SrTiO3 crystalline nanoparticles were prepared using the microwave-assisted hydrothermal method at 140 °C with synthesis times varying from 4 to 160 min. Sample characterization showed that the method is effective in obtaining nanoparticles in a relatively short time, which have the highest photoluminescence emission. The crystalline phase of perovskite-type SrTiO3 is not significantly influenced by synthesis time. However, the SrTiO3 phase is already obtained with a 4 min synthesis time. Also, all samples exhibited photoluminescence at room temperature in the blue-green region, where intensity decreased with increasing synthesis time and particle size. The samples synthesized with the shortest time showed higher photoluminescence emission and smaller particle sizes. The morphology obtained based on FE-SEM showed cubic nanoparticles with inhomogeneous grain growth at higher temperatures of synthesis in addition to the formation of new architectures.

The supramolecular structure of organic thin films is a key factor in their optical and electrical properties and, consequently, in the technological applications involving organic electronic. Here, thin films of a perylene derivative, the bis butylimido perylene (BuPTCD), were produced by vacuum thermal evaporation (PVD, physical vapor deposition). The main objective is to investigate the supramolecular structure of the BuPTCD in these PVD films, which implies to control their thickness at nanometer scale and to determine their molecular organization, morphology at micro and nanometer scales and crystallinity. The ultraviolet-visible absorption reveals a uniform growth of the PVD films. The optical and atomic force microscopy images show a homogeneous surface of the film at micro and nanometer scales, respectively. The X-ray diffraction indicates that both powder and PVD film are in the crystalline form. Complementary, a preferential head-on orientation of the molecules in the PVD films is determined via infrared absorption spectroscopy. Besides, the annealing process (200 o C) did not affect the molecular organization of the PVD films, revealing a thermal stability of the BuPTCD molecules within the PVD films. Through DC electrical measurements, an electrical conductivity of 7.45x10 -10 S/m was determined for BuPTCD PVD films onto Au interdigitated electrodes (IDE-structured devices), which can be enhanced, under illumination, by two orders of magnitude (photoconductivity effect). As proof-of-concept, the IDE-structured devices are tested as gas sensor for trifluoroacetic acid.

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CaZrO 3 nanoparticles were obtained by a new synthesis route: nucleation using the microwave-assisted hydrothermal method (MAH) and crystallization by heat treatment. Structural characterization by X-ray diffraction (XRD) was performed for the synthesized material and after heat treatment at 700, 800, 900, 1000 and 1200°C. At 800°C, the lakargite phase crystallization (CaZrO 3) starts and portions of the non-stoichiometric calciumzirconium oxide phase were observed by XRD and Raman spectroscopy. A residual CaCO 3 phase was present in the untreated samples. At 1200°C, the well-crystallized stoichiometric and non-stoichiometric mixed oxide phases of CaZrO 3 (crystallites of about 75 nm) were observed, along with particle agglomerates often in the micrometer range. The synthesized material was subjected to differential thermal analysis, which revealed carbonate degradation at approximately 695°C, resulting in a small loss of mass of 6%. An endothermic reaction at 85°C was observed for water loss, where there was a considerable amount of energy involved. This result showed the sensitivity to moisture absorption and adsorption processes of the CaZrO 3 sample, obtained by the MAH route. UV-Vis spectroscopy showed the characteristic gap energies for the two phases, which were 2.9 (non-stoichiometric) and 4.9 eV (stoichiometric), values smaller than those obtained by usual synthesis routes.