Nanocrystalline cathodes for PC-SOFCs

Ceramic proton conductors are of great interest for the development of solid oxide fuel cells (PC-SOFC) operating at relatively low temperatures between 400 and 700 ºC. Perovskites based on BaCeO3-δ exhibit the highest proton conductivity among this class of materials, however, they are susceptible to hydra-tion and carbonation in presence of water vapor and CO2 [1]. In contrast, the chemical stability of BaZrO3-based protonic conductors is better, but they require sintering temperatures as high as 1700 ºC and usually suffer from high intrinsic grain boundary resistance, limiting the final performance. Partial substitution of Zr for Ce in Ba(Ce0.9-xZrx)Y0.2O3-δ allows obtaining electrolytes with both high proton conductivity and good chemical stability. The performance of a PC-SOFC at low tempe-ratures depends significantly on the ohmic resis-tance of the electrolyte, although it can be lowered by reducing the electrolyte thickness. Another im-portant limiting factor is the increase of the cathode polarization resistance due to the thermally activated nature of the oxygen reduction reaction. For this reason, it is essential to obtain high efficiency cathodes operating at reduced temperatures. In this work, BaCe0.6Zr0.2Y0.2O3-δ (BCZY) powders were prepared by freeze-drying precursor method. These powders were mixed with a Zn-containing solution as sintering additive in order to obtain dense pellets with submicrometric grain size at only 1200 ºC. After that, La0.6Sr0.4Co0.8Fe0.2O3 nanocrystalline electrodes were deposited symmet-rically onto dense pellets BCZY by conventional spray-pyrolysis [3]. The structure, microstructure and electrochemical properties of these electrodes have been examined by XRD, FE-SEM and im-pedance spectroscopy. The stability of these elec-trodes at intermediate temperatures was evaluated as a function of time. These nanocrystalline cathodes exhibit a sub-stantial improvement of the electrode polarization resistance with respect to the same materials pre-pared by screen-printing method at high sintering temperatures, e.g. 0.7 and 3.2 cm2 at 600ºC for LSCF cathodes prepared by spray-pyrolysis and screen-printing method respectively (Fig. 1). An anode supported cell with composition LSCF/BCZY/NiO-BCZY was also prepared to test the electrochemical performance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Neuromarketing aplicado al marketing digital en el sector textil español

En este trabajo de fin de grado vamos a concretar los conceptos de neuromarketing y de marketing digital, para la posterior aplicación de las conclusiones de las investigaciones de neuromarketing al marketing digital, concretamente en el sector textil español. Para ello, seleccionaremos varias investigaciones de neuromarketing que tienen que ver con diferentes incentivos de compra, como las novedades, los productos y servicios gratuitos o las acciones promocionales, además nos detendremos a observar el diseño de las tiendas online, a analizar si poseen tienda física y observar si realizan acciones de fidelización que les permita llegar a ser una lovebrand.Universidad de Sevilla. Grado en Comunicación Audiovisua

Los límites de la confrontación : la Iglesia Católica y el gobierno peronista (Tucumán, 1952-1955)

Desde fines de 1954, la Iglesia católica desempeñó un rol central en el golpe de Estado que puso fin al gobierno de Perón. El proceso por el cual la institución eclesiástica pasó a integrar el espectro opositor al peronismo fue abordado teniendo en cuenta fundamentalmente el caso de la Capital Federal y la ciudad de Córdoba, lugares clave para estudiar la trama de la insurrección cívico-militar. El objetivo del artículo es analizar el itinerario de las relaciones entabladas entre la Iglesia católica y el gobierno en Tucumán entre 1952 y 1955. Se sostiene que en el escenario provincial no se registró el progresivo deterioro de las relaciones entre la Iglesia y el peronismo que fueron visibles en el escenario metropolitano y en otras diócesis del país, observándose, por el contrario, un campo de colaboración que se mantuvo en forma ininterrumpida hasta 1955. De ese modo, sin negar las tensiones que surcaron el camino de las relaciones entre la Iglesia católica y el gobierno provincial, el presente artículo sostiene que en Tucumán no se observó la escalada de violencia y el enfrentamiento abierto que surgió desde 1954 como una constante en otras zonas del país. Esto nos lleva a interrogarnos sobre los factores que se conjugaron para dar cauce al clima expectante que predominó en la sociedad tucumana y por las repercusiones de los acontecimientos que se sucedieron a nivel nacional durante los tramos finales del gobierno peronista, como así también emprender un análisis comparativo de las estrategias que siguió la jerarquía eclesiástica y el movimiento laico en la Capital Federal y en la ciudad de Córdoba.Since the end of 1954, the Catholic Church played a central role in the coup d'etat of September 1955, which brought to an end Peron’s government. The process by which the ecclesiastical institution step to integrate the spectrum opponent of peronism was addressed taking into account the case of the Capital Federal and the city of Cordoba, key locations to explore the insurrection civic-military. The aim of the paper is to analyze the itinerary of relations between the Catholic Church and government in Tucumán (1952-1955). It is argued that in the province is not registred the progressive deterioration of relations between the Church and Peronism that were visible in the metropolitan scene and in other dioceses of the country, showing, on the contrary, a field of collaboration that remained uninterrupted until 1955. In this way, without denying the tensions that streaked the path of the relations between the Catholic Church and the provincial government, this article argues that in Tucumán was not observed the escalation of violence and confrontation that emerged since 1954 as a constant in other areas of the country. This leads us to wonder about the factors that have combined to give way for the expectant climate that prevailed in the Tucumán society and the impact of the events which took place at the national level during the final stages of the Peronist government, as well as undertake a comparative analysis of the strategies followed by the ecclesiastical hierarchy and the lay movement in the Capital Federal and in the city of Cordoba.Fil: Santos Lepera, Lucía. Universidad Nacional de Tucumá

High efficiency cathodes for SOFCs prepared by spray-pyrolysis

In recent years, lowering the operating temper-ature of the Solid Oxide Fuel Cells (SOFCs) to the intermediate temperature range (500-700 ºC) has become the main challenge for this technology. The electrolyte resistance might be substantially reduced by using thin film electrolytes. However, the cathode polarization resitance is responsible for much of the loss in performance at low temperatures. Thus, the development of cathode materials with high electro-catalytic activity for the oxygen reduction reaction (ORR) is essential for this technology. Lanthanum strontium manganite La1-xSrxMnO3- (LSM) is the cathode material most widely used in SOFCs. However, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and poor ionic conductivity, limiting its application at high temperatures. Alternative mixed ionic-electronic conductors, such as La1-xSrxCo1-yFeyO3-δ (LSCF) and GdBaCo2O5+x (GBC) has been investi-gated, exhibiting better performances in the inter-mediate temperature range [1]. The performance of these electrodes might be improved at reduced temperature by extending the triple phase bounda-ry length at which gas, electrode and electrolyte phases are simultaneously in contact, serving as the predominant site for the electrochemical reac-tions. To date, the preparation of electrodes via wet infiltration of a cation solution into a porous electrolyte backbone is one of the most effective methods to increase the TPB area and to improve the efficiency of the cathodes, despite the limitations of this process for large-scale manufacturing of SOFCs. In this contribution an alternative preparation method based on spray-pyrolisis deposition into an electrolyte backbone is proposed, which posses a series of advantages with respect to the classical wet infiltration process, including easy industrial implementation, preparation in one single deposition/thermal step as well as low cost [2]. The most widely used cathodes in SOFCs technology were prepared by this alternative method process: La1-xSrxMnO3- and La0.6Sr0.4Co1-yFeyO3-δ (y = 0-2) series. The electrodes were deposited on porous Ce0.8Gd0.1O1.95 (CGO) backbones at 250 ºC by conventional spray pyrolysis from an aqueous precursor solution of metal nitrates. The structure, microstructure and electrochemical properties of these materials have been investigated by X-ray diffraction, field-emission SEM (Fig. 1.a) and im-pedance spectroscopy in symmetrical cells. The values of polarization resistance (Fig. 1.b) are ex-tremely low, ranging from 0.40 cm2 for LSM to 0.07 cm2 for LSCF0.2 at 600 ºC in air, compared to those previously reported in the literature for commercial electrolytes deposited at high tempera-ture, e.g. 25 cm2 for LSM.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Ce0.8Gd0.2O2‐δ / La0.6Sr0.4CoO3 Heterostructures prepared by pulsed laser deposition

Oxide interfaces have received greater attention due to the possibility to obtain properties that are very different from bulk materials. Due to the wide variety of electronic and ionic phenomena than can be detected at the interfaces, such materials have many technological applications [1]. Attention is being drawn to oxide heterostructures, a new family of artificial materials where electronic and ionic properties can be modulated at the interfaces by varying the characteristics of the layers [2, 3]. Slight variations in the near anionic-cationic order might take place if there exists strained interfaces. The interest in multilayared heterostructures derives from the mobility deffects and the space-charge-zone effects at the interfaces. In addition, a new degree of freedom related to the capacitive and resistive contributions is provided as a consequence of the size effects of these artificial structures. In the present work, for the first time, we investigate the structure, microstructure and electrical properties of a new family of heterostructured materials with alternated thin layers of La0.6Sr0.4CoO3 (LSC) and Ce0.8Gd0.2O2-δ (CGO) deposited by pulsed laser deposition on (110) NdGaO3 (NGO) single crystal substrates. In order to evaluate the interfacial contribution to ionic-electronic conductivity and know what is actually happens at the interface of MIECs, different heterostructures were prepared by varying both the number of bilayers (N) and the total thickness of the samples (N = 2 and 5; and the thickness were 50, 100 and 300 nm).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Novel microstructural strategies to enhance the electrochemical performance of La0.8Sr0.2MnO3-δ cathodes

Solid oxide fuel cells (SOFCs) are one of the most efficient technologies for direct conversion of fuels to electricity. La0.8Sr0.2MnO3-δ (LSM) is the cathode material most widely used in SOFCs [1], however, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and low ionic conductivity, which limits its application at reduced temperatures. In this material the electrochemically active reaction sites are restricted to the triple-phase boundary (TPB) near the electrolyte/electrode interface, where the electrolyte, air and electrode meet. Different strategies have been investigated to enlarge the TPB area of LSM, such as the production of nanocrystalline powders by precursor routes, preparation of composites by infiltration methods and thin films [2-4]. Here we present and compare innovative procedures to extend the TPB of LSM in contact with yttria-stabilized zirconia electrolyte: i) nanocrystalline LSM films deposited by spray-pyrolysis on polished YSZ electrolyte; ii) the addition of polymethyl methacrylate microspheres as pore formers during the spray-pyrolysis deposition to further increase the porosity of these films and (iii) the deposition of LSM by spray-pyrolysis on porous backbones of Zr0.84Y0.16O1.92 (YSZ), Ce0.9Gd0.1O1.95 (CGO) and Bi1.5Y0.5O3- (BYO) electrolytes previously fixed onto the YSZ electrolyte. The most remarkable peculiarity of this novel preparation method, compared to the traditional impregnation, is the formation of LSM thick film of 500 nm on the electrode surface (Fig. 1), which improves the electrical conductivity of the composite cathode. Thus, the optimization of this novel method would be an alternative to the classical infiltration with several advantages for the industry of planar SOFCs allowing the deposition of a wide variety of ceramic films over large areas with more uniform distribution of the catalyst, lower cost and only one deposition step is required to form the electrode. The morphology and electrochemical performance of the electrode have been investigated by scanning electron microscopy and impedance spectroscopy. Very low values of area specific resistance were obtained ranging from 1.4 cm2 for LSM deposited on polished YSZ to 0.06 cm2 for LSM deposited onto BYO backbone at a measured temperature of 650 ºC. This electrodes exhibit high performance even after annealing at 950 ºC making them interesting for applications at intermediate temperatures.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Guía del investigador en la ciudad de San Miguel de Tucumán

El articulo introduce al lector a una caracterización de la ciudad de San Miguel de Tucumán desde un punto de vista social y cultural y brinda información sobre los acervos de archivos y bibliotecas de interés para los investigadores en historia.Fil: Gutiérrez, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucumán. Instituto Superior de Estudios Sociales; ArgentinaFil: Santos Lepera, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucumán. Instituto Superior de Estudios Sociales; Argentin

Transitando rumbos paralelos: radicales y católicos durante el primer peronismo en Tucumán

La dinámica de las relaciones entre la Iglesia católica y el radicalismo ocupó un lugar subsidiario en la historiografía sobre el primer peronismo. Desde una escala provincial dotada de matices divergentes respecto de los escenarios cordobés y metropolitano, el artículo rastrea los vaivenes de la relación entre radicales y católicos a lo largo del período y propone una interpretación sobre las características particulares que adoptó su participación en la coyuntura que culminó con el derrocamiento de Perón.The dynamics of the relationship between the Catholic Church and the radicalism occupied a subsidiary place in the historiography of the first peronism. From a provincial scale characterized with divergent nuances in relation to Córdoba and metropolitan scenarios, the article traces the fluctuations of the relationship between radicals and Catholics throughout the period and proposes an interpretation of the particular characteristics adopted by its participation in the conjuncture that culminates in the overthrow of Perón.Fil: Santos Lepera, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucuman. Instituto Superior de Estudios Sociales; ArgentinaFil: Lichtmajer, Leandro Ary. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucuman. Instituto Superior de Estudios Sociales; Argentin

Stability of epitaxial heterostructured materials

Heterostructured materials are a new family of artificial compounds where the electronic and ionic properties can be modulated by varying the characteristics of the different material layers. These properties arise from the formation of structural oxygen defects in the crystal lattice that result in the activation of charge electrical carriers. Oxygen-deficient perovskite oxides, such as La1-xSrxCoO3-δ (LSC), present mixed oxide/electronic conduction; however, the long-term instability due to superficial carbonation of LSC-based cathodes is a crucial drawback for their practical application. In this study, thin film-heterostructures of alternating layers of La0.6Sr0.4CoO3-δ and Ce0.8Gd0.2O2-δ (CGO) were deposited on (110) NdGaO3 (NGO) single crystal substrates by pulsed laser deposition (PLD). The number of interfaces and the thickness were varied to obtain epitaxial structures with highly coherence layers. Moreover, two different kinds of architectures, without and with a CGO termination layer, were prepared in order to study the stability of the samples under different thermal cycles in air. Structural characterization was made by using Rocking Curve and Reciprocal Space Mapping techniques. CGO layers are rotated 45º respect to the substrate and LSC ones due to the different sizes of cell parameters. The quality of the samples was examined by HR-TEM and all of them presented well defined interfaces (Figure 1). Electrical characterization confirms that the conductivity can be modulated by varying the number of interfaces and thickness. Samples without CGO termination are unstable in air atmosphere due to surface carbonation, which was confirmed by XPS and HR-TEM.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec