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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 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Selective etching of TiN over TaN and vice versa in chlorine-containing plasmas

Selectivity of etching between physical vapor-deposited TiN and TaN was studied in chlorine-containing plasmas, under isotropic etching conditions. Etching rates for blanket films were measured in-situ using optical emission of the N{sub 2} (C{sup 3}{Pi}{sub u}{yields}B{sup 3}{Pi}{sub g}) bandhead at 337 nm to determine the etching time, and transmission electron microscopy to determine the starting film thickness. The etching selectivity in Cl{sub 2}/He or HCl/He plasmas was poor (<2:1). There was a window of very high selectivity of etching TiN over TaN by adding small amounts (<1%) of O{sub 2} in the Cl{sub 2}/He plasma. Reverse selectivity (10:1 of TaN etching over TiN) was observed when adding small amounts of O{sub 2} to the HCl/He plasma. Results are explained on the basis of the volatility of plausible reaction products.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial Ag–Cu nanoparticles

Ultrathin films consisting of polyelectrolyte layers prepared by layer-by-layer deposition technique and containing also Ag and Cu nanoparticles exhibit superior antibacterial activity toward Escherichia coli. These films have been investigated with XPS measurements under square wave excitation at two different frequencies, in order to further our understanding about the chemical/physical nature of the nanoparticles. Dubbed as dynamical XPS, such measurements bring out similarities and differences among the surface structures by correlating the binding energy shifts of the corresponding XPS peaks. Accordingly, it is observed that the Cu2p, Ag3d of the metal nanoparticles, and S2p of cysteine, the stabilizer and the capping agent, exhibit similar shifts. On the other hand, the C1s, N1s, and S2p peaks of the polyelectrolyte layers shift differently. This finding leads us the claim that the Ag and Cu atoms are in a nanoalloy structure, capped with cystein, as opposed to phase separated entities.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Si content in methacrylamide-containing A- b -(B- r -C) block copolymers and its impact on reactive ion etching properties

Block copolymers (BCPs) of an A-block-(B-random-C) architecture have been explored as materials for nanolithography because the composition and chemistry of the random block enables modification of thermodynamic and wetting properties to meet manufacturing criteria. Here, in this study, A-b-(B-r-C) BCPs created by an amidation reaction of polystyrene-block-poly(pentafluorophenyl methacrylate) (PS-b-PPFMA) with controlled amounts of Si add insight to previous conclusions about the dual contributions of BCP chemistry and reactive ion etch (RIE) gas chemistry on etch properties. We focus on two RIE etch characteristics: organosilicon etch resistance in H 2 /N 2 plasma etching and enhanced removal of non-styrenic structures in an Ar/O 2 etch. Consistent with previous studies, higher amounts of Si result in greater etch resistance under H 2 /N 2 RIE, where at least ∼10 wt. % Si is necessary to exhibit sufficient etch resistance. By contrast, Ar/O 2 etching resulted in etch rates independent of Si content. We observe previously unreported surface roughening aligned with morphological domains during the H 2 /N 2 etch of modified PS-b-PPFMA BCPs. Limited in the amount of allowable Si to attain equal surface energy between blocks, these BCPs are further disqualified in forming a Si-containing mask. However, in an Ar/O 2 etch, the same BCPs exhibit suitable etch contrast and smooth domain structures, forming a uniform PS mask. Ultimately, this study uses the chemical flexibility of these materials to demonstrate the mechanisms of interactions between BCP and etch chemistry that must be considered to design effective materials for pattern transfer applications.

Eom, Christopher J. [University of Chicago, IL (Un↗
DOE OSTI2026

Vapor phase deposition of alumina on interior surfaces of tritium storage containers

Efficient tritium management and containment are critical challenges for nuclear fusion. To mitigate issues related to permeation into structural materials and isotopic exchange with protium, permeation barriers must be applied to the nonplanar internal surfaces of tritium handling components. In this study, we developed an atomic layer deposition (ALD) system to deposit films on canisters used to store and transport tritium. Growth conditions for deposition of Al 2 O 3 were mapped spatially along the length of a canister using silicon witness samples characterized by ellipsometry, atomic force microscopy, and x-ray reflectivity (XRR). We identified ALD process windows for growth at temperatures between 100 and 140 °C. Furthermore, we compared films grown on our Si witness samples to those grown on polished stainless steel 316 (SS316). X-ray photoelectron spectroscopy indicates two distinct chemical states for the alumina, while XRR confirms that the overall growth rate is similar to the 1.1 Å/cycle that we observed on the Si witness samples.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Orientation control of high-χ triblock copolymer for sub-10 nm patterning using fluorine-containing polymeric additives

Directed self-assembly (DSA) of block copolymers (BCPs) Is one of the most promising techniques to tackle the ever-increasing demand for subllthographic features In semiconductor industries. BCPs with high Flory-Huggins parameter (chi) are of particular Interest due to their ability to self-assemble at the length scale of sub-10 nm. However, such high-chi BCPs typically have imbalanced surface energies between respective blocks, making it a challenge to achieve desired perpendicular orientation. To address this challenge, we mixed a fluorine-containing polymeric additive with poly(2-vlnylpyrldine)-block-polystyrene-block-poly(2-vlnylpyrldine) (P2VP-b-PS-b-P2VP) and successfully controlled the orientation of the high-chi triblock copolymer. The additive selectively mixes with P2VP block through hydrogen bonding and can reduce the dissimilarity of surface energies between PS and P2VP blocks. After optimizing additive dose and annealing conditions, desired perpendicular orientation formed upon simple thermal annealing. We further demonstrated DSA of this material system with five times density multiplication and a half-pitch as small as 8.5 nm. This material system Is also amenable to sequential Infiltration synthesis treatment to selectively grow metal oxide In P2VP domains, which can facilitate the subsequent pattern transfer. We believe that this integration-friendly DSA platform using simple thermal annealing holds the great potential for sub-10 nm nanopatterning applications.

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

Laser damage comparisons of broad-bandwidth, high-reflection optical coatings containing TiO 2 , Nb 2 O 5 , or Ta 2 O 5 high-index layers

Broad bandwidth coatings allow angle of incidence flexibility and accommodate spectral shifts due to aging and water absorption. Higher refractive index materials in optical coatings, such as TiO 2 , Nb 2 O 5 , and Ta 2 O 5 , can be used to achieve broader bandwidths compared to coatings that contain HfO 2 high index layers. We have identified the deposition settings that lead to the highest index, lowest absorption layers of TiO 2 , Nb 2 O 5 , and Ta 2 O 5 , via e-beam evaporation using ion-assisted deposition. We paired these high index materials with SiO 2 as the low index material to create broad bandwidth high reflection coatings centered at 1054 nm for 45 deg angle of incidence and P polarization. Furthermore, high reflection bandwidths as large as 231 nm were realized. Laser damage tests of these coatings using the ISO 11254 and NIF-MEL protocols are presented, which revealed that the Ta 2 O 5 /SiO 2 coating exhibits the highest resistance to laser damage, at the expense of lower bandwidth compared to the TiO 2 /SiO 2 and Nb 2 O 5 /SiO 2 coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Poster — Thur Eve — 12: Implementation of a Clinical Lung Tumour High Dose Containment Verification Procedure using Respiratory Cone-Beam CT (4DCBCT) on a Varian TrueBeam Linac

Lung tumours move due to respiratory motion. This is managed during planning by acquiring a 4DCT and capturing the excursion of the GTV (gross tumour volume) throughout the breathing cycle within an IGTV (Internal Gross Tumour Volume) contour. Patients undergo a verification cone-beam CT (CBCT) scan immediately prior to treatment. 3D reconstructed images do not consider tumour motion, resulting in image artefacts, such as blurring. This may lead to difficulty in identifying the tumour on reconstructed images. It would be valuable to create a 4DCBCT reconstruction of the tumour motion to confirm that does indeed remain within the planned IGTV. CBCT projections of a Quasar Respiratory Motion Phantom are acquired in Treatment mode (half-fan scan) on a Varian TrueBeam accelerator. This phantom contains a mobile, low-density lung insert with an embedded 3cm diameter tumour object. It is programmed to create a 15s periodic, 2cm (sup/inf) displacement. A Varian Real-time Position Management (RPM) tracking-box is placed on the phantom breathing platform. Breathing phase information is automatically integrated into the projection image files. Using in-house Matlab programs and RTK (Reconstruction Tool Kit) open-source toolboxes, the projections are re-binned into 10 phases and a 4DCBCT scan reconstructed. The planning IGTV is registered to the 4DCBCT and the tumour excursion is verified to remain within the planned contour. This technique successfully reconstructs 4DCBCT images using clinical modes for a breathing phantom. UBC-BCCA ethics approval has been obtained to perform 4DCBCT reconstructions on lung patients (REB#H12-00192). Clinical images will be accrued starting April 2014.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Modular polyketide synthase contains two reaction chambers that operate asynchronously

Type I modular polyketide synthases are homodimeric multidomain assembly line enzymes that synthesize a variety of polyketide natural products by performing polyketide chain extension and β-keto group modification reactions. We determined the 2.4-angstrom-resolution x-ray crystal structure and the 3.1-angstrom-resolution cryo–electron microscopy structure of the Lsd14 polyketide synthase, stalled at the transacylation and condensation steps, respectively. These structures revealed how the constituent domains are positioned relative to each other, how they rearrange depending on the step in the reaction cycle, and the specific interactions formed between the domains. Like the evolutionarily related mammalian fatty acid synthase, Lsd14 contains two reaction chambers, but only one chamber in Lsd14 has the full complement of catalytic domains, indicating that only one chamber produces the polyketide product at any given time.

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

Advanced Techniques for Sample Processing of the Reusable Metal-Containing Raw Material (Review)

A review of the sample processing of different types of reusable metal-containing material (catalytic agents, e-wastes, cuttings, etc.) is given in the article; the purpose of the sample processing is the further analysis in the form of solutions: dilution in the mineral acid mix, alloying with different fluxes, leaching, etc. Increase in the temperature and pressure, ultrasonic impact, and microwave radiation are applied for the purpose of sample processing intensification. Methods of sample processing with application of sorbate concentration for the further definition of not only the noble, nonferrous, and rare metals but also the toxic elements are described. The review shows that the stage of sample processing is very important for achieving the potential of the applied analytical methods.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Combined Methods of Analysis of Metal-Containing Raw Material (Review)

Methods of analysis of reusable metal-containing material (RMR) are considered in the review: X-ray fluorescence, atomic absorption spectrophotometry, and atomic emission and mass spectrometry with inductively coupled plasma. Peculiarities of the applied methods are shown, and a method of analysis with consideration of the specificity of RMR should be developed for every object. In the most cases, the methods of sample processing harmonized with the applied method of analysis and sample content.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Luminescence properties of europium(III) compounds with quinaldic acid and nitrogen-containing ligands

Luminescent mixed-ligand Eu(III) complexes with quinaldic acid and nitrogen-containing dimeric ligands are synthesized. The thermal and spectral-luminescent properties of the obtained mixedligand Eu(III) complexes are studied. It is shown that a water molecule and a neutral ligand are detached during thermolysis in two stages with endothermic effects. It is found that the quinaldinate ion is coordinated to a europium(III) ion in a bidentate fashion. The Stark structure of the 5D{sub 0}–7F{sub j} (j = 0, 1, 2) transitions in the low-temperature luminescence spectra of europium(III) complexes is analyzed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Determination of the Disperse Composition of a PbO Suspension Containing Aggregates of Particles of Lamellar Shape by the Laser-Polarimetry Method

The results of measurements of the scattering matrix at a wavelength of 0.63 μm in the range of scattering angles of 10°–155° are presented for an aqueous suspension of lead oxide containing particles of plate form and their aggregates of monomers with dimensions of ~5 nm. The results of the measurements are compared with the results of calculations for axially symmetric scatterers (ellipsoids of rotation, cylinders). It is shown that the presence of aggregates affects the scattering properties of such a medium. The results of reconstructing the distribution of particles of a disperse medium in sizes from the measurements data of the scattering matrix are presented. The reconstruction of the distributions was carried out by solving the problem of optimizing the sum of the squared deviations of the experimental and calculated values of matrix elements in the framework of the model of axially symmetric scatterers. It is shown that the distribution of particles by sizes is more accurately reconstructed by minimizing the sum of the squares of the deviations for the sum of the diagonal elements. The obtained distribution is compared with the distribution measured by the method of dynamic light scattering.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Raman Scattering of Light by Molecules of Methyl Orange Dye on the Surface of Silicon Containing Ion-Synthesized Silver Nanoparticles

The possibility of using a new composite material based on porous silicon containing silver nanoparticles and synthesized by means of a unique implantation nanotechnology as an optically sensitive material in biological and chemical sensors is tested experimentally. It is demonstrated that detection of small amounts of the studied organic substance (methyl orange dye) is possible due to the effect of surface-enhanced Raman scattering (SERS) from the molecules affected by the local electromagnetic field of the silver nanoparticles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Photolysis of Diazo Dye in Solutions and Films Containing Zinc and Silver Oxides

Photolysis of Chicago Sky Blue diazo dye in aqueous solutions and films containing zinc and silver oxides is studied. The presence of zinc and silver nitrates in aqueous solutions of this dye considerably increase the rate of its photolysis under UV irradiation. ZnO and ZnO:Ag oxide films and composite coatings with zinc and silver nitrates also considerably affect the photolysis of Chicago Sky Blue diazo dye.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Synthesis of 2-arylidenebenzocycloalkanones containing N-donor heterocyclic rings

A series of 2-arylidenebenzocycloalkanones containing heterocyclic rings 1–8 were prepared and characterized by IR, {sup 1}H NMR and elemental analyses. X-ray diffraction study of 6 reveals that the cyclohexyl ring of the 3,4-dihydronaphthalen-1(2H)-one adopts a chair conformation with a maximum deviation of 0.547(3) Å and makes dihedral angles of 52.24(17)° and 11.23(16)°, respectively, with the benzene plane and the mean plane of the benzimidazole ring.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Stereochemistry of silicon in oxygen-containing compounds

Specific stereochemical features of silicon in oxygen-containing compounds, including hybrid silicates with all oxygen atoms of SiO{sub n} groups ({sub n} = 4, 5, or 6) entering into the composition of organic anions or molecules, are described by characteristics of Voronoi—Dirichlet polyhedra. It is found that in rutile-like stishovite and post-stishovite phases with the structures similar to those of СаСl{sub 2}, α-PbO{sub 2}, or pyrite FeS{sub 2}, the volume of Voronoi—Dirichlet polyhedra of silicon and oxygen atoms decreases linearly with pressure increasing to 268 GPa. Based on these results, the possibility of formation of new post-stishovite phases is shown, namely, the fluorite-like structure (transition predicted at ~400 GPa) and a body-centered cubic lattice with statistical arrangement of silicon and oxygen atoms (~900 GPa).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗