alloying on structural, electronic and magnetic properties of L1 0 Fe–Ni

We present a systematic study of the effect of Pd-alloying on phase stability, electronic structure, and elastic properties in L1 0 Fe–Ni using density-functional theory. Being from the same group of the periodic table, Pd is the best candidate for chemical alloying. The Fe–Ni/Fe–Pd/Ni–Pd bond-length increases with increasing Pd-concentration, which weakens the hybridization between low lying energy states below Fermi-level. The reduced hybridization decreases the relative thermodynamic stability of L1 0 Fe(Ni 1–x Pd x ) until x = 0.75. Beyond this concentration, the relative stability gets enhanced, which is attributed to a unique change in the lattice distortion (c/a). The elastic properties show a non-monotonous behavior as a function of x, which is again due to a specific change-over in the uniaxial strain. We found that Pd alloying increases the local Fe moment and structural anisotropy of L1 0 FeNi, which are important for applications such as microwave absorption, refrigeration systems, recording devices, imaging and sensors. Here, we believe that the present study for the chemical alloying effect can provide critical insights toward the understanding of electronic-structure and elastic behavior of other technologically important materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Hardware, methodology and applications of 2 + D backscatter Mössbauer spectroscopy with simultaneous x-ray and γ-ray detection

Abstract A unique method is presented for the acquisition and analysis of 57 Fe backscatter Mössbauer spectra with simultaneous detection of the resonant 14.4 keV γ -rays and the characteristic 6.4 keV x-rays, using a custom-built multi-parameter analyser constructed on the basis of commercial analogue to digital converters and high-speed digital latches. The system allows for the simultaneous registration of Doppler-modulation velocities and photon energies, with up to 4096 and 8192 digital channels respectively. This arrangement is in contrast to most related systems, which detect at a single narrow energy window per detector. Samples of arbitrary atomic structure, morphology and surface topography can be studied without altering the setup or the analysis procedure, provided that the samples are at least micrometre sized. The hardware and software that are used to acquire data with minimal dead time are described and the custom and self-contained methods for post-measurement energy discrimination, background correction and velocity-axis folding are discussed. The data are fit using a general Hamiltonian model for the nuclear energy levels of 57 Fe and a quantum mechanical description of the angular momentum coupling is utilised, with consideration of the crystalline and chemical disorder of the sample under examination. Three examples of distinct magnetic systems, with thicknesses ranging from 5 μ m to 6 mm, that were studied using this method are presented, these are: an amorphous CoFeB-based ribbon with ultra-soft coercivity for high-frequency applications, magnetically hard Nd-Fe-B thick films on Si substrates, examined in both as-deposited and annealed states, and a sample from the nickel-rich iron meteorite NWA 6259 that contains the atomically ordered, elevated coercivity, L 1 0 phase of FeNi, tetrataenite. The wide applicability and usefulness of this method is thus demonstrated on three distinct sample morphologies that required little to no surface preparation prior to examination.

Engineering↗
DOE OSTI2020

Effective pair potential for random fcc CoCrFeMnNi alloys

The single-phase equiatomic CoCrFeMnNi alloy is a random solid solution of five elements on the face-centered cubic lattice, whose pure constituents crystallize in very different structures and exhibit diverse magnetic properties. Due to the randomness of the alloy, 80% of nearest neighbor bonds are between unlike elements and thus the details of bonding in pure structures are less important. The elastic moduli of this alloy give rise to small Cauchy pressure C 12 - C 44 , which suggests that the dominant part of bonding may be described by a simple pair potential. We test this hypothesis by developing a long-range Lennard-Jones potential in which the equilibrium crystal structures of pure constituents are taken as reference. The standard mixing rules for regular solutions are then adopted to obtain parameters for bonds between unlike elements in the quinary system. The transferability of this potential to quaternary CoCrFeNi, ternary CoCrNi, and binary FeNi alloys is investigated and the predictions compared with experiments and density functional theory calculations. By sampling over a large number of random configurations, we investigate the effect of compositional randomness on misfit volumes, energies of point defects and stacking faults, and the dislocation friction stresses experienced by moving edge and screw dislocations.

Materials Science↗
DOE OSTI2021

Flux Switching Permanent Magnet Motor with Metal Amorphous Nanocomposite Soft Magnetic Material and Rare Earth Free Permanent Magnets

The power losses in high power-density motors due to high rotational speed and/or high pole counts may be reduced adopting metal amorphous nanocomposites (MANCs) featuring low power loss and a relatively high flux density (~1.3 T). We recently proposed a flux switching permanent magnet (FSPM) motor with a rating of 2.5 kW at 1400 Hz electrical speed by incorporating low loss (< 3 W/kg at 1 kHz) FeNi-based MANC material with projected iron loss of about 5 W. The motor design allows use of rare earth-free permanent magnets. For incorporation of MANC materials, an axial flux motor where the rotor and stator core are made from a wound ribbon core has been developed. We have performed a 3-d FEA to optimize the design and built and tested a prototype demonstrating that the low loss MANC material can be used for motor applications.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2024

Emerging magnetic materials for electric vehicle drive motors

Abstract Increasing demand for electric vehicles (EVs) is increasing demand for the permanent magnets that drive their motors, as approximately 80% of modern EV drivetrains rely on high-performance permanent magnets to convert electricity into torque. In turn, these high-performance permanent magnets rely on rare earth elements for their magnetic properties. These elements are “critical” (i.e., at risk of limiting the growth of renewable energy technologies such as EVs), which motivates an exploration for alternative materials. In this article, we overview the relevant fundamentals of permanent magnets, describe commercialized and emerging materials, and add perspective on future areas of research. Currently, the leading magnetic material for EV motors is Nd 2 Fe 14 B, with samarium-cobalt compounds (SmCo 5 and Sm 2 Co 17 ) providing the only high-performing commercialized alternative. Emerging materials that address criticality concerns include Sm 2 Fe 17 N 3 , Fe 16 N 2 , and the L1 0 structure of FeNi, which use lower cost elements that produce similar magnetic properties. However, these temperature-sensitive materials are incompatible with current metallurgical processing techniques. We provide perspective on how advances in low-temperature synthesis and processing science could unlock new classes of high-performing magnetic materials for a paradigm shift beyond rare earth-based magnets. In doing so, we explore the question: What magnetic materials will drive future EVs? Graphical abstract

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Prediction and Control of Atomic Ordering in Electrodeposited Binary Alloy Films: Direct Synthesis of L10 Magnetic Phases

Permanent magnet materials are essential components in renewable energy technology, underlying, electric vehicles, hybrids, wind turbines and more. Today commercial permanent magnets based on Nd-Fe-B exhibit an energy product of ~ 400 kJ/m 3 , capable to run wind turbines efficiently. Unfortunately, the supplies of rare-earth elements are centralized, and their availability may see volatility over time. This state of affairs stimulates the search for the search for rare-earth-free permanent magnetic materials. The L1 0 crystal structure underlines an important class of chemical ordered alloys that exhibit uniaxial magnetocrystalline anisotropy. This material has been considered an excellent candidate for rare-earth-free permanent magnets. In this program, a series of systematic experiments were performed and analysed in order to understand the effect of each. In order to synthesize L 10-Fe-Ni, one has to circumvent the sluggish kinetic and the limited driving force resulted from the low order-disorder temperature (~320°C) of the system. A strategy was found to trigger a martensitic transformation from the FCC phase to one of the non-cubic phases by high-strain methods. The body-centered tetragonal Fe-Ni obtained by this strategy was considered as a precursor of L10 Fe-Ni. The formation of BCT Fe-Ni via a displacive process was also implemented at the nanoscale by using tailored AuNi@FeNi core@shell.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Emerging magnetic materials for electric vehicle drive motors [Slides]

Increasing demand for electric vehicles (EVs) is increasing demand for the permanent magnets that drive their motors, as approximately 80% of modern EV drivetrains rely on high-performance permanent magnets to convert electricity into torque. In turn, these high-performance permanent magnets rely on rare earth elements for their magnetic properties. These elements are "critical" (i.e., at risk of limiting the growth of renewable energy technologies such as EVs), which motivates an exploration for alternative materials. In this article, we overview the relevant fundamentals of permanent magnets, describe commercialized and emerging materials, and add perspective on future areas of research. Currently, the leading magnetic material for EV motors is Nd 2 Fe 14 B, with samarium-cobalt compounds (SmCo 5 and Sm 2 Co 17 ) providing the only high-performing commercialized alternative. Emerging materials that address criticality concerns include Sm 2 Fe 17 N 3 , Fe 16 N 2 , and the L10 structure of FeNi, which use lower cost elements that produce similar magnetic properties. However, these temperature-sensitive materials are incompatible with current metallurgical processing techniques. We provide perspective on how advances in low-temperature synthesis and processing science could unlock new classes of high-performing magnetic materials for a paradigm shift beyond rare earth-based magnets. In doing so, we explore the question: What magnetic materials will drive future EVs?

42 ENGINEERING↗
DOE OSTI2020

Melting Curve and Phase Relations of Fe-Ni Alloys: Implications for the Earth's Core Composition

We discuss that nickel is the second most abundant element in the Earth's core. However, the properties of Fe-Ni alloys are still poorly constrained under planetary cores conditions, in particular concerning the effect of Ni on the melting curve of Fe. Here we show that Ni alloying up to 36 wt% does not affect the melting curve of Fe up to 100 GPa. However, Ni strongly modifies the hexagonal-closed-packed/face-centered-cubic (hcp/fcc) phase boundary, pushing the hcp/fcc/liquid triple point of Fe-20wt%Ni to higher pressures and temperatures. Our results allow constraining the triple point for Fe-10wt%Ni, a composition relevant for the Earth interior, and point out a decrease of the melting temperature at core-mantle boundary by 400 K with respect to pure Fe. A lower amount of light elements than previously predicted is thus required to reduce the crystallization temperature of core materials below that of a peridotitic lower mantle, in better agreement with geochemical observations.

36 MATERIALS SCIENCE↗