Percolative ceramic composites with giant dielectric constants and low dielectric losses

Abstract

Percolative composites with significant dielectric properties have been synthesized from Ba_0.8Sr_0.2TiO₃ matrix, Ag particles and a PbO-B₂O₃ glass dopant by a traditional ceramic method. Such composites possess a high dielectric constant (ε_r ∼ 24 000), which is stable with frequency and temperature, and very low loss (tan δ ∼ 0.035). The results demonstrate that the insulating glass dopant can serve as an electron barrier to restrict the electron transport between metallic particles, thus leading to a stable dielectric constant and low dielectric loss. Besides improving the dielectric properties, the presence of glass dopant further lowers the sintering temperature, being compatible with the current preparation of electronic elements. The proposed approach is generic and provides a new avenue to obtain percolative composites with excellent dielectric properties, which make it a promising material to be used in high dielectric constant components.