Dielectric relaxation and magnetic properties of Cr doped GaFeO3

Polycrystalline GaFe1-xCrxO3 (x = 0.05, 0.1 and 0.15) samples were prepared by solid state reaction. The monophasic compounds crystallize in the orthorhombic space group Pc2(1)n and the unit cell volume decreases with increasing Cr content. The saturated magnetization and magnetic transition temperature of the ceramics decrease due to the dilution of the magnetic interaction with Cr concentration. The dielectric properties were investigated from 133 to 353 K at various frequencies (100-10(7) Hz). Whereas the dielectric constant decreases with Cr content an increase in dielectric loss tangent was observed. The activation energies of the compounds (calculated both from loss and modulus spectrum) are the same and have values similar to 0.22 eV and 0.27 eV for Cr = 10% and 15%, respectively, and hence the relaxation process may be attributed to the same type of charge carrier. A separation of the grain and grain boundary properties has been achieved using an equivalent circuit model. The capacitance and resistances associated with the grain boundary were found to be higher than those associated with grain.