Effects of SiO2 coating on the dielectric and ferroelectric properties of BaTiO3-SiO2 composites

In this paper, a series of BaTiO3-SiO2 composites were fabricated by using a combined process of SiO2 wet chemical coating and conventional ceramic process, and the effects of SiO2 coating on microstructures, dielectric and ferroelectric properties were investigated. XRD diffraction patterns illustrated a typical perovskite structure of the SiO2 coated BaTiO3 particles, which confirmed an amorphous phase of the coated SiO2 shell. A secondary phase, BaTiSiO5, was obvious in the sintered composites, which was caused by the interface reaction of BaTiO3 cores and SiO2 shells and has great effects on the properties. It was found that dielectric constant decreased with increasing content of SiO2 in composites and the dielectric constant peak associated with dielectric temperature dependence curve was suppressed accordingly. The P-E loop of composites got slimmer and polarization decreased with increasing content of SiO2, while the breakdown strength could be remarkable enhanced.