Dielectric behaviour of erbium substituted Mn–Zn ferrites

Abstract. Dielectric properties such as dielectric constant (e¢) and dielectric loss tangent (tan d) of mixed Mn–Zn–Er ferrites having the compositional formula Mn0×58Zn0×37Fe2×05–xErxO4 (where x = 0×2, 0×4, 0×6, 0×8 and 1×0) were measured at room temperature in the frequency range 1–13 MHz using a HP 4192A impedance ana-lyser. Plots of dielectric constant (e¢) vs frequency show a normal dielectric behaviour of spinel ferrites. The frequency dependence of dielectric loss tangent (tan d) was found to be abnormal, giving a peak at certain fr-quency for all mixed Mn–Zn–Er ferrites. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. Plots of dielectric constant vs temperature have shown a transition near the Curie temperature for all the samples of Mn–Zn–Er ferrites. However, Mn0×58Zn0×37Er1×0Fe1×05O4 does not show a transition. On the basis of these results an explanation for the dielec-tric mechanism in Mn–Zn–Er ferrites is suggested