Frequency dependence of dielectric properties of metallodielectric SrTiO3-Pt composites

The frequency dependence of dielectric properties of SrTiO3-Pt (platinum) composites has been investigated. The SrTiO3-Pt composites sintered at 1300 °C for 2 h was prepared by using conventional ceramic fabrication method. The dense metallodielectric composites without chemical reaction between SrTiO3 and Pt during sintering process were obtained. The relative permittivity (ɛr) of SrTiO3-Pt composites was increased with increase of amount of Pt. The maximum ɛr of 2150 at 1 MHz was obtained for the composite of SrTiO3-27 vol.% Pt. Moreover, the SrTiO3-Pt composites exhibited high values of ɛr at low frequencies than at high frequencies due to space charge polarization. The loss tangent (tan δ) of SrTiO3-Pt composites increased with increasing amount of Pt, and decreased with increasing frequency up to 1 MHz. However, the tan δ of SrTiO3-Pt composites was significantly increased at microwave frequency due to abrupt increase of ac conductivity of composite.