Investigation on conductivity anomalies in ferrites using impedance spectroscopy

Temperature dependent conductivity of materials is one prime interest of materials science. Many ferrite materials are reported showing conductivity anomalies with temperature. CoFe2O4, Mn0.5Zn0.5Fe2O4 and SrFe12O19 are studied for the conductivity anomalies with impedance spectroscopy. Conductivity data of the samples obtained during heating show anomalies with temperature, while during cooling do not show any anomalies and follow Arrhenius behaviour. The anomalies in ac conductivity σ′(ω) and dielectric constant ε′(ω) corroborated with the TGA and it is attributed to the absorption of water by the material before performing the experiment. Hence it is recommended to perform the electrical measurements during cooling of the sample from high temperature. Keywords: Impedance/dielectric spectroscopy, Ac conductivity, Ferrite