Effect of Si/Ti substitution on magnetic properties of cobalt-cadmium ferrites

Polycrystalline samples of mixed ferrites Cd(0.5)Co(0.5+t)A(t)Fe(2-2t)O(4), where A = Si or Ti and t = 0.0, 0.1, 0.2, 0.3 and 0.4 were prepared by ceramic processing. X-ray analysis showed that the lattice constant increases with increasing Ti whereas it decreases with increasing Si. The saturation magnetization (M-s) decreases slowly for t less than or equal to 0.2 Ti and afterwards rapidly. In the case of Si-substitutions, the M-s increases slightly for x less than or equal to 0.2 and then decreases. The M-s value is higher for the case of Si-substitutions than that of Ti ones. The Curie temperature (T-c) decreases with t in case of Ti and increases in case of Si. The initial permeability (mu(i)) increases slowly for t less than or equal to 0.2, and suddenly for t > 0.2 for Ti. In case of Si-substitutions the mu(i) continuously decreases with t. Permeability with frequency showed dispersion behaviour. Relaxation frequencies shift to lower value in case of Ti and to higher value in case of Si-substitution. The variation in permeability is explained on the basis of single ion model. (C) 1999 Kluwer Academic Publishers.