Effect of magnesium on relaxation frequency of Ni–Zn nanoferrites

[Formula: see text] (x = 0, 0.4, 0.8, 0.10, 0.12 and 0.16) samples have been synthesized by sol–gel method using polyvinyl alcohol (PVA) as chelating agent. The synthesized samples were sintered at 1000[Formula: see text]C for 1 h. The X-ray diffraction (XRD) confirms single phase spinel structure and scanning electron microscope (SEM) confirms the uniform grain with increasing grain growth with increase concentration of magnesium (Mg) (x). A slight increase in saturation magnetization (VSM) has been observed for low concentrations of magnesium which disappear for higher concentrations of magnesium [Formula: see text] in these materials. Decrease in room temperature DC resistivity with magnesium concentration has been attributed to grain growth. The permeability measured for the ferrites exhibits high permeability for increase in the magnesium content. The permeability behavior is understood on the basis of domain wall contribution and grain growth. Frequency dependence of permeability as measured suggests that the suitability of all the samples for high frequency core applications as the operating frequency lies beyond 110 MHz.