EFFECT OF CADMIUM-TERBIUM SUBSTITUTION IONS ON DIELECTRIC PROPERTIES OF Mg0.5-xCdx Co0.5Cr0.04Tby Fe1.96-yO4 FERRITES

A series of Mg0.5-x Cdx Co0.5Cr0.04Tby Fe1.96-yO4 (with 0 <= x <= 0.5 and 0 <= y <= 0.10) ferrites has been synthesized by sol-gel auto combustion method. The synthesized samples were characterized using thermal (TGA/DTA) and morphological (SEM/EDX). The dielectric properties of these were also carried out. The decrease of permittivity with the increase of frequency in the range of 1MHz to 3GHz follows the Maxwell-Wagner model. Moreover, the (Cd2+, Tb3+) partial substituted ions have smaller values of loss tangent and dielectric constant which is favorable for the applications where low losses are desired. The value of ac conductivity increased with an increase in the frequency and decreased with substitution of Cd2+ and Tb3+ which reflects the hopping mechanism due to electron of exchange Fe2+ and Fe3+ at respective sites and also small polaron of divalent cations. Electric module of the presented sample showed semicircle attribution to the grain boundary effect. Such materials are considered as electromagnetic attenuation materials, suitable for switching and microwave devices.