Effects of MgO Content on Dielectric Properties of Ba0.94Bi0.04Sn0.06Ti0.94O3/MgO Composite Ceramics

The composite ceramics of Ba 0.94 Bi 0.04 Sn 0.06 Ti 0.94 O 3 (BBST) with x wt.% MgO (0 ≤ x ≤ 30) were prepared by solid-state sintering. The effects of MgO content on the microstructure and dielectric properties of the composite ceramics have been investigated. The results show that MgO is uniformly distributed in BBST matrix and enhances the relative density of composite ceramics remarkably, which effectively optimizes the performances of dielectric loss, alternating current (AC) breakdown strength (BDS) and insulation. With the content of MgO increasing from 0 wt.% to 30 wt.%, the dielectric constant decreases from 2900 to 920, dielectric loss decreases from 0.011 to 0.0065, BDS is improved from 26 kV/cm to 53.6 kV/cm and leakage current density decreases from 2.96 × 10 −7 A/cm 2 to 9.55 × 10 −8 A/cm 2 . The ceramic added with 30 wt.% MgO exhibits the best comprehensive dielectric properties, which is a superior dielectric used in high-voltage ceramic capacitors.