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PLA nanocomposites containing 1 wt% ZnO nanofibers have been prepared by solvent-cast 3D printing. The ZnO nanofibers were produced by electrospinning and dispersed in PLA by ultrasound. Scanning electron microscopy revealed that the fibers were dispersed throughout the nanocomposite. Surface specimen assessment by atomic force microscopy indicated the presence of nanofibers near the surface of the nanocomposite. TGA tests showed the nanocomposite had a lower thermal stability than the neat PLA, probably induced by PLA hydrolysis catalyzed by ZnO. DSC results revealed higher crystallinity in the nanocomposite, induced both by the presence of ZnO nanofibers and by the 3D printing process, though the 3D printing process showed to be more important in increasing the crystallinity. XRD results also showed a higher crystallinity for the nanocomposite. The study opens an interesting field for the development of PLA/ZnO nanocomposites using ZnO nanofibers made by electrospinning, e.g. in medical and packaging applications.

E. F. Chinaglia*,**, and I. C. Oppenheim* *Department of Metallurgy and Materials Engineering, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2463, Sao Paulo, SP, 05508-900, Brasil. **Shimadzu do Brasil Comercio Ltda., Av. Marques de Sao Vicente, 1771, Sao Paulo-SP, 01139-003, Brasil. e-mail: tatachi@usp.br Keywords: resistivity, surface morphology, thin films, titanium, zirconium, sputtering, atomic force microscopy, reflection coefficient, Mayadas-Shazkes Thin film morphology and electrical resistivity play an important role in modern technologies. In particular, subcomponents fabricated by Ti play an increasing role in microelectronic device technology as well as in the biomedical area [1-2]. Here the influence of substrate temperature (during deposition) and film thickness on the surface morphology and electrical resistivity of polycrystalline Ti and Zr thin films have been investigated. The well established Matthiessen’s rule, originally suggested for bulk metals, is also valid for thin metal films [3]. The rule states that the various electron scattering processes that contribute to the total electrical resistivity (ρ) of a metallic thin film do so independently and additively; i.e., ρ = ρ

Morphological and crystallographic characteristics of HfOx with different oxygen concentrations (0 ≤ x ≤ 2.5) and thicknesses (18 nm ≤ t ≤ 310 nm) were analyzed in this work before and after thermal annealing at 700°C in N2 atmosphere for 1h. The morphology of the as-deposited, low oxygen concentration films (t = 100 nm) is formed by a well-defined granular structure with grains around 20 nm in diameter. For higher oxygen concentration, the roughness increases, as a consequence of a very porous surface morphology. At the same time, the crystallographic structure changes from HCP with a {0002} preferred orientation to an amorphous structure as oxygen concentration increases. As the thickness of the HfO2 films increases, we also observed the formation of a high surface porosity, with pore diameter ranging from 80 nm to 120 nm. The changes observed in morphology and crystallinity of the films, as we increase the concentration of contaminants, occurs because of the lowering of the adatoms surface diffusion, which prevents them from reaching lower energy points during the formation of the microstructure of the films. Furthermore, this lowered surface diffusion favors the process of grain renucleation, which leads to roughness increasing, and to an enhancement of the formation of porous surfaces. After annealing, all films exhibit the monoclinic crystallographic phase associated with HfO2. Surface morphology of the films is consistent with a polycrystalline structure with grain diameters varying between 10 nm and 200 nm. As their size increases, the grains become very faceted, a finding consistent with the improvement in film crystallinity. Our results suggest that long-time annealing promotes the diffusion of oxygen from the SiO2-Hf interface to the film, compensating any O2 deficit in the film. Formation of the monoclinic phase is also favored by the improvement in the film stoichiometry promoted by thermal treatment. Also, the critical size of the nuclei, associated with a grain growth in a particular crystallographic orientation, decreases as a consequence of the high temperature during thermal annealing. Therefore, formation of faceted grains and increasing of surface roughness are favored in thicker films.

Samples of Li 2 O.2B 2 O 3 doped with CuO have been produced by melting appropriate mixtures of Li 2 CO. 3 and H 3 BO 3 at 980°C and then quenching to room temperature. Glasses thus obtained were devitrified. The absorption spectra of non-irradiated and irradiated samples indicate that γ radiation changes Cu 2+ into Cu + . ESR spectra of Cu-doped lithium borate exhibits the typical BOHC centres 'five-line-plus-a-shoulder' between the ±1/2 M n -lines. It is proposed that by heating the Cu-doped lithium borate, BOHC has an important role in the TL emission process.

Dye-sensitized nanocrystalline solar cells (DSSC) or photoeletrochemical solar cells were firstly described by Gratzel and O’Reagan in the early 1990s (Sauvage et. al., 2010) and they have reached the global photovoltaic market since 2007. Later on, the investments in nanotechnology enabled the rapid development of DSSC cells with nanostructured thin films. According to a review performed by Hong Lin et. al. (Lin et. al., 2009) the numbers of papers focusing on the development of the DSSC cells increased in last decade, being mainly originated in countries such as Japan, China, South Korea, Swiss and USA, where there is an enlarged integration of nanotechnology, electrochemical and polymers research and finantial supported projects like National Photovoltaic Program by Department of Energy (DOE) and NEDO’s New Sunshine from USA and Japan, respectively. Some research groups of the institutions (Kim et. Al., 2010),which have recently obtained efficiencies around 10%, are EPFL (11.2% in 2005) and AIST (10% in 2006). They have used the N719 colorant in devices with area 0.16cm2 and 0.25cm2. On the other hand, Sharp, Tokyo University and Sumitomo Osaka Cell have used the black dye colorant in devices with areas of approximately 0.22cm2, providing the efficiencies of about 11.1%, 10.2% and 10% in the years 2006, 2006 and 2007, respectively. In 2006, Tokyo University has also reached the efficiency of 10.5% in devices with 0.25cm2 area, but using -diketonide colorant. Initially, the DSSC (Sauvage et. al., 2010) were based on a nanocrystalline semiconductor (pristine titanium dioxide) coated with a monolayer of charge-transfer dye, with a broad absorption band (generally, polypyridyl complexes of ruthenium and osmium), to sensitize the film. The principle of operation of these devices can be divided into: a) the photo-current generation that occurs when the incident photons absorbs in the dye, generates electronhole pairs and injects electrons into the conduction band of the semiconductor (Ru2+ -> Ru3+ + e-), and b) the carrier transport that occurs because of the migration of these electrons through the nanostructured semiconductor to the anode (Kim et. al., 2010). Thus, since this device requires an electrode with a conduction band with a lower level than the dye one, the

Crystallographic and surface morphological characteristics of polycrystalline hcp Ti and Zr thin films were studied as a function of the homologous substrate temperature TS/TM and the thickness t of the films (28 nm ≤ t ≤ 380 nm). TS is the substrate temperature during deposition and TM is the melting point of the film's material. For the whole range of considered temperatures (0.14 ≤ TS/TM ≤ 0.48) Zr films presented a {0002} crystallographic orientation. As TS/TM increased, Ti films suffered a transition from a columnar grain structure with {0002} preferential crystallographic orientation to a cone-like-shape grain structure with {1011} preferential crystallographic orientation. Our results suggest that Zr films suffer a structural transition from Zone T to Zone II at temperatures similar to those predicted by Thornton's Structure Zone Model for thick films while Ti films do not have a microstructure typical of Zone II even for relatively high values of TS/TM, presenting a transition from Zone I to Zone T in the studied range of temperatures.

The hysteresis loop and the two principal remanence curves of CoCrPt and CoCr thin films of different compositions are studied. ΔM curves indicate mainly the presence of weak dipolar intergranular interactions in the magnetic films, and the CoCrPt films show an almost non-interacting behavior. The crystallographic properties of the CoCrPt films do not seem to explain the observed enhancement in the magnetic coercivity of the CoCr films with addition of Pt.