Frequency and Compositional Variation of Dielectric Parameters for La substituted M-Hexaferrite

Abstract

In the present investigation Polycrystalline compounds with chemical formula Ca x Sr y Ba 1-x-y Fe 12-z La z O 19 with (x = 0.1, 0.25, 0.4; z = 0.1, 0.2, 0.3 & y = 0.2) were synthesized by high temperature solid state diffusion reactions. The dielectric constant (ε') dielectric loss tangent (tanδ) and complex dielectric constant (ε *) of the compounds were studied in the frequency range of 10Hz –2MHz. The dielectric parameters for the compound shows normal dielectric behavior as observed in hexaferrites. The study of frequency dependence dielectric loss tangent (tanδ) was found to be giving a peak around certain frequency range (16 to 35Hz) for present compounds. The dielectric constant for these mixed ferrites was found approximately inversely proportional to the square root of their respective resistivity. The frequency variation of ε' and tanδ is explained by Koop's phenomenological theory and hopping frequency of electrons between Fe 2+ and Fe 3+ on octahedral sites.