Synthesis and characterization of LaNixCo1-xO3: Role of microstructure on magnetic properties

Perovskite-type structures with the composition LaNixCo1-xO3 (x=0.3, 0.5, 0.7) were synthesized by a modified sol-gel method. Using transitional metal elements on the lanthanum base perovskites, properties could be tuned by doping the structure. Thermogravimetric analysis (TGA) evidenced a temperature of 350 degrees C as the start point of the perovskite-phase formation. Scanning electron microscopy (SEM) images showed the microstructure changes (grain size) of the cobalt-doped perovskite due to composition. In addition, it was shown that magnetic properties of the samples were dependent of cobalt content; experimental results pointed to the existence of disordered spins interactions, which were more evident with the decrease of cobalt content and the existence of ferromagnetic coupling among spins of the samples. These results showed the feasibility of producing a family of compounds with the desired properties, manipulating composition and therefore the microstructure.