The abnormal increase of tunability in ferroelectric-dielectric composite ceramics and its origin

The ternary ferroelectric-dielectric composite ceramics Ba0.45Sr0.55TiO3-MgO-Mg2TiO4 were prepared by solid-stated method and the dielectric tunable properties of composite ceramics were investigated. The abnormal increased tunability in the ternary ferroelectric-dielectric composite ceramics was observed, which shows further that the abnormal increase of tunability exists universally in ferroelectric-dielectric composite. A simple 3D Finite Element Method model was constructed to simulate the dielectric response and explore the origin of abnormal increase of tunability in ferroelectric-dielectric composite. The simulation results of tunability show the same trend as the experimental data. Further analysis of the electric field distribution in ferroelectric-dielectric composites indicated that the abnormal increase of tunability originates from the enhancement of the electric field on a fraction of the ferroelectrics around dielectrics.