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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 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Analysis of Tank 38H (HTF-38-16-80, 81) and Tank 43H (HTF-43-16-82, 83) Samples for Support of the Enrichment Control and Corrosion Control Programs

SRNL analyzed samples from Tank 38H and Tank 43H to support ECP and CCP. The total uranium in the Tank 38H surface sample was 57.6 mg/L, while the sub-surface sample was 106 mg/L. The Tank 43H samples ranged from 50.0 to 51.9 mg/L total uranium. The U-235 percentage was consistent for all four samples at 0.62%. The total uranium and percent U-235 results appear consistent with recent Tank 38H and Tank 43H uranium measurements. The Tank 38H plutonium results show a large difference between the surface and sub-surface sample concentrations and somewhat higher concentrations than previous samples. The Pu-238 concentration is more than forty times higher in the Tank 38H sub-surface sample than the surface sample. The surface and sub-surface Tank 43H samples contain similar plutonium concentrations and are within the range of values measured on previous samples. The four samples analyzed show silicon concentrations somewhat higher than the previous sample with values ranging from 104 to 213 mg/L.

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

Interfacial Charge Engineering in Ferroelectric-Controlled Mott Transistors

Heteroepitaxial coupling at complex oxide interfaces introduces a powerful tool for engineering the charge degree of freedom in strongly correlated materials, which can be utilized to achieve tailored functionalities that are inaccessible in the bulk form. In this work, the charge-transfer effect between two strongly correlated oxides, Sm 0.5 Nd 0.5 NiO 3 (SNNO) and La 0.67 Sr 0.33 MnO 3 (LSMO), is exploited to realize a giant enhancement of the ferroelectric field effect in a prototype Mott field-effect transistor. By switching the polarization field of a ferroelectric Pb(Zr,Ti)O 3 (PZT) gate, nonvolatile resistance modulation in the Mott transistors with single-layer SNNO and bilayer SNNO/LSMO channels is induced. For the same channel thickness, the bilayer channels exhibit up to two orders of magnitude higher resistance-switching ratio at 300 K, which is attributed to the intricate interplay between the charge screening at the PZT/SNNO interface and the charge transfer at the SNNO/LSMO interface. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy studies of SNNO/LSMO heterostructures reveal about 0.1 electron per 2D unit cell transferred between the interfacial Mn and Ni layers, which is corroborated by first-principles density functional theory calculations. The study points to an effective strategy to design functional complex oxide interfaces for developing high-performance nanoelectronic and spintronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Solid‐State Prealkylation of Electrode Architectures (SPEAR): Direct Control of Prelithiation Levels in Silicon Anodes and Electrochemical Cycling

The Solid-state Prealkylation of Electrode ARchitectures (SPEAR) is different than traditional electrochemical prealkylation processes. Through SPEAR, alkylation is driven by solid-state diffusion without the simultaneous SEI formation concomitant with polarization. Here, we investigate the prelithiation of 80 wt. % Si-based anodes to varying amounts (up to Li 1.38 Si) to understand the trade-off between improved Li capacity and expansion-induced stress. Through dilatometry, we found that solid-state lithiation led to filling of the electrode pores through silicon expansion. This swelling changed the SEI formation process and accessibility of the silicon compared to an electrochemically lithiated electrode. Indeed, optimal prelithiation to Li 0.82 Si increases the initial C/3 cycling capacity post-SEI formation up to 43%, consistent with deeper Si activation through the electrode bulk. Prelithiation and cycling cells prelithiated beyond Li 0.82 Si results in a state of charge (SOC) close to 100% which facilitates parasitic degradation mechanisms and volume expansion of the Si electrode. The results demonstrate a pathway to modify silicon activation/SEI formation to enable high-energy electrodes.

Musgrove, Amanda L. [Oak Ridge National Laboratory↗
DOE OSTI2016

Inter‐Fullerene Electronic Coupling Controls the Efficiency of Photoinduced Charge Generation in Organic Bulk Heterojunctions

Photoinduced charge generation (PCG) dynamics are notoriously difficult to correlate with specific molecular properties in device relevant polymer:fullerene organic photovoltaic blend films due to the highly complex nature of the solid state blend morphology. Here, this study uses six judiciously selected trifluoromethylfullerenes blended with the prototypical polymer poly(3‐hexylthiophene) and measure the PCG dynamics in 50 fs–500 ns time scales with time‐resolved microwave conductivity and femtosecond transient absorption spectroscopy. The isomeric purity and thorough chemical characterization of the fullerenes used in this study allow for a detailed correlation between molecular properties, driving force, local intermolecular electronic coupling and, ultimately, the efficiency of PCG yield. The findings show that the molecular design of the fullerene not only determines inter‐fullerene electronic coupling, but also influences the decay dynamics of free holes in the donor phase even when the polymer microstructure remains unchanged.

Larson, Bryon W.↗