Dielectric behaviour of nano-crystalline spinel Ni_0·2Ca_0·8Fe₂O₄ and their nano-composite with polypyrrole

Abstract

The spinel ferrite nano-particles of chemical composition Ni_0·2Ca_0·8Fe₂O₄ have been prepared by sol-gel method. Subsequently, the nanoparticles are encapsulated with the intrinsically conducting polymer shell of polypyrrole. The X-ray diffraction patterns confirm the single phase cubic spinel structure of the materials. To understand the dielectric properties of the materials, frequency-dependent dielectric measurement has been performed at 300 K in the range of 100 mHz to 2 MHz. On polymerization, both the dielectric strength as well the dielectric loss is significantly increased. Also, the dielectric conductivity, which arises from the electron hopping mechanism, is considerably increased on polymerization.