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

In this paper, a series of BaTiO
₃
-SiO
₂
composites were fabricated by using a combined process of SiO
₂
wet chemical coating and conventional ceramic process, and the effects of SiO
₂
coating on microstructures, dielectric and ferroelectric properties were investigated. XRD diffraction patterns illustrated a typical perovskite structure of the SiO
₂
coated BaTiO
₃
particles, which confirmed an amorphous phase of the coated SiO
₂
shell. A secondary phase, BaTiSiO
₅
, was obvious in the sintered composites, which was caused by the interface reaction of BaTiO
₃
cores and SiO
₂
shells and has great effects on the properties. It was found that dielectric constant decreased with increasing content of SiO
₂
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 SiO
₂
, while the breakdown strength could be remarkable enhanced.