Ferroelectric domains are one of the dominant morphological features in BaTiO_3 based ceramics. The configuration and types of domains depend on the microstructure obtained during sintering process and on the presence of additives. In this paper comparative investigations of microstructure, domain structure and dielectric properties of BaTiO_3 based ceramics, doped with different amount of NbaOs and CaZrO_3, have been done. The microstructure characteristics together with the observation of ferroelectric domain structures were investigated using scanning electron microscope equipped with EDS. The permittivity dependence of temperature is analyzed in respect of grain size and domain structure. Due to the compositional heterogeneity and to the presence of Nb-enriched regions with rod like grains, the permittivity in Nb_2O_5-doped BaTiO_3 samples was lower compared to the same one obtained in CaZrO_3 doped ceramics. Both 90° and 180 domain-wall structures are presented and banded domain structure is associated with grains greater than 2 urn. In CaZrO_3-doped BaTiO_3 a single domain configuration prevails. The observed domain wall area indicated that the domain structure is restricted to the grain boundaries with few exemptions of continuous domains beyond grain boundaries.
展开▼
