MICROSTRUCTURE AND DIELECTRIC-PROPERTIES OF BATIO3 DOPED WITH NIOBIUM AND COBALT

The influence of Niobium and Cobalt on the microstructural and dielectric properties of BaTiO3 with different Ba/Ti ratio was studied. The dopants were coprecipitated over the BaTiO3 particles. The dopants located at the grain boundaries act as grain inhibitors. On the contrary, the dopants which are incorporated in solid solution produce exaggerated grain growth. The existence of glass-forming impurities in the BaTiO3 starting powders, favours such a behaviour. A higher size of the starting particles with a stoichiometric ratio Ba/Ti less-than-or-equal-to 1 promotes the obtaining of materials with X7R capacitor characteristics. The increase of the dopant content produces a higher incorporation of the dopant cations on the perovskite lattice, and, a subsequent decrease cf the Curie temperature.