Effects of synthesis methods on properties of ABO3 and A2BO4 perovskites

Abstract

Ba0.5Sr0.5Co0.8Fe0.2O3-d(BSCF), La0.7Sr0.3Ga0.7Fe0.2Mg0.1O3-d (LSGFM), La0.8Sr0.2Ga0.8Mg0.15Co0.05O3-d (LSGCM), PrSrCoO4 (PSC), PrSrNiO4 (PSN) were investigated in the scope of reducing their particle sizes to improve the electrical conductivity and thermal expansion coefficient (TEC) for using as a new mixed electronic-ionic conducting materials in solid oxide fuel cells (SOFCs). The compounds were synthesized by sol gel and hydrothermal methods using various chelating agents. Characterized by XRD and SEM, BSCF, LSGFM and LSGCM perovskites showed single phase with cubic ABO3 structure whereas PSC and PSN displayed the tetragonal K2NiF4–type structure. Moreover, the crystallite and particle sizes of the perovskites synthesized by the hydrothermal method were smaller and more homogeneous than those of the sol gel method. Among all of the BSCFs, the BSCF synthesized by the sol gel method using ethylene glycol combined with citric acid as chelating agents showed highest conductivity (61.2 S/cm) at 550oC. For PSC and PSN the maximum conductivity was 202.6 S/cm at 800oC and 854.5 S/cm at 27oC respectively. In case of LSGFM and LSGCM, the values were 0.32 S/cm and 0.0246 S/cm at 800oC. Thermal expansion results, the smallest TEC value of BSCF was in the range of 15.6436-24.4395x10-6(oC) -1. TEC of PSC was 19.7471x10-6(oC) -1 whereas that of PSN was in the range of 11.8786-13.8377x10-6(oC)-1. TEC values of LSGFM and LSGCM were in the ranges of 14.1057-16.6132x10-6(oC)-1and 5.4556-14.0485 x10-6(oC) -1 respectively.