Grain Size Effect on Dielectric Properties of Ba(Zr,Ti)O₃ Ceramics

We demonstrated the size effect on the dielectric properties of BaZr_xTi_1-xO₃ (x = 0.2 and 0.25) ceramics that showed relaxor behavior. Fine-grained BaZr_xTi_1-xO₃ ceramics with micrometer- and nanometer-sized grains were fabricated by the two-step sintering method and aerosol deposition (AD) method, respectively. From the dielectric measurement, the permittivity of the BaZr_xTi_1-xO₃ ceramics markedly decreased with decreasing grain size below 3 µm. The permittivity of the BaZr_xTi_1-xO₃ nanograined ceramics decreased with increasing Zr content and was much smaller than the permittivity of the BaTiO₃ nanograined ceramics. These results indicated that the BaZr_xTi_1-xO₃ ceramics were more susceptible to the grain size effect than the pure BaTiO₃ ceramics. The dielectric responses to temperature and frequency suggested that the volume fraction of polar nanoregions decreased and the relaxor characteristics increased with decreasing grain size in BaZr_xTi_1-xO₃ ceramics.