Improved tunability accompanying with reduced permittivity in Ba0.5Sr0.5TiO3-MgO composite ceramics achieved by spark plasma sintering

Abstract

• Improve tunability and reduce permittivity in Ba 0.5 Sr 0.5 TiO 3 -MgO composite ceramics achieved by spark plasma sintering. • Suppressing doping effect and redistributing electric field results in decreased permittivity and increased tunability. • Increasing MgO content, permittivity of composite ceramics decreases and tunability shows a trend of first rise and then fall. • The tunability of composite ceramics with 30 wt% MgO under 3 kV/mm can reach to 16.53%, even higher than pure BST. Ba 0.5 Sr 0.5 TiO 3 -MgO composite ceramics have been prepared through spark plasma sintering (SPS) process. Phase composition, microstructures and dielectric properties have been systematically characterized. In this composite system, with the gradual increase of the MgO content, the dielectric constant of the composite ceramics drops drastically. On the contrary, when the MgO content varies between 0% and 30%, the tunability of composite ceramics have not decreased significantly, but increased instead. High tunability of 16.53% and relatively low dielectric constant of 415 are realized simultaneous at 3 kV/mm, 10 kHz when the dielectric content is 30%. Its tunability is even higher than pure Ba 0.5 Sr 0.5 TiO 3 under the same electric field condition, which indicates that SPS is an effective means to suppress the ion diffusion between ferroelectric-dielectric composite ceramics and improve the tunability.