Developing ABO3 perovskites synthesized by the Pechini method for their potential application as cathode material in solid oxide fuel cells: Structural and electrical properties

Abstract

In this research, the effect of La substitution by Pr cation in the A-site of ABO₃ perovskites was carried out using the Pechini method for use in solid state fuel cells (SOFCs). The atomic compositions of Pr varied from x = 0.35, 0.49, 0.53, 0.56, 0.63 and 0.7 in the La_0.7−xPr_xCa_0.3MnO₃ (LPCM) perovskites. The XRD patterns indicated that all the perovskites crystallized in the orthorhombic system with Pnma space group, but only in atomic compositions of 0.53 and 0.70 is possible to obtain pure phases; whereas the other compositions present narrow peaks of La and Pr oxides that are reduced with the amount of the cationic substitution. The Rietveld methodology and its analysis by the Goldsmith tolerance factor indicated that the stability of the samples was achieved through Jahn-Teller distortion in the b-axis. The Mn³⁺/Mn⁴⁺ atomic ratios determined by XPS measurements suggested that the substitution of La ions by Pr promotes the hole doped system instead of electron system. The electrical conductivity showed that the synthesized perovskites are mixed ionic and electronic conductors which positively influence their application in SOFCs. In particular, the La_0.17Pr_0.53Ca0_.3MnO₃ may be a good cathode candidate for these devices.