Physical and microstructural characterization of La_0,60Sr_0,40Co_0,20Fe_0,80O_3-δ and Ba_0,50Sr_0,50Co_0,80Fe_0,20O_3-δ ceramics

The La_0,60Sr_0,40Co_0,20Fe_0,80O_3-δ (LSCF) and Ba_0,50Sr_0,50Co_0,80Fe_0,20O_3-δ (BSCF) oxides are studied as cathodes in Solid Oxide Fuel Cell. The objective of this study is to characterize physically and microstructural these materials. The LSCF was synthesized by citrate technique and BSCF for citrates-EDTA, processed under the same conditions. The characterizations of ceramics were performed by X-ray diffraction, dilatometry, scanning electron microscopy and apparent density for Archimedes principle. According to the diffraction technique, confirmed the presence of single phases for LSCF to 800 deg C and BSCF to 900 deg C, with orthorhombic and cubic structures, respectively. For dilatometry were determined the sintering temperatures, near of 1050 deg C to BSCF and 1100 deg C to LSCF. The sintered micrographs at 1000, 1050 and 1100 deg C for 2 hours showed homogeneity microstructure, containing porosity and, attacked thermally, a homogeneous distribution of grains. Finally by bulk density, was estimated porosity between 20 and 30%. (author)