Structure and magnetic properties of Cd and Ti/Si substituted cobalt ferrites

Polycrystalline samples of mixed ferrites Co1-xCdxFe2O4 and of 0.05 Ti/Si substituted ones were prepared by ceramic method. X-ray analysis showed that the lattice parameter increases with increasing Cd content. The apparent density and X-ray density exhibit similar behaviour. IR spectra show two main bands. The force constants obtained using the center frequency have been observed to increase with internuclear separation of the octahedral site whereas normal behaviour with tetrahedral site was observed. Magnetic moment eta(B) is found to increase with increasing Cd up to x = 0.4 and thereafter it decreases. This behaviour is explained on the basis of Neel's and Y-K model, The X-ac-T plots indicate thr similar behaviour. However, Curie temperature continuously decreases with increasing Cd content. The initial permeability (mu(i)) increases with increasing Cd up to x less than or equal to 0.4 and then decreases. With the addition of Ti, the permeability suddenly increases for x greater than or equal to 0.4, whereas, mu(i) remains constant for Si containing samples. The permeability with frequency show dispersion behaviour. Low frequency dispersion is due to the magnetic wall motion. Relaxation frequency decreases with an increase of Cd content. This is explained on the basis of Globus model. (C) 1998 Elsevier Science S.A. All rights reserved.