Abengoa Research SL

Aluminum titanium oxynitrides were studied as candidate materials for high temperature absorbers in solar selective coatings due to their excellent stability and their tuneable optical behavior.A set of individual Al_yTi_1-y(O_xN_1-x) layers with different oxygen content was prepared by cathodic vacuum arc (CVA) deposition.The composition, morphol., phase structure and microstructure of the films were characterized by elastic recoil detection (ERD), scanning and transmission electron microscopy and X-ray diffraction.An fcc phase structure is found in a broad compositional range of Al_yTi_1-y(O_xN_1-x).Simultaneously, sample microstructure and morphol. undergo systematic changes from a columnar growth to the development of a heterogeneous structure with spherical nanoparticle inclusions when the oxygen concentration is increased.The optical properties were determined by spectroscopic ellipsometry and UV-Vis-NIR and FTIR spectrophotometry.A comprehensive anal. of the film properties allowed an accurate modeling of the optical constants of the Al_yTi_1-y(O_xN_1-x) in the whole wavelength range of solar interest (from 190 nm to 25 μm).It points to a transition from metallic to dielec. behavior with increasing oxygen content.Consequently, it is demonstrated that the optical properties of these Al_yTi_1-y(O_xN_1-x) deposited films can be controlled in a wide range from metallic to dielec. character by adjusting the oxygen concentration, opening a huge range of possibilities for the design of solar selective coatings (SSC) based on this material.Complete SSC, including a TiN layer as IR reflector, were designed by applying optical simulations, obtaining excellent optical selective properties of α = 94.0% and ε_RT = 4.8%.

It has been shown recently that the perovskite oxide SrVO3 is a transparent conductor with optical and electrical properties outreaching those of the most used material indium tin oxide (ITO). These properties, observed in the crystalline phase, imply the strong potential of SrVO3 for use as a lower cost alternative to ITO, but the possible integration of this perovskite oxide material in actual electronic devices is still an open question. One of the possible approaches for the integration of oxide materials is the use of amorphous thin films, allowing low thermal budgets to preserve the performances of the electronic device. Therefore, in this study, the electrical and optical properties of amorphous or poorly crystallized thin SrVO3 films are investigated.

Amphiphilic nanohybrid catalysts (Ru particles supported on carbon nanotube-metal oxide hybrids) enable the formation of water-in-oil emulsions and have a pos. influence on the Fischer-Tropsch synthesis (FTS) activity and selectivity to desirable products in comparison with those obtained in single-phase solvents under the same reaction conditions.The reaction experiments were conducted at 473 K in a batch reactor that uses H₂/CO syngas as a feed at 2.0-3.5 molar ratio and 4136.85 kPa total pressure.One of the main effects observed when using the biphasic mixture instead of a single solvent is the spontaneous separation of products by solubility differences, which affect mass-transfer-dependent secondary reactions.Another pos. effect of using the biphasic system arises from the enhanced FTS activity observed in the presence of condensed aqueous phase.Finally, the presence of an emulsion seems to improve the C₁/C₅₊ product balance, which can be explained by a dual-site model recently proposed in the literature.