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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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Microstructural investigation of an extruded austenitic oxide dispersion strengthened steel containing a carbon-containing process control agent
The adhesion of austenitic oxide dispersion strengthened (ODS) steel during mechanical alloying and a decreased powder production yield can be overcome by the addition of a process control agent: stearic acid. Here, the influence of stearic acid and the introduction of carbon in an extruded and annealed austenitic ODS steel was investigated. In particular the impact of carbon on the precipitate formation, the stability of particle and grain sizes during a heat treatment of 2 h at temperatures in a range between 500 and 1100 °C and the resulting grain size were investigated. No direct influence of carbon on the formation of precipitates was detected in the as-extruded condition. The orientation relationship of oxide nano-particles and the austenitic matrix was found to be size dependent. Also, a surprising growth of oxide precipitates was recorded, which starts at annealing temperatures as low as 700 °C. Precipitates in other steels do not show a growth in this temperature regime at all. For that reason, a possible link between the unexpected growth and the formation of carbides was investigated. M 7 C 3 and M 23 C 6 carbides were found in every sample condition and we were able to show that their amount follows a trend suggested by thermodynamic simulations. The grain size of the extruded austenitic ODS steel was examined and a grain refinement was found after a heat treatment of 2 h at 700 °C or higher was performed. That is caused by the inhabitation of further grain growth after nucleation as part of the recrystallization process has happened. The dragging force exerted by precipitates is strong enough to pin grain boundaries. Furthermore, no direct impact of carbon on the oxide precipitate growth was found, an indirect impact of carbon on the growth of ODS precipitates is supposed but requires long-term annealing studies to be verified.
Calendar and PHEV Cycle Life Aging of High-Energy, Lithium-Ion Cells Containing Blended Spinel and Layered-Oxide Cathodes
One hundred seven commercially available, off-the-shelf, 1.2-Ah cells were tested for calendar life and CS cycle- and CD cycle-life using the new USABC PHEV Battery Test Manual. Here, the effects of temperature on calendar life, on CS cycle life, and on CD cycle life; the effects of SOC on calendar life and on CS cycle life; and the effects of rest time on CD cycle life were investigated. The results indicated that the test procedures caused performance decline in the cells in an expected manner, calendar < CS cycling < CD cycling. In some cases, the kinetic law changed with test type, from linear-with-time to about t2. Additionally, temperature was found to stress the cells more than SOC, causing increased changes in performance with increasing temperature.
Synthesis and characterization of new fluoride-containing manganese vanadates A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}VO{sub 4}F
Large single crystals of A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}VO{sub 4}F were grown using a high-temperature (~600 °C) hydrothermal technique. Single crystal X-ray diffraction and powder X-ray diffraction were utilized to characterize the structures, which both possess MnO{sub 4}F{sub 2} building blocks. The A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} series crystallizes as a new structure type in space group Pbcn (No. 60), Z=4 (Rb{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}: a=7.4389(17) Å, b=11.574(3) Å, c=10.914(2) Å; Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}: a=7.5615(15) Å, b=11.745(2) Å, c=11.127(2) Å). The structure is composed of zigzag chains of edge-sharing MnO{sub 4}F{sub 2} units running along the a-axis, and interconnected through V{sub 2}O{sub 7} pyrovanadate groups. Temperature dependent magnetic susceptibility measurements on this interesting one-dimensional structural feature based on Mn{sup 2+} indicated that Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} is antiferromagnetic with a Neél temperature, T{sub N}=~3 K and a Weiss constant, θ, of −11.7(1) K. Raman and infrared spectra were also analyzed to identify the fundamental V–O vibrational modes in Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}. Mn{sub 2}(VO{sub 4})F crystalizes in the monoclinic space group of C2/c (no. 15), Z=8 with unit cell parameters of a=13.559(2) Å, b=6.8036(7) Å, c=10.1408(13) Å and β=116.16(3)°. The structure is associated with those of triplite and wagnerite. Dynamic fluorine disorder gives rise to complex alternating chains of five-and six-coordinate Mn{sup 2+}. These interpenetrating chains are additionally connected through isolated VO{sub 4} tetrahedra to form the condensed structure. - Graphical abstract: New vanadate fluorides A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}(VO{sub 4})F have been synthesized hydrothermally. Upon cooling, the one-dimensional Mn(II) substructure results in antiferromagnetic ordering. Display Omitted - Highlights: • Single crystals of A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}, (A=Rb, Cs) and Mn{sub 2}VO{sub 4}F were grown hydrothermally. • The use of fluoride mineralizers in the synthesis led to the formation of new compounds without OH{sup −} groups. • The structure of A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} features zigzag chains of MnO{sub 4}F{sub 2} units. • Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} exhibits antiferromagnetic ordering with a Neel temperature of ~3 K. • Mn{sub 2}VO{sub 4}F possesses a condensed framework structure with disordered fluorine atoms.
Eu2P7X and Ba2As7X (X = Br, I): Chiral double-Zintl salts containing heptapnictotricyclane clusters
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Synthesis and enhanced light absorption of alumina matrix nanocomposites containing multilayer oxide nanorods and silver nanoparticles
Highlights: {yields} Multilayer oxide nanorods (nanocables) were obtained via chemical processing. {yields} Ag nanoparticles were deposited between the core and shell layers of the nanorods. {yields} The structure and composition of the nanorods were analyzed by SEM and TEM. {yields} CoO nanorods and Ag nanoparticles enhance light absorption of the nanocomposites. -- Abstract: In this paper, multilayer oxide nanorods were deposited in the nanopores of anodic aluminum oxide (AAO) via solution infiltration followed by heat treatment. The nanorods have a core-shell structure. First, the shell (nanotube) with the thickness of about 40 nm was made of TiO{sub 2} through the hydrolysis of (NH{sub 4}){sub 2}TiF{sub 6}. Second, silver nanoparticles with the diameter of about 3 nm were added into the TiO{sub 2} layer through thermal decomposition of AgNO{sub 3} at elevated temperatures. Then, cylindrical cores (nanorods) of CoO and ZnO with 200 nm diameter were prepared, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and composition of the nanorods. UV-vis light absorption measurements in the wavelength range from 350 to 1000 nm were performed to study the effect of nanorod and nanoparticle addition on the light absorption property of the alumina nanocomposites. It is found that CoO nanorods increase the light absorption of the alumina matrix composite in the wavelength range from 500 nm to 800 nm, but the TiO{sub 2} shell does not increase the light absorption much. The ZnO nanorods do not change the light absorption either. However, the addition of silver nanoparticles significantly enhances light absorption of both AAO/TiO{sub 2}/Ag/CoO and AAO/TiO{sub 2}/Ag/ZnO nanocomposites. This increase in the visible light absorption reveals that there exists surface plasmon around the fine silver nanoparticles in the nanorods.
Can ionic liquids be used as templating agents for controlled design of uranium-containing nanomaterials?
Graphical abstract: - Highlights: • Uranium oxides nanoparticles prepared using ionic liquids. • IL cation alkyl length impacts oxide morphology. • Low temperature UO{sub 2} synthesis. - Abstract: Nanostructured uranium oxides have been prepared in ionic liquids as templating agents. Using the ionic liquids as reaction media for inorganic nanomaterials takes advantage of the pre-organized structure of the ionic liquids which in turn controls the morphology of the inorganic nanomaterials. Variation of ionic liquid cation structure was investigated to determine the impact on the uranium oxide morphologies. For two ionic liquid cations, increasing the alkyl chain length increases the aspect ratio of the resulting nanostructured oxides. Understanding the resulting metal oxide morphologies could enhance fuel stability and design.
Scale-up of amine-containing thin-film composite membranes for CO2 capture from flue gas
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Microstructural and creep properties of boron- and zirconium-containing cobalt-based superalloys
Not provided.
Positive Allosteric Modulators of GluN2A-Containing NMDARs with Distinct Modes of Action and Impacts on Circuit Function
Abstract not provided
Microstructure of colloid-polymer mixtures containing charged colloidal disks and weakly-adsorbing polymers
Not Available