Materials Literature
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The dielectric permittivity \ensuremath{\varepsilon} at frequencies from ${(10}^{\ensuremath{-}1}--{10}^{\ensuremath{-}5})\mathrm{Hz}$ to ${10}^{5}\mathrm{Hz}$ is studied in perovskite $(1\ensuremath{-}x)\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}\ensuremath{-}x{\mathrm{PbTiO}}_{3}$ relaxor fer…
Using molecular-dynamics simulations we study the thermodynamic behavior of a single-component covalent material described by the recently proposed environment-dependent interatomic potential (EDIP). The parametrization of EDIP for silicon exhibits a range of unusual properties typically found in more complex material…
We extend a tight-binding total energy method to include f-electrons, and apply it to the study of the structural and elastic properties of a range of elements from Be to U. We find that the tight-binding parameters are as accurate and transferable for f-electron systems as they are for d-electron systems. In both cas…
Gold nanoparticles coated with stabilizing thiolate monolayers of N-(2-mercaptopropionyl)glycine (tiopronin) and N, N-trimethyl(undecylmercapto)ammonium quench the fluorescence of [Ru(bpy) 3 ] 2+ in aqueous solution. The tiopronin monolayer protected clusters (MPCs) exert energy-transfer quenching by both collisional…
We discuss recent developments and present new findings in the colloidal description of soft polymeric macromolecular aggregates. For various macromolecular architectures, such as linear chains, star polymers, dendrimers, and polyelectrolyte stars, the effective interactions between suitably chosen coordinates are sho…
Polymer−clay nanocomposites of styrene and methyl methacrylate have been prepared by bulk, solution, suspension, and emulsion polymerization as well as by melt blending. Two different organic modifications of montmorillonite have been used: one contains a styryl monomer on the ammonium ion while the other has no doubl…
This paper presents the use of nanoscale chemistry to synthesize a multilevel, hierarchically built nanoparticle, which we define as a nanoclinic, for targeted diagnostics and therapy. This nanoclinic, produced by multistep chemistry in a nanosize micelle, consists of a thin silica shell encapsulating magnetic (Fe 2 O…
The egg-type core microstructure where one alloy encases another has previously been obtained during experiments in space. Working with copper-iron base alloys prepared by conventional gas atomization, we were able to obtain this microstructure under gravity conditions. The minor liquid phase always formed the core of…
The heteropolyanions of W, Mo, and V, which have found numerous applications, are formed simply by acidification of solutions of their oxoanions. Under similar conditions, these oxoanion precursors are not available for Nb, and Nb-oxo chemistry is dominated by formation of the Lindquist ion [Nb6O19]8- only. However, h…
The addition of non-adsorbing polymer to a colloidal suspension induces an interparticle ‘depletion’ attraction whose range and depth can be ‘tuned’ independently by altering the polymer’s molecular weight and concentration respectively. Over the past decade, one particularly simple experimental realization of such a…
Synthetic polymers offer a wealth of opportunities to design responsive materials triggered by external stimuli. Changing the length, chemical composition, architecture, and topology of the chains allows response mechanisms and rates to be easily manipulated; and devices based on the entropy of the chains, surface ene…
Nonlinear viscoelastic properties are reported for composites of fumed silica with various surface treatments and matrices of poly(vinyl acetate) of different molecular weights as well as a copolymer matrix of vinyl acetate and vinyl alcohol. Data above the glass transition temperature are reported here. The increase…
Ferroelectric switching and nanoscale domain dynamics were investigated using atomic force microscopy on monocrystalline $\mathrm{P}\mathrm{b}\mathrm{(}\mathrm{Z}{\mathrm{r}}_{\mathrm{0.2}}\mathrm{T}{\mathrm{i}}_{\mathrm{0.8}}\mathrm{)}{\mathrm{O}}_{\mathrm{3}}$ thin films. Measurements of domain size versus writing t…
pi-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of pi-conju…
The correlated Pariser–Parr–Pople model Hamiltonian for interacting π-electrons is employed for calculating frequency dependent linear polarizability as well as first and second hyperpolarizabilities of linear chain phosphazenes (–P=N–)x (x=3–6). The model parameters for phosphorus and nitrogen are obtained by compari…
We have carried out NPT molecular dynamics simulations of isolated ellipsoids in a glass forming binary mixture to gain insight into the nature of orientational relaxation (OR) in a viscous liquid. At high pressures when the liquid is highly viscous, the OR is found to occur mainly via correlated hopping, sometimes in…
In the framework of the two-step model of Auger decay the orientation of the krypton ${3d}^{\ensuremath{-}1}$ and xenon ${4d}^{\ensuremath{-}1}$ primary hole states has been determined as a function of photon energy. This was achieved by carrying out spin-polarization measurements of the Kr ${M}_{4,5}{N}_{2,3}{N}_{2,3…
We have studied the electrical conductivity of well–aligned samples of hexahexylthiotriphenylene (HHTT) and hexapentyloxyanthraquinone (HPA) in the pure, as well as doped, states. The former compound was doped with 0.62 mol % by weight of the electron acceptor, trinitrofluorenone (TNF), the latter with 0.60 mol % by w…
The magnetic properties of the molecular cluster ${\mathrm{Mn}}_{12}\mathrm{Ac}$ are due to the four ${\mathrm{Mn}}^{3+}$ ions that have spins $S=3/2$ and the eight ${\mathrm{Mn}}^{4+}$ ions with spins $S=2.$ These spins are coupled by an exchange mechanism. We determine the four exchange couplings assuming a Heisenbe…
A novel soluble aryl amide-bridged ladderlike polymethylsiloxane (A-LPMS) was synthesized by stepwise coupling polymerization on the basis of amido H-bonding self-assembling template from monomer N,N'-bis(3-methyldiethoxylsilylpropyl)-[4,4'-oxybis(benzyl amide)]. The monomer was prepared in a high yield by the hydrosi…