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Using small colloidal clusters with dumbbell, triplet, tetrahedral, octahedral geometry as elementary building blocks, we investigate the templated-assisted cluster-cluster aggregation into hierarchical clusters, namely superclusters, by means of Monte Carlo simulations. We find that the colloidal superclusters made of dumbbells and triplets produces a unique structural motif that is similar to that of clusters of single colloids, whereas the superclusters composed of tetrahedral and octahedral clusters possess a more complex structure. However, despite their complexity, such structures can be predicted based on a decomposition using triplets as a core and the number of initial “building block” clusters. In particular, a majority of the observable superclusters are members of a particular category of nonconvex deltahedra (Cundy deltahedra). These findings could be useful in preparation of complex colloidal molecules.

The minimization principle of the second moment of the mass distribution ( M 2 ) is responsible for the unique structure of three-dimensional clusters by using emulsion droplet evaporation. Herein we study the structure of two-dimensional clusters of colloidal particles bound at the interface of liquid droplets in the plane. We found that, differently from the three-dimensional system, the two-dimensional clusters have multiple degenerate configurations (isomers). An interesting feature of such two-dimensional clusters is that they have the same packings as those belonging to a class of geometric figures known as polyiamonds. In particular, except for the six-particle cluster, many higher order clusters of polyiamond have not been reported previously. Using a simple geometrical approach, based on the number of ways to generate a packing, we calculated the occupation probabilities of distinct isomeric clusters. The level of agreement with the results of metropolis Monte Carlo simulations was good for clusters containing up to nine particles, suggesting that our two-dimensional cluster structures are not a result of the minimization of the second moment. In addition, the structure of these clusters is somewhat insensitive to the range and depth of the interparticle potential, in good agreement with the results in the literature.

The SnO2/g-C3N4 nanocomposite materials were successfully synthesized via the solid reaction and sonochemistry methods. The properties of the obtained product were investigated using several methods: X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and Scanning electron microscope. The photocatalytic properties of the samples were evaluated through the photodegradation of Rhodamine B solution. The results demonstrate that the SnO2/g-C3N4 prepared by the sonochemistry method exhibits higher photocatalytic activity than that prepared by the solid reaction method. This enhanced photocatalytic activity is attributed to the formation of heterostructures between SnO2 and g-C3N4 materials, resulting in the efficient separation of photo-generated electron-hole pairs. Furthermore, the nanocomposite exhibits a larger specific surface area compared to the product obtained through the solid reaction method. [ABSTRACT FROM AUTHOR]

Zn1-xMnxO films (0\leqx\leq 0.070) were grown by plasma-assisted molecular beam epitaxy on Si substrates with AlN buffer layers. For low Mn concentration samples, x\leq 0.02 , photoluminescence spectra show strong near band edge emission. Strong phonon and exciton coupling-induced resonant Raman scattering was observed. Paramagnetic, antiferromagnetic, and ferromagnetic phases were observed. Room temperature ferromagnetism for all samples was attributed to the bound magnetic polaron effect. [ABSTRACT FROM AUTHOR]

Amorphous CoFe2O4 nanoparticles have been successfully synthesized by the chemical microwave-assisted method. The crystallization process and the hard magnetic properties of prepared nanoparticles were systematically investigated in terms of thermal analysis and in situ measurement of magnetization dynamics. The as-prepared sample was amorphous, which was confirmed by various techniques, such as high resolution transmission electron microscopy, with electron diffraction and X-ray diffraction. The thermal analysis using differential scanning calorimetry showed that crystallization from CoFe2O4 amorphous state to CoFe2O4 crystalline started at 290 ^\circC . Crystallization activation energy was determined using the Kissinger model with a value of 1.09 eV. A study of the temperature dependence of magnetization supported the crystallization process of cobalt ferrite nanoparticles. Magnetic measurement indicated that the as-prepared amorphous particles were superparamagnetic. Compared with the bulk material, the observed value of saturation magnetization of the annealed sample was significantly low (27 emu/g) due to its nanocrystalline nature. [ABSTRACT FROM AUTHOR]

We investigate the crystallization process of NiFe2O4 nanoparticles prepared by microwave heating technique, which were then characterized using X-ray diffraction, high-resolution transmission electron microscopy, the differential scanning calorimetry, Raman scattering, Fourier transformed infrared spectra (FTIR), and magnetic measurements. The results showed that crystallization of the amorphous NiFe2O4 nanoparticles occurred at around 300 ^\circC . The best crystallization quality would be obtained by annealing the sample at 500 ^\circC . After crystallization, the sample shows ferromagnetic behavior with a saturation magnetization of about 30 emu/g. The FTIR and Raman measurements also provided further information about the crystallization process and the phase transformation of the NiFe2O4 nanoparticles. [ABSTRACT FROM AUTHOR]