SEARCH · Engineering Papers
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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This work reports a new strategy toward the design of a new class of supported catalysts with intrinsic high-temperature stabilities through entropy maximization.
A composite cathode consisting of fluorite (Bi 0.75 Y 0.25 ) 0.93 Ce 0.07 O 1.5±δ and perovskite La 0.8 Sr 0.2 MnO 3 is synthesized by in situ single-step phase formation and microstructure assembly.
Supercritical methanol upgrading with a CuMgAlO x catalyst is effective at depolymerizing and hydrodeoxygenating lignin into monomers and oligomers.
This work clarifies the mechanism of the formation of hollow nanostructures (nanotubes and nanospheres) during the InOOH to rh-In 2 O 3 transformation.
The stability of the novel Pu( iv ) silicate, Cs 2 PuSi 6 O 15 , was predicted from a combination of crystal chemical reasoning and DFT calculations and confirmed by its synthesis via flux crystal growth.
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Recent studies have suggested that Co-free, Ni-rich layered cathodes (e.g., doped LiNiO2) can provide promising battery performance for practical applications. However, these layered cathodes suffer from significant surface instability during various stages of the sample history, which generates inherent challenges for achieving stable battery performance and obtaining statistically representative characterization results. To reliably report the surface chemistry of these materials, delicate controls of stepwise sample preparation are required. In this study, we aim to reveal how the surface chemistry of LiNiO2 based materials changes with various environments, including human exhalation, sample storage, sample preparation, electrochemistry cycling, and surface doping. Our results demonstrate that the surface of these materials is highly reactive and prone to alter at various stages of sample handling and characterization. The sensitive surface could impact the interpretation of the surface chemical and structural information, including surface carbonate formation, transition metal reduction and dissolution, and surface reconstruction. Importantly, the heterogeneity of the surface degradation calls for a consolidation of nanoscale, high-resolution characterization, and ensemble-averaged methods in order to improve statistical representation. Furthermore, the doping chemistry can effectively mitigate the surface degradation and improve overall battery performance due to the enhanced surface oxygen retention. Our study highlights the necessity of strict measurements through complementary characterizations at multiple length scales to eliminate unintentional biased conclusions.
Commercial 2D carbon materials are shown to be largely nanographite with a small percentage of single layer material present.
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The kinetics of ion exchange of Zr/Sn(IV) phosphonate-phosphate hybrid ion exchange materials have been studied with several types of ions of specific interest to nuclear fuel recycling including Nd 3+ at 4.5 and 43 mM and NpO 2 + at 2.9 mM spanning multiple HNO 3 concentrations. In most cases the equilibrium was reached in less than 12 h. The ion exchange behavior followed that of pseudo first-order adsorption with rates ranging from 0.430–4.10 h -1 and 0.290–0.435 h -1 for Nd 3+ and NpO 2 + , respectively. A separation with both Nd 3+ and NpO 2 + present was performed, resulting in separation factors of 1.9–12, 1.7–6.6, and 2.0–5.7 at 1×10 -1 , 1×10 -2 , and 1×10 -3 M HNO 3 , respectively.
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We construct the elemental distribution and lattice strain maps from the measured atomic column positions in a (LaNiO3)(4)/(LaMnO3)(2) superlattice over a large field of view. The correlation between the distribution of B-cations and the lattice parameter in the form of Vegard's law is validated using atomic resolution energy dispersive x-ray spectroscopy (EDS). The maps show negligible Mn intermixing in the LaNiO3 layer, while Ni intermixing in the LaMnO3 layer improves away from the substrate interface to 9.5 atomic% from the 8th period onwards, indicating that the superlattice interfacial sharpness is established as the distance from the substrate increases. The maps allow an observation of the compositional defects of the B-sites, which is not possible by Z-contrast alone. Thus, this study demonstrates a promising approach for atomic scale correlative study of lattice strain and composition, and a method for the calibration of atomic resolution EDS maps.
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