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.