Effect of interfacial area and particle size on the microstructure and dielectric properties of BaTiO₃-SiO₂ nanocomposites

The BaTiO₃-SiO₂ nanocomposites with different interfacial area and component were fabricated from a conventional sintering process using BaTiO₃@SiO₂ core-shell nanoparticles. It was identified that the dielectric properties of BaTiO₃ based ceramics-glass were modified due to the difference in interfacial regions, and the crystalline structure of BT could be influenced by sintering with a relatively high content of SiO₂ to varying degrees depends on the interfacial area between the constituents. It was experimentally found that the ε_r of BaTiO₃ ceramics using the nanoparticles with a size of 50 nm was obviously higher than that of the ones sintered from the larger nanoparticles; for BaTiO₃-SiO₂ nanocomposites, the ε_r was slightly increased and the tanδ was decreased with the increasing size of nanoparticles. It was believed that due to of the denser structure and largely raised proportion of 90^o ferroelastic domain walls formed on interfaces, the 200BT-SiO₂ and 300BT-SiO₂ exhibit a larger P_s, smaller remnant polarization (P_r) and therefore, larger energy density than that of the ones using very fine fillers.