Materials Literature
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The preparation of porous hierarchical architectures that have structural features spanning from the nanometer to micrometer and even larger dimensions and that exhibit certain functionalities is one of the new challenging frontiers in materials chemistry. The sol-gel process is one of the most promising synthesis rou…
With one or two exceptions, biological materials are "soft", meaning that they combine viscous and elastic elements. This mechanical behavior results from self-assembled supramolecular structures that are stabilized by noncovalent interactions. It is an ongoing and profound challenge to understand the self-organizatio…
Porous silica coatings were prepared by acid- and base-catalyzed sol−gel method. Surface morphology studies by atomic force microscopy showed smooth surface for acid-catalyzed coatings while base catalysis resulted in coarse particle morphology. On increasing the tetraethyl orthosilicate to base molar ratio from 1:1 t…
Metal or semimetal alkoxides substituted with nonhydrolyzable organic groups are important precursors for inorganic-organic hybrid materials. Understanding the chemistry and structural issues of such precursors is a prerequisite for a rational materials design. Examples are given in this Account, mainly from the chemi…
With the development of monochromators for transmission electron microscopes, valence electron-energy-loss spectroscopy (VEELS) has become a powerful technique to study the band structure of materials with high spatial resolution. However, artifacts such as Cerenkov radiation pose a limit for interpretation of the low…
Abstract In this report we outline recent work on the evaluation of magnesium carbonate‐based flame retardants for polymers commonly used in halogen‐free flame retardant wire and cable applications: poly(ethylene‐co‐vinyl acetate) (EVA) and poly(ethylene‐co‐ethyl acrylate) (EEA). Natural magnesium carbonate (magnesite…
Superhydrophobic polyolefin surfaces were prepared by simultaneous micro- and nanostructuring. Electropolished aluminum foil was microstructured with a micro working robot and then anodized in polyprotic acid. The surface microstructure can be tailored by adjusting the settings of the micro working robot and the nanos…
Sheet materials: Manganese oxide nanosheets and their oriented thin films can be prepared by a bottom-up approach in aqueous solution under ambient conditions (left). Chelation between the manganese species and ethylenediaminetetraacetate (EDTA) ligands results in birnessite-type nanosheets (see micrographs and diffra…
Erbium silicate thin films that have a good morphology are synthesized by radiofrequency magnetron sputtering. Properly annealed films exhibit efficient luminescence at 1535 nm, and all of the Er ions in the material (about 1022 cm–3) are demonstrated to be optically active. The possibility to efficiently excite Er io…
Abstract Three polystyrene (PS)/clay hybrid systems have been prepared via in situ polymerization of styrene in the presence of unmodified sodium montmorillonite (Na‐MMT) clay, MMT modified with zwitterionic cationic surfactant octadecyldimethyl betaine (C18DMB) and MMT modified with polymerizable cationic surfactant…
The possible formation of oxides or thin oxide films (surface oxides) on late transition-metal surfaces has recently been recognized as an essential ingredient when aiming to understand catalytic oxidation reactions under technologically relevant gas phase conditions. Using $\mathrm{CO}$ oxidation at $\mathrm{Pd}(100)…
We investigate the temperature evolution of the electronic structure of ferromagnetic CaB$_6$ using ultra-high resolution photoemission spectroscopy; electronic structure of paramagnetic LaB$_6$ is used as a reference. High resolution spectra of CaB$_6$ reveal finite density of states at the Fermi level, $ε_F$ at all…
The structural evolution of epitaxial mono-oriented (i.e. with the c-axis perpendicular to the interface) ferroelectric Pb(Zr0.2,Ti0.8)O3 thin film has been investigated, using high resolution, temperature dependent, X-ray diffraction. The full set of lattice parameters was obtained, it allowed to estimate the variati…
We have studied the role of Ga 3d states in determining the properties of bulk as well as nanoparticles of GaN using PAW potentials. A significant contribution of the Ga d states in the valence band is found to arise from the interaction of Ga 4d states with the dominantly N p states making up the valence band. The er…
For the first time a Fddd network structure is found in a poly(styrene-b-isoprene) (S-I) diblock copolymer melts by using small-angle X-ray scattering and transmission electron microscope, as predicted by Tyler et al. by using calculations with self-consistent field theory for diblock copolymer melts. The phase diagra…
We investigate electron transport through single conjugated molecules - including benzenedithiol, oligo-phenylene-ethynylenes of different lengths, and a ferrocene-containing molecule sandwiched between two gold electrodes with different contact structures - by using a single-particle Green function method combined wi…
Fluorescent and luminescent reporters that signal molecular events of interest by modulating the ratio of peaks in their emission profile have advantages over reporters that simply modulate their emission intensity, since ratiometric measurement is concentration-independent and allows them to be effective in complex c…
The structure and mechanical properties of a simple two-dimensional model of a cohesive powder are investigated by molecular dynamics simulations. Micromechanical ingredients involve elasticity, friction, a short range attraction and, possibly, rolling resistance (RR) in contacts. The microstructure of the cohesive pa…
Energetically the single sheet of graphite (graphene) is more stable than the nanotube. The energy difference between the two systems can be directly related to the strain energy involved in rolling up the graphene sheet to form the nanotube. We have carried out first principle electronic structure calculations and ev…
Spatially resolved photocurrent measurements on carbon nanotube field-effect transistors (CNFETs) operated in various transport regimes are reported. It is demonstrated that the photocurrents measured at different biasing conditions provide access to the electronic band structure profile of the nanotube channel. A com…