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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 OSTI2021

Correlative analysis of structure and chemistry of Li x FePO 4 platelets using 4D-STEM and X-ray ptychography

Lithium iron phosphate (Li x FePO 4 ), a cathode material used in rechargeable Li-ion batteries, phase separates upon de/lithiation under equilibrium. The interfacial structure and chemistry within these cathode materials affects Li-ion transport, and therefore battery performance. Here, correlative imaging of Li x FePO 4 was performed using four-dimensional scanning transmission electron microscopy (4D-STEM), scanning transmission X-ray microscopy (STXM), and X-ray ptychography in order to analyze the local structure and chemistry of the same particle set. Over 50,000 diffraction patterns from 10 particles provided measurements of both structure and chemistry at a nanoscale spatial resolution (16.6–49.5 nm) over wide (several micron) fields-of-view with statistical robustness. Li x FePO 4 particles at varying stages of delithiation were measured to examine the evolution of structure and chemistry as a function of delithiation. In lithiated and delithiated particles, local variations were observed in the degree of lithiation even while local lattice structures remained comparatively constant, and calculation of linear coefficients of chemical expansion suggest pinning of the lattice structures in these populations. Partially delithiated particles displayed broadly core–shell-like structures, however, with highly variable behavior both locally and per individual particle that exhibited distinctive intermediate regions at the interface between phases, and pockets within the lithiated core that correspond to FePO 4 in structure and chemistry. The results provide insight into the Li x FePO 4 system, subtleties in the scope and applicability of Vegard’s law (linear lattice parameter-composition behavior) under local versus global measurements, and demonstrate a powerful new combination of experimental and analytical modalities for bridging the crucial gap between local and statistical characterization.

25 ENERGY STORAGE↗
DOE OSTI2023

Electronic structural and lattice thermodynamic properties of MAlO2 and M5AlO4 (M = Li, Na, K) sorbents for CO2 capture applications

Abstract The electronic properties and thermal stabilities of MAlO 2 and M 5 AlO 4 (M = Li, Na, K) are investigated by density functional theory and lattice phonon dynamics. Based on the calculated electronic and lattice thermodynamic properties, their abilities to capture CO 2 as solid sorbents are analyzed. The calculated electronic structural properties of MAlO 2 and M 5 AlO 4 indicate that all these alkali aluminates are semiconductors with a bandgap range of 2.4 ~ 6.4 eV. The 1st valence bands of these alkali aluminates are located 0 ~ − 6 eV under Fermi levels and are mainly contributed by p orbitals of O, s and p orbitals of Al and M. The phonon vibrational frequencies of M 5 AlO 4 spread at a lower frequency range compared to their MAlO 2 phases. With increasing temperature, the calculated phonon free energies of M 5 AlO 4 decrease faster than their corresponding MAlO 2 while their entropies have opposite trends. The reaction 2MAlO 2 + CO 2 = M 2 CO 3 + Al 2 O 3 has higher reaction heat and Gibbs free energy change than those of corresponding reaction 2 / 5 M 5 AlO 4 + CO 2 = M 2 CO 3 + 1 / 5 Al 2 O 3 , which shows the former reaction possesses lower turnover temperature. Among the alkali aluminates studied, the β-NaAlO 2 , lt-KAlO 2 , and γ-LiAlO 2 are better candidates that could be applied for CO 2 capture technologies. Graphical Abstract

36 MATERIALS SCIENCE↗
DOE OSTI2023

Heat Transfer Characteristics of Particle and Air Flow Through Additively Manufactured Lattice Frame Material Based on Octet-Shape Topology

Particle-to-supercritical carbon dioxide (sCO 2 ) heat exchanger is a critical component in next-generation concentrating solar power (CSP) plants. The inherently low heat transfer between falling particles and sCO 2 imposes a challenge toward economic justification of levelized cost of electricity produced through solar energy. Introduction of integrated porous media with the walls bounding particle flow has the potential to enhance the overall particle-to-sCO 2 heat exchanger performance. Here, this paper presents an experimental study on heat transfer characterization of additively manufactured lattice frame material based on Octet-shaped unit cell with particles and air as working fluids. The lattice structures were additively manufactured in stainless steel (SS) 316L and SS420 (with 40% bronze infiltration) via Binder jetting process, where the lattice porosities were varied between 0.75 and 0.9. The mean particle diameters were varied from 266 μm to 966 μm. The effective thermal conductivity and averaged heat transfer coefficient were determined through steady-state experiments. It was found that the presence of lattice enhances the effective thermal conductivity by 2–4 times when compared to packed bed of particles alone. Furthermore, for gravity-assisted particle flow through lattice panel, significantly high convective heat transfer coefficients ranging from 200 W/m2K to 400 W/m2K were obtained for the range of particle diameters tested. The superior thermal transport properties of Octet-shape-based lattice frame for particle flow makes it a very promising candidate for particle-to-sCO 2 heat exchanger for CSP application.

14 SOLAR ENERGY↗
DOE OSTI2024

Experimental investigation of heat treatments on the mechanical performance of grade 300 maraging steel strut-based lattices

Lightweight and strong components are essential for reducing energy consumption and enhancing efficiency. Lattice structures are one such geometry utilized to achieve weight reduction. This study investigates the mechanical properties of various lattice structures fabricated from Maraging Steel (EOS MS1) using the Direct Metal Laser Sintering (DMLS) method. The samples include three distinct cellular geometries: body-centered cubic (BCC), face-centered cubic (FCC), and octet truss configurations, which are subjected to tensile and compressive tests. The primary goal of this research is to evaluate the impact of heat treatment on the mechanical properties of cellular architecture under tensile and compressive loading conditions. Destructive, nondestructive testing, and simulation results were also obtained from different heat treatment processes. It was found that the age-hardened specimens performed the best overall in terms of ultimate tensile/compressive strength and elongation. The top-performing topologies in compression and tension were found to be the octet structure, as they were able to withstand the most loading and straining when compared to the other specimens.

Engineering↗
DOE OSTI2024

Test capsules for measuring a change in at least one property of a material, and related methods

A test capsule for measuring at least one property of a material exposed to nuclear radiation comprises a lattice structure configured to exhibit a change in at least one property responsive to exposure to nuclear radiation. The lattice structure comprises a first strut and a second strut connected to the first strut at a node. Related test capsules and methods are also described.

Roach, Robert A.↗
NASA NTRS1977

Continuum models for static and dynamic analysis of repetitive lattices

A simple, rational approach is presented for developing continuum models for large repetitive lattice structures subjected to static and dynamic loadings. The procedure involves introducing kinematic assumptions to reduce the dimensionality of the lattice, and equating the strain and kinetic energies of the continuum model to those of the original lattice structure. The proposed procedure is applied to obtain effective elastic and dynamic characteristics of continuum plate models for double-layered grids. Numerical results are presented of stress and free vibration problems for two double-layered grids. These problems demonstrate the high accuracy of the continuum plate models developed. Also, an assessment is made of different approximations to these models.

Noor, A. K.↗
DOE OSTI2022

Modular Adaptive Packing for Integrally Cooled Absorbers

Process intensification is one cornerstone in ION Clean Energy’s (ION) efforts to lowering CO2 capture cost. ION has modeled, designed, and fabricated an innovative gas-liquid contactor known as Modular Adaptive Packing (MAP). During two successful SBIR Phase I and II projects entitled: “Rapid Design and Testing of Novel Gas-Liquid Contacting Devices for Post-Combustion CO2 Capture via 3D-printing”, ION developed and proved this new technology at bench scale. MAP, a 3D-printed lattice-structured packing, combines the absorber gas/liquid contactor with an innovative in-situ heat-exchanger. Thanks to the capabilities of 3D-printing, the lattice structure of MAP contains hollow channels through which coolant water can be pumped to remove the heat of reaction from CO2 absorption. ION refers to this novel method of heat exchange as intracooling. After 25.4 cm (10 in) diameter MAP modules were fabricated, ION built and tested a packing characterization rig at its pilot facility in Boulder, Colorado, U.S.A. To provide baseline results for the characterization rig, ION tested Sulzer’s Mellapak™ 250Y (MP250Y) as a standard structured packing. ION’s MAP was then compared directly to the baseline MP250Y packing to evaluate key indicators including pressure drop, liquid hold-up, and effective area. MAP has a higher pressure drop than MP250Y at the same gas velocities in addition to greater liquid holdup. However, ION found that MAP displays a higher wetting coverage of 93% compared to 65% for MP250Y and reduces shearing forces that result in undesirable droplet formation. Using Optimized Gas Treating’s (OGT) rate-based simulation software ProTreat®, a conceptual evaluation of MAP was modeled for a CO2 absorber using 30 wt% MEA solvent over a range of lean loadings at 90% CO2 capture from a coal-fired power plant. ION modeled a 25-meter column absorber for both the standard MP250Y packing and a hybrid column. The hybrid absorber contained 10 m of MP250Y packing at the top and bottom with the middle 5 meters comprised of MAP. Compared to a traditional intercooled absorber, MAP can remove 22% more heat and increase overall MEA carrying capacity by 4% without increasing overall pressure drop.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

In Situ 4D‐STEM Imaging of the Orientation of Lamellar Clusters in Polymer Crystallization

In semi‐crystalline polymeric materials, the initial stages of nucleation and the growth path of crystalline domains can determine the final performance. Here, in this work, we used four‐dimensional scanning transmission electron microscopy (4D‐STEM) imaging to analyze the changes in lamellar orientation in high‐density polyethylene (HDPE) during heating and cooling. This method allowed us to quantitatively detect the formation of lamellae clusters with different in‐plane orientations, which are not visible with traditional methods. Our analysis provided detailed insights into the orientation and size changes of crystalline domains. Additionally, this technique enabled direct observation of lattice structures in hierarchical lamellae and the growth of crystals, confirming the local variability in lamellar orientation. This innovative approach significantly improves our understanding of polymer crystallization, linking changes in morphology and lattice structures at different length scales.

4D-STEM↗
DOE OSTI2021

Unraveling transition-metal-mediated stability of spinel oxide via in situ neutron scattering

The energy materials performance is intrinsically determined by structures from the average lattice structure to the atom arrangement, valence, and distribution of the containing transition metal (TM) elements. Understanding the mechanism of the structure transition and atom rearrangement via synthesis or processing is key to expediting the exploration of excellent energy materials. In this work, in situ neutron scattering is employed to reveal the real-time structure evolution, including the TM-O bonds, lattice, TM valence and the migration of the high-voltage spinel cathode LiNi 0.5 Mn 1.5 O 4 . The transition-metal-mediated spinel destabilization under the annealing at the oxygen-deficient atmosphere is pinpointed. Additionally, the formation of Mn 3+ is correlated to the TM migration activation, TM disordered rearrangement in the spinel, and the transition to a layered-rocksalt phase. The further TM interdiffusion and Mn 2+ reduction are also revealed with multi-stage thermodynamics and kinetics. The mechanisms of phase transition and atom migrations as functions of temperature, time and atmosphere present important guidance on the synthesis in various-valence element containing oxides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Superlubric-pinned transition of a two-dimensional solid dusty plasma under a periodic triangular substrate

Here, the superlubric-pinned transition in the depinning dynamics of a two-dimensional (2D) solid dusty plasma modulated by 2D triangular periodic substrates is investigated using Langevin dynamical simulations. When the lattice structure of the 2D solid dusty plasma perfectly matches the triangular substrate, two distinctive pinned and moving ordered states are observed as the external uniform driving force gradually increases from zero. When there is a mismatch between the lattice structure and the triangular substrate, however, on shallow substrates, it is discovered that all of the particles can slide freely on the substrate even when the applied driving force is tiny. This is a typical example of superlubricity, which is caused by the competition between the substrate-particle and particle-particle interactions. If the substrate depth increases further, as the driving force increases from zero, there are three dynamical states consisting of the pinned state, the disordered plastic flow state, and the moving ordered state. In an underdense system, where there are fewer particles than potential well minima, it is found that the occurrence of the three different dynamical states is controlled by the depth of the substrate, which is quantitatively characterized using the average mobility.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Abrupt orthorhombic relaxation in compressively strained ultrathin SrRuO 3 films

Lattice structure can dictate electronic and magnetic properties of a material. Especially, reconstruction at a surface or heterointerface can create properties that are fundamentally different from those of the corresponding bulk material. In this work, we have investigated the lattice structure on the surface and in the thin films of epitaxial SrRuO 3 with the film thickness up to 22 pseudo-cubic unit cells (u.c.), using the combination of surface sensitive low energy electron diffraction and bulk sensitive scanning transmission electron microscopy. Our analysis indicates that, in contrast to many perovskite oxides, the RuO6 tilt and rotational distortions appear even in single unit cell SrRuO 3 thin films on cubic SrTiO 3 , while the full relaxation to the bulk-like orthorhombic structures takes 3-4 u.c. from the interface for thicker films. Yet the TiO 6 octahedra of the substrate near the interface with SrRuO 3 films show no sign of distortion, unlike those near the interface with CaRuO 3 films. Two orthogonal in-plane rotated structural domains are identified. These octahedral distortions are essential for the understanding of the thickness dependent transport and magnetism in ultrathin films.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Structure and lattice excitations of the copper substituted lead oxyapatite Pb 9.06⁢(7)⁢ Cu 0.94⁢(6)⁢ (PO 3.92⁢(4) ) 6 ⁢O 0.96⁢(3)

The copper substituted lead oxyapatite, Pb 10-x⁢ Cu x (PO 3.92⁢(4) ) 6 ⁢O 0.96⁢(3) [x = 0.94(6)] was studied using neutron and x-ray diffraction and neutron spectroscopy techniques. The crystal structure of the main phase of our sample, which has come to be colloquially known as LK-99, is verified to possess a hexagonal structure with space group P6 3 /m, alongside the presence of impurity phases Cu and Cu 2 ⁢S. We determine the primary substitution location of the Cu as the Pb1 (6⁢ℎ) site, with a small substitution at the Pb2 (4⁢f) site. Consequently, no clear Cu-doping-induced structural distortion was observed in the investigated temperature region between 10 K and 300 K. Specially, we did not observe a reduction of coordinate number at the Pb2 site or a clear tilting of PO 4 tetrahedron. Magnetic characterization reveals a diamagnetic signal in the specimen, accompanied by a very weak ferromagnetic component at 2 K. No long-range magnetic order down to 10 K was detected by the neutron diffraction. Inelastic neutron scattering measurements did not show magnetic excitations for energies up to 350 meV. There is no sign of a superconducting resonance in the excitation spectrum of this material. The measured phonon density of states compares well with density functional theory calculations performed for the main LK-99 phase and its impurity phases. Our study may shed some insight into the role of the favored substitution site of copper in the absence of structural distortion and superconductivity in LK-99.

36 MATERIALS SCIENCE↗
NASA NTRS1998

Semiconductor apparatus utilizing gradient freeze and liquid-solid techniques

Transition metals of Group VIII (Co, Rh and Ir) have been prepared as semiconductor compounds with the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freezing techniques and/or liquid phase sintering techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 1200 cm.sup.2.V.sup.-1.s.sup.-1) and good Seebeck coefficients (up to 150 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a substantial increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

Fleurial, Jean-Pierre↗
NASA NTRS1997

High performance thermoelectric materials and methods of preparation

Transition metals (T) of Group VIII (Co, Rh and Ir) have been prepared as semiconductor alloys with Sb having the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor alloys and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor alloys having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freeze techniques, liquid-solid phase sintering techniques, low temperature powder sintering and/or hot-pressing. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 8000 cm.sup.2.V.sup.-1.s.sup.-1), good Seebeck coefficients (up to 400 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.), and low thermal conductivities (as low as 15 mW/cmK). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a two fold increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

Fleurial, Jean-Pierre↗
DOE OSTI2025

SnSe 1-x S x Alloys: Anisotropic Van der Waals Semiconductors with Tunable Bandgaps

Alloying is one of the main tools of bandgap engineering, allowing the tuning of crystal structure, lattice parameters, and electronic structure of 3D and 2D/layered semiconductors. Among the latter, it can play a key role in tailoring the properties of tin monochalcogenides, a class of van der Waals semiconductors of interest for optoelectronics, thermoelectrics, ferroelectrics, and valleytronics. Here, the study investigates the synthesis and properties of large flakes of the anion substitution alloys SnSe 1-x S x . Alloy flakes across a wide range of compositions are obtained systematically by repeated growth from the same mixed (SnS, SnSe) powder precursor. Combined experiment and theory show full miscibility for all compositions, along with tunable lattice constants, bandgaps, and vibrational modes. Atomic resolution imaging demonstrates the accumulation of S and Se in alternating layers in the SnSe 1-x S x unit cell, attributed to growth kinetics. Polarized Raman spectroscopy confirms anisotropic vibrational modes; the calculated and measured band structure shows systematic changes in the band edge energies and anisotropic electronic structure due to the anisotropic in-plane lattice of the monochalcogenides. Cathodoluminescence, finally, indicates that a unique configuration of two non-degenerate, direct valleys along orthogonal k-space directions persists all the way from SnS to SnSe, making SnSe 1-x S x alloys interesting for valleytronics.

36 MATERIALS SCIENCE↗
DOE OSTI2025

High pressure structural and lattice dynamics study of α-In2Se3

Layered α-In2Se3 has been studied using a combined in situ synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy study in a diamond anvil cell up to 60+ GPa, at room temperature. Helium, which remains fairly hydrostatic up to the highest pressure in this study, was used as the pressure-transmitting medium. The results from both experimental methods reveal a pressure-induced structural phase transition from α-In2Se3 to a monoclinic β'-In2Se3 structure at ≈1 GPa, in agreement with previous studies. Based on our detailed measurements using both experimental techniques and the F-f formalism, the β'-In2Se3 structure remains stable up to 45 GPa, without a clear indication of a phase transition toward the previously reported β-In2Se3 phase. Above this pressure, In2Se3 adopts a disordered solid-solution-like orthorhombic structure, phase IV. The results are discussed in comparison with the relevant previous studies of α-In2Se3 under pressure.

Feng, Shiyu↗
DOE OSTI2026

Performance assessment of 3D printed multi-material energy absorber for automotive bumper: pedestrian lower extremity protection

Designing an energy absorber for automotive bumpers involves balancing low-speed and high-speed impacts to ensure safety, reduce repair costs, and meet regulatory standards. Here, this study explores a novel design using multi-material 3D printing and structural optimization to fabricate a lightweight and cost-efficient energy absorber. The design effectively dissipates energy in low-speed collisions and minimizes force transmission in high-speed pedestrain impacts, helping to meet both safety and performance requirements. The energy absorber design combines 20% carbon fiber-reinforced acrylonitrile butadiene styrene (CF-ABS) and thermoplastic polyurethane (TPU) for optimal stiffness and flexibility. It uses 3D-printed lattice structures optimized through finite element simulations to help meet both low-speed and high-speed impact requirements. Full-scale energy absorbers were 3D-printed using optimized CF-ABS/TPU blends and tested under high-speed impact using the Flexible Pedestrian Legform Impactor (Flex-PLI). For fair comparison, a baseline bumper with a traditional triangular lattice structure, also 3D-printed from the same CF-ABS/TPU materials, was similarly tested. Interestingly, both the optimized and baseline 3D-printed energy absorbers showed nearly identical performance, successfully meeting injury limits. Their performances were also benchmarked against an injection-molded energy absorber. While both 3D-printed and injection-molded designs met injury limits, the 3D-printed absorber exhibited a higher tibia bending moment, indicating an opportunity for further optimization. A Techno-Economic Analysis compared the costs of producing energy absorbers using traditional manufacturing and 3D printing. The analysis highlighted that 3D printing offers cost benefits for low to medium production volumes, with the total cost per energy absorber at ∼ $\$$74, compared to traditional methods that become economical beyond 2000 units.

Additive manufacturing↗
NASA NTRSDate not supplied

Three-Dimensional Reconstruction of Defects and Structures in Additively Manufactured Parts with Automated Serial Sectioning

Metal additive manufacturing (AM) processes have been demonstrated to be effective at reducing costs and lead times associated with complex components for space flight applications. Laser powderbed fusion (L-PBF) is a commonly used AM technology due to the ability to produce complex parts with fine feature resolution in a wide variety of alloys and applications. L-PBF, like many other manufacturing processes, can produce minor flaws in parts when in nominal operation as well as process-escape defects when process abnormalities occur. The effects of the flaws and methods of detecting the flaws are a subject of interest to understand the difficulties in detecting these flaws with current technology and how much risk the flaws or defects pose to potential flight parts. Using a RoboMet.3D automated serial sectioning system, seeded defects as well as minor process flaws can be imaged and reconstructed in three dimensions to compare to non-destructive evaluation (NDE) techniques, such as x-ray computed tomography (CT), neutron CT, and in-situ monitoring. The RoboMet automates the metallography process by automatically grinding, polishing, and imaging samples in a single system and providing the control data for NDE comparisons to know the real size of defects built into coupons. These comparisons provide an understanding behind the technological limitations of the NDE techniques for different alloys. The same serial sectioning methods have also been utilized to characterize the surfaces of parts to reconstruct the surfaces and take measurements of internal features not easily examined with non-destructive methods. Using the RoboMet, fine lattice structures built with L-PBF have been characterized to determine the actual thicknesses of struts and density of the lattice structures. These structures have been used as finer build supports for the L-PBF process, designs for fine catalysts, and other design considerations for small components. The RoboMet data helps to inform the modeling and design efforts around these fine components.

additive manufacturing↗