Síntesis y caracterización de la doble perovskita BaSrCoFe$_{1 - x}$Ni$_{x}$O$_{5.5}$ como cátodo para celdas SOFC

Abstract

Have been synthesized via sol-gel method and characterized by X-ray diffraction (XRD), electrical conductivity and thermal expansion coefficient (TEC), new material composites BaSrCoFe$_{1 - x}$Ni$_{x}$O$_{5.5}$ (double perovskite type) with the addition of Ni in solid solution Ni$_{x}$ (x = 0.025, 0.05, 0.075, 0.1 and 0.2), as alternative cathodes for solid oxide fuel cells of intermediate temperature (SOFC-IT). XRD confirmed the formation of the tetragonal structure perovskite phase BaSrCoFe$_{1 - x}$Ni$_{x}$O$_{5.5}$, with the presence of small peaks identified in 2$\theta $ values below 30$^{\circ}$ as BaCO$_{3}$ and CoFe$_{2}$O$_{4}$. The electrical conductivity increases with temperature between 350-470$^{\circ}$C and then decreases due to the loss of oxygen in the net, which causes differences in conductivity. Semiconductor behavior was obtained in all compositions. TEC determination, showed a linear dependence inversely proportional to the concentration of Ni. Our results of electrical conductivity and TEC, lead us to the conclusion that the cathodes between 0.1 and 0.2 Ni, have the greatest possibility for application in IT-SOFC.