Impedance study of giant dielectric permittivity in BaTi0.4(Fe0.5Nb0.5)0.6O3 ceramic

The BaTi0.4(Fe0.5Nb0.5)0.6O3 ceramic is synthesized by a solid-state reaction technique. The X-ray diffraction of the sample at room temperature shows a cubic phase. The dielectric properties are investigated as a function of frequency (20–106 Hz) at different temperatures (80–417 K). A giant low frequency dielectric permittivity (εr′∼3.105) was obtained. Two dielectric relaxation peaks were observed on the curve of dielectric loss vs. temperature. The intrinsic dielectric permittivity calculated by impedance spectroscopy from the values of the obtained bulk capacitances were remarkably high 230<εr′<330. The extrinsic factors play an important role on their dielectric response giving rise to a giant dielectric permittivity at T>150 K. The heterogeneities conduction in the grains, grain boundaries and interfacial layers are related to a Maxwell–Wagner relaxation.