High-frequency dielectric behaviour of erbium substituted Ni-Zn ferrites

Dielectric properties such as dielectric constant (ε') and dielectric loss tangent (tan δ) of mixed Ni-Zn-Er ferrites have been measured at room temperature in the frequency range 1-13 MHz using a HP 4192A impedance analyser. Plots of dielectric constant (ε') versus frequency show a normal dielectric behaviour of spinel ferrites. The frequency dependence of dielectric loss tangent (tan δ) is found to be abnormal, giving a peak at certain frequency for all mixed Ni-Zn-Er ferrites. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. Plot of dielectric constant versus temperature has shown a transition near the Curie temperature for all the samples of Ni-Zn-Er ferrites. On the basis of these results an explanation for the dielectric mechanism in Ni-Zn-Er ferrites is suggested