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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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9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 Ǻ, the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.

Hung, Ching-cheh↗
NASA NTRS1970

Aerial photography for sensing plant anomalies

Changes in the red tonal response of Kodak Ektrachrome Infrared Aero 8443 film (EIR) are often incorrectly attributed solely to variations in infrared light reflectance of plant leaves, when the primary influence is a difference in visible light reflectance induced by varying chlorophyll contents. Comparisons are made among aerial photographic images of high- and low-chlorophyll foliage. New growth, foot rot, and boron and chloride nutrient toxicites produce low-chlorophyll foliage, and EIR transparency images of light red or white compared with dark-red images of high-chlorophyll foliage. Deposits of the sooty mold fungus that subsists on the honeydew produced by brown soft scale insects, obscure the citrus leaves' green color. Infected trees appear as black images on EIR film transparencies compared with red images of healthy trees.

Gausman, H. W.↗
NASA NTRS1982

Removing Chlorides From Metallurgical-Grade Silicon

Process for making low-cost silicon for solar cells is further improved. Silane product recycled to feed stripper column converts some of heavy impurities to volatile ones that pass off at top of column with light wastes. Impurities--chlorides of arsenic, phosphorus, and boron-would otherwise be carried to subsequent distillations where they would be difficult to remove. Since only a small amount of silane is recycled, silicon production efficiency remains high.

Breneman, W. C.↗
NASA NTRS2024

High Yield Exfoliation of a Sub-Micron Hexagonal Boron Nitride Using a Solvent Free Method

Sodium fluoride (NaF) has been found to be an activation agent in exfoliating a hexagonal boron nitride (hBN) platelet, using solvent free method. The procedure was carried out by enhancing the intercalation of ferric chloride (FeCl3) in an intermediate step, up to 330 °C, followed by removal of the by-product at room temperature. In this research, five additional common salts including lithium fluoride, potassium fluoride, lithium chloride, sodium chloride, and potassium chloride, were examined and compared to NaF for their effectiveness in producing the most exfoliation of a commercially available sub-micron-size hBN. It was found that, all fluoride and chloride salts significantly activated the intercalation of FeCl3 into this hBN. Analyses and characterization from X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscoy revealed NaCl to be one of most effective agents without further heat treatment and the least expensive salt in the intercalating reaction and exfoliation process. The synthetic route of this solvent free method is straightforward with 89% yield and above which can be produced on a large scale.

boron nitride↗
NASA NTRS1984

An investigation of chemically-induced improvement in saturation moisture characteristics of epoxies

MY-720/DDS epoxy samples were treated with three selected chemical compounds to render the active H-sites inactive for moisture absorption. Treating the epoxy castings with acetyl chloride and dichlorodimethyl silane leads only to surface changes indicating that these molecules are too large to penetrate the epoxy castings. Boron trifluoride, on the other hand, does penetrate the epoxy chain as is indicated by the formation of green domains in the interior of the castings. However, the process of saturating the specimens with moisture appears to leach out the chemical additives--thereby nullifying their possible ameliorative effects.

Singh, J. J.↗
NASA NTRS1987

Preparation of B-trichloroborazine

The present invention relates to a method of preparing B-trichloroborazine. Generally, the method includes the combination of gaseous boron trichloride in an anhydrous aprotic organic solvent followed by addition of excess gaseous ammonia at ambient temperature or below. The reaction mixture is heated to about 100 to 140 C followed by cooling, removal of the solid ammonium chloride at ambient temperature, distillation of the solvent under vacuum if necessary at a temperature of up to about 112 C, and recovery of the B-trichloroborazine. Solvents include toluene, benzene, xylene, chlorinated hydrocarbons, chlorinated aromatic compounds, or mixtures thereof. Toluene is a preferred solvent. The process provides a convenient synthesis of a material which often decomposes on standing. B-trichloroborazine is useful in a number of chemical reactions, and particularly in the formation of high temperature inorganic polymers and polymer precursors.

Riccitiello, Salvatore R.↗
NASA NTRS2018

Methods for Intercalating and Exfoliating Hexagonal Boron Nitride

Methods that facilitate exfoliation of hexagonal boron nitride (hBN), exfoliated hBN, and associated intermediate products are disclosed. Such a method can include the acts of mixing a sample of hBN with an activation agent (e.g., NaF, etc.) and a selected set of chemicals (e.g., a metal chloride) and intercalating the set of chemicals into the hBN to obtain intercalated hBN. Additionally, such a method can include the acts of hydrating the set of chemicals (i.e., the intercalates), and converting the set of chemicals to a set of oxide nanoparticles when exfoliating the intercalated hBN. The exfoliated hBN can be washed (e.g., with HCl, etc.) to remove remaining nanoparticles.

Hung, Ching-cheh↗
NASA NTRS1979

Recycling plant, human and animal wastes to plant nutrients in a closed ecological system

The essential minerals for plant growth are nitrogen, phosphorous, potassium (macronutrients), calcium, magnesium, sulfur (secondary nutrients), iron, manganese, boron, copper, zinc, chlorine, sodium, and molybdenum (micronutrients). The first step in recycling wastes will undoubtedly be oxidation of carbon and hydrogen to CO2 and H2O. Transformation of minerals to plant nutrients depends upon the mode of oxidation to define the state of the nutrients. For the purpose of illustrating the type of processing required, ash and off-gas compositions of an incineration process were assumed and subsequent processing requirements were identified. Several processing schemes are described for separating out sodium chloride from the ash, leading to reformulation of a nutrient solution which should be acceptable to plants.

Meissner, H. P.↗