SOME AC ELECTRICAL PROPERTIES OF Li-Mg FERRITES

摘要

The ac resistivity (Pac), dielectric constant (∈), dielectric loss tangent (tan δ) and initial permeability (ui) of mixed Li_0.5-MgxFe_2.5-x2O_4 (where x = 0.l, 0.2, 0.3, 0.4, 0.5, and 0.6) ferrite system were measured at room temper- ature as a function of frequency in the range from l kHz to l MHz. The resistivity of all the samples decreased with increase in frequency, indicating that the samples exhibited normal ferrimagnetic behavior. The compositional variation of resistivity and dielectric constant indicated the inverse trends of each other. The sample with x = 0.3 showed the lowest resistivity and the highest dielectric constant. The dielectric loss tangent showed maxima at 3 kHz for x = 0.2 samples and at l5-20 kHz for x = 0.3 and 0.4 samples. All of the variations are explained on the basis of Fe~2+/Fe~3+ ion concentration on octahedral sites as well as the electronic hopping frequency between Fe~2+ <=> Fe~3+ ions.