Dielectric and impedance properties' studies of the of lead doped (PbO)-Co2Y type hexaferrite (Ba2Co2Fe12O22 (CO2Y))

In the present work, the preparation of a layered magnetic ceramic oxide Ba2Co2Fe12O22 (CO2Y) is described by the solid state reaction method. X-ray diffraction (XRD) technique was used to study the structural properties. The Rietveld refinement method has confirmed a hexagonal crystal structure with lattice parameters (a = b = 5.8560 (angstrom) over bar and c = 43.4977 (angstrom) over bar; alpha = beta = 90 degrees and gamma = 120 degrees). The dielectric and electrical modulus properties were studied over a range of frequency (1 Hz to 1 MHz) and temperature (313-493 K) using the complex impedance spectroscopy (CIS) technique. The impedance plot showed the first semicircle at high frequency which corresponds to grain effect and the second semicircle at lower frequency which corresponds to grain boundary (conduction phenomenon). A complex modulus spectrum was carried out in order to understand the mechanism of the electrical transport process, which indicates that a non-exponential type of conductivity relaxation is present in this material. The values of the activation energy of the compound (calculated both from dc conductivity and modulus spectrum) are very similar, and hence the relaxation process may be attributed to the same type of charge carriers. The study of the dielectric property, conductivity and loss of ferrite materials, as a function of temperature, is important for microwave absorption applications. The protection of sensitive circuits from the interference of external microwave radiation, is an important technological application of these materials. (C) 2010 Elsevier B.V. All rights reserved.