We report on the synthesis of phase-pure TiO(2) nanoparticles in anatase, rutile and brookite structures, using amorphous titania as a common starting material. Phase formation was achieved by hydrothermal treatment at elevated temperatures with the appropriate reactants. Anatase nanoparticles were obtained using acetic acid, while phase-pure rutile and brookite nanoparticles were obtained with hydrochloric acid at a different concentration. The nanomaterials were characterized using x-ray diffraction, UV-visible reflectance spectroscopy, dynamic light scattering, and transmission electron microscopy. We propose that anatase formation is dominated by surface energy effects, and that rutile and brookite formation follows a dissolution-precipitation mechanism, where chains of sixfold-coordinated titanium complexes arrange into different crystal structures depending on the reactant chemistry. The particle growth kinetics under hydrothermal conditions are determined by coarsening and aggregation-recrystallization processes, allowing control over the average nanoparticle size.

Getting on the tube: A single‐step method to attach silver nanoparticles on the surfaces of nitrogen‐doped multi‐walled carbon nanotubes is described (as depicted in the picture). Ag nanoparticles (2–10 nm diameter) are synthesized by reduction of a Ag salt, and then mixed with the nanotubes in a technique that does not require acid treatment. Similar methods with undoped nanotubes yield less well‐coated nanotubes. Interactions with solvent species are believed to play a role in the decoration mechanism.

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Nanocrystalline ZnO particles have been prepared with different methods using zinc cyclohexanebutyrate as precursor in dimethyl sulfoxide (DMSO) medium via alkaline hydrolysis. A series of preparations were carried out in the presence of layered silicates (kaolinite and montmorillonite). It was revealed by different measurement techniques that the presence of the clay minerals has a stabilization influence on the size of the ZnO nanocrystals. UV-vis absorption spectra show a blue shift when the nanoparticles are prepared in the presence of the clay minerals. The average particle diameters calculated from the Brus equation ranged from 2.6 to 13.0 nm. The UV-vis spectra of the synthesized nanoparticles did not show any red shift after 2-3 days, demonstrating that stable ZnO nanocrystals are present in the dispersions. The presence of the ZnO nanoparticles was also proven by fluorescence measurements. A number of the nanoparticles are incorporated into the interlamellar space of the clays, and an intercalated structure is formed as proven by X-ray diffraction (XRD) measurements. The size of the nanoparticles in the interlamellar space is in the range of 1-2 nm according to the XRD patterns. Transmission electron microscopy and high-resolution transmission electron microscopy investigations were applied to determine directly the particle size and the size distribution of the nanoparticles.