Microstructure design of dielectric ceramics

In order to design the microstructure of ceramics with desired dielectric p roperty, an estimation method of dielectric constant of ceramics taking int o account the characteristics of microstructure of the ceramics is proposed . In the estimation model, the microstructure of ceramics is represented by the assembly of unit cells comprising of grain, pore and grain boundary. T he sizes of grain and pore and the thickness of grain boundary in each unit cell were determined exactly according to their size and thickness distrib utions in a real ceramic. The dielectric constant of the assembly can be ca lculated on the basis of equivalent circuit theory. The estimated values of dielectric constant of ceramic BaTiO3 using the pro posed estimation method agree well with experimental ones. The dependence o f characteristics of microstructure on the dielectric constant was clarifie d by the estimation of dielectric constants for the assemblies of unit cell s with different characteristics. The microstructure of ceramic BaTiO3 with desired dielectric properties can be designed by using the proposed estima tion method.