Structural characterization of self-assembled ZnO nanoparticles obtained by the sol-gel method from Zn(CH3COO)2·2H2O.

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.

Influence of substrate orientation on the morphology and orientation of LaNiO3 thin films.

LaNiO(3) thin films were successfully prepared by a chemical method from citrate precursors. The LNO precursor solution was spin-coated onto Si (100) and Si (111) substrates. To obtain epitaxial or highly oriented films, the deposited layers were slowly heated in a gradient thermal field, with a heating rate of 1 degrees min(-1), and annealed at 700 degrees C. The influence of different substrate orientations on the thin film morphology was investigated using atomic force microscopy and X-ray diffraction analysis. Well-crystallized films with grains aligned along a certain direction were obtained on both substrates. Films deposited on both substrates were very smooth, but with a different grain size and shape depending on the crystal orientation. Films deposited on Si (100) grew in the (110) direction and had elongated grains, whereas those on Si (111) grew in the (211) direction and had a quasi-square grain shape.