Preparation and Electrical Properties of Ba2TiOSi2−xGe xO7 ( x = 0.0 and 0 . 2 ) Ferroelectric Ceramics

Polycrystalline ceramic samples of pure and germanium (Ge4+) doped fresnoite of general formula Ba2TiOSi2−xGexO7 (x=0.0 and 0.2) have been prepared by solid state reaction technique. The formation of the single phase compound was confirmed by X-ray diffraction and the structural parameters were refined by the Rietveld refinement technique. The dc conductivity of both the materials has been measured as a function of temperature from room temperature to 753 K and activation energy was calculated using the relation σ = σoexp(-Ea/kt). The activation energy 4.74 eV obtained for the pure compound is very high in comparison with 1.47 eV of Ge4+-substituted compound. The frequency and temperature dependent dielectric behavior of both the compounds have been studied. The real and imaginary parts of the dielectric constant increase with the increase of temperature.