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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Findings on the structure and formation of luminescent protein-stabilized gold clusters reveal interlocked gold-thiolate rings and a unique bio-assembled pathway.
Combining X-ray diffraction, Raman spectroscopy, and ab initio simulations we characterize an extremely hydrogen-rich phase with the chemical formula (NH 3 BH 3 )(H 2 ) x (x = 1.5). This phase was formed by compressing ammonia borane (AB, NH 3 BH 3 ) in an environment with an excess of molecular hydrogen (H 2 ). This compound can store a total of 26.8 wt% hydrogen, both as molecular hydrogen and chemically bonded hydrogen in AB, making it one of the most hydrogen-rich solids currently known. The new compound possesses a layered AB structure where additional H 2 molecules reside in channels created through the weaving of AB layers. The unconventional dihydrogen bonding network of the new compound is significantly modified from its parent AB phase and contains H•••H contacts between adjacent AB molecules and between AB and H 2 molecules. H–H can be either a proton donor or a proton acceptor that forms new types of dihydrogen bonding with the host AB molecules, which are depicted as H–H•••H–B or H–H•••H–N, respectively. Furthermore, this study not only demonstrates the strategy and the promise of using pressure for new material synthesis, but also unleashes the power of combining experiments and ab initio calculations for elucidating novel structures and unusual bonding configurations in dense low-Z materials.
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.