TEMPERATURE DEPENDENT DIELECTRIC BEHAVIOR OF NANOCRYSTALLINE Ca FERRITE

Abstract

Dielectric behaviour of Nanocrystalline CaFe 2 O 4 ferrite synthesized by advanced sol-gel method has been investigated as a function of frequency at different temperatures. Rietveld profile refinement of the XRD pattern confirms formation of cubic spinel structure of the specimen.The dispersion in dielectric behavior of CaFe 2 O 4 ferrite sample has been observed in the temperature range of 100-250˚C as a function of frequency in the range 75 kHz to 10 MHz Both the real value of dielectric constant (ε′) and the dielectric loss factor (tanδ) decrease with frequency. This decrease in the values of ε′ and tanδ could be explained on the basis of available ferrous, i.e. Fe 2+ , ions on octahedral sites such that beyond a certain frequency of applied electric field the electronic exchange between the ferrous and ferric ions i.e. Fe 2+ ↔Fe 3+ cannot follow the applied alternating electric field.