Dielectric behaviour of lithium-cobalt mixed ferrites

Lithium-cobalt mixed ferrites of different compositions have been prepared by the double sintering technique, the final sintering temperature being 1100 degreesC. A study of the dielectric constant of these mixed ferrites, as a function of composition and frequency, has been undertaken. The dielectric constant is found to decrease continuously with increasing cobalt content. This has been explained on the basis of the availability of Fe ions on the octahedral sites. The dielectric constant also decreases with increasing frequency for all the samples under study. The reduction in the dielectric constant at higher frequencies has been explained on the basis of the fact that beyond a certain frequency of the externally applied electric field, the electronic exchange between the ferrous and ferric ions cannot follow the frequency of the alternating field. (C) 2002 Published by Elsevier Science B.V.