Domain Contribution to Dielectric Properties of Fine-Grained BaTiO 3 Ceramics

Pure BaTiO 3 ceramics with various grain sizes were prepared by a conventional sintering method, a two-step sintering method, and a rate-controlled two-step sintering method. The permittivity of the ceramics increased with decreasing grain size when the grain size was more than 1.1 µm, while that decreased when the grain size was below 1 µm. Field emission scanning electron microscopy (FE-SEM) observations revealed that most of the domains in BaTiO 3 grains had simple lamellar structures, and 90° domain width decreased with decreasing grain size. By ultrawide range dielectric spectroscopy, the domain contribution to the permittivity was investigated. For the BaTiO 3 ceramics with grain sizes over 1 µm, the dipole and ionic polarizabilities were enhanced by the high domain density. In contrast, for the BaTiO 3 ceramics with grain sizes below 1 µm, these polarizabilities were weakened.