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Covering MFI-type zeolite crystals with Al2O3 by atomic layer deposition is shown to make the external zeolite crystal impermeable for guest molecules. By corresponding manipulations of the crystal certain faces can be opened for guest molecules. In this way, IR microimaging can be applied to record the evolution of transient intracrystalline concentration profiles along the crystals longitudinal extension. The introduced method of covering may provide the possibility of observing fluxes of reactant and product molecules within single zeolite crystals during catalytic reactions. [ABSTRACT FROM AUTHOR]

It is shown that both the growth and shrinkage of hollow shells in Ag/Pd hemispherical core-shell nanostructures take place at the same temperature. The crossover time, t cr, between these regimes is shifted to lower values with increasing temperature. This result confirms that the growth and shrinkage regimes are controlled by the faster and slower diffusion coefficients (D Ag and D Pd), respectively. The pore radius, confirming recent theoretical predictions, linearly depends on the initial particle radius, and the slope of this straight line increases with the average composition of the faster component. [ABSTRACT FROM AUTHOR]

Interdiffusion has been studied in Ag/Au hemispherical core-shell structures on sapphire substrate. In isothermal heat treatments first a relatively fast growth of nanovoids was observed, which was followed by a slower shrinkage process. The void formation is interpreted by pure Kirkendall-porosity formation since Ag-50%Au solid solution has been formed in the shell. In contrary, in all previous publications on hollow nanoshell formation a chemical reaction took place and the shell consisted of the reaction product (i.e., of sulphide or oxide). Furthermore, in these cases the shrinkage was observed at temperatures higher than the formation temperature. [ABSTRACT FROM AUTHOR]

The existence of the miscibility gap in the Cu-Ni system has been an issue in both computational and experimental discussions for half a century. Here we propose a new miscibility gap in the Cu-Ni system measured in nano-layered films by Secondary Neutral Mass Spectrometry. The maximum of the symmetrical miscibility curve is around 780K at Cu 50% Ni 50% . This is the first experiment determining the miscibility from the measurement of the atomic fraction of Copper and Nickel in the whole composition range. [ABSTRACT FROM AUTHOR]