SEARCH · Engineering Papers
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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A novel structural and chemical synthesis of Cs–O derived materials has been demonstrated via X-ray irradiation of Cs 2 C 2 H 2 O 5 at high pressure.
We have used two-photon photoemission (2PPE) spectroscopy and first-principles density functional theory calculations to investigate the electronic structure and photoabsorption of the reduced anatase TiO 2 (101) and rutile TiO 2 (110) surfaces.
Low concentrations of cationic silica nanoparticles impact lung surfactant membrane structure while anionic nanoparticles have minimal effect.
A systematic photoelectron spectroscopy and theoretical study of divalent transition metal EDTA complexes illustrating the intrinsic correlations of redox properties in the gas and solution phases.
Our results reveal that conversion reactions and structural changes in NiO thin film electrodes begin near the theoretical lithiation potential.
Structure characterization and classification is frequently based on local environment information of all or selected atomic sites in the crystal structure.
Unraveling the correlations between the geometry, the relative energy and the electronic structure of metal oxide nanostructures is crucial for a better control of their size, shape and properties. Here, we investigated these correlations for stoichiometric thorium dioxide clusters ranging from ThO 2 to Th 8 O 16 using a chemically-driven geometry search algorithm in combination with state-of-the-art first principles calculations. This strategy allows us to homogeneously screen the potential energy surface of actinide oxide clusters for the first time. It is found that the presence of peroxo and superoxo groups tends to increase the total energy of the system by at least 3.5 eV and 7 eV, respectively. For the larger clusters, the presence of terminal oxygen atoms increases the energy by about 0.5 eV. Regarding the electronic structure, it is found that the HOMO–LUMO gap is larger in systems containing only bridging oxygen atoms (~2–3.5 eV) than for systems containing oxo groups (~1–3 eV), peroxo groups (~0–2 eV), and superoxo groups (~0–1 eV). Furthermore, while the LUMO is always dominated by thorium orbitals, the composition of the HOMO changes in the presence or the absence of oxo, peroxo and/or superoxo groups: in the presence of peroxo groups, it is dominated by thorium orbitals, in all other cases, it is dominated by oxygen orbitals, and is rather localized in the presence of terminal oxo or superoxo groups. These correlations are of great interest for synthesizing clusters with tailored properties, especially for applications in the field of nuclear energy and heterogeneous catalysis.
New 1,8-naphthalenediolate supported boronic, diboronic and boric acid esters and boronium salts have been synthesized and structurally characterized.
KIrO 3 in the body-centered cubic variant of the KSbO 3 -type structure is reported.
Structural evolution occurs upon A-site partial substitution of Sr by Yb in SrCoO 3−δ , leading to enhanced performance and stability.
Abstract not provided
This work demonstrates the use of reflection–adsorption infrared spectroscopy for continually monitoring the structure of organic thin films as a function of thickness and temperature to complement diffraction methods.
Recent progress in the development of copper-alloy catalysts is highlighted, focusing on the structural and mechanistic characterizations of the catalysts in different catalytic reactions, and challenges and opportunities in future research.
To identify the genesis of the differing magnetic behaviors for the ferro- (FO) and metamagnetic (MM) polymorphs of [FeCp* 2 ][TCNQ] the low temperature structures of each polymorph were determined from high-resolution synchrotron powder diffraction data.
This article presents a perspective on what we think are key topics related to the structure and structural dynamics of ILs and to some extent high-temperature molten salts.
X-ray absorption spectroscopy is utilized to study the distribution of Au and Ag within the metal core of the Au 104 Ag 40 (PET) 60 nanocluster, revealing a Ag single-atom alloy structure associated with unique bonding properties.
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
A cluster deposition method was used to produce a film of loosely aggregated particles of Fe-Fe3O4 core-shell nanoclusters with an 8 nm iron core size and 2 nm oxide shell thickness. The film of particles on a silicon substrate was irradiated with 5.5 MeV Si2+ ions to a fluence of 1016 cm-2 near room temperature, and computer simulations based on the SRIM (Stopping and Range of Ions in Matter) code show that the implanted Si species stops near the film-substrate interface. The ion irradiation creates a structural change in the film with corresponding chemical and magnetic changes. X-ray diffraction shows that the core size and chemistry stay the same but the shell becomes FeO that grows to a thickness of 17 nm. Helium ion microscopy shows that the previously separate particles have densified into a nearly continuous film. Major loop magnetic hysteresis measurements show a decrease in saturation magnetization that we attribute to the presence of the antiferromagnetic (AFM) FeO shell. First-order reversal curve measurements on the irradiated film performed with a vibrating sample magnetometer show that the AFM shell prevents the particles from interacting magnetically, leading to low coercivity from the iron core and little bias field from the core interactions. These results, and others reported previously on different compositions (Fe3O4 or FeO+Fe3N nanoclusters), show that the ion irradiation behavior of nanocluster films such as these depends strongly on the initial nanostructure and chemistry.