Zinc oxide nanopowders were synthesized by the sol-gel method from an ethanol solution of zinc acetate dihydrate. Detailed structural and microstructural investigations were carried out using x-ray diffraction, Raman spectroscopy, thermogravimetric and differential thermal analyses, as well as high-resolution transmission electron microscopy (TEM) and field-emission scanning electron microscopy. The intermediate compound of the reaction was layered zinc hydroxide acetate that further transforms into hexagonally shaped ZnO crystalline nanoplates (d(m) = 4 nm), which aggregate into larger spherical particles. According to the TEM analysis the ZnO nanoparticles were self-assembled into larger particles with the same orientation, i.e. aligned lattice planes of the particles. A further solvothermal treatment resulted in hexagonal, prismatic ZnO mesocrystals.

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In this work single phase hexagonal YMnO 3 powders were prepared starting from Y(CH 3 COO) 3 Á xH 2 O, Mn(CH 3 COO) 2 Á 4H 2 O, KMnO 4 and KOH using methods of conventional (280 1C for 6 h) or microwave assisted hydrothermal synthesis (200 1C for 2 h) followed by calcination at 1200 1C for 2 h. According to FESEM analysis the calcined powders consisted of submicronic YMnO 3 particles, which were uniform in shape and size. Ceramic samples were obtained by sintering the as-synthesized powders at 1400 1C for 2 h. XRD analysis confirmed the presence of the single phase hexagonal YMnO 3 . SEM analysis showed a dense and homogeneous microstructure with typical inter-and intra-grain cracks. Magnetic measurements indicated ferrimagnetic properties that were explained by non-stoichiometry of the obtained compound and an excess of manganese that was confirmed by ICP analysis.