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Results for “Morphology optimization”

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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

Metal three-dimensional (3D) printing includes a vast number of operation and material parameters with complex dependencies, which significantly complicates process optimization, materials development, and real-time monitoring and control. We leverage ultrahigh-speed synchrotron X-ray imaging and high-fidelity multiphysics modeling to identify simple yet universal scaling laws for keyhole stability and porosity in metal 3D printing. The laws apply broadly and remain accurate for different materials, processing conditions, and printing machines. We define a dimensionless number, the Keyhole number, to predict aspect ratio of a keyhole and the morphological transition from stable at low Keyhole number to chaotic at high Keyhole number. Furthermore, we discover inherent correlation between keyhole stability and porosity formation in metal 3D printing. By reducing the dimensions of the formulation of these challenging problems, the compact scaling laws will aid process optimization and defect elimination during metal 3D printing, and potentially lead to a quantitative predictive framework.

42 ENGINEERING↗
DOE OSTI2022

Single‐Crystal LiNi x Mn y Co 1− x − y O 2 Cathodes for Extreme Fast Charging

Abstract Ni‐rich layered LiNi x Mn y Co 1− x − y O 2 (NMCs, x ≥ 0.8) are poised to be the dominating cathode materials for lithium‐ion batteries for the foreseeable future. Conventional polycrystalline NMCs, however, suffer from severe cracking along the grain boundaries of primary particles and capacity loss under high charge and/or discharge rates, hindering their implementation in fast‐charging electric vehicular (EV) batteries. Single‐crystal (SC) NMCs are attractive alternatives as they eliminate intergranular cracking and allow for grain‐level surface optimization for fast Li transport. In the present study, the authors report synthetic approaches to produce SC LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NMC811) samples with different morphologies: Oct‐SC811 with predominating (012)‐family surface and Poly‐SC811 with predominating (104)‐family surface. Poly‐SC811, representing the first experimentally synthesized NMC811 single crystals with (104) surface, delivers superior performance even at the ultra‐high rate of 6 C. Through detailed X‐ray analysis and electron microscopy characterization, it is shown that the enhanced performance originates from better chemical and structural stabilities, faster Li + diffusion kinetics, suppressed side reactions with electrolyte, and excellent cracking resistance. These insights provide important design guidelines in the future development of fast‐charging NMC‐type cathode materials.

Lu, Yanying↗
DOE OSTI2025

Autonomous platform for solution processing of electronic polymers

The manipulation of electronic polymers’ solid-state properties through processing is crucial in electronics and energy research. Yet, efficiently processing electronic polymer solutions into thin films with specific properties remains a formidable challenge. We introduce Polybot, an artificial intelligence (AI) driven automated material laboratory designed to autonomously explore processing pathways for achieving high-conductivity, low-defect electronic polymers films. Leveraging importance-guided Bayesian optimization, Polybot efficiently navigates a complex 7-dimensional processing space. In particular, the automated workflow and algorithms effectively explore the search space, mitigate biases, employ statistical methods to ensure data repeatability, and concurrently optimize multiple objectives with precision. The experimental campaign yields scale-up fabrication recipes, producing transparent conductive thin films with averaged conductivity exceeding 4500 S/cm. Feature importance analysis and morphological characterizations reveal key design factors. This work signifies a significant step towards transforming the manufacturing of electronic polymers, highlighting the potential of AI-driven automation in material science.

Wang, Chengshi [Argonne National Laboratory (ANL),↗
DOE OSTI2021

Light-Induced Al Plating on Si for Fabrication of an Ag-Free All-Al Solar Cell

Light-induced electroplating of Al as the front electrode on the n-type emitter of Si solar cells is proposed as a substitute for screen-printed Ag. The advantages and disadvantages of Al over Cu as the front electrode are discussed. The power of a green laser used for patterning of the SiN x antireflection coating is optimized. Conditions for removal of laser damage and contamination on the laser-patterned surface are identified. The effect of plating temperature and post-annealing temperature on Al morphology and resistivity are investigated. Several plating additives are explored to improve the morphology and resistivity of the Al film. Nicotinic acid produces the lowest resistivity of 3.1 μ Ω-cm. However, the lowest contact resistivity between light-induced Al and Si is 69 mΩ-cm 2 due to laser-induced damage to the emitter. The Al film spikes through the thin n-type emitter when annealed at 500 °C causing cell failure. The process reproducibility is also poor due to atmospheric moisture.

14 SOLAR ENERGY↗
DOE OSTI2025

Raptor

Raptor is an efficient Python-based tool for predicting the formation and morphology of stochastic lack of fusion defects in metal AM processes. A major obstacle for the qualification and certification of additively manufactured parts in critical applications continues to be performance variability caused in part by porosity-related defects. High-fidelity process models that could predict these defect features are currently too computationally expensive for component-level analysis. To address this, Raptor employs a high-performance geometric method to model the dynamic melt pool rather than relying on computationally intensive thermal fluid dynamics. This allows Raptor to rapidly identify regions of unmelted material that correspond to lack of fusion pores. The efficiency of this approach significantly reduces the time and resources needed for generating 3D defect predictions, which enables users to conduct large-scale parameter studies and evaluate how process variations affect part quality. The framework offers operational flexibility; users can execute simulations through a simple command line interface or integrate core functions as a library within larger computational workflows. Simulation outputs include 3D porosity maps for visualization and tools for quantitative morphological analysis. These results are suitable for direct comparison with experimental characterization data from methods such as X-ray computed tomography and can be used for statistical process optimization.

Subraveti, Vamsi [Vanderbilt Univ., Nashville, TN ↗
DOE OSTI2023

Processing Temperature Effect on Failure Behavior of Unidirectional Thermoplastic Polymer-fiber-reinforced Polymers (PFRPs)

This study aimed to examine the influence of processing temperature on the mechanical and morphological characteristics of unidirectional (UD) thermoplastic polymer-fiber-reinforced polymers (PFRPs), utilizing UHMWPE-polymer-fiber-reinforced HDPE composites as an example. To achieve this objective, UD thermoplastic PFRPs were produced through filament winding and hot pressing techniques, employing five distinct processing temperatures within the range spanning from the melting onset temperature of the polymer matrix to the melting peak temperature of the reinforcing polymer fiber. By conducting the uni-axial tensile tests on the UD UHMWPE-polymer-fiber-reinforced HDPE composites fabricated at different processing temperatures, it was shown that the optimal longitudinal tensile properties of the composites, comparable with glass-fiber-reinforced thermoset or thermoplastic polymers (GFRPs or GFRTPs) can be achieved when the processing temperature does not significantly exceeds the melting onset temperature of the reinforcing polymer fiber. However, when the processing temperature exceeds this threshold, the mechanical properties of the composites are significantly reduced, as evidenced by the transition in the failure morphology from the presence of significant splitting cracks to the occurrence of plastic necking due to the complete melting of the reinforcing polymer fibers in a composite. Particularly, the ductile behavior of the optimal thermoplastic PFRPs investigated in this study is superior than that of carbon-fiber-reinforced thermoset or thermoplastic polymers (CFRPs or CFRTPs) and even GFRPs and GFRTPs. This study not only provides valuable insights into the proper fabrication of high-performance thermoplastic PFRPs but also offers useful experimental data that can aid in the validation and development of computational models, particularly those related to processing modeling.

Qiao, Yao↗
DOE OSTI2020

Microclusters of Kinked Silicon Nanowires Synthesized by a Recyclable Iodide Process for High-Performance Lithium-Ion Battery Anodes

Silicon shows great promise as a high-capacity anode material for lithium-ion batteries. Nanostructuring silicon minimizes the impact of fracturing during charging and discharging. However, synthesizing nanostructured silicon typically requires complicated procedures with high manufacturing costs. Additionally, these complicated procedures typically have poor secondary particle formation, a requirement to achieve a high tap density. Here, a cost-effective synthesis procedure which generates nearly ideal secondary particle clusters of nanostructured silicon is developed. The cost-effectiveness is a result of the in operando generation of silicon iodide from iodine gas and low-grade silicon microparticle. Decomposition of silicon iodide into crystalline silicon and iodine gas enables recycling of the iodine gas, allowing for near full reutilization of iodine in the following cycles. Additionally, the optimal nanostructures and microstructures of silicon synthesized by the recyclable iodide decomposition reaction enables 83.6% capacity retention over 1000 cycles. The good performance is a result of well-maintained morphology during cycling, enabling reutilization of the solid electrolyte interphase.

25 ENERGY STORAGE↗
DOE OSTI2021

Alignment frustration in block copolymer films with block copolymer grafted TiO 2 nanoparticles under soft-shear cold zone annealing

Block copolymers (BCPs) have received significant attention as promising candidates for sequestering nanoparticles and fabrication of aligned nanostructures with optimal optical or electrical properties. We investigate the influence of static and dynamic thermal field on the alignment of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) BCP morphology with the loading of novel poly(methyl methacrylate-block-Polystyrene) (PMMA-b-PS)-grafted-TiO 2 nanoparticles (BCP-g-TiO 2 ). Observation of characteristics IR peaks for PMMA and PS in BCP-g-TiO 2 nanoparticles and Transmission Electron Microscopy (TEM) results of the outer coating of core nanoparticle, validate the grafting to approach in synthesizing BCP-g-TiO 2 . In this work, we report that under the sharp dynamic thermal field, at low loading of BCP-g-TiO 2 , there is good dispersion of nanoparticles in unidirectionally aligned BCP matrix in film interior probed by GISAXS, while, at high nanoparticle loading (~10 wt%), there is local frustration in the unidirectional alignment of the BCP matrix due to aggregation of BCP-g-TiO 2 nanoparticles. However, Grazing incidence small angle X-ray scattering (GISAXS) shows clearly that the BCP films remain largely locally ordered at the domain scale, despite these large perturbations to long-range ordering even at high loading level, while bringing in new TiO 2 functionality to the BCP films, such as UVO absorptivity or biofouling prevention, important to potential new applications of such membranes.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

3D Printed Nanoporous Separators Based on Polymerization-Induced Phase Separation for Fast-Charging, High Cycling Stability Li-Ion Batteries

Fast charging and stable lithium-ion batteries (LIBs) require prompt Li ion transport between electrodes. 3D porous separators can potentially improve ion transport at both the microscale and macroscale levels. Additive manufacturing (AM) is an ideal tool to produce and study 3D porous separators of LIBs, although little work has been reported in this area. Here, we demonstrate porous structural control in layer-by-layer printed hexanediol diacrylate (HDDA) separators using a projection micro stereolithography (PμSL) AM technology and present their corresponding battery performance in lithium nickel manganese cobalt oxide (NMC)/graphite full cells. The composition of photocurable resin determines the porous morphology (e.g., bicontinuous and droplet-like), while the settings of printing layer thickness and number of exposures can be used to adjust the porosity (e.g., from 27% to 63%). Optimal resin and print conditions are determined, and the resulting separator exhibits superior Li ion conductivity and therefore higher rate performance and longer cycling life. Compared with a Celgard 2325 separator, the optimized porous HDDA separator increases the 10C-rate capacity by 34% and decreases the capacity degradation rate at the 1C-rate by 4.9%. In conclusion, this work paves the way for future AM of 3D separators for high-energy, high-power, and long-cycling-life LIBs.

25 ENERGY STORAGE↗
DOE OSTI2026

Reaction Mechanism of Electrodeposited ε-MnO 2 : A Proton-Centered Pathway in Aqueous Zn-Ion Systems

Aqueous Zn/MnO 2 batteries have garnered significant interests owing to their abundance, high theoretical specific capacity, safety, and low cost. However, large-scale application of these systems is limited by the incomplete understanding of the MnO 2 reaction chemistry. The different crystal lattice structures among MnO 2 polymorphs contribute to the variations in reported reaction mechanisms. Among them, ε-MnO 2 polymorph, the dominant phase in electrolytic manganese dioxide (EMD), is notably observed during the charge cycles of aqueous Zn/MnO 2 batteries. Here, in this work, we investigate the electrochemical behavior of an ε-MnO 2 cathode synthesized via electrodeposition from a ZnSO 4 and MnSO 4 electrolyte, onto a 3-dimensional carbon cloth substrate. Proton intercalation emerges as the dominant charge storage mechanism, critically enabling the reversibility of ε-MnO 2 during cycling, as revealed by operando synchrotron X-ray diffraction and X-ray absorption spectroscopy. Additionally, a proton-coupled dissolution/redeposition pathway operates alongside minor Zn 2+ intercalation, as quantified by Rietveld refinement. Morphological and chemical heterogeneities are studied by transmission X-ray microscopy further validates this reaction mechanism. These mechanistic insights provide the foundation for rationally designing Zn/MnO 2 batteries with optimized proton dynamics and charge transfer, advancing these systems as a viable solution for safe, cost-effective grid-scale energy storage.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Eco–Friendly Solvent Engineered CsPbI 2.77 Br 0.23 Ink for Large–Area and Scalable High Performance Perovskite Solar Cells

The performance of large-area perovskite solar cells (PSCs) has been assessed for typical compositions, such as methylammonium lead iodide (MAPbI 3 ), using a blade coater, slot-die coater, solution shearing, ink-jet printing, and thermal evaporation. However, the fabrication of large-area all-inorganic perovskite films is not well developed. This study develops, for the first time, an eco-friendly solvent engineered all-inorganic perovskite ink of dimethyl sulfoxide (DMSO) as a main solvent with the addition of acetonitrile (ACN), 2-methoxyethanol (2-ME), or a mixture of ACN and 2-ME to fabricate large-area CsPbI 2.77 Br 0.23 films with slot-die coater at low temperatures (40–50 °C). The perovskite phase, morphology, defect density, and optoelectrical properties of prepared with different solvent ratios are thoroughly examined and they are correlated with their respective colloidal size distribution and solar cell performance. Here, the optimized slot-die-coated CsPbI 2.77 Br 0.23 perovskite film, which is prepared from the eco-friendly binary solvents dimethyl sulfoxide:acetonitrile (0.8:0.2 v/v), demonstrates an impressive power conversion efficiency (PCE) of 19.05%. Moreover, the device maintains ≈91% of its original PCE after 1 month at 20% relative humidity in the dark. It is believed that this study will accelerate the reliable manufacturing of perovskite devices.

binary and ternary solvent↗
DOE OSTI2026

Nondestructive ultrasonic characterization of a triple-weld-bead wire arc additively manufactured ER70S-6 S-curved wall

Understanding build-scale microstructural variation in wire arc additive manufacturing (WAAM) of low-carbon steels is essential for ensuring consistent structure–property relationships throughout large components. Conventional destructive characterization techniques, such as scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), are time-intensive and limited to localized regions, making comprehensive evaluation of large WAAM structures challenging. In this study, a nondestructive ultrasonic approach was employed to characterize a 252 mm tall ER70S-6 S-curved WAAM wall produced using a triple-bead deposition strategy. Optical and SEM analysis revealed a repeating dual-region microstructure consisting of uniform polygonal ferrite at melt pool centers and heterogeneous ferrite with coarse and fine grains near melt pool boundaries, attributed to cyclic thermal conditions. Longitudinal ultrasonic backscatter imaging was used to evaluate the continuity of this periodicity along the full build height. The ultrasonic response exhibited a consistent repeating pattern that correlated with the observed layer-wise microstructural variation. X-ray computed tomography confirmed the absence of detectable porosity, indicating that ultrasonic contrast is primarily governed by grain morphology. Overall, the results indicate that longitudinal backscatter ultrasound is a promising nondestructive characterization technique for validating microstructural variations along the s-curved WAAM wall, with significant potential for microstructure optimization and process control.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A Geometric Measure Theory Approach to Identify Complex Structural Features on Soft Matter Surfaces

The structural features that protrude above or below a soft matter interface are well-known to be related to interfacially mediated chemical reactivity and transport processes. It is a challenge to develop a robust algorithm for identifying these organized surface structures, as the morphology can be highly varied and they may exist on top of an interface containing significant interfacial roughness. A new algorithm that employs concepts from geometric measure theory, algebraic topology, and optimization is developed to identify candidate structures at a soft matter surface, and then, using a probabilistic approach, to rank their likelihood of being a complex structural feature. The algorithm is tested for a surfactant laden water/oil interface, where it is robust to identifying protrusions responsible for water transport against a set identified by visual inspection. To our knowledge, this is the first example of applying geometric measure theory to analyze the properties of a chemical/materials science system.

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

Melt Pool characteristics on surface roughness and printability of 316L stainless steel in laser powder bed fusion

Purpose Surface quality and porosity significantly influence the structural and functional properties of the final product. This study aims to establish and explain the underlying relationships among processing parameters, top surface roughness and porosity level in additively manufactured 316L stainless steel. Design/methodology/approach A systematic variation of printing process parameters was conducted to print cubic samples based on laser power, speed and their combinations of energy density. Melt pool morphologies and dimensions, surface roughness quantified by arithmetic mean height (Sa) and porosity levels were characterized via optical confocal microscopy. Findings The study reveals that the laser power required to achieve optimal top surface quality increases with the volumetric energy density (VED) levels. A smooth top surface (Sa < 15 µm) or a rough surface with humps at high VEDs (VED > 133.3 J/mm 3 ) can serve as indicators for fully dense bulk samples, while rough top surfaces resulting from melt pool discontinuity correlate with high porosity levels. Under insufficient VED, melt pool discontinuity dominates the top surface. At high VEDs, surface quality improves with increased power as mitigation of melt pool discontinuity, followed by the deterioration with hump formation. Originality/value This study reveals and summarizes the formation mechanism of dominant features on top surface features and offers a potential method to predict the porosity by observing the top surface features with consideration of processing conditions.

Engineering↗
DOE OSTI2021

MemXCT: Design, Optimization, Scaling, and Reproducibility of X-Ray Tomography Imaging

Here, this work extends our previous research entitled "MemXCT: Memory-centric X-ray CT Reconstruction with Massive Parallelization" that was originally published at SC19 conference (Hidayetoglu et al., 2019) with reproducibility of the computational imaging performance. X-ray computed tomography (XCT) is regularly used at synchrotron light sources to study the internal morphology of materials at high resolution. However, experimental constraints, such as radiation sensitivity, can result in noisy or undersampled measurements. Further, depending on the resolution, sample size and data acquisition rates, the resulting noisy dataset can be in the order of terabytes. Advanced iterative reconstruction techniques can produce high-quality images from noisy measurements, but their computational requirements have made their use an exception rather than the rule. We propose a novel memory-centric approach that avoids redundant computations at the expense of additional memory complexity. We develop a memory-centric iterative reconstruction system, MemXCT, that uses an optimized SpMV implementation with two-level pseudo-Hilbert ordering and multi-stage input buffering. We evaluate MemXCT on various supercomputer architectures involving KNL and GPU. MemXCT can reconstruct a large (11Kx11K) mouse brain tomogram in 10 seconds using 4096 KNL nodes (256K cores). The results presented in our original article at the SC19 were based on large-scale supercomputing resources. The MemXCT application was selected for the Student Cluster Competition (SCC) Reproducibility Challenge and evaluated on a variety of cloud computing resources by universities around the world in the SC20 conference. We summarize the results of the top-ranked SCC Reproducibility Challenge teams and identify the most pertinent measures for ensuring the reproducibility of our experiments in this article.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Optimization of the Growth of the Van der Waals Materials Bi 2 Se 3 and (Bi 0.5 In 0.5 ) 2 Se 3 by Molecular Beam Epitaxy

The naturally existing chalcogenide Bi 2 Se 3 is topologically nontrivial due to the band inversion caused by the strong spin-orbit coupling inside the bulk of the material. Here, the surface states are spin polarized, protected by the time-inversion symmetry, and thus robust to the scattering caused by nonmagnetic defects. A high-purity topological insulator thin film can be easily grown via molecular beam epitaxy (MBE) on various substrates to enable novel electronics, optics, and spintronics applications. However, the unique surface state properties have historically been limited by the film quality, which is evaluated by crystallinity, surface morphology, and transport data. Here we propose and investigate different MBE growth strategies to improve the quality of Bi 2 Se 3 thin films grown by MBE. Based on the surface passivation status, we have classified the substrates into two categories, self-passivated or unpassivated, and determine the optimal growth mechanisms on the representative sapphire and GaAs, respectively. For Bi 2 Se 3 on GaAs, the surface passivation status determines the dominant growth mechanism. In the end, growths of the topological trivial insulator (Bi 0.5 In 0.5 ) 2 Se 3 (BIS) on GaAs are investigated following the protocols proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Flux Synthesis of A-site Disordered Perovskite La 0.5 M 0.5 TiO 3 (M$=$Li, Na, K) Nanorods Tailored for Solid Composite Electrolytes

Inorganic fillers play an important role in improving the ionic conductivity of solid composite electrolytes (SCEs) for Li-ion batteries. Among inorganic fillers, perovskite-type lithium lanthanum titanate (LLTO) stands out for its high bulk Li + conductivity on the order of 10 -3 S cm -1 at room temperature. According to a literature survey, the optimal LLTO filler should possess the following characteristics: i) a single-crystal structure to minimize grain boundaries; ii) a small particle size to increase the filler/polymer interface area; iii) a 1D morphology for efficient interface channels; and iv) cubic symmetry to facilitate rapid bulk Li + diffusion within the filler. However, the synthesis of single crystal, 1D LLTO nanomaterials with cubic symmetry is challenging. Herein, a flux strategy is developed to synthesize La 0.5 M 0.5 TiO 3 (LMTO, M$=$Li, Na, and K) single-crystal nanorods with an A-site-disordered, cubic perovskite phase. The flux media promotes the oriented growth of nanorods, prevents nanorods from sintering, and provides multiple alkali metal ion doping at M sites to stabilize the cubic phase. SCEs compositing the Li + -conducting LMTO nanorods as fillers and poly[vinylene carbonate- co -lithium sulfonyl(trifluoromethane sulfonyl)imide methacrylate] matrix exhibit more than twice the conductivity of the neat polymer electrolyte (30.6 vs 14.0 µS cm -1 at 303 K).

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

A First-Principles Approach to Modeling Surface Site Stabilities on Multimetallic Catalysts

The study of multimetallic alloys and the multitude of possible surface compositions have sparked a tremendous interest in engineering low-cost materials with high activity and selectivity in heterogeneous catalysis. Multimetallic systems provide complementary functionalities and an unprecedented tunability when designing catalyst formulations. However, due to their immense structural and compositional complexity, the investigation and identification of an optimal catalyst is a tedious and time-consuming process, both experimentally and theoretically. Therefore, theoretical design principles are highly desirable to accelerate the screening of catalyst structures across the vast compositional space. In this paper, we introduce a simple and general model for predicting the site stability of multimetallic surfaces and nanoparticles, which is based on physical principles. The model requires only a small set of density functional theory (DFT) calculations of metal atom binding energies on monometallic and dilute alloy surface slabs to optimize the parameters in the simple model. The resulting model allows for the quantification of the stability of any particular atom site in any conceivable chemical environment across a wide range of morphologies, sizes, and arrangements by interpolating the derived parameters from a monometallic system to a completely diluted alloyed system. Herein, we demonstrate the robustness of the model across an extensive data set of transition metal alloy surfaces and 147-atoms cuboctahedral nanoparticles (NPs) composed of IrRhRu and PtPdRu. In conclusion, our approach yields mean absolute errors of ≈0.15 (IrRhRu), 0.20 (PtPdRu), 0.19 (IrRhRu NP), and 0.26 (PtPdRu NP) eV relative to site binding energies calculated using DFT.

36 MATERIALS SCIENCE↗