Improving sintering behaviour of BaTiO3 by small doping additions

The dielectric properties of BaTiO3 ceramics are associated with its microstructure, which depends on the stoichiometric ratio, dopant nature, and ceramic processing. Optimum densification at low temperatures to reduce the amount of noble metals in electrodes for Multilayer Ceramic Capacitors (MLC) requires the use of liquid phase sintering. However, depending on the nature and amount of such a liquid phase, exaggerated grain growth is produced. In order to increase the capacitance in BaTiO3-based multilayer capacitors, increasing the dielectric constant by careful and homogeneous development of the microstructure, is necessary. The correct distribution of dopant on the particles' surface leads to a modification of their features by reacting with surface cations such as Ba2+. Such a modification allows densification at low temperatures with very small amounts of liquid phase. As a consequence, good control of grain size is obtained which enhances the dielectric properties of the BaTiO3 ceramics. The controlled microstructure also allows the reduction of the layer width in multilayer arrangements.