Effect of tetra ionic substitution on the dielectric properties of Cu-ferrite

X-ray diffraction (XRD), of the two systems of mixed ferrites Cu1+xTixFe2-2xO4 (where x = 0.0, 0.1, 0.2, 0.3, and 0.4); indicates that the samples of x = 0 (CuFe2O4) and x = 0.1 of the Cu-Ti system were formed in tetragonal structure and all other samples of the two system were formed in the cubic system. The ac conductivity (σ) over tilde $, dielectric constant epsilon', dielectric loss epsilon and the loss tangent tan delta were determined against frequency at room temperature for Cu-Ge and Cu-Ti ferrites. The measurements of (σ) over tilde $ and tan delta were performed over a wide range of frequency and temperature. The Maxwell-Wagner model was applied to analyze the dielectric properties of the investigated systems, according to which the dielectric parameters such as the relaxation time tau. A value of tau(1), = 5 x 10(-7) s was found for Cu-Ge ferrite and tau(2) = 1.85 x 10(-6) s for Cu-Ti ferrites. The hopping rate (g) was found to be 2 x 10(6) s(-1) and 5.4 x 10(5) s(-1) for the two systems Cu-Ge and Cu-Ti ferrites, respectively. The conduction of the two-ferrite systems was discussed on the basis of the hopping mechanism. The activation energy for conduction was calculated and found in the range of 0.27-0.39 eV for Cu-Ge ferrite and 0.21-0.30 eV for Cu-Ti ferrite. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.