Polymeric membranes were developed using a SPEEK (sulfonated poly(ether ether ketone)) polymer matrix, containing titanium oxide (TiO 2) (incorporated by sol-gel method). SPEEK with different sulfonation degrees (SD): 63% and 50% were used. The influence of sulfonation degree on membrane properties was investigated. The thermal analysis (TGA and DTGA) and X-ray diffraction (XRD) were carried out to characterize the membranes and electrochemical impedance spectroscopy (EIS) was carried out to evaluate the proton conductivity of the membranes. The proton conductivities in water were of 3.25 to 37.08 mS.cm-1. Experimental data of impedance spectroscopy were analyzed with equivalent circuits using the Zview software, and the results showed that, the best fitted was at 80 °C.

In this work, sol-gel/dip-coating process for obtaining yttria stabilized zirconia (YSZ, ZrO 2-8% Y 2 O 3) films deposited onto LSM-YSZ (lanthanum strontium manganite (LSM, La0.7Sr0.3MnO3) mixed with YSZ) with different proportions (20/80, 50/50, 80/20) was investigated. The films were deposited on substrate varying the number of layers deposited. LSM powders were obtained by the combustion method using metal nitrates and urea and YSZ was commercial. LSM-YSZ composite powders were obtained by the solid state method, through ball-milling of a mixture of LSM-YSZ (mass ratio) powder for 4 h with 500 rpm using ZrO2 balls as milling media. For LSM-YSZ substrate a study of sintering temperature was performed, where the optimum sintering temperature for each LSM-YSZ studied proportion was obtained. According to our results, it was found that 1100 ºC is the optimum sintering temperature for 20/80, 950 ºC is the optimum sintering temperature for 50/50 and 900 ºC is the optimum sintering temperature for 80/20 because of the good phase formation. The films were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The films showed LSM, YSZ, SrZrO3 and La2O3 phases. Crack-free, homogeneous and well adhered films were obtained with a thickness between 3 and 38 µm. In this work, YSZ films with appropriate thickness were obtained for application as SOFC electrolyte.

Yttria-stabilized zirconia (YSZ, ZrO 2 -8%Y 2 O 3 ) films were deposited onto lanthanum strontium manganite (LSM, La 0.7 Sr 0.3 MnO 3 ) substrates using dip-coating process aiming for the application in solid oxide fuel cells (SOFCs). YSZ precursor was prepared by sol-gel method; three values of the organic/inorganic concentration ratio (1, 3 and 5) were utilized and the sol viscosity was adjusted (60 mPa·s and 100 mPa·s) before deposition on the substrate. The influence of these synthesis parameters on the structure and morphology of the deposited films was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The films showed characteristic peaks of LSM, YSZ (with cubic structure) and secondary phases of SrZrO 3 and La 2 O 3 . Depending on the synthesis conditions, crack-free, homogeneous and well adhered films were obtained, with thickness of 11-24 m.

The effects of sintering temperature (T sinter ) and sintering time (t sinter ) were investigated for Pb 0⋅95 Sr 0⋅05 (Zr 0⋅53 Ti 0⋅47 )O 3 + x%wtCr 2 O 3 system to determine the optimum regimen of sintering. The study was performed by determining the following parameters: relative density (ρ rel ) and sintering rate (ε . ρ ). The grain size was diminished when small amounts of Cr 2 O 3 were added to system and was enhanced when the sintering temperature and time was increased. The dielectric constant becomes maximum and the electric loss becomes minimum with the sintering temperature of 1290°C. The optimum regimen of sintering is T sinter = 1290°C during 70 min. The piezoelectric properties for the optimum regimen of sintering were studied.

Compositions with x=0.1, 0.2, 0.4, and 0.5 in the system ( Pb 0.95 Sr 0.05)·( Zr 0.53 Ti 0.47) O 3+x wt % Cr 2 O 3 (PSZTC) were synthesized using conventional ceramic method. Addition of Cr 2 O 3 stabilized the tetragonal phase against the rhombohedral one. Scanning electron microscopy (SEM) showed a decrease of the mean grain size when increasing the doping level. The permittivity and electrical conductivities of the PSZTC compounds have been investigated and the activation energies were calculated.