We report on energetic surface reconstruction phenomena observed on bimetallic nanoparticle systems of AuPd and AuCu, similar to a resolidification effect observed during the cooling process in lead clusters. These binary alloy nanoparticles show the fivefold edges truncated, resulting in [100] facets on decahedral structures, an effect largely envisioned and reported theoretically, with no experimental evidence so far. We demonstrate experimentally as well as by computational simulations that this new eutectic structure is favored in such nanoalloy systems.

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Colloidal solid-solution-like Au-Ag alloy nanoclusters of different compositions were synthesized through citrate reduction of mixed metal ions of low concentrations, without using any other protective or capping agents. Optical absorption of the alloy nanoclusters was studied both theoretically and experimentally. The position of the surface plasmon resonance (SPR) absorption band of the nanoclusters could be tuned from 419 nm to 521 nm through the variation of their composition. Considering effective dielectric constant of the alloy, optical absorption spectra for the nanoclusters were calculated using Mie theory, and compared with the experimentally obtained spectra. Theoretically obtained optical spectra well resembled the experimental spectra when the true size distribution of the nanoparticles was considered. High-resolution transmission electron microscopy (HREM), high-angle annular dark field (HAADF) imaging, and energy dispersive spectroscopy (EDS) revealed the true alloy nature of the nanoparticles with nominal composition being preserved. The synthesis technique can be extended to other bimetallic alloy nanoclusters containing Ag.

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The inJuence of milling level on the rheological behavior of processed mustard was investigated using three different particle sizes (slightly-coarse, standard, and fine) prepared according to a standard formulation and pilot-plant replication of the commercial methodology. All samples showed unimodalpopulationbased particle size distributions which were described by the population-mode (dpoJ. On a volume basis, all milling levels had well-defined bimodal distributions consisting of a smaller-and a larger-size group of particles described by their modes (d and D ) . The most important particle size index in relating milling level to rheological behavior was not the population mode (dpop) but the larger-size volume mode (0) from the bimodal distribution. The coarser the milling, the higher the larger-size volume mode (D), and higher the values of: a ) Apparent viscosity of nonmixed samples (qJ, b ) Bingham yield stress ((T,) and plastic apparent viscosity (qp), c ) Shear stress constant ( A ) and coefficient of thixotropic breakdown ( B ) from the Weltman stress decay model, d ) Yield stress (go) and consistency index ( K ) from the Herschel-Bulkley model, and e ) Storage (GI) and loss (G") moduli. As indicators of structure-texture relationship, the above rheological parameters can be profitably utilized to study the effect of manufacturing practices on long term storage stability of the product.

A method for obtaining nanosized LaCoO3crystals from calcination of a precursor powder synthesized by a hydrothermal route is reported. Details concerning the evolution of the microstructure and formation mechanism of the perovskite phase were studied by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and thermal analysis. It was found that the morphology of the sample progressively turns from a mix of fibers and rods to interconnected nanocrystals. It is determined that LaCoO3phase is produced by a reaction of cobalt and lanthanum oxides, the latter produced by a two-step dehydration process of La(OH)3. Finally, it was found that nearly stoichiometric LaCoO3nanocrystals can be obtained at temperatures as low as 850°C. Nevertheless, whether higher calcination temperatures are used, appropriate reaction times and a controlled atmosphere are required in order to avoid formation of lanthanum carbonates and high density of lattice defects.

Small (1-5 nm) metallic nanoparticles of Pt, Au, and Au/Pt of different nominal compositions in colloidal form were synthesized by a chemical reduction method using polymer (PVP) as protecting agent. Analytical techniques like HREM and UV-vis spectroscopy have been used to characterize the morphology and structural properties of these small particles. Theoretical simulations based on molecular dynamical have been used to interpret the experimental structural results and analyze the macroscopic properties like stability and catalytic selectivity of these nanoparticles based on the morphology and atomic distribution in the clusters.