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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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Metallic nickel silicides: Experiments and theory for NiSi and first principles calculations for other phases
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In-pile test results of U-silicide or U-nitride coated U-7Mo particle dispersion fuel in Al
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57 Fe Mössbauer study of Lu 2 Fe 3 Si 5 iron silicide superconductor
With the advent of Fe–As based superconductivity it has become important to study how superconductivity manifests itself in details of 57 Fe Mössbauer spectroscopy of conventional, Fe-bearing superconductors. The iron-based superconductor Lu 2 Fe 3 Si 5 has been studied by 57 Fe Mössbauer spectroscopy over the temperature range from 4.4 K to room temperature with particular attention to the region close to the superconducting transition temperature (T c =6.1 K). Consistent with the two crystallographic sites for Fe in this structure, the observed spectra appear to have a pattern consisting of two doublets over the whole temperature range. Furthermore, the value of Debye temperature was estimated from temperature dependence of the isomer shift and the total spectral area and compared with the specific heat capacity data. Neither abnormal behavior of the hyperfine parameters at or near T c , nor phonon softening were observed.
The effect of metal silicide formation on silicon nanowire-based lithium-ion battery anode capacity
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Recent progress in p-type thermoelectric magnesium silicide based solid solutions
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U 8 Al 19 Si 6 , A Uranium Aluminide Silicide with a Stuffed Supercell Grown from Aluminum Flux
In this work, U 8 Al 19 Si 6 is formed from the reaction of uranium oxide and silicon in aluminum flux. Growth of this material is dependent on the presence of surface hydroxyl groups on alumina in the crucible. The compound forms as large cuboid crystals with a complex new structure that is a cubic stuffed supercell of UAl 3 (AuCu 3 parent structure type). It features a 4-fold expansion of the unit cell axis and the addition of atoms on two extra positions resulting in Pm$\bar{3n}$ symmetry. The ordered distribution of aluminum and silicon was determined using single crystal neutron diffraction. The magnetic susceptibility shows temperature independent paramagnetic behavior, while heat capacity measurements are consistent with Fermi liquid characteristics at low temperatures where the Sommerfeld constant is enhanced in comparison to that of a conventional metal. Lastly, these bulk thermodynamic properties indicate that U 8 Al 19 Si 6 is an itinerant electron Pauli paramagnet with moderately enhanced mass charge carrier quasiparticles.
Fluoroethylene Carbonate Breakdown Mechanisms and Energetics on Two Lithium Silicide Surfaces
Lithium-ion batteries are a leading energy storage technology. One challenge with lithium-ion batteries is the reductive decomposition of electrolyte on the surface, forming a passivating, solid–electrolyte interphase (SEI). The SEI prevents further electrolyte breakdown and consumption, but if not formed properly, may also consume lithium ions and prevent lithium-ion diffusion to the anode. Fluoroethylene carbonate (FEC) is currently one of the best electrolyte additives used to form a more robust SEI on silicon anodes. In this study, we use density functional theory (DFT) to investigate the spontaneous breakdown mechanisms, energies, and charge transfers of FEC on the surface of a silicon anode in a lesser lithiated LiSi and a more lithiated Li 15 Si 4 state. The reductive decomposition of FEC on LiSi and Li 15 Si 4 to F, CO 2 , and CH 2 CHO is energetically most favorable on both surfaces, but F, CO, and OCH 2 CHO can also be formed. The breakdown of FEC via either of the breakdown mechanisms is about 2 times more favorable on the Li 15 Si 4 surface than on the LiSi surface. Lastly, the Bader charge transferred from the anode to the FEC breakdown products is larger when forming F, CO 2 , and CH 2 CHO than when forming F, CO, and OCH 2 CHO and is also larger on the Li 15 Si 4 surface than on the LiSi surface.
Vapor Phase Conversion Synthesis of Higher Manganese Silicide (MnSi[subscript 1.75]) Nanowire Arrays for Thermoelectric Applications
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Real-Time Observations of Interfacial Lithiation in a Metal Silicide Thin Film
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Polaronic transport and current blockades in epitaxial silicide nanowires and nanowire arrays
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Functionalized nona-silicide [Si 9 R 3 ] Zintl clusters: a new class of superhalogens
Superatoms, due to their various applications in redox and materials chemistry, have been a major topic of study in cluster science. Superhalogens constitute a special class of superatoms that mimic the chemistry of halogens and serve as building blocks of novel materials such as super and hyper salts, perovskite-based solar cells, solid-state electrolytes, and ferroelectric materials. These applications have led to a constant search for new class of superhalogens. Here, in this study, using density functional theory, we show that recently synthesized [Si 9 {Si ( t Bu) 2 H} 3 ] and [Si 9 {Si (TMS) 3 } 3 ] Zintl clusters not only behave like halogens but also when functionalized with suitable ligands exhibit superhalogen characteristics. Frontier molecular orbital (FMO) analyses give insights into the electron-accepting nature of the Zintl clusters. Additional bonding techniques such as energy density at the bond critical point (BCP) and adaptive natural density partitioning (AdNDP) gives complementary information about the nature of bonding in Si 9 -based Zintl clusters. The potential of these Zintl clusters in the synthesis of new electrolytes in Li-ion batteries is also investigated.