DIELECTRIC PROPERTIES OF BaTiO3 DOPED WITH Er2O3 AND Yb2O3 BASED ON INTERGRANULAR CONTACTS MODEL

摘要

Taking into account that microstructure properties of barium-titanate based materials, expressed in grain boundary contacts, are of basic importance for electric properties of these material, in this study, the model of intergranular impedance is established using the equivalent electrical scheme characterized by corresponding frequency characteristic. Globally, BaTiO_3-ceramics sample is consisted of a huge number of mutually contacted grains which form clusters. For each of them, it is possible to establish the equivalent electrical model and, for defined set of input parameters, using symbolic analysis, obtain the frequency diagram. Realizing the totality of relations between clusters grains groups, their microelectrical schemes and corresponding frequency characteristics, from one side, and global equivalent electrical scheme and corresponding acquired frequency characteristics of BaTiO_3-ceramics samples, on the other side, we set a goal of coinciding experimental results with the summing effect of microelectric equivalent schemes. The model is successfully tested on barium titanate ceramics doped with Er_2O_3. Yb_2O_3.