Abnormal high dielectric constant in SmFeO3 semiconductor ceramics

The dielectric properties and impedance spectroscopy (IS) of perovskite SmFeO₃ ceramics were studied in the frequency range of 100 Hz-1 MHz in the temperature range from 80 K to 300 K. These materials exhibited colossal dielectric constant of ∼10⁴ at room temperature. The response is similar to that observed for relaxor-ferroelectrics. IS data analysis indicates the ceramic to be electrically heterogeneous semiconductor consisting of semiconducting grains with dielectric constant 20 and more resistive grain boundaries. We conclude, therefore that grain boundary effect is the primary source for the high effective dielectric constant in SmFeO₃ ceramics.