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LaxSr1–xCo1–yFeyO3(LSCF) is a promising material for intermediate temperature solid oxide fuel cell (IT-SOFC) cathodes. The fabrication of LSCF cathodes composed of fibers might enhance SOFC dispositive currents due to facilitating gas permeability through a porous structure. In the present work, La0.6Sr0.4Co1–yFeyO3(y= 0.2–1.0) fibers were obtained by electrospinning, and the structure and electrical properties were investigated. 1 μm wide LSCF fibers were obtained after the electrospun fibers were thermal treated at 1000 °C to remove the polymer and form the crystalline perovskite materials. The electrical conductivity of LSCF fibers as a function of temperature was measured using 2-point and 4-point probe methodologies for all compositions prepared, and the associate charge carrier activation energies were calculated using the Arrhenius model. The electrical conductivity increases with an increase in temperature from room temperature to 700 °C; this suggests a predominant small-polaron hopping mechanism. Above 700 °C, the LSCF fibers show a semiconductor-metal transition, and the electrical conductivity decreases.

Tricalcium phosphate cement (α-TCP) can be used in various fields of health, including as drug delivery systems. The application of a biomaterial based on α-TCP could enable both the constant drug delivery as support and shape damaged muscleskeletics tissues until which can be regenerated by the organism itself, replacing the biomaterial, while maintaining stable levels of the drug in the organism. The aim of this study was to evaluate the release of gentamicin sulfate using the technique of electrochemical impedance spectroscopy in drug delivery systems of α-TCP. The results obtained in vitro study validated the proposed methodology for assessment of controlled drug delivery systems on the basis of α-TCP.

The improvement on the development of porous ceramic materials has leaded to new technologies in thermal insulation, for example, composite materials for better performance of pressure vessels in rocket engines. Within this context, the present work aims to evaluate the ability of a refractory ceramic base alumina/zirconia through the processes of co-precipitation and replica method in an organic fiber template. The green body was burnt-out and sintered at 1200-1600°C to obtain the continuous porous ceramic fibers. In the FEG-SEM analysis, an interconnected porous structure with small grains was observed. The crystalline phases were determined by X-ray diffraction and compared to micro-Raman results regarding the crystalline structure confirms that there present in the material zirconia is composed of more than one phase. Porosity was calculated through a mercury porosimeter as 77.9%, and the Laser Flash method gave a thermal conductivity value of 1.61 K W.m−1.K−1 for the Al2O3-ZrO2 fibers.

The synthesis of ceramic materials from polymeric precursors has been the subject of numerous studies due to lower energy cost compared to conventional processing. The study aims to research and develop synthesis of calcium aluminate powders via the polymeric precursor method, in order to obtain the pure phase of hepta-aluminate dodecálcio (C12A7) with mayenita mineral name, since it has applications like: special cements and components for high temperature fuel cells. A study of the evolution of crystalline phases by X-ray diffraction was performed, the vibrational modes of atomic location in crystalline phases were studied by micro-Raman spectroscopy was also performed and images from scanning electron microscopy. From the characterizations carried out on the material can be seen that the sintering temperature of 1200°C was obtained pure phase, so the choice of synthesis shown to be effective due to the complexity of obtaining this phase pure.

Tricalcium aluminate (C3A) are used for different applications such as thermal insulation, cement, refractory concrete as binders or binders. The aim of this work is to study the synthesis and sintering behaviour of C3A samples. The chemical synthesis was performed by means of polymeric precursor method from metalic nitrates dissolved in ethylene glycol and citric acid forming a polymeric resin. The evolution of the crystalline phases was accomplished by X ray Diffraction (XRD). Thermogravimetric (TG), Differential Thermal Analysis (DTG) and Thermal Expansion were performed in order to verify the thermal properties of the material. From the characterizations carried out it may be concluded that the synthesis of polymeric precursors via allowed obtaining pure phase of C3A at 1000°C low temperatures. The temperature of 1350°C it possible to obtain materials having grain morphology with uniform size and densely packed.

Environmental context The high demand and use of nanomaterials in commercial products have led to increased concerns about their effect on the environment and human health. Because CuO nanoparticles are widely used in several products, it is necessary to understand and predict their behaviour and fate in the environment. We report a study on the aggregation and surface charge of CuO nanoparticles under environmentally relevant conditions to better predict the mobility and bioavailability of these materials in natural waters. Abstract In this study, the role of pH, ionic strength and humic acids (HAs) on the aggregation kinetics and surface charge of commercial copper oxide (CuO) nanoparticles were examined. Results show that the aggregation of CuO nanoparticles is favoured near pH 10, which was determined as the isoelectric point where the hydrodynamic diameter of the aggregates is the greatest. The aggregation of CuO nanoparticles is also ionic strength dependent. The increase in the ionic strength reduces the zeta potential, which leads to an increase in aggregation until 0.15M. After this point an increase in ionic strength has no influence on aggregation. In the presence of HA for concentrations below 4mgCL-1, aggregation was enhanced for acidic to neutral pH, whereas for higher concentrations, at all pH tested, aggregation does not change. The influence of HA on CuO nanoparticles is due to steric and electrostatic interactions. The sedimentation rates of CuO nanoparticles showed a relation between particle diameter and zeta potentials values confirmed by Derjaguin–Landau–Verwey–Overbeek calculations. The results obtained have important implications for predicting the stability and fate of CuO nanoparticles in natural water.

For the combustion synthesis of strontium doped lanthanum manganite (LSM), different fuels can be used influencing the phase formation and also the powder morphology. Both are important features that can improve the material performance when used in a solid oxide fuel cell cathode. Urea and sucrose are fuels used to synthesize distinct LSM powders, thus the purpose of this work was to mix these fuels in order to obtain nanocrystalline LSM powders with a differentiated morphology, more convenient for the desired application. After calcination at 750°C for 3 hours the powder generated a pure phase LSM X-ray diffraction pattern and the micrographs taken in the transmission and scanning electron microscopes revealed a very peculiar morphology with specific surface area (BET) of 13 m²/g. Calcination led to a single phase and more crystalline material but showed no influence in the powder morphology.

Many studies have been reported in the literature related to YSZ films deposited on dense substrate or applied directly on the SOFC anode. However, there are not a lot of studies about the YSZ deposition on the cathode. The present work aims to obtain yttria-stabilized zirconia (YSZ), using the spray pyrolysis technique, for their application as electrolyte in solid oxide fuel cells (SOFC). The films were obtained from a precursor solution containing zirconium and yttrium salts, dissolved in ethanol and propylene glycol (1:1), this solution was sprayed onto a heated LSM porous substrate. The substrate temperature was varied in order to obtain dense and homogeneous films. After deposition, the films were heat treated, aiming to crystallize and stabilize the zirconia cubic phase. The films were characterized by Scanning Electron Microscopy (SEM), thermal analysis, X-ray diffraction and Fourier transform Infrared Spectroscopy (FT-IR).

Ferritic stainless steels have been used to produce interconnects for intermediate temperature solid oxide fuel cells (ITSOFC) due to their appropriate properties. Ferritic stainless steel presents mechanical stability, much higher thermal and electronic conductivities; significantly lower cost, and mechanical resistance than austenitic steels. Besides, it presents a thermal expansion coefficient compatible with the other materials of the cell components. However, in the range of this device operating temperature (600 °C 800 °C) it can occur the formation of poorly conducting oxide (Cr2O3) reducing the fuel cell performance. The aim of this work was to obtain oxide coatings starting with La, Sr and Co nitrates applied by spray-pyrolysis technique on a stainless steel AISI 430 substrate. The coatings obtained were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy. The oxidation resistance of the ferritic stainless steel, coated with a perovskite (La0,6Sr0,4CoO3) film, was investigated by isothermal oxidation. The results showed that the coating obtained promoted the increase of the ferritic stainless steel oxidation resistance. However, after the oxidation test, it was observed a Cr enrichment and a very pronounced Sr enrichment, near to the alloy/coating interface, which can be associate to the decomposition of La0,6Sr0,4CoO3 film.

The development of solid oxide fuel cell has shown that the thin film concept for the electrode supported designs, based on the yttria-stabilized zirconia, is more promising than the research of new electrolyte materials. In this work, the spray pyrolysis process was investigated in order to obtain dense thin films of YSZ on porous ceramic substrates. High porosity LSM, a typical material of SOFC cathodes, was used as substrate. The precursor solution was obtained by zirconium and yttrium salts dissolved in a mixture of ethanol and propylene glycol, with volume ratio 1:1. The substrate was heated and maintained at a constant temperature (280°C, 340°C or 560°C). The as-obtained films were heat treated in a temperature of 700°C, aiming to obtain yttria-stabilized-zirconia films from the amorphous film. The morphology and microstructure of the films were characterized by scanning electron microscopy and X-ray diffraction.