EFFECT OF GD3+ SUBSTITUTION ON DIELECTRIC BEHAVIOR OF COPPER-CADMIUM FERRITES

The dielectric constant, epsilon', loss tangent (tan delta) and a.c. resistivity (rho(a.c.)) are measured in the frequency range of 100 Hz to 5 MHz for the series of samples CdxCu1-xFe2-yGdyO4 prepared by the ceramic technique. The dispersion in epsilon' for all the values of x and y = 0 and 0.1 shows a normal behaviour except for y = 0.1 and x = 0.4. The lowering of dielectric intensity in substituted ferrites (y = 0.1) and fast dispersion of (rho(a.c.)) with frequency, are explained as due to the reduced number of Fe3+ participating in the polarization process and the hindrances caused by Gd3+ to the polarization process by localizing Fe2+ ions thereby increasing the resistivity and activation energy. The dispersion in tan delta for unsubstituted samples (y = 0.0) shows a normal trend while substituted sam ples (y = 0.1) show relaxation behaviour, which is explained by existing theories.