Materials Literature
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We report a numerical study of crystal nucleation in a system of weakly charged colloids. The interaction between the colloids is approximated by a repulsive hard-core Yukawa potential. We studied the dependence of the nucleation barrier and the nucleation rate on supersaturation as a function of both contact value an…
The effects of the synthesis parameters on the properties of the cubic Im 3 m SBA-16 have been investigated systematically for the first time. We show that the total pore volume, pore diameter, and ratio micro-/mesopores can be controlled very efficiently by changing the synthesis time, temperature, and the TEOS/surfa…
A new kind of luminescent organic−inorganic hybrid material (denoted Hybrid I) consisting of europium 1,10-phenanthroline complexes covalently attached to a silica-based network was prepared by a sol−gel process. 1,10-Phenanthroline grafted to 3-(triethoxysilyl)propyl isocyanate was used as one of the precursors for t…
In the first decade of the 20th century, nearly a hundred years of work on the phenomenon of Brownian motion culminated in theory and experiments that demonstrated irrefutably the discontinuous or molecular nature of matter. Colloidal suspensions and the phenomenon of Brownian motion thus became the key to confirmatio…
We have studied magnetic and transport properties on different manganese oxide based compounds exhibiting phase separation: polycrystalline La5/8-yPryCa3/8MnO3 (y=0.3) and La1/2Ca1/2Mn1-zFezO3 (z = 0.05), and single crystals of La5/8-yPryCa3/8MnO3 (y=0.35). Time dependent effects indicate that the fractions of the coe…
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…