Evaluation of a.c. conductivity of rubber ferrite composites from dielectric measurements

Abstract

The effect of frequency, composition and temperature on the a.c. electrical conductivity were studied for the ceramic, Ni_1−xZn_xFe₂O₄, as well as the filler (Ni_1−xZn_xFe₂O₄) incorporated rubber ferrite composites (RFCs). Ni_1−xZn_xFe₂O₄ (where) (bix)varies from 0 to 1 in steps of 0.2 were prepared by usual ceramic techniques. They were then incorporated into a butyl rubber matrix according to a specific recipe. The a.c. electrical conductivity (σ_a.c) calculations were carried out by using the data available from dielectric measurements and by employing a simple relationship. The a.c. conductivity values were found to be of the order of 10⁻³ S/m. Analysis of the results shows that σ_a.c. increases with increase of frequency and the change is same for both ceramic Ni_1−xZn_xFe₂O₄ and RFCs. σ_a.c increases initially with the increase of zinc content and then decreases with increase of zinc. Same behaviour is observed for RFCs too. The dependence of σ_a.c on the volume fraction of the magnetic filler was also studied and it was found that the a.c. conductivity of RFCs increases with increase of volume fraction of the magnetic filler. Temperature dependence of conductivity was studied for both ceramic and rubber ferrite composites. Conductivity shows a linear dependence with temperature in the case of ceramic samples.