[en] The nanometric precursors of neodymium oxide of various morphology from fibrous to well-dispersed spheroidal were prepared via a solvothermal reaction routes. The precursors and their thermal evolution to neodymium oxide phase were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was found that the reaction parameters, kind of solvent as well as neodymium salt used played a key role for the product formation of desired morphology and structure. Similarly, kind of neodymium oxide precursor determined the morphology and the crystal structure (haxagonal or cubic) of the final oxide. The potential application of Nd₂O₃ precursors prepared by solvothermal method as convenient material for preparation of homogeneous thin coatings on planar substrates is shown

[en] Nanocrystalline neodymium oxide precursor particles have been prepared for the first time by a microwave-assisted hydrothermal route from a solution containing Nd(CH₃COO)₃.H₂O. Further thermal treatment of the as-prepared precursors resulted in the formation of the well-crystallized Nd₂O₃ (cubic or trigonal) nanoparticles with fibrous or rod-like morphology. It was found that neodymium oxide is mesoporous material owning the specific surface area up to 130 m²/g. The proposed synthesis, in contrast to conventional hydrothermal method, offers very rapid heating with better yield and high reproducibility

[en] Nanocrystalline ceria particles were successfully prepared under mild conditions of temperature and pressure by microwave-assisted technique from a diethylene glycol solution containing metal nitrate and hexamine as precipitating agent. As-prepared powder and further thermal treatment samples were characterized in terms of crystalline structure and phase purity, particle shape and size distribution using X-ray diffraction, transmission electron microscopy and electron diffraction, FTIR and Raman spectroscopy, textural (surface area and porosity) and thermal (DTA-TG) analysis. It was found that the morphology of the as-prepared powder is sphere-like with an average particle size of about 3 nm and narrow size distribution. Textural analysis revealed high specific surface area (180 m²/g) and microporous structure of as-prepared CeO₂. After thermal treatment, an increase in the degree of crystallinity and shift of pore size distrubution towards mesoporous region was observed. The properties of microwave-assisted solvothermal prepared ceria make them an advanced material suitable for use in optical, catalytic or high-tech ceramic applications

[en] Poly-N-vinyl-2-pyrrolidone (PVP) stabilized Pd nanoparticles and nanophase zinc aluminate spinel (ZnAl₂O₄) were prepared in different solvents by using microwave-assisted solvothermal method. The obtained materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), textural studies (porosity and surface area) and other techniques, and used as precursors of heterogeneous metal colloid catalysts. A Pd/ZnAl₂O₄ system was found to be promising catalyst of light hydrocarbon combustion

[en] Uniform and stable Ru nanoparticles were synthesized by reduction of RuCl₃ in ethylene glycol (EG) in the presence of poly(N-vinyl-2-pyrrolidone) by using microwave-assisted solvothermal method. The obtained materials were characterized by UV-vis, FT-IR, XPS, XRD and TEM techniques, and used as precursors of heterogeneous metal colloid catalysts. Characterization by TEM showed that as-prepared PVP-stabilized Ru nanoparticles have small average diameters (below 2 nm) and narrow size distributions (1-3 nm). Diffraction data confirmed that a crystallite size is around 2.0 nm. A colloidal Ru/γ-Al₂O₃ catalyst was obtained by two different methods: immobilization of the PVP-stabilized Ru colloid on the support or by in situ deposition of Ru colloid, e.g., reduction of RuCl₃ with EG in the presence of the γ-alumina. It was found that both synthesis methods produced the Ru/γ-Al₂O₃ catalysts with narrow size distributions of metallic nanoparticles, that are distributed uniformly over the support. However, only in situ preparation of the colloidal Ru/γ-Al₂O₃ catalyst results in chlorine free system with high activity for hydrogen chemisorption. The H₂ uptake on the Ru(PVP)/γ-Al₂O₃ catalyst was very low because the ruthenium surface was strongly occluded with a thin layer of polymer molecules

[en] Nanocrystalline (average crystallite size 3 nm), single-phase zinc aluminate with spinel structure (ZnAl₂O₄) was prepared under solvothermal conditions at medium temperature and pressure (200 ^oC, 2.5 MPa), and heating time (0.5 h), using zinc acetate and aluminium isopropoxide as precursors, 1,4-butanediol as solvent, and by using two different heating methods: microwaves (MW) and conventional. Structural and physicochemical properties of ZnAl₂O₄ samples and Pt catalysts supported on them, were investigated using X-ray diffraction (XRD), electron microscopy (HRTEM), infrared spectroscopy (FTIR), H₂ chemisorption and N₂ adsorption-desorption measurements. Catalytic performances of 0.5 and 1% Pt/ZnAl₂O₄ samples were evaluated in the total oxidation of iso-butane reaction. Solvothermally obtained ZnAl₂O₄ is characterized by a high specific surface area (above 400 m²/g) with narrow pore size distributions centered below 5 nm. Additionally, ZnAl₂O₄ prepared using MW heating presented superior thermal stability (>900 ^oC). Pt catalysts supported on such prepared ZnAl₂O₄ were found to exhibit good activity in iso-butane combustion, which could be correlated with a high metallic dispersion and low particle sizes.