Abstract
M-type Ca-Sr hexaferrite, spinel CoFe2O4 ferrite and their composites were synthesized by co-precipitation method. The structural and morphological characterization was carried out by X-ray diffraction (XRD) and electron microscopy (SEM and TEM). Their frequency dependent dielectric properties and DC resistivity measurements were carried out and discussed in detail. XRD patterns demonstrated that composites consisted of both phases i.e. hexagonal and cubic. In addition, the average crystalline size estimated from XRD data was in the range 19-38 nm. The SEM images revealed that the prepared ferrite particles are aggregated and relatively spherical in shape. DC electrical resistivity study revealed the semiconductor nature of ferrite particles and their composites. The variation of dielectric constant and dielectric loss with temperature and frequency were examined on the basis of Maxwell-Wagner model. It was observed that DC electrical resistivity of all synthesized compounds decreased with increased temperature exhibiting typical semiconductor characteristics. The activation energy obtained from temperature-dependent measurements was found in consistent with room temperature resistivity. The high value of dielectric parameters and enhanced value of resistivity suggested that the prepared materials are useful for electromagnetic attenuation and microwave devices applications.