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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Effect of phosphorus additions on the sintering and transport properties of proton conducting BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}}

The influence of phosphorous additions on the sintering and electrical transport properties of the proton-conducting perovskite BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}} (BZY) has been studied with a view to the use of phosphates as typical dispersants for the formation of stabilised solid suspensions or as possible sintering aids. P{sub 2}O{sub 5} additions, (1-x)BZY{center_dot}xP{sub 2}O{sub 5}, monotonously promote densification in the intermediate compositional range 0.04{<=}x{<=}0.08. Nonetheless, BZY reacts with phosphorous forming the phase Ba{sub 3}(PO{sub 4}){sub 2} at temperatures as low as 600 Degree-Sign C. The associated loss of Ba from the perovskite, leads to a decrease in the perovskite lattice parameter, the formation of yttria-based impurity phases and impaired grain growth. Such reaction has an extremely detrimental effect on bulk and grain boundary conductivities. It is, therefore, vital that the current results are taken into account by the protonics community when attempting to prepare the stabilised solid suspensions of BZY nanopowders required for thin ceramic applications. Alternative dispersants to phosphate esters must be found. - Graphical Abstract: Sintering experiments performed at 1500 Degree-Sign C for 5 h and at 1400 Degree-Sign C for 24 h of (1-x)BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}}{center_dot}xP{sub 2}O{sub 5} in the range x=0-0.10. Highlights: Black-Right-Pointing-Pointer P{sub 2}O{sub 5} additions, (1-x)BZY{center_dot}xP{sub 2}O{sub 5}, promote densification in the intermediate compositional range 0.04{<=}x{<=}0.08. Black-Right-Pointing-Pointer BZY reacts with phosphorous forming the phase Ba{sub 3}(PO{sub 4}){sub 2} at temperatures as low as 600 Degree-Sign C. Black-Right-Pointing-Pointer Detrimental effects on bulk and grain boundary conductivities are shown. Black-Right-Pointing-Pointer Alternative dispersants to phosphate esters must be found.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Phosphorus-Atom Transfer from Phosphaethynolate to an Alkylidyne

A low-spin and mononuclear vanadium complex, ( Me nacnac)V(CO)(η 2 -P≡C t Bu) ( 2 ) ( Me nacnac - =[ArNC(CH 3 )] 2 CH, Ar=2,6- i Pr 2 C 6 H 3 ), was prepared upon treatment of the vanadium neopentylidyne complex ( Me nacnac)V≡C t Bu(OTf) ( 1 ) with Na(OCP)(diox) 2.5 (diox=1,4-dioxane), while the isoelectronic ate-complex [Na(15-crown-5)]{([ArNC(CH 2 )]CH[C(CH 3 )NAr])V(CO)(η 2 -P≡C t Bu)} ( 4 ), was obtained via the reaction of Na(OCP)(diox) 2.5 and ([ArNC(CH 2 )]CH[C(CH 3 )NAr])V≡C t Bu(OEt 2 ) ( 3 ) in the presence of crown-ether. Computational studies suggest that the P-atom transfer proceeds by [2+2]-cycloaddition of the P≡C bond across the V≡C t Bu moiety, followed by a reductive decarbonylation to form the V-C≡O linkage. Additionally, the nature of the electronic ground state in diamagnetic complexes, 2 and 4 , was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X-ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X-ray single-crystal structural characterization. In combination, these data are consistent with a low-valent vanadium ion in complexes 2 and 4 . This study represents the first example of a metathesis reaction between the P-atom of [PCO] - and an alkylidyne ligand.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

A novel battery scheme: Coupling nanostructured phosphorus anodes with lithium sulfide cathodes

Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society. Lithium-sulfur batteries, with a high theoretical specific energy, are promising candidates for next generation energy storage. However, the use of Li metal in Li-S batteries compromises both safety and performance, enabling dendrite formation and causing fast capacity degradation. Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system, such as a Si/Li2S couple, with limited success in performance. Recently, there is a focus on red P as a favorable anode material to host Li. In this work, we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li 2 S coated carbon nanofiber cathode. We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li 2 S cathode. Our proof of concept full-cell displays remarkable specific capacity, rate and cycling performances. We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.

25 ENERGY STORAGE↗
DOE OSTI2013

Interaction of yttrium with nickel and phosphorus: Phase diagram and structural chemistry

The interaction between the components of the ternary Y–Ni–P system has been investigated by means of electron probe microanalysis, X-ray phase and structure analyses, and the isothermal section of the phase diagram at 1070 K has been constructed for the first time. Existence of the earlier reported eight ternary phosphides of yttrium and nickel was confirmed, among them seven ternaries are daltonide compounds: YNi{sub 4}P{sub 2} (ZrFe{sub 4}Si{sub 2}-type structure), Y{sub 2}Ni{sub 12}P{sub 7} (Zr{sub 2}Fe{sub 12}P{sub 7}-type structure), Y{sub 6}Ni{sub 20}P{sub 13} (Zr{sub 6}Ni{sub 20}P{sub 13}-type structure), Y{sub 6}Ni{sub 14.9}P{sub 10.18} (own structure type), Y{sub 20}Ni{sub 42}P{sub 30.34} (Sm{sub 20}Ni{sub 41.6}P{sub 30}-type structure), Y{sub 15}Ni{sub 28}P{sub 21} (Tb{sub 15}Ni{sub 28}P{sub 21}-type structure), and YNiP (Tb{sub 1−x}NiP-type structure), whereas YNi{sub 1.66−1.78}P{sub 2} (ThCr{sub 2}Si{sub 2}-type structure) is a berthollide compound with small homogeneity range. The crystal structures of the some ternary phosphides have been determined by X-ray powder diffraction (YNi{sub 4}P{sub 2} and YNi{sub 1.66−1.78}P{sub 2}) and single crystal diffraction (Y{sub 2}Ni{sub 12}P{sub 7}) techniques. - Graphical abstract: Structure block with the composition Ln{sub 10}M{sub 21}X{sub 15} of the homologous series of the compounds (Ln,M){sub ∼2}X. Display Omitted - Highlights: • The phase diagram of Y–Ni–P at 1070 K has been constructed. • Existence of the eight ternary phosphides of yttrium and nickel has been confirmed. • The crystal structures of YNi{sub 4}P{sub 2} and YNi{sub 1.66-1.78}P{sub 2} have been determined by powder X-ray diffraction. • The crystal structure of Y{sub 2}Ni{sub 12}P{sub 7} has been established by single crystal diffraction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Interaction of tantalum, chromium, and phosphorus at 1070 K: Phase diagram and structural chemistry

Solid-state phase equilibria have been established in the Ta–Cr–P system in the region of 0–67 at% P at 1070 K through powder X-ray diffraction analysis. Mutual substitution of Ta and Cr in binary phosphides gives rise to significant homogeneity ranges in Ta{sub 1.00–0.66}Cr{sub 0–0.34}P (NbAs-type; a=3.332(3)–3.1366(3) Å, c=11.386(4)–11.364(2) Å), Ta{sub 3.0–2.1}Cr{sub 0–0.9}P (Ti{sub 3}P-type, a=10.156(2)–9.9992(2) Å, c=5.015(1)–4.956(2) Å), and Cr{sub 3.0–2.4}Ta{sub 0–0.6}P (Ni{sub 3}P-type, a=9.186(5)–9.217(4) Å, c=4.557(3)–4.5911(3) Å). A limited homogeneity range is found in the ternary phase Ta{sub 1.0–0.8}Cr{sub 1.0–1.2}P (TiNiSi-type, a=6.2344(5)–6.141(2) Å, b=3.5034(3)–3.3769(6) Å, c=7.3769(6)–7.357(2) Å). The OsGe{sub 2}-type structures (space group C2/m) of a new P-rich compound, Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} (a=8.8586(3) Å, b=3.2670(2) Å, c=7.4871(2) Å, β=119.315(2)°) as well as of the Ti-containing analogue Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} (a=8.8592(5) Å, b=3.2663(3) Å, c=7.4870(5) Å, β=119.309(2)°) were refined from powder X-ray diffraction data. - Graphical abstract: Solid-state phase equilibria have been established in the Ta–Cr–P system in the region of 0–67 at% P at 1070 K through powder X-ray diffraction analysis. Mutual substitution of Ta and Cr in binary phosphides gives rise to significant homogeneity ranges in Ta{sub 1.00–0.66}Cr{sub 0–0.34}P, Ta{sub 3.0–2.1}Cr{sub 0–0.9}P, and Cr{sub 3.0–2.4}Ta{sub 0–0.6}P. A limited homogeneity range is found in the ternary phase Ta{sub 1.0–0.8}Cr{sub 1.0–1.2}P. The OsGe{sub 2}-type structures of a new P-rich compound, Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} as well as of the Ti-containing analogue Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} were establish from powder X-ray diffraction data. No homogeneity ranges for binary compounds Cr{sub 12}P{sub 7}, Cr{sub 2}P, Ta{sub 5}P{sub 3} were detected. - Highlights: • The phase diagram of Ta–Cr–P at 1070 K has been constructed. • New ternary compounds Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} and Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} were established. • Ta{sub 1.0−0.8}Cr{sub 1.0−1.2}P and Ta{sub 0.86+x}Ti{sub 0.15-x}P{sub 2}(x= 0−0.07) exhibit homogeneity ranges. • The binary compounds reveal homogeneity ranges by Ta/Cr and Cr/Ta substitutions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Slow pyrolysis enhances the recovery and reuse of phosphorus and reduces metal leaching from biosolids

Highlights: • Waste water biosolids offer a source of P for agricultural applications. • Biosolids with and without alum were converted into biochar. • Conversion of biosolids containing alum into biochar liberated bound P for re-use. • Conversion of biosolids into biochar eliminated metal leaching from biosolids. • Pyrolysis enhances P recycling and reduces metal leaching from municipal waste. - Abstract: In this study, biochar is produced from biosolids with and without alum at a range of temperatures and simulated oxidative aging of the biochars is conducted to quantify the long-term leaching of P and metals. While biosolids containing alum had negligible amounts of plant-available P, after pyrolysis >90% of the P became immediately available for plant growth. When biosolids with no alum were converted into biochar there was a small increase in the availability of P but a larger pool was available after oxidation. Both of the biosolids leached significant amounts of metals after oxidation. In contrast, the biochars had a very low available metal content and this did not increase with oxidation, demonstrating a stable metal content. Pyrolysis is an effective waste management strategy for biosolids that can simultaneously reduce the leaching of metals and increase the efficiency of recycling of P for beneficial re-use.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Electrochemical Li Intercalation in Black Phosphorus: In Situ and Ex Situ Studies

A systematic study on electrochemical charge transfer in Li-doped black phosphorous (BP) was carried out by both in-situ and ex-situ Raman scattering. Galvanostatic discharge of dedicated in-situ electrochemical cell for Raman spectroscopy was used to study time evolution of vibrational modes under lithiation. In addition to the peak broadening which is a result of structural expansion, peaks corresponding to all three atomic vibrational modes A 1 g , B 2 g and A 2 g were found to red-shift as a result of lithiation. Peaks B 2 g and A 2 g were shifted about 1.6 times more towards lower wavenumbers in comparison to A 1 g . Further characterizations using optical and electron microscopy showed that the intercalation of BP is highly anisotropic, where channels along the zigzag direction were found to be the easy direction for intercalation. X-ray diffraction on intercalated samples confirmed a reduction of thickness as lithiation weakens interlayer bonding, thus resulting in a partial exfoliation of BP flakes. Here, first principle studies using density function theory (DFT) were used to develop a theoretical model for the intercalation mechanism. The discrepancy between the experimental and the theoretical results was also addressed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Phosphorus doping of Si nanocrystals embedded in silicon oxynitride determined by atom probe tomography

Silicon nanocrystals (SiNCs) embedded in a silicon oxide matrix were studied by 3D atom probe tomography (APT). The distribution of the SiNC diameter was found to have a mean value of 3.7 ± 0.8 nm. The elemental composition of these particles was determined by employing two different approaches: (i) The proximity histogram method and (ii) a cluster identification algorithm based on maximum-atom separations. Both approaches give very similar values in terms of the amount of P, O, and Si within the SiNCs: the mean atomic concentrations are c{sub P} = 0.77% ± 0.4%, c{sub O} = 12.3% ± 2.1%, and c{sub Si} = 85.3% ± 2.1%. A detailed cluster analysis implies that, on average, a 4.5-nm SiNC would contain around 30 P atoms, whereas a 2.0-nm SiNC would contain only around 3 P atoms. Radial concentration profiles obtained for these SiNCs indicate that the P content is inhomogeneous and possibly enhanced at the boundary as compared to the interior of the NCs. About 20% of the P atoms are found to be incorporated into the SiNCs, whereas roughly 30% are trapped within the interfacial layer (with a thickness of ∼ 0.8 nm); the remainder resides in the surrounding matrix. Cluster-size dependent P concentrations support the view of self-purification in the Si nanostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Boron- and phosphorus-doped silicon germanium alloy nanocrystals—Nonthermal plasma synthesis and gas-phase thin film deposition

Alloyed silicon-germanium (SiGe) nanostructures are the topic of renewed research due to applications in modern optoelectronics and high-temperature thermoelectric materials. However, common techniques for producing nanostructured SiGe focus on bulk processing; therefore little is known of the physical properties of SiGe nanocrystals (NCs) synthesized from molecular precursors. In this letter, we synthesize and deposit thin films of doped SiGe NCs using a single, flow-through nonthermal plasma reactor and inertial impaction. Using x-ray and vibrational analysis, we show that the SiGe NC structure appears truly alloyed for Si{sub 1−x}Ge{sub x} for 0.16 < x < 0.24, and quantify the atomic dopant incorporation within the SiGe NC films.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs). In this work bulk Si with the resistivity as low as ∼ 0.8 (40) mΩ•cm has been produced by hot pressing P (B)-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature is the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity) of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤ ∼ 30 cm{sup -2}V{sup -1}s{sup -1}) mainly due to the scattering of carriers induced by structural defects such as pores.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Phosphorus and boron diffusion paths in polycrystalline silicon gate of a trench-type three-dimensional metal-oxide-semiconductor field effect transistor investigated by atom probe tomography

The dopant (P and B) diffusion path in n- and p-types polycrystalline-Si gates of trench-type three-dimensional (3D) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated using atom probe tomography, based on the annealing time dependence of the dopant distribution at 900 °C. Remarkable differences were observed between P and B diffusion behavior. In the initial stage of diffusion, P atoms diffuse into deeper regions from the implanted region along grain boundaries in the n-type polycrystalline-Si gate. With longer annealing times, segregation of P on the grain boundaries was observed; however, few P atoms were observed within the large grains or on the gate/gate oxide interface distant from grain boundaries. These results indicate that P atoms diffuse along grain boundaries much faster than through the bulk or along the gate/gate oxide interface. On the other hand, in the p-type polycrystalline-Si gate, segregation of B was observed only at the initial stage of diffusion. After further annealing, the B atoms became uniformly distributed, and no clear segregation of B was observed. Therefore, B atoms diffuse not only along the grain boundary but also through the bulk. Furthermore, B atoms diffused deeper than P atoms along the grain boundaries under the same annealing conditions. This information on the diffusion behavior of P and B is essential for optimizing annealing conditions in order to control the P and B distributions in the polycrystalline-Si gates of trench-type 3D MOSFETs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗