Colossal dielectric constant in PrFeO3 semiconductor ceramics

The perovskite PrFeO3 ceramics were synthesized via sol-gel method. The dielectric properties and impedance spectroscopy (IS) of these ceramics were studied in the frequency range from 100 Hz to 1000 kHz in the temperature range from 80 K to 300 K. These materials exhibited colossal dielectric constant value of similar to 10(4) at room temperature. The response is similar to that observed for relax-orferroelectrics. IS data analysis indicates the ceramics to be electrically heterogeneous semiconductor consisting of semiconducting grains with dielectric constant 30 and more resistive grain boundaries with effective dielectric constant similar to 10(4). We conclude, therefore that grain boundary effect is the primary source for the high effective permittivity in PrFeO3 ceramics. (C) 2011 Elsevier Masson SAS. All rights reserved.