Study of Sintering Temperature Effects on the Structural and Electrical Properties of Mg0.6Co0.4FeCrO4 Ferrites Synthesized by the Sol-Gel Method

In the present study, Mg0.6Co0.4FeCrO4 ferrite samples were synthesized by sol-gel method at 900 degrees C and 1100 degrees C. We have studied in detail the effect of the sintering temperature on their structural, infrared, electrical and dielectric properties. The results showed that by increasing the sintering temperature, the lattice constant, the grain size, the intensities of absorption bands, the conductivity and dielectric constants of the samples increase. The X-ray diffraction results show that our samples crystallize in the cubic structure with Fd3m space group. FTIR spectra showed an absorption band corresponded to metal-oxygen stretching vibration in the tetrahedral sites. A metal-semiconductor transition was observed for the samples at a specific temperature T-MS. When the sintering temperature increases, the value of the electrical conductivity increases, however the transition temperature (T-MS) between metal and semi-conductor behaviors remains unchanged. Dielectric constants rapidly decrease as frequency rises. This phenomenon has been explained using the Maxwell-Wagner theory of interfacial polarization. The electrical modulus and impedance investigation demonstrate that the samples exhibit an electrical relaxation phenomenon that is not of the Debye type. The equivalent electrical circuit with [R-g // CPEg + R-gb //CPEgb] configuration is the most appropriate model to modelize the prepared samples. The activation energies calculated from the dc conductivity, impedance, and modulus studies are quite close, indicating that the relaxation and conduction processes are caused by the same defect.